More specific deals with:
- Aerosol measurement Harmonization activities and improvements
- Observations and measurement campaigns including the observation of optical properties of aerosols
- Radiative transfer in cloud-free and cloudy atmosphere including three-dimensional modeling aspects
- Validation of satellite products using ground-based observations
- Aerosol effects in solar energy production
The session deals with aerosol measurements from both ground based passive and active sensors and also from satellite based ones. It deals with measurement aspects, new techniques, synergies of measurements and modeling towards higher quality products. In addition, it includes presentations on satellite validation and satellite based climatologies. Finally it deals with aerosol effects on solar radiation and solar energy and also aerosol assimilation in aerosol models. A number of presentations are dealing with Dust aerosol measurements, modeling and effects.
The session is directly linked, but is not limited to, the Harmonia COST action community that deals with aerosol global network measurement harmonization and also the Aerosol Clouds and Trace gases European Research infrastructure (ACTRIS) and more speciffic the Calibration of Aerosol Remote sensing (CARS) group related activities and research.
In this contribution, the aerosol optical depth (AOD), the single scattering albedo (SSA) and the refractive index (RI) simultaneously retrieved by measurements from a SKYNET PREDE Sun/Moon photometer (Nakajima et al., 2020) and an AERONET/PHOTONS CIMEL sunphotometer (Giles et al., 2019) in Rome (Italy) over the period 2018-2022 are compared to highlight the effect of different anemological patterns on aerosol columnar optical properties in the urban environment at different wavelengths.
The k-means clustering algorithm (Hartigan and Wong, 1979) is applied to the hourly-averaged measurements of wind intensity and direction collected by seven surface meteorological stations, permitting to discern the atmospheric circulation patterns on both local and synoptic scales based on a set of seven parameters, including the wind components during the typical time frame of onset/offset of the sea breeze. Several internal cluster validation methods are used to verify the correctness of the methodology. Four clusters are found, identifying the sea/land breeze regime with sea breeze blowing from the South-West and South, persistent north-east and South-East synoptic wind conditions, respectively. The aerosol optical properties are provided by instruments co-located at the urban site of the Boundary-layer Air Quality-analysis Using Network of Instruments (BAQUNIN, 41.90° N, 12.52° E, https://www.baqunin.eu/, Iannarelli et al., 2021) atmospheric observatory. The BAQUNIN site is particularly relevant for studies on aerosols properties as it hosts instruments from different international networks (e.g., AERONET, SKYNET, PANDONIA, EUBREWnet).
The dataset used for the SKYNET/AERONET comparison is obtained by selecting only the measurements carried out by the two instruments in a time frame in ±1min (i.e., simultaneous) and only for the days in which the daily-averaged AOD value (associated with the daily anemological pattern) can be assumed as representative of the entire day. This latter condition is valid if there is at least one measurement for each of the time slots identified by the typical AOD daily cycle (<8 UTC, 9-13 UTC, and >14 UTC).
Preliminary results show a great correlation between AOD measurements for each cluster and for each wavelength. Specifically, the AOD from CIMEL is on average slightly greater than the AOD from PREDE at all wavelengths, with the exception of 1020 nm, although the difference is always <0.02. Comparisons for the are aerosol parameters are yet under evaluation. Finally, the cluster characterized by southerly synoptic wind is associated with the highest AOD values at all wavelengths. On the contrary, the cluster with synoptic northerly wind is associated with minimum AOD values, while the clusters dominated by the sea/land breeze regime show similar characteristics, with intermediate AOD valued compared to the other clusters
How to cite: Di Bernardino, A., Campanelli, M., Iannarelli, A., and Casadio, S.: Comparison of AERONET and Skynet retrievals under different anemological conditions in the urban site of Rome (Italy), EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-257, https://doi.org/10.5194/ems2024-257, 2024.
Photometers are the most accurate instruments to retrieve the aerosol optical depth (AOD) for a given spectral channel (e.g. 500 nm). There are three main networks of photometers: GAW-PFR (Global Atmosphere Watch - Precision Filter Radiometer) using the instrument PFR (Precision Spectral radiometer), AERONET (AErosol RObotic NETwork): AOD and aerosol properties measurements network using Cimel CE-318 photometer, and SkyNet (SKY Measurements NETwork), using the instrument Prede POM (Precise design Of Meteorological). These three networks use different instruments, different measurement methods, different calibration methods and different retrieval methods algorithms).
The Meteorological observatory Lindenberg (MOL-RAO) from German meteorological service (Deutscher Wetterdienst: DWD) in Lindenberg (Tauche, Germany) is the only site worldwide operating permanently the three instruments of these three networks. There is a dataset of 11 years (since 2013) of colocated and synchronized AOD measurements of GAW-PFR, AERONET, SKYNET photometry networks at this station.
In this study, supported by COST action HARMONIA and initiated at the COST HARMONIA training school “Sky over BerLin”, we quantify the differences in the AOD from the products of these three different networks, we investigate the sources of these differences, computing the corrections on the optical depth (rayleigh, ozone, NO2) regarding amount of components consider in inputs of the retrieval algorithm and the equation used by the algorithm to consider these corrections. Analizing the temporal and air mass dependences o the differences and analyzing which differences are artificial (different way of computing with different inputs or equations during the retrievals) or inherent to the measurement itself (instrumental difference, calibration issues).
How to cite: Doppler, L., Balenzategui, J. L., Garcia-Suñer, M., González-Sicilia, P., Masoom, A., Papadimitiriou, N., Salgueiro, V., and Karanikolas, A.: AOD differences analysis Prede-PFR-Cimel on a 11 years dataset at Meteorological Observatory Lindenberg, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-590, https://doi.org/10.5194/ems2024-590, 2024.
Sun/sky radiometers are one of the finest instruments to observe and understand the effect of aerosols in the atmosphere. By looking at the Sun using radiometers and using Beer’s law to measure the attenuation, we retrieve the aerosol properties during the daytime. This method has been used for many years to understand aerosol properties. AERONET and SKYNET are two of the most important international networks. On the contrary, data during night-time is still in the provisional phase for both AERONET and SKYNET. As part of the SKYNET network, we have successfully implemented an algorithm to retrieve the aerosol optical depth (AOD) using the moon as a source of light. This study aims to present the first SKYNET results obtained during night-time at Tor Vergata (41.84° N, 12.65° E; 117 m. a.s.l.), located 20 km SE from Rome city. The site is equipped with lunar radiometers from both AERONET and SKYNET networks, which make it a well-suited location to observe the atmospheric column both during the day and at night. In this study, we will present the time series of AOD for daytime and night-time, and the intercomparison with the AERONET observations for the common channels. We will also present, following the WMO directives, the differences between AERONET and SKYNET for the four common channels (500 nm, 675 nm, 870 nm, 1020 nm) in order to check for consistency of measurements. The importance of night-time AOD is filling the nocturnal data gaps, maintaining the continuity between two successive daytime data, as well as understanding the daily dynamics of aerosols. We still envisage the improvement in the retrieval algorithms and cloud screening methods. The improvement of results at Tor Vergata will help us to set up the algorithm at other sites in the SKYNET, with the ultimate objective of filling the data gaps specially in higher latitudes.
Keywords: Lunar radiometer, Aerosol optical depth, SKYNET
Acknowledgements: The current analysis has been done in the frame of the COST Action CA21119 HARMONIA, supported by COST (European Cooperation in Science and Technology). The Spanish Ministry of Economy and Competitiveness also fund the research through project PID2022-138730OB-I00. The participation of G. Kumar has been supported by the Santiago Grisolia program fellowship GRISOLIAP/2021/048. We thank AERONET, PHOTONS and SKYNET for their scientific and technical support.
How to cite: Kumar, G., Campanelli, M., Garcia, M., Estellés, V., Uchiyama, A., Matsunaga, T., Yamazaki, A., Iannarelli, A., Casadio, S., Mevi, G., and Ferrante, N.: First time AOD measurements obtained during night-time using lunar POM radiometer at Tor Vergata site (Italy), EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1031, https://doi.org/10.5194/ems2024-1031, 2024.
Several sun photometer networks (e.g. the Aerosol Robotic Network (AERONET), the Global Atmospheric Watch-Precision Filter Radiometer (GAW-PFR) retrieve aerosol optical depth (AOD). AERONET provides more aerosol properties such as the effective radius and the single scattering albedo through inversion modelling using sky radiance measurements. However, the data availability for such properties is limited due to the low number of sky radiance scans and cloudiness. In contrast, AOD measurements are significantly more frequent (every minute for GAW-PFR). In the past, methods were developed to retrieve aerosol properties using only direct sun scans. Kazadzis et al., 2014 used linear estimation technique to retrieve the effective radius and volume concentration using only AOD measurements. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) uses multi-term least square method to retrieve the AOD, the volume concentration, the median radius and geometric standard deviation separately for fine and coarse mode. Previous studies concern the application of GRASP-AOD to CIMEL sun photometers [Torres & Fuertes, 2021]. In this study, we aim to apply it to GAW-PFR instruments (PFRs) at common locations with AERONET, assess the retrieval homogeneity with AERONET products and investigate the effect of the wavelength differences and AOD uncertainties. Also, we aim to apply the method to the Precision Spectroradiometers (PSR) and investigate the potential improvements using higher spectral range and resolution. Preliminary retrievals in a common GAW-PFR and ARONET station Hohenpeissenberg) show good results for the fine and coarse mode AOD separation and the fine mode median radius (correlation factor with AERONET standard inversions >0.9 for AOD and >0.8 for fine mode radius). For the coarse mode the retrievals are less accurate, mainly for the median radius in which GRASP-AOD shows low sensitivity to its fluctuations.
References
Kazadzis, S., Veselovskii, I., Amiridis, V., Gröbner, J., Suvorina, A., Nyeki, S., Gerasopoulos, E., Kouremeti, N., Taylor, M., Tsekeri, A., and Wehrli, C. (2014): Aerosol microphysical retrievals from precision filter radiometer direct solar radiation measurements and comparison with AERONET, Atmos. Meas. Tech., 7, 2013–2025, https://doi.org/10.5194/amt-7-2013-2014.
Torres, B. and Fuertes, D. (2021): Characterization of aerosol size properties from measurements of spectral optical depth: a global validation of the GRASP-AOD code using long-term AERONET data, Atmos. Meas. Tech., 14, 4471–4506, https://doi.org/10.5194/amt-14-4471-2021.
How to cite: Karanikolas, A., Torres, B., Herreras Giralda, M., Momoi, M., Kouremeti, N., Gröbner, J., Doppler, L., and Kazadzis, S.: Retrieval of Aerosol Properties from Direct Solar Irradiance Data with High Temporal and Spectral Resolution Using GRASP , EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-778, https://doi.org/10.5194/ems2024-778, 2024.
Sun photometers retrieve Aerosol Optical Depth (AOD) from direct solar irradiance observations when sun disk is not obscured by clouds. Therefore, identifying cloud-contaminated measurements is crucial for achieving high-quality AOD retrieval. Cloud flagging algorithms are instrumental in this process, as failure to accurately flag clouds can have significant impact on AOD retrieval and related applications e.g., air quality monitoring, numerical weather prediction, atmospheric transport models and data synergism.
This work aims at synergistically leverage ground-based instruments to analyze the performance of existing stand-alone algorithms in different scenarios, including periods of high-variability due to clouds, and extreme weather events like wildfires, dust storms, etc. To this direction, we used co-located Pandonia Global Network Pandora spectroradiometer and Global Atmosphere Watch Precision filter radiometer (PFR) network instrument and analyzed the performance of existing algorithms over the course of 2023 at Izana station.
PFR and Pandora measurements were synchronized with a time window of 1 min. For this analysis, PFR flags comprise two scenarios for clear-sun and flagged data, while Pandora has nine double-digit quality flags (QF) representing a combination of uncertainty (high: 0, medium: 1, low: 2) and data quality assurance (assured: 0, not assured:1, unusable data: 2). The analysis revealed good agreement between Pandora QF10 and PFR clear-sun flag (96.45%) followed by QF11 and QF12 (2.29% and 1.26%, respectively). Conversely, for PFR flagged data, corresponding percentages for Pandora QF10, QF11 and QF12 were 57.83%, 12.58% and 29.6%, respectively. Daily variation of Pandora QFs for 1-year indicated 34 days with Saharan dust episodes (concluded from HYSPLIT 24-h backward trajectories at levels from 500 to 6000 m above ground level originating from the Saharan region) on which for PFR clear sun flag, QF10 flag was more than 90% of daily number of comparison points indicating that dust events did not deteriorate much the flagging agreement between the two instruments. On the contrary, there were 20 dust free days with QF10 below 90% (most days had number of daily comparison points below 40, indicating high variability due to clouds). PFR clear-sun flag based and Pandora QF10 based AOD distribution showed respective geometric mean ranging from 0.02 to 0.04 and respective standard deviation ranging from 3.24 to 2.35 at 862 nm to 367 nm, respectively. This attempt of synergistic use of different measuring instruments can be useful for enhancing cloud flagging algorithms, thereby contributing to higher quality retrieval product.
Acknowledgement
This research has been supported by European Space Agency (ESA) in the frame of Instrument Data quality Evaluation and Assessment Service – Quality Assurance for Earth Observation (IDEAS-QA4EO) project, ACTRIS Switzerland project funded by Swiss State Secretariat for Education Research and Innovation and COST Action HARMONIA CA21119, supported by COST (European Cooperation in Science and Technology).
How to cite: Masoom, A., Kouremeti, N., Kazadzis, S., Killian, M., Kreuter, A., and Raptis, I.-P.: Performance analysis and synergistic use of cloud flagging algorithms of ground-based remote sensing instrumentations, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-365, https://doi.org/10.5194/ems2024-365, 2024.
Cloud screening is an essential component of the Aerosol Optical Depth (AOD) retrieval from photometry measurements: the cloud contaminated observations have to be identified and flagged out from the AOD end products. Methods vary on the instruments considered but all apply strict criteria when it comes to determine whether the sun was obstructed by a cloud or not and therefore whether the retrieval is valid. Cloud screening can be performed also using other observations, such as broadband radiation measurements or all-sky camera images. In this work a comparison between the different screening methods will be presented, using data from the Meteorological Observatory Lindenberg from Lindenberg (Tauche, Germany; 52.2°N - 14.1°E, 120 m asl) where observations from pyranometers, pyrgeometers, photometers and all-sky camera are available. For broadband radiation measurements, cloud screening will be performed with two different algorithms: RADFLUX[1] and BrightSun[2]. The first is a clear-sky model, based on global and diffuse shortwave components, able to also yield cloud fraction. The second is a hybrid method that can work either as a clear-sky or clear-sun method, depending on the input model chosen and input measurements available: all clear-sun models will be run along with a few selected clear-sky ones. Cloud screened data are available for both CIMEL (AERONET) and PFR (GAW-PFR) instruments following the respective methodologies of the networks they belong to, in particular, both AERONET [3] and CAELIS [4] algorithms are run for CIMEL data. Cloud screening and cloud cover from all-sky camera are obtained instead by different algorithms[5], one of them being able to also distinguish between thin and opaque clouds. The clear/obstructed sun information obtained from these different methodologies will also be associated with the cloud fraction obtained by broadband radiation measurements and the sky camera cloud masks.
Bibliography
[1] Riihimaki et al. (2019): Radiative Flux Analysis (RADFLUXANAL) Value-Added Product: Retrieval of Clear-Sky Broadband Radiative Fluxes and Other Derived Values (No. DOE/SC-ARM-TR-228, 1569477), doi: 10.2172/1569477
[2] Bright et al. (2020): Bright-Sun: A globally applicable 1-min irradiance clear-sky detection model. Renewable and Sustainable Energy Reviews 121, 109706. doi: 10.1016/j.rser.2020.109706
[3] Giles et al. (2019): Advancements in the Aerosol Robotic Network (AERONET) Version 3 database – automated near-real-time quality control algorithm with improved cloud screening for Sun photometer aerosol optical depth (AOD) measurements. Atmos. Meas. Tech. 12, 169–209. doi: 10.5194/amt-12-169-2019
[4] González et al. (2020): Daytime and nighttime aerosol optical depth implementation in CÆLIS. Geoscientific Instrumentation, Methods and Data Systems, 9, 417–433. doi: 10.5194/gi-9-417-2020
[5] González-Fernández et al. (2024): A neural network to retrieve cloud cover from all-sky cameras: a case of study over Antarctic. Quarterly Journal of the Royal Meteorological Society, Under Review, QJ-23-0272.R1
How to cite: Frangipani, C., Doppler, L., Román, R., Wacker, S., Lupi, A., and Vitale, V.: Differences between cloud screening methodologies for broadband radiation, narrowband radiation and all-sky camera observations, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-514, https://doi.org/10.5194/ems2024-514, 2024.
This study investigates the integration of Unmanned Aerial Vehicle (UAV)-based in-situ aerosol particle size distributions (PSD) with ground-based remote sensing techniques to estimate columnar particle size-distributions and vertically resolved aerosol concentrations. Observations of aerosol vertical distribution are essential for understanding their radiative impact on the atmosphere and interactions with clouds. Ground-based lidar-photometer setups are commonly employed to capture simultaneous information on both columnar and vertical aerosol physical and optical properties, providing complementary insights. For the retrieval of vertically resolved aerosol concentrations from aerosol extinction, one commonly employs an inversion parameter known as the effective radius and which is a product of the measured PSD.
Our study focuses on integrating Optical Particle Counters (OPCs, UCASS and POPS) and impactors for collecting high-altitude aerosol samples onto UAVs and conducting flights near co-located lidar and sunphotometers, utilizing the Unmanned Systems Research Laboratory (USRL; https://usrl.cyi.ac.cy) of The Cyprus Institute (CYI). Three diverse atmospheric campaigns in Cyprus, Cape Verde, and Greece are exploited for this purpose. These campaigns target different aerosol compositions and atmospheric conditions, providing a comprehensive dataset for evaluation. We aim to establish the link between the in-situ and remote sensing methods by exploiting scattering computations and retrieval algorithms.
Preliminary findings from the Fall Campaign in Cyprus reveal simultaneous observations from lidar, sunphotometer and UAV in-situ optical particle counters during a dust episode. UAV-based PSDs demonstrate larger particle concentrations within the 1 to 10 μm range compared to AERONET retrievals. This feature is expected to influence the resulting concentrations computed from the lidar, because larger particles contribute the most to mass concentration and extinction, resulting in increased magnitudes for both parameters. This increase affects the effective radius, which (together with the density, the size- and shape- dependent scattering efficiency) is one of the conversion parameters between extinction and mass.
Overall, we seek to explore the synergy of UAV-based high-altitude in-situ observations with highly spatiotemporally resolved lidar profiles to enhance our understanding of observations of the aerosol-intensive and extensive properties at different layers. This integration aims to understand and mitigate remote-sensing-only biases, address uncertainties, and characterize the reliance on assumptions.
How to cite: Papetta, A., Kezoudi, M., Stopford, C., Thornberry, T., Sciare, J., and Marenco, F.: Integrating UAV-Based In-Situ and Ground-Based Remote Sensing Observations for Enhanced Aerosol Profiling, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1103, https://doi.org/10.5194/ems2024-1103, 2024.
Remote sensing techniques are essential to monitor and characterise atmospheric aerosol. On the one hand, ceilometers have been proved to be an effective tool for detection and monitoring not only clouds, but also aerosol particle. In recent years, the developments of automatic lidars and ceilometers with profiling capabilities as well as advances in the calibration techniques related to such devices offer the capacity of characterizing optical properties such as aerosol backscatter coefficient. On the other hand, sun-photometers are a commonly employed instrument to monitor integrated products. GRASPpac is a new retrieval algorithm which is gaining relevance in recent years using the synergy between both instruments to obtain aerosol vertical profiling and microphysical properties (Román et al., 2018).
This study presents the comparison of vertical aerosol backscattering coefficient (βaer) profiles obtained by GRASPpac retrieval from the synergy between the CHM15K (Lufft, Germany) ceilometer and the sun-photometer CE318-T (Cimel, France). In this way a comparison with Klett inversion (backward and forward) method using CHM15K ceilometer data is carried out. Forward retrieval is based on E-PROFILE calibration (Weigner and Geiß, 2012). A total of 48 βaer profiles measured during daytime at the aeroogical station of MeteoSwiss at Payerne (Switzerland) between 2017 and 2019 were used for this comparison.
GRASPpac profiles are provided in a logarithmic vertical scale. The Klett ceilometer profiles were interpolated. The same GRASPpac height grid to enable a valid comparison. Moreover, the ceilometer signal was averaged in 30-minute bins to match GRASPpac time resolution. After all the corrections were applied, a statistical analysis was conducted to validate the profiles.
This work was supported by Grant PID2021- 128008OB-I00 funded by MCIN/AEI/10.13039/501100011033/ FEDER "A way of making Europe", and the project AEROMOST (ProExcel_00204) by the Junta de Andalucía. Francisco Navas-Guzmán received funding from the Ramón y Cajal program (ref. RYC2019-027519-I) of the Spanish Ministry of Science and Innovation.
Román, R., et al. (2018): Retrieval of aerosol profiles combining sunphotometer and ceilometer measurements in GRASP code, Atmos. Res., 204, 161-177.
Wiegner, M. and Geiß, A. (2012): Aerosol profiling with the Jenoptik ceilometer CHM15kx, Atmos. Meas. Tech., 5, 1953–1964.
How to cite: Muñiz-Rosado, J., Cazorla, A., Román, R., Haefele, A., van Hove, M., Herrero del Barrio, C., Bravo-Aranda, J. A., Granados-Muñoz, M. J., del Águila, A., Diaz-Zurita, A., Herrera, M., Wienhold, F. G., Brunamonti, S., Toledano, C., Alados-Arboledas, L., and Navas-Guzmán, F.: Evaluation of aerosol properties from sun-photometer and ceilometer by means GRASP algorithm, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1057, https://doi.org/10.5194/ems2024-1057, 2024.
Mineral dust is a major component of tropospheric aerosols, and plays a significant role in the Earth’s energy balance (both directly and indirectly through impact on clouds), air quality, health, transportation, and solar energy. Although being natural particles, their emission mechanisms are linked to the ground surface state (vegetation cover, soil type and moisture) and the surface winds, which are all impacted by human activities and climate change. The radiative impact of dust depends on many parameters, such as total amount, vertical distribution, particle size and composition.
The Mineral Aerosol Profiling from Infrared Radiances (MAPIR) algorithm focuses on retrieving dust total amount (in terms of Aerosol Optical Depth or AOD) and vertical distribution from satellite observations in the thermal infrared (TIR), by the Infrared Atmospheric Sounding Interferometer (IASI) satellite instrument. As far as aerosols are concerned, the TIR spectral range has the advantage of being sensitive almost exclusively to mineral aerosols (with specific absorption around 10µm), making it intrinsically specific to mineral dust and volcanic ash.
We have recently developed a new version of the MAPIR algorithm (version 5.1), requiring validation. As there is currently no validation data obtained in the thermal infrared, we can only use aerosol data obtained in the solar spectral range. Comparing data obtained with totally different sensors, using a different spectral range (therefore sensitive to different types of particles) and different types of algorithms includes significant challenges. In this contribution, we will discuss those challenges. We will show comparisons of MAPIR dust AOD with AErosol RObotic NETwork (AERONET) Standard Deconvolution Algorithm (SDA) coarse mode AOD, and focus on some specific events where we observe a large difference. For those events, additional satellite data (e.g. Cloud-Aerosol Lidar with Orthogonal Polarization - CALIOP, MODerate resolution Imaging Spectroradiometer - MODIS) will be used for in-depth analysis of the event and investigating the plausible causes for discrepancy.
How to cite: Vandenbussche, S., Moses, V. D., and De Mazière, M.: Validation of satellite thermal infrared dust aerosol optical depth : challenges and results, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-821, https://doi.org/10.5194/ems2024-821, 2024.
Dust aerosols constitute one of the key climatic drivers, playing also a vital role in various environmental processes. Additionally, they can have adverse impacts on air quality, thereby affecting human health. Worldwide, the most active dust sources are encompassed across North Africa and in the Middle East emitting massive dust loads which are transported in nearby and distant areas. Such widespread phenomena are well captured by spaceborne instruments. The present study exploits synergies between satellite sensors deploying passive and active remote sensing techniques towards upgrading mineral particles monitoring. Our key objective is to improve the quality of the mid-visible (532nm) dust optical depth (DOD) obtained by the CALIOP lidar, mounted on the polar-orbiting CALIPSO satellite. CALIOP is equipped with a depolarization channel that enables an accurate detection of non-spherical mineral particles. Nevertheless, CALIOP tends to underestimate the columnar optical depth and one of the contributing factors is the misrepresentation of the predefined lidar ratio (LR) in the retrieval algorithms. In elastic lidars (such as CALIOP), the definition of LR is crucial for converting the backscatter to extinction coefficient and subsequently deriving the columnar optical depth (i.e., integration of the extinction throughout aerosol layers). Here, the latter parameter is constrained by GRASP aerosol retrievals utilizing as inputs multidirectional polarimetric observations acquired in the visible spectrum (9 spectral channels) by the POLDER instruments. Evaluation studies have justified the high-accuracy of the GRASP-POLDER aerosol products over the “challenging” (in terms of retrievals performance) bright deserts. We are analyzing atmospheric scenes in the Sahara Desert and the Arabian Peninsula only when dust aerosols are probed by CALIOP throughout the period when the CALIOP/POLDER instruments were flying in tandem in the A-Train constellation. By employing an iterative approach, the CALIOP-POLDER optical depth departures are minimized in order to extract a representative LR. For intercomparison purposes, LR is also calculated independently via the GRASP algorithm. The extensive volume of CALIOP-POLDER collocated samples will realize a mapping of LRs depicting possible spatial patterns. The integration of EMIT mineralogical retrievals will enhance the obtained findings. Our methodology will be expanded to all the major deserts of the planet, each characterized by different soil and optical properties, which are both determinant for LRs. Moreover, similar analyses will be enhanced in the future by utilizing products from the PACE and the EarthCARE satellite missions. Finally, it is anticipated that the optimized CALIOP/CALIPSO dust products will improve the assessment of the dust-induced perturbations of the Earth-Atmosphere radiation budget.
Acknowledgements: The current research has been supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (Project Acronym: ATLANTAS, Project number: 544).
How to cite: Moustaka, A., Gkikas, A., Proestakis, E., Lopatin, A., Kazadzis, S., Dubovik, O., Tourpali, K., Zerefos, C., and Amiridis, V.: A synergy between CALIOP-CALIPSO and GRASP-POLDER retrievals towards advancing monitoring capabilities of dust aerosols across North Africa and Middle East, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-591, https://doi.org/10.5194/ems2024-591, 2024.
Significant is the complex role of atmospheric dust in the climate system, environmental conditions, and human health. However, the impact of dust layers residing in the atmosphere vary strongly based on the mineral dust physical and chemical properties as well as the particle size distribution, ranging from less than 0.1 μm to over 100 μm in diameter. More specifically, it is documented that larger mineral dust particles are more efficiently removed through dry deposition near the source regions and act more efficiently as CCN and/or IN, while fine dust particles are more prone to long-range transport, affecting air quality and human health over distances of thousands of kilometers downwind.
Here, a new four-dimensional, multiyear, and near-global climate data record is introduced, established with the overarching objective to decouple the submicrometer and supermicrometer components in terms of diameter of atmospheric dust layers. More specifically, this separation is realized through a combination of (1) the total pure-dust product from the ESA-LIVAS database, and (2) the supermicrometer-mode component of atmospheric dust, as extracted through implementation of the first step of the two-step POLIPHON technique. Accordingly, the submicrometer-mode component of atmospheric dust is derived as the residual between the total pure-dust and supermicrometer-mode component of pure-dust.
The decoupling scheme is applied to CALIPSO observations at 532nm, resulting in quality-assured profiles of backscatter coefficient at 532nm, extinction coefficient at 532nm, and mass concentration, for both submicrometer-mode and supermicrometer-mode of atmospheric pure-dust. These datasets are established with original CALIOP resolution along the CALIPSO orbit-path and in averaged profiles of 1ox1o spatial and seasonal temporal resolution, covering over 15 years of Earth Observation. This climate data record is considered unique, providing valuable insight into the characteristics of the atmospheric pure-dust components, thus contributing to a better understanding of their impact on climate, environment, and human health.
Acknowledgements
The research study was supported by the AXA Research Fund for postdoctoral researchers under the project entitled “Earth Observation for Air-Quality - Dust Fine-Mode (EO4AQ-DustFM)”.
How to cite: Proestakis, E., Gkikas, A., Georgiou, T., Kampouri, A., Drakaki, E., Ryder, C. L., Marenco, F., Marinou, E., and Amiridis, V.: A near-global multiyear climate data record of the submicrometer-mode and supermicrometer-mode components of atmospheric pure-dust, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-709, https://doi.org/10.5194/ems2024-709, 2024.
The Mediterranean basin is a region of great interest for studying atmospheric aerosols considering that it is one of the most vulnerable areas of the planet for climate change. Due to the extensive range of air masses that it receives, Mediterranean hosts a variety of aerosol species with dust particles constituting the major component of the total aerosol burden. Previous studies have demonstrated that across the Mediterranean, dust loads’ intensity is maximized in the eastern sector of the basin. The prevailing atmospheric circulation as well as the proximity with the most active deserts worldwide (i.e., Sahara, Arabian Peninsula) interpret the pronounced dust presence in the Eastern Mediterranean. The current study seeks to investigate the temporal variation of dust optical depth (DOD) in the Eastern Mediterranean, as well as in the neighboring deserts of North Africa and the Middle East. At a further step, emphasis is given on the understanding of the role/importance of the atmospheric and terrestrial mechanisms driving the obtained dust trends across various time scales. DODs are derived from the updated version of the MIDAS (ModIs Dust AeroSol) dataset, which delivers daily columnar optical depths, on a global scale and at fine spatial resolution (0.1° x 0.1°), over a 22-year period (2001–2022). A collection of ancillary datasets is employed to shed light on the factors governing dust life cycle components (i.e., emission, transport, removal). For the atmospheric state (i.e., synoptic circulation, near-surface winds), we are processing numerical products from the ERA5 reanalysis operated by ECMWF. Data from the Copernicus Climate Data Store (CDS) are exploited for depicting the temporal variability of the surface state (i.e., soil moisture, vegetation). Additionally, we are taking into consideration large-scale atmospheric circulation patterns (e.g., North Atlantic Oscillation). We anticipate that the obtained outcomes will contribute to the continuous effort of the modelling community to advance climate models utilized for the dust projections in the forthcoming decades.
This research has been supported by the CLIMPACT II (“Support for upgrading the operation of the National Network for Climate Change)”, funded by the Public Investment Program of Greece, General Secretary of Research and Technology/Ministry of Development and Investments.
How to cite: Logothetis, S.-A., Gkikas, A., Kazadzis, S., Kazantzidis, A., Amiridis, V., and Zerefos, C.: Dust trends in the Eastern Mediterranean and the surrounding deserts during 2001-2022, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-633, https://doi.org/10.5194/ems2024-633, 2024.
Two billion tons of dust are annually suspended in the Earth´s atmosphere. HLD contributes about 5% to the global atmospheric dust budget. Active HLD sources cover > 1,600,000 km2 and are located in both the Northern (Iceland, Alaska, Canada, Greenland, Svalbard, North Eurasia, and Scandinavia) and Southern (Antarctica, Patagonia, New Zealand) Hemispheres. In-situ HLD measurements are sparse, but numerous research groups investigate HLD and its impacts on climate in terms of effects on cryosphere, cloud properties and marine environment (IceDust Association, UArctic Thematic Network on HLD, NORDDUST, CAMS NCP Iceland).
Long-term dust in situ measurements conducted in Arctic deserts of Iceland and Antarctic deserts of Eastern Antarctic Peninsula in 2018-2024 revealed some of the most severe dust storms in terms of particulate matter (PM) concentrations. While one-minute PM10 concentrations is Iceland exceeded 50,000 ugm-3, hourly PM10 means in James Ross Island, Antarctica exceeded 300 ugm-3 in 2021-22. Additionally, examples of aerosol measurements from Svalbard and Greenland will be shown. There are newly two online models (DREAM, SILAM) providing daily operational dust forecasts of HLD. DREAM is first operational dust forecast for Icelandic dust available at the World Meteorological Organization Sand/Dust Storm Warning Advisory and Assessment System (WMO SDS-WAS). SILAM from the Finnish Meteorological Institute provides HLD forecast for both circumpolar regions.
Icelandic dust has impacts on atmosphere, cryosphere, atmospheric chemistry, clouds, air quality and radiation. It has critical impacts on cryosphere as it is suspended at high latitudes, decreasing albedo of both glacial ice/snow similarly as Black Carbon. Icelandic dust reduces supercooled water content of mixed phase clouds changing their albedo. Suspended Icelandic dust tends to be more absorbing towards the near-infrared. The imaginary part of the complex refractive index k(λ) between 660–950 nm is 2–8 times higher than most of the dust samples sourced in northern Africa and eastern Asia. There is also an evidence that volcanic dust particles scavenge efficiently SO2 and NO2 to form sulphites/sulfates and nitrous acid. High concentrations of volcanic dust and Eyjafjallajokull ash were associated with up to 20% decline in ozone concentrations in 2010. In marine environment, Icelandic dust with high total Fe content (10-13 wt%) and the initial Fe solubility of 0.08-0.6%, can impact primary productivity and nitrogen fixation in the N Atlantic Ocean, leading to additional carbon uptake.
Sand and dust storms, including HLD, were identified as a hazard that affects 11 of the 17 Sustainable Development Goals. IceDust Association with > 110 members from 57 institutions in 22 countries became member aerosol association of the European Aerosol Assembly in 2022. In addition, HLD has potential to increase the research interest of HARMONIA members/stakeholders in comparing observations from established measurement sites at high latitudes and numerous areas without monitoring.
How to cite: Dagsson-Waldhauserova, P., Meinander, O., and members, I.: Challenges in High Latitude Dust (HLD) measurements and HLD interactions with clouds and solar radiation, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1043, https://doi.org/10.5194/ems2024-1043, 2024.
Mineral dust stands out as a pivotal climate modulator due to its substantial mass, optical depth, and long-term atmospheric life cycle. It impacts the atmospheric radiative balance, influences cloud dynamics and precipitation patterns, and exerts notable effects on terrestrial and aquatic ecosystems as well as human health. The extent and intensity of these impacts are governed by the mineral composition of dust particles sourced from diverse regions worldwide. METAL-WRF is an advanced numerical framework extending the GOCART-AFWA dust scheme in WRF-Chem 4.4.1 and it is designed to simulate the atmospheric dynamics of dust mineral components, including emission, transport, dry deposition due to gravitational settling, and wet deposition due to the scavenging of dust particles by the hydrometeors. The model accounts for ten mineral types: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, phosphorus, and iron. In the previous version of METAL-WRF the mineralogical composition of dust is derived from the global geological datasets GMINER30 and FERRUM30. A significant improvement in the mapping of dust composition comes from NASA's EMIT sensor that has been operational aboard the International Space Station (ISS) since July 2022. EMIT utilizes advanced imaging spectroscopy to capture light across visible and infrared wavelengths, identifying distinct spectral signatures indicative of surface mineral composition. In this study, we introduce the integration of the first comprehensive EMIT mineralogical dataset in METAL-WRF. The model is used for the simulation of atmospheric dust in HARMONIA 2024 Berlin school. We discuss the comparative distribution of various mineral dust types in the Mediterranean between METAL-WRF simulations incorporating EMIT mineralogy data and earlier versions relying on GMINER30 and FERRUM30 geological databases. The effects of the different mineral types in radiative transfer and ice nuclei activation are examined for specific case studies in comparison with ground based and spaceborne observations.
Acknowledgments. The authors acknowledge financial support from the Hellenic Foundation for Research and Innovation project “Mineralogy of Dust Emissions and Impacts on Environment and Health (MegDeth - HFRI no. 703)” and from the COST Action CA21119, “HARMONIA: International network for harmonization of atmospheric aerosol retrievals from ground-based photometers”.
How to cite: Solomos, S., Spyrou, C., Bartsotas, N. S., Kalogeri, C., Fountoulakis, I., Zerefos, C. S., Aslanoğlu, Y., Chadoulis, R.-T., Charalampous, G., Herrero-Anta, S., Herrero del Barrio, C., Kouklaki, D., Moustaka, A., Mytilinaios, M., and Papetta, A.: Development of METAL-WRF model for the description of mineral dust processes in the atmosphere based on NASA's EMIT satellite retrievals, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-176, https://doi.org/10.5194/ems2024-176, 2024.
More than 50% of the global population is hosted in cities of the world. The United Nations estimate that the number of inhabitants in the cities will be increased by about 2.5 billion people by 2050. Worldwide, the most pronounced urban population growth (up to 90%) is projected for Asia and Africa. Such a population increase is expected to also increase the emissions of fine aerosols originating from anthropogenic activities. The World Health Organization estimates that the exposure to fine aerosol particles is responsible for 4.2 million premature deaths on an annual basis. In some countries, strategic national measures (i.e., U.S. and European Clean Air Acts, China's Air Pollution Prevention and Control plan) are applied for the mitigation of aerosol emissions. Such initiatives have been designed to tackle the urgent needs for combating air quality degradation, which in turn has subsequent impacts on human health.
In this study, high resolution satellite-based data of aerosol optical depth (AOD) from the MODerate resolution Imaging Spectroradiometer onboard the Aqua satellite (MODIS-Aqua), in addition to ground-based sun photometric aerosol measurements and population data for 81 megacities (cities with more than 10 million inhabitants) are analyzed. Aspects that are addressed deal with the correlation of AOD variability and population growth and the effect of regional emissions in the AOD vs population links. As an example, India and China show contradictory AOD trends, being continuously increasing for India and declining for China, despite the recorded population growth in both countries. In addition, high spatial resolution data identify intra-city correlations among aerosols and population growth. In this case ground-based observations are also used aiming to understand possible spatial AOD inhomogeneities within a few kilometers in megacities and in the neighboring areas. Moreover, in the context of this work, long-term AOD retrievals obtained by the MAIAC (Multi-Angle Implementation of Atmospheric Correction) will be used for better data availability and for the potential to use additional auxiliary data to investigate the effects on several aspects. Finally, as a number of megacities are affected by natural aerosols (e.g. desert dust) we have tried to eliminate such effects as they are not linked with population growth, by using a fine spatial resolution dust optical depth product derived by the MIDAS (ModIs Dust AeroSol) dataset.
Acknowledgements
This study was funded by the COST (European Cooperation in Science and Technology) funding agency for research and innovation network; COST Action HARMONIA (International network for harmonization of atmospheric aerosol retrievals from ground-based photometers), CA21119.
How to cite: Papachristopoulou, K., Michailidis, K., Ciocan, G., Kosmopoulos, G., Poutli, M., Tokgöz, D. D. G., Dosev, S., Balakrishnan, P., Gkikas, A., and Kazadzis, S.: Aerosol optical depth regime over megacities and possible links with their population changes , EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-313, https://doi.org/10.5194/ems2024-313, 2024.
The Mediterranean Basin is one of the sunniest regions globally. Thus, aerosols, and especially dust, play a key role in radiative transfer processes in the atmosphere, which locally can be comparable to or even more significant than the role of clouds. The physical (i.e., size, shape) and chemical (e.g., composition) properties of dust that is transported across the Mediterranean Basin depend strongly on its origin, as well as on its ageing and mixing with other atmospheric constituents. For instance, the mixing of dust with anthropogenic particles can alter its chemical composition and hygroscopicity/ hygroscopic properties. Changing physical and/or chemical properties of dust also alter its optical properties and subsequently its radiative effects.
By analyzing synergistically back-trajectories of the air masses at different altitudes from the HYSPLIT model, aerosol optical properties from Aerosol Robotic Network (AERONET), and dust optical depth from the ModIs Dust AeroSol (MIDAS) climatology, we identified three strong dust events in the period 2015 – 2022 where dust originated from different regions of Africa and the Middle East and travelled over many AERONET stations located in (and near) the Mediterranean Basin (in an area covering latitudes from 30° N to 45° N and longitudes from -10° E to 40° E. After identifying the origin of desert dust, we studied the changes in its optical (Optical Depth, Angstrom Exponent, Single Scattering Albedo) and microphysical (size distribution) properties as derived from different AERONET stations, using quality assured, AERONET level 2 (version 3), products. Finally, Radiative Transfer (RT) simulations for clear sky (cloudless) conditions were performed, employing the UVSPEC model from the libRadtran package in order to estimate the impact of dust, as well as the effect of its changing optical properties, on downwelling surface solar radiation in terms of Global Horizontal Irradiance (GHI) and Direct Normal Irradiance (DNI).
Acknowledgements: Authors would like to acknowledge the Action Harmonia CA21119 supported by COST (European Cooperation in Science and Technology).
How to cite: Chadoulis, R.-T., Aslanoğlu, S. Y., Charalampous, G., Herrero-Anta, S., Herrero del Barrio, C., Kouklaki, D., Moustaka, A., Mytilinaios, M., Papetta, A., Solomos, S., Gkikas, A., Spyrou, C., Papadimitriou, N., Vandenbussche, S., and Fountoulakis, I.: Desert dust outbreaks at the Mediterranean Basin: Optical properties and impact on surface solar radiation, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-569, https://doi.org/10.5194/ems2024-569, 2024.
Aerosols play a dominant role in the solar radiation field and Earth's energy budget, inducing considerable climatic forcing (IPCC, 2022). Dust particles and water vapor (WV) can change the atmospheric thermodynamic stability through radiative heating and/or cooling (Gutleben et al, 2019). Although the quantification of these aspects is crucial, the difficulty in defining the aerosols microphysical and optical properties along with their high spatial and temporal variability makes this quantification challenging. Despite the considerable progress in recent years regarding this topic, sophisticated atmospheric field experiments that provide highly accurate information are essential, not only to enrich knowledge, but for the validation and the improvement of ongoing and future satellite-based products.
The current study provides valuable information on dust and WV radiative effects through a unique dataset of synergistic high-quality measurements during the ASKOS ESA campaign in Cabo Verde. Specifically, the study utilizes sophisticated ground-based remote sensing, airborne (UAV) in-situ measurements, along with surface solar irradiance measurements and airborne (UAV and radiosonde) profiling of temperature and WV. The under-study period (summer of 2022) coincides with the annual peak of dust transport in the Atlantic.
To derive realistic optical properties of the dust particles along with their vertical distribution in the atmosphere, we use the airborne in-situ observations of particle microphysical properties (size, shape and mineralogical composition). The calculated optical properties are evaluated using multi-wavelength ground-based lidar measurements. Then, radiative transfer (RT) simulations are performed under clear and cloudy sky conditions employing the libRadtran RT package (Mayer & Kylling, 2005; Emde et al., 2016). The RT simulations of shortwave radiation at the bottom of the atmosphere are compared with surface broadband radiation measurements. Finally, the heating rate (HR) calculations are evaluated against changes in the temperature profile of the atmosphere.
Acknowledgements: This research was financially supported by the PANGEA4CalVal project (Grant Agreement 101079201) funded by the European Union . DK, ΑΤ, ΚP, PR and SK would like to acknowledge COST Action HARMONIA (International network for harmonization of atmospheric aerosol retrievals from ground-based photometers), CA2119, supported by COST (European Cooperation in Science and Technology).
References
Emde, C., Buras-Schnell, R., Kylling, A., Mayer, B., Gasteiger, J., Hamann, U., Kylling, J., Richter, B., Pause, C., Dowling, T., Bugliaro. L. (2016). The libRadtran software package for radiative transfer calculations (version 2.0.1), Geoscientific Model Development, 9(5), 1647–1672, https://doi.org/10.5194/gmd-9-1647-2016.
Gutleben, M., Groß, S., Wirth, M., Emde, C., and Mayer, B. (2019). Impacts of Water Vapor on Saharan Air Layer Radiative Heating. Geophysical Research Letters. 46, https://doi.org/10.1029/2019GL085344.
Intergovernmental Panel on Climate Change (IPCC) (2022), Land–climate interactions. In: Climate Change and Land: IPCC Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems. Cambridge University Press,131-248.
Mayer, B., Kylling, A. (2005), Technical note: The libRadtran software package for radiative transfer calculations - description and examples of use. Atmos. Chem. Phys., 5(7), 1855–1877, https://doi.org/10.5194/acp-5-1855-2005.
How to cite: Kouklaki, D., Tsekeri, A., Papachristopoulou, K., Gialitaki, A., Paptis, P.-I., Mayer, B., Emde, C., Marinou, E., Amiridis, V., and Kazadzis, S.: Desert dust and water vapor radiative effects using airborne and ground-based measurements and simulations, during the ESA ASKOS campaign in Cabo Verde., EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-705, https://doi.org/10.5194/ems2024-705, 2024.
Aerosols are important atmospheric constituents, playing a major role in many atmospheric processes and capable of altering the Earth’s radiation budget, through direct and indirect effects, thus acting as major drivers of climate forcing. Understanding and quantifying the ways in which different types of aerosols interact with radiation is therefore crucial.
The investigation focuses on the radiative effects of transported aerosols originating from the Tajogaite volcanic eruption at La Palma, Canary Islands (Spain), which occurred between September and December 2021. The Iberian Peninsula was on the path of a few occurrences of atmospheric aerosol plumes originating from the eruptive region, with a notable case between 11 and 13 October. The primary aim of the study is to examine the radiative effects of volcanic aerosols in different spectral regions, during this period over Évora and Granada. Sun-photometer and lidar measurements available at these sites provide comprehensive columnar and vertically resolved aerosol data. It was already reported that volcanic ash was limited to regions nearby the source, and that particularly during the 3-day period (11-13 October) considered, the ash cloud covered an area below 100 km2. Observations on 12 October indicate that the volcanic plume transport towards Iberia was characterized by low particle depolarization ratios (with a mean value of 0.08±0.02) and a high backscatter-related Angström exponent between 532–1064 nm (with a mean value of 1.4±0.24). These values suggest that the plumes transported for longer distances predominantly contained small spherical sulphate particles. A mean aerosol optical depth of 0.12±0.021 at 532 nm, was registered on 12 October at the sites considered. Lidar measurements revealed a layer of small particles roughly located between 2.5 and 5.0 km above sea level at Évora, with a slightly lower bottom at Granada (~2 km).
The radiative effects in the UV, VIS-NIR, and IR spectral regions will be assessed using the uvspec program within the LibRadtran software package. This tool enables the calculation of radiative fluxes at different vertical levels using measured aerosol properties, including the particle extinction coefficient profiles. The impact of the aerosol vertical distribution on the radiative effects, as well as their assessment at the surface and TOA levels, will be presented.
How to cite: Costa, M. J., Salgueiro, V., Pérez-Ramírez, D., Román, R., Bortoli, D., Guerrero-Rascado, J. L., Potes, M., and Alados-Arboledas, L.: Radiative effects of volcanic aerosols over Southwestern Iberia, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-874, https://doi.org/10.5194/ems2024-874, 2024.
Aerosols affect surface solar radiation (SSR) by modifying cloud properties. For solar energy applications, either for photovoltaics (PV) or concentrating solar power (CSP) systems, understanding of spatio-temporal variability of aerosol is essential for short-term forecasts of solar radiation.
This study aims to quantify interday variability of the commonly used proxy for optical properties of aerosols - aerosol optical depth (AOD) at the wavelength of 500 nm and to assess the deviation in direct normal irradiance (DNI) and in global horizontal irradiance (GHI) caused by AOD variation using radiative transfer modeling.
The following AOD data are used: AOD forecasts for the next day from the Copernicus Atmosphere Monitoring Service (CAMS); ground-based AOD measurements from the Aerosol Robotic Network (AERONET); ModIs/Terra high spatial resolution data set (MIDAS) which is based on satellite retrievals. We select locations with different aerosol types around the globe based on AERONET stations, where at each site more than 1500 daily values for consecutive days from 2010 to 2020 are available. We adopt the persistence approach using AOD data from AERONET and MIDAS and compare them with CAMS forecasts. The AOD data from AERONET serve as ground truth for validation. Under cloudless conditions, AOD variability informs the deviation of DNI and GHI forecasts from the observation. Furthermore, we attempt a worldwide clustering of aerosol types based on chemical modeling. Interday AOD variability is high in megacities with high aerosol load and in the proximity of highly variable aerosol sources such as desert dust and biomass burning (fires).
This work should deepen our knowledge of spatio-temporal variability of aerosol in the context of AOD and SSR prediction, thus contributing to the quality and reliability of solar resource assessment.
How to cite: Hou, X., Papachristopoulou, K., Masoom, A., and Kazadzis, S.: Aerosol forecast and its effect on surface solar radiation, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-370, https://doi.org/10.5194/ems2024-370, 2024.
Harmonia is a COST Action funded by the European Cooperation in Science and Technology. It deals with networking and scientific activities related with columnar aerosol measurements and involves scientists dealing with measurements, model assimilation , satellite validation but also software and instrument developers. The scope of the presentation is to provide an overview of the global status of aerosol sun photometer networks and the homogenization activities performed towards reducing spatiotemporal aerosol properties uncertainties.
Harmonia COST Action aims to establish a network involving institutions, instrument developers, scientific and commercial end users, in order to homogenize aerosol retrievals using mainly solar and sky but also lunar and star photometers from different networks. It aims bridging user needs and the science and technology expertise residing in academia and industry, through:
- Increasing the interactions and knowledge exchanges between several atmospheric aerosol measurement networks.
- Standardizing and improving of existing products and tools, toward a “harmony” in the aerosol photometry.
- Stimulating the communication between operational agencies and academia, increasing the applicability of aerosol related products.
- Capacity building towards instrument operators on improving the use of solar, lunar and stellar radiometry/photometry instrumentation.
- Encouraging the dialogue between researchers and instrument manufacturers towards instrument technical improvements.
The presentation aims to provide an overview of the current methods to measure aerosol columnar properties from the surface and also an overview of the homogenization activities towards better ground-based products towards better representation of the aerosol field and aerosol effects on climate, model assimilation and satellite validation. Including:
- The current state of the art of instrument calibration including project results towards establishing a traceability to the SI system of units,
- Aerosol sun photometric networks` common international comparison towards measurement homogenization
- The status of the Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS), Calibration of aerosol remote sensing and links to Harmonia
Acknowledgement
This research has been supported by the This article/publication is based upon work from COST Action HARMONIA, supported by COST (European Cooperation in Science and Technology) .
How to cite: Kazadzis, S. and the COST action Harmonia Core group: Harmonia COST Action: Overview of aerosol optical depth calibration and homogenization activities, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-69, https://doi.org/10.5194/ems2024-69, 2024.
An extreme mesoscale dust storm hit Türkiye's capital, Ankara, on 12th of September, 2020. During the storm, there was no long-range dust transport, particularly from the neighboring desert regions of North Africa and the Middle East. Instead, convective systems in the surroundings of Konya province, located south of Ankara, generated high-speed winds of up to 30 m/s, causing a significant amount of continental dust to rise from the district of Polatlı, situated about 70 km southwest of Ankara. Quickly evolving into a haboob, the storm brought life in Polatlı to a halt for approximately 20 minutes. As it progressed northeastward, the storm lost its haboob effect, but its impact on air quality persisted for about 24 hours, affecting not only Polatlı but also surrounding settlements, including central Ankara. MODIS Aqua overpass could catch the event partially but the observed AOD levels reached over 1. The air quality index reached hazardous levels, with the Polatlı air quality monitoring station recording a record hourly average PM10 concentration of 5,446 µg/m3 during the event. The primary cause was a dramatic change in land cover. Polatlı, covering an area of approximately 22 thousand hectares, is predominantly engaged in dry farming, with 80% of the land dedicated to it. The prolonged absence of rainfall, coupled with improper farming practices, has led to desertification of the land cover and, consequently, its susceptibility to erosion by wind. This study analyzes the mechanisms leading to the formation, progression, and environmental impacts of the storm using data from the Turkish State Meteorological Institute's observations and the C-Band Doppler weather radar data; CALIPSO and MODIS aerosol observations; Sentinel moisture and normalized vegetation difference indices; and measurement data from air quality monitoring stations belonging to the Ministry of Environment, Urbanization, and Climate Change.
How to cite: Aslanoğlu, S. Y. and Güllü, G.: Assessing an Haboob Event Triggered by Land Cover/Land Use Change: A Case Study of Polatlı, Türkiye, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-389, https://doi.org/10.5194/ems2024-389, 2024.
Solar energy will play key role in the effort for the decoupling from fossil fuels in the forthcoming decades. Minimizing the cost to energy production ratio for photovoltaics (PV) installations is key for the maximization of the potential benefits from their use. For this purpose, solar energy production models can be exploited for nowcasting, forecasting, and for climatological studies. PV panels are usually installed with tilt angles optimized for maximum energy production, and thus the energy production is usually not proportional to the global horizontal irradiance (GHI), which is the variable that is commonly measured at the surface. Both, the direct and the diffuse solar irradiances reaching the PV panels are necessary (to be used as inputs to the solar energy models) for the accurate quantification of the produced energy when the PV efficiency is known. Nevertheless, ground-based measurements of the diffuse irradiance are scarce, and estimates of the surface solar radiation (SSR) components (direct and diffuse), relied on Earth observations are usually more uncertain than ground-based measurements. The Global Solar Energy Estimator (GSEE) is a widely used open access solar energy simulation library which takes as input either the GHI or both, the GHI and the diffuse horizontal irradiance (DHI). It simulates the produced energy for various types of PV panels at the tilt angles specified by the user, or for panels that are rotating at one or two dimensions. GSEE can estimate the solar energy production for specific locations taking as inputs the SSR parameters at timescales ranging from instantaneous to monthly integrals. When only the GHI is provided as input, multi-parametric equations are applied to estimate the DHI, and subsequently the produced energy (after applying further parameterizations to estimate the DHI fraction that reaches the panels). To quantify the uncertainty in the estimates of the energy production when only GHI is utilized as input with respect to aerosol and cloudiness conditions we use high quality measurements of the GHI and DHI at three stations of the Baseline Surface Radiation Network (BSRN) (Lindenberg, Carpentras, and Tamanraset) for one year (2017). In parallel, we perform the same analysis using the satellite GHI and DHI estimates from the Copernicus Atmospheric Monitoring Service (CAMS) for the aforementioned stations aiming to quantify the uncertainties in the energy production estimates when they are used instead of ground-based measurements.
Acknowledgements
This work has been supported by the action titled “Support for upgrading the operation of the National Network for Climate Change (CLIMPACT II)”, funded by the Public Investment Program of Greece, General Secretary of Research and Technology/Ministry of Development and Investments. The authors would also like to acknowledge the Action Harmonia CA21119 supported by COST (European Cooperation in Science and Technology).
How to cite: Papadimitriou, N., Fountoulakis, I., Papachristopoulou, K., Gkikas, A., Kazadzis, S., Kapsomenakis, J., and Zerefos, C.: Parameterization of the direct and diffuse surface solar radiation components in the Global Solar Energy Estimator (GSEE) and related uncertainties in the energy production simulations, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-518, https://doi.org/10.5194/ems2024-518, 2024.
Aerosols are a significant factor in the radiative forcing of the Earth, influencing both climate and air quality. Accurate monitoring and measurement of aerosol properties are therefore essential. The spatial and temporal extent of these measurements is critical for analyzing the global distribution of aerosols and detecting shifts in global trends. The World Meteorological Organization’s Global Atmosphere Watch (GAW) program highlights the importance of Aerosol Optical Depth (AOD) as a key metric in studying atmospheric aerosols. To facilitate these studies, several networks of sun-sky-lunar photometers have been established over the years. Prominent among these are the AErosols RObotic NETwork (AERONET), Sky Measurements Network (SKYNET), and the Global Atmosphere Watch - Precision Filter Radiometer (GAW/PFR). Each network employs distinct instruments, calibration techniques, and data retrieval methods, leading to variations in the AOD measurements obtained.
The Izaña Observatory, located at 2,373 meters above sea level on the island of Tenerife, Spain (28.3ºN; 16.5ºW), is managed by the Izaña Atmospheric Research Center which is part of the Spanish Meteorological Agency (AEMET). Its elevated position in the free troposphere provides ideal conditions for employing the Langley plot calibration method. This technique benefits from minimal atmospheric interference, which significantly enhances the accuracy of solar and atmospheric measurements. In November 2019, the observatory launched a year-long intercomparison campaign, employing a diverse array of sun-sky-lunar photometers including a Prede POM unit from SKYNET and a Cimel CE318-T model from AERONET, to systematically compare and validate their data.
The objective of this study is to leverage the concurrent measurements obtained from both instruments to conduct simultaneous Langley plot calibrations. By doing so, we aim to elucidate and identify the primary differences between the photometers. This analysis will not only highlight discrepancies but also contribute to enhancing the calibration accuracy of both networks. This approach will provide insights into the consistency and reliability of the AOD measurements, facilitating improvements in measurement techniques and data comparability across different networks.
How to cite: González-Sicilia, P., Campanelli, M., Estellés, V., Barreto, Á., Doppler, L., Almansa, A. F., Álvarez-Losada, Ó., Kumar, G., and García, R. D.: Harmonizing solar photometry calibration methods: A Cross-Network Calibration Study at Izaña Observatory, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-356, https://doi.org/10.5194/ems2024-356, 2024.
Aerosols impact surface solar irradiance, both directly, by scattering and absorbing solar irradiance, and indirectly, by acting as cloud condensation nuclei. Dust aerosols, a major component of tropospheric aerosols, play a significant role in climate change by engaging in various physical processes and interactions. The Direct Radiative Effect (DRE) of dust aerosols can significantly influence local atmospheric temperatures - typically cooling the ground - and affects broader climatic conditions. The effect of dust on energy production is substantial, as it can reduce the efficiency of solar panels by scattering incoming solar energy. The degree of this reduction depends on the properties of the airborne dust. Additionally, dust’s impact at the Top of the Atmosphere (TOA), includes altering the Earth's radiation budget by reflecting incoming solar radiation back to space and absorbing certain wavelengths, which can affect global temperature patterns and atmospheric dynamics. Despite the crucial impact of dust on climate systems, the understanding of this parameter remains limited.
This study explores the impact of dust aerosols on surface solar radiation and the shortwave radiation at the Top of the Atmosphere (TOA) at Agia Marina Xyliatou, Cyprus (35.04 N; 33.06 E; 535m above sea level), a region heavily influenced by dust originated from two desert regions: the Sahara and the Arabian Peninsula. The direct radiative effects of dust on solar shortwave radiation at ground level and TOA are evaluated, utilizing measurements from the Agia Marina Xyliatou Station and radiative transfer (RT) modeling with LibRadtran RT package for the years 2015-2022. The findings underscore the significant influence of dust, particularly during the spring and autumn seasons when dust events are most frequent. Seasonal variations in aerosol optical properties and their climatic implications are detailed, highlighting the differences in dust origins and their respective impacts on surface solar radiation levels (mean value of DRE -53.01±27.02 W/m2). This research contributes to a better understanding of the regional climatic effects of aerosols and aids in the management of solar energy resources in dust-prone regions.
Acknowledgments: “This research is performed under the auspices of the Memorandum of Understanding between ERASTOTHENES CoE and The Cyprus Institute. The authors acknowledge the ‘EXCELSIOR’: ERATOSTHENES: EΧcellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu).The ‘EXCELSIOR’ project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology”. This project has also received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 856612 and the Cyprus Government (EMME-CARE).
How to cite: Charalampous, G., Fragkos, K., Fountoulakis, I., Marenco, F., Derimian, Y., Karpasitis, A., Nisantzi, A., Mamouri, R.-E., Hadjimitsis, D., and Kazadzis, S.: Assessment of Dust Impact on Shortwave Surface Irradiance: A Seven-Year Study at Agia Marina Xyliatou, Cyprus, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-610, https://doi.org/10.5194/ems2024-610, 2024.
In May-June 2024, an intercomparison campaign is scheduled to take place in Valladolid, Spain, comparing different photometer models. Specifically, the campaign will involve the PREDE POM-02L from the Institute of Polar Sciences (CNR-ISP), the CIMEL CE318-T from the Atmospheric Optics Group (GOA) at Valladolid University, and the PFR from the Physikalisch-Meteorologisches Observatorium Davos (PMOD). The primary objective of this campaign is to assess the effectiveness of a personalized algorithm for determining Aerosol Optical Depth (AOD) and Angstrom Exponent (α), while also evaluating the quality of these measurements by comparing them with data from the AERONET station operated by the GOA. AOD measurements will be conducted at various wavelengths: 440, 500, 675, and 870 nm for CIMEL; 400, 500, 675, and 870 nm for PREDE; and 440, 500, and 870 nm for PFR; α will be evaluated between 500 and 870 nm for all the photometers. For the multi-instrument intercomparison, the recommendations defined in 2005 by the WMO during the event ’WMO/GAW expert workshop on a global surface network for long-term observations of columnar aerosol optical properties' will be followed. These consist of: (i) acquiring more than 1000 points over at least 5 days of measurements, with AOD500 between 0.04 and 0.20; (ii) ensuring traceability with 95% uncertainty within 0.005 + 0.01/m; (iii) using the 500±3 nm and 865±5 nm channels, with a bandwidth of 15 nm or less, since these channels are mostly free from absorption effects. Valladolid, a medium-size city in the northern Castilian plateau, typically experiences continental aerosols as the predominant aerosol type. AOD values tend to be lowest during winter, gradually increasing to peak levels in late spring and summer. Maximum AOD values in Valladolid are often associated with the presence of dust particles from Saharan dust outbreaks, which are characterized by low α values. This intercomparison campaign, spanning late spring and early summer, provides an opportunity to observe the first significant desert dust transport events at the site. Additionally, biomass-burning events, associated with high AOD and high α values, may also be observed during this period. Detecting and studying these events will be another key focus of the campaign. In conclusion, this campaign offers us a chance to assess how well different sun-photometers work. Additionally, we’ll be able to study how desert dust and biomass burning events affect the site during this period.
How to cite: Pulimeno, S., Mazzola, M., Lupi, A., Vitale, V., Toledano, C., González, R., Kouremeti, N., and Kazadzis, S.: Assessing Sun-Photometer Performance: Insights from an Intercomparison Campaign in Valladolid, Spain , EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-642, https://doi.org/10.5194/ems2024-642, 2024.
The amount of solar ultraviolet radiation (UV) is a crucial parameter due to its relation to health effects, being associated with more than 90% of melanomas. But it also has significant influences on ecosystems, environments and the Earth’s atmospheric processes.
In this work, we analyze the temporal trends exhibited by the daily values of UV erythemal irradiance (UVER) and the ultraviolet Index (UVI) at noon and the daily maximum. The measurements were taken with a YES-UVB-1 radiometer located at Burjassot AtmoSpheric Station (BASS, 39º 350N, 0º 250W, 60 m.a.s.l.), covering a measurement period from 2003 to 2023. The seasonal behavior of these parameters have been characterized previously by Marín et al. (2023). The Mann-Kendall test has been now used to identify increasing or decreasing temporal trends in the data. This is a randomization vs. trend test, based on ranges. In addition to identifying the existence of a temporal trend, the Sen’s slope estimator allows to calculate the annual rate of change. Due to the seasonality of the variables, the seasonal extension of the test was applied, using the monthly medians instead of annual values.
The UVER exhibits statistically significant increasing trends in February, May, June, July and December at 90%, 90%, 95%, 90% and 90% confidence levels, respectively. UVI at noon also shows statistically significant increasing trends in February, May, June, September and December at 90%, 99%, 99%, 80% and 80% confidence levels, respectively. Lastly, the maximum daily UVI has increased in May, June and September at 95%, 99% and 90% confidence levels. Similar results have been reported by Marson et al. (2021) at United States, attributing the increased US melanoma incidence to ground-level UV radiation intensity trends; and by Fountoulakis et al. (2021) for several months (especially in April and summer months) in three sites of Italy.
Further analysis will make use of simultaneous atmospheric composition and meteorology datasets at Valencia site to clarify the main causes for such short- and long-term trends, by use of regression analyses. It will be studied whether factors such as the decrease in total aerosol extinction and absorbing species such as black carbon could influence the trends.
How to cite: Matos, V., Marín, M. J., Gómez-Amo, J. L., Estellés, V., and Utrillas, M. P.: Temporal trends of global UV solar irradiation over the last 20 years in Valencia (eastern Spain), EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-681, https://doi.org/10.5194/ems2024-681, 2024.
The Sunphotometer Airborne Validation Experiment (SAVEX-D) was carried out in the Cape Verde archipelago, along with the ICE-D (Ice in Clouds Experiment - Dust) campaign, led by the Met Office and the Universities of Leeds and Manchester (United Kingdom) in summer 2015. The aim of the SAVEX-D experiment was to verify and validate the retrievals of both AERONET’s and SKYNET’s ground based sun-photometers for columnar aerosol optical properties, particularly the aerosol size distributions, with the use of airborne in situ measurements. To this end, a Cimel CE318 (AERONET) and a Prede POM01 (SKYNET) were installed at Praia (Cape Verde), and their retrievals were compared with those obtained with several in-situ instruments equipped in the FAAM BAe-146 research aircraft, such as PCASP, CDP and 2DS. In addition, data from AERONET’s long-term site on Sal was employed. The motivation behind this experiment was related to the non-negligible discrepancies between the retrieved aerosol properties from AERONET and SKYNET networks reported in previous studies. In fact, it is essential to better characterise aerosol retrievals from sun-photometers, since these are employed as inputs in climatological studies, aerosol model verifications and validation of satellite products. The location of the site, downwind of the Sahara Desert (a major source of dust aerosols) is a key aspect of the experiment. In the two flights that were performed (16th and 25th August 2015), dust dominated the aerosol mixture, with a measured AOD about 0.4 - 0.6. Cimel and Prede measurements were inverted through different available versions of the AERONET and SKYNET algorithms. Among the retrieved aerosol properties, aerosol size distribution is of particular interest, as it can be compared to the vertically integrated size distributions obtained from the in-situ instrumentation in the aircraft. From the results, it is observed that both AERONET version 2 and different versions of Skyrad algorithm from SKYNET are consistent in the interval 0.2 - 2.0 µm. However, discrepancies between networks become more noticeable at the extremes of the distributions. In addition, it is shown that AERONET underestimates the size distribution of coarse particles, and that differences in the coarse mode are significant when non-sphericity is considered in the MRI version of the Skyrad inversion algorithm. Further plans include the comparison with new versions of both AERONET and SKYNET algorithms, and GRASP retrievals obtained from inversion of both Cimel and Prede measurements.
How to cite: Garcia-Suñer, M., Estellés, V., Marenco, F., Ryder, C., Kumar, G., Momoi, M., Campanelli, M., O'Sullivan, D., Brooke, J., and Buxmann, J.: Validation of AERONET and SKYNET columnar aerosol size distributions by comparison with aircraft in situ measurements at Cape Verde, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-717, https://doi.org/10.5194/ems2024-717, 2024.
Among the many existing aerosol detection techniques, lunar photometry is particularly appealing, since its combination with sun-photometer retrievals could allow a quasi-continuous monitoring of aerosol properties. Great efforts have therefore been devoted to improve the instrumentation and especially the calibration methods, so as to sort out the inherent difficulties in the computation of the -not constant- extraterrestrial lunar irradiance. Thus, assessing the coherence between solar and lunar retrievals is of utmost importance. In this work, the agreement between Level 1.5 solar and lunar retrievals of Aerosol Optical Depth (AOD) and the Ångström Exponent (α) in AERONET’s Burjassot (Valencia) site from July 2015 to January 2024 are evaluated. Then, inter- and intra-annual monthly means are compared and validated through a correlation study. In agreement with previous analyses of solar measurements over this region, higher values of AOD are observed in summer months in comparison with the rest of the year. This could be related to factors such as particle stagnation, hygroscopic processes, secondary aerosol formation (favoured by higher irradiation levels), or dust outbreaks, which are more frequent at this time of the year. Indeed, the latter could be responsible for a secondary AOD maximum found in April. On the other hand, hourly means from both data sets will be also jointly analyzed in order to study the consistency of retrievals in the transition from day to night and vice versa. In these cases, factors such as the influence of the Moon phase and the interval of time between the last and first Sun and Moon measurements, respectively, will be taken into account. Finally, after checking the agreement between solar and lunar data, hence justifying their joint use, AOD temporal evolution from solar and lunar data are examined, concluding that AOD tends to decrease along the years. This result is not unexpected, taking into account the decreasing AOD trends over Europe and North America that have been reported by several authors.
How to cite: Garcia-Suñer, M., Matos, V., Kumar, G., Estellés, V., and Utrillas, M. P.: Validation of Aerosol Optical Depth and Ångström Exponent retrieved by solar and lunar photometry techniques in Burjassot (Valencia), EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-753, https://doi.org/10.5194/ems2024-753, 2024.
One of the key parameters affecting the levels of solar radiation reaching the ground is the single scattering albedo (SSA). The SSA shows how strongly aerosols absorb radiation and its value between 0 (no absorption) and 1 (absorption of the total incident radiation). The spectral SSA corresponding to the aerosol scattering of the total direct solar irradiance extinction through the total atmospheric aerosol column can be retrieved through sun-photometric measurements. Currently, the main columnar SSA product worldwide is the Aerosol Robotic Network (AERONET) product retrieved from a combination of spectral AOD and sky radiance measurements using an inversion modelling approach. Outputs are provided at 4 selected wavelengths between 440–1020 nm. The quality assured dataset (L2.0 AERONET product) is restricted to observations under Aerosol Optical Depth (AOD) above 0.4 at 440 nm, at solar zenith angles of 54 - 75° so they are limited to a small number of retrievals per day. This criterion is estimated to exclude around 95% of the annual global AOD values at 440 nm and 89% over land [Andrews et al., 2017].
In this study, we retrieve the SSA by the inversion of the direct to global spectral solar irradiance ratio [Kazadzis et al., 2016]. The solar irradiance measurements are provided by a precision spectroradiometer (PSR) deployed in 2 locations: Thiseio, Athens, Greece during the ASPIRE (Atmospheric parameters affecting SPectral solar IRradiance and solar Energy) campaign and Meteorologisches Observatorium Lindenberg (MOL-RAO), Lindenberg, Germany. The goal is to investigate whether the PSR measurements can be used to increase the data availability, accuracy, spectral range and spectral resolution of SSA retrievals. To retrieve the SSA, we compare the ratio between the direct and global spectra of the PSR with the respective values derived by radiative transfer model simulations for different AOD conditions. The PSR is able to measure with high frequency direct and global solar irradiance (approximately every 5 minutes) within the spectral range of 300 nm-1020 nm, at 1024 wavelengths. Its calibration is traceable to SI and its direct normal spectral irradiance has an expanded uncertainty of 1.7-2% [Gröbner & Kouremeti, 2019].
References
Andrews, E., Ogren, J.A, Kinne, S. and Samset, B., Comparison of AOD, AAOD and column single scattering albedo from AERONET retrievals and in situ profiling measurements, Atmospheric Chemistry and Physics, 17(9), 6041-6072, 2017.
Gröbner, J., and Kouremeti, N., The Precision Solar Spectroradiometer (PSR) for direct solar irradiance measurements. Solar Energy, 185, 199-210, 2019.
Kazadzis, S., Raptis, P., Kouremeti, N., Amiridis, V., Arola, A., Gerasopoulos, E., and Schuster, G. L.: Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment, Atmos. Meas. Tech., 9, 5997–6011, https://doi.org/10.5194/amt-9-5997-2016, 2016.
How to cite: Karanikolas, A., Raptis, P. I., Kouremeti, N., Gröbner, J., Doppler, L., Fountoulakis, I., Kouklaki, D., Papachristopoulou, K., and Kazadzis, S.: Retrieval of single scattering albedo using spectral solar measurements from a precision spectroradiometer (PSR), EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-712, https://doi.org/10.5194/ems2024-712, 2024.
Aerosol optical depth (AOD) is a key parameter for many scientific fields like air pollution and climate modelling. Ground-based AOD measurements outperform the other datasets in terms of data accuracy but still lack spatiotemporal resolution, while satellite/reanalysis encompasses the opposite behaviour. The overreaching goal of this study is to present a retrieval technique for cloud-free conditions that can be used to reproduce the AOD at the high temporal resolution of radiometric instruments. For the purposes of this analysis, reference measurements of aerosols (AERONET) and solar irradiance (BSRN) have been used. The retrieval technique uses various machine learning (ML) algorithms (e.g., gradient boosting machines, random forests, neural networks, etc.) by testing different components of ground-based solar radiation measurements in order to retrieve AOD at the 1-min temporal resolution of AERONET retrievals. In particular, each ML algorithm includes as an input parameter the optical air mass (m), water vapor (WV), and the direct or global clearness index. The WV is accessed through the Copernicus Atmosphere Monitoring Service Reanalysis, operated by ECMWF. For each ML algorithm, a randomized cross-validation searching method is applied to retrieve the optimal ML model architecture.
The ML-derived AOD retrievals are compared against reference ground-based (AERONET), satellite (MODIS), and reanalysis (MERRA-2, CAMS) AOD retrievals at 26 AERONET-BSRN stations under different aerosol and climatic conditions from 2004 to 2019. We validated the MLA-based AODs against reference AERONET retrievals, finding root mean square error (RMSE) values ranging from 0.01 to 0.15, irrespective of the underlying climate and aerosol environments. Among the different ML algorithms, the artificial neural networks outperformed the other algorithms in terms of RMSE at 54% of the measurement sites. The overall performance of ML-based AODs against AERONET revealed a high coefficient of determination (R2 = 0.97), a mean absolute error of 0.01, and an RMSE of 0.02.
How to cite: Logothetis, S.-A., Salamalikis, V., Kosmopoulos, G., and Kazantzidis, A.: Aerosol optical depth retrieval using ground-based solar irradiance measurements and machine learning, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-948, https://doi.org/10.5194/ems2024-948, 2024.
In the present study we focus our attention on determine aerosol properties from HDR All-Sky calibrated imagery. Even if this methodology is designed to be used regardless of the sky conditions, we especially explore the sensitivity to partially cloud scenarios, which is the main novelty of this work. Our methodology is based on using a small sector of the image that contains the principal plane of the Sun. The RGB principal plane radiances are associated to the Aerosol Optical Depth (AOD) and Ångström exponent (AE) AERONET observations through a Gaussian Process Regression (GPR) machine learning (ML) model. The cloudy points in our working sector are previously identified and then the correspondent free-sky radiances simulated with the aid of the Perez model. Therefore, the entire principal plane signal as if no clouds are present is synthetized and used as the ML model input. As the outputs of the ML model are the AOD and AE, the ML find a hidden relationship between these quantities and provide a useful prediction method. Finally, 2 years dataset has been used to test the method considering different atmospheric conditions related to the presence of clouds and aerosols, according to their amount and type. Since we used a GPR as ML model, we took advantage of the statistically propagated uncertainty the model relates to the outputs to give a proxy of an error of measurement to the predicted quantities. We also used these uncertainties to develop a method that evaluate the quality of predictions themselves. This quality assurance method may be fine-tuned according to the desired accuracy based on the application for which it is intended. Our AOD and AE predictions show an excellent overall agreement with AERONET measurements that substantially improves when our quality assurance method is applied. In that case, we obtain a high degree of correlation (R2 >0.97) and an overall MAE lower than the nominal uncertainty of AERONET measurements (0.006 and 0.05 for AOD and AE, respectively). Moreover, more than 83% and 77% of the predictions fall within the nominal uncertainty associated with AERONET measurements for AOD and AE, respectively. A comprehensive sensitivity analysis of the factors affecting the performance of the proposed methodology confirms that our method is stable and not very sensitive to external and methodological factors, especially when we apply quality assurance criteria. All this supports that our methodology is a reliable alternative to retrieve the optical properties of aerosols independently of the cloud conditions. Our results may contribute to the operational use of all-sky cameras, which may be an interesting complement regarding the study of aerosol-cloud interactions in partially cloud scenarios.
How to cite: Scarlatti, F., Gómez-Amo, J. L., C. Valdelomar, P., Matos, V., Estelles, V., and Utrillas, M. P.: Aerosol properties retrieval in partially cloud conditions using HDR All-Sky imagery, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1049, https://doi.org/10.5194/ems2024-1049, 2024.
Desert dust, as the most abundant aerosol type in the atmosphere, plays an important role in Earth’s climate and weather by influencing the radiation balance. The direct radiative effect of dust involves the scattering and absorption of both solar and thermal radiation; however, the net contribution of dust to radiative forcing remains quite uncertain [1]. This depends on the properties of the dust particles such as their size and composition (mineralogy), which in turn are related to their origin and to any changes they undergo (e.g., mixing) during their transport. The characterization of dust properties is therefore very important and requires the observation of its optical and microphysical properties across the atmospheric column using remote sensing techniques [2].
The present study focuses on the Mediterranean region, one of the major climate change hotspots globally. Its proximity to the most important sources of dust on the planet (i.e., Sahara Desert and Middle East) results in frequent dust episodes throughout the year. The Italian peninsula offers an advantage for such studies due to its central location within the Mediterranean basin and the extensive network of stations that hosts, which carry out systematic measurements of aerosol properties [3]. In this study, we used quality assured (level 2.0) AERONET data [4] from the last twenty years and, by applying aerosol typing methods, we identified dust outbreaks that affected several AERONET sites across the country. Then, we used dust-related profiles retrieved from EARLINET/ACTRIS observations [5, 6] and the MONARCH dust reanalysis [7] to detect the dust layers over the stations, and we estimated the origin and route of the air mass from the back trajectories of the HYSPLIT model [8]. Finally, we investigated how the dust optical and microphysical properties differ depending on the source of origin and the transport route.
Acknowledgements
The CNR-IMAA co-authors acknowledge the IR0000032 – ITINERIS, Italian Integrated Environmental Research Infrastructures System (D.D. n. 130/2022 - CUP B53C22002150006) funded by EU - Next Generation EU PNRR- Mission 4 “Education and Research” - Component 2: “From research to business” - Investment 3.1: “Fund for the realisation of an integrated system of research and innovation infrastructures”.
They also acknowledge the ACTRIS-IT (Aerosol, Clouds and Trace Gases Research Infrastructure - Italian contribution) funded by the MUR (Italian Ministry of University and Research).
The authors acknowledge the Action Harmonia CA21119 supported by COST (European Cooperation in Science and Technology).
References
[1] Myhre et al., https://doi.org/10.1017/CBO9781107415324.018, 2013
[2] Mona et al., https://doi.org/10.1175/BAMS-D-23-0005.1, 2023
[3] https://itineris.cnr.it/
[4] https://aeronet.gsfc.nasa.gov/
[5] https://www.earlinet.org/
[6] https://www.actris.eu/
[7] Di Tomaso et al., https://doi.org/10.5194/essd-14-2785-2022, 2022
[8] https://www.ready.noaa.gov/HYSPLIT.php
How to cite: Mytilinaios, M., Amodeo, A., De Rosa, B., Papagiannopoulos, N., Papanikolaou, C.-A., Aslanoglu, Y., Chadoulis, R.-T., Charalampous, G., Fountoulakis, I., Kouklaki, D., Moustaka, A., Papetta, A., Solomos, S., and Mona, L.: Study of optical and microphysical properties of atmospheric desert dust observed over the Italian peninsula by remote sensing techniques, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-899, https://doi.org/10.5194/ems2024-899, 2024.
Lunar photometry is an emerging technique capable of filling the gaps in aerosol monitoring at night-time. This is particularly crucial in high latitudes and polar regions due to the prolonged absence of solar illumination. One of the most principal obstacles we encounter in monitoring aerosols at night-time using the Moon as a light source is the need for accurate extraterrestrial lunar irradiance due to the fast change of the Moon’s illumination over time. The RIMO (ROLO Implementation for Moon's Observation; Barreto et al., 2019) model is an implementation of the ROLO (RObotic Lunar Observatory) model. RIMO was performed by the polar aerosol community to estimate the AOD at night-time, transferring the calibration of the solar channels to nocturnal measurements by means of the Sun-Moon gain factor method. A further correction of the RIMO model, the so-called RIMO correction factor (RCF), has served to improve the accuracy of the lunar product (Román et al., 2020). Similar approaches to correct the ROLO or RIMO biases have been developed by AERONET and Skynet teams (Uchiyama et al., 2019).
In this study, we will use an 11-month dataset of day- and night-time photometric measurements taken with the CE318-T photometer at Roque de Los Muchachos (La Palma, Canary Islands, Spain). This high-altitude observatory (2396 m above sea level) is an excellent location for astronomy and atmospheric observations. Day and night photometer observations performed at this pristine site are used to study and evaluate the differences between the AOD retrieved with the CE318-T photometer using RCF and AERONET lunar products.
Acknowledgments: This article/publication is based upon work from COST Action Harmonia CA21119, supported by COST (European Cooperation in Science and Technology). The authors would like to thank the NASA-AERONET network, AEROSPAIN Central Facility (https://aerospain.aemet.es/) and ACTRIS (grant agreement No 871115) to ensure the calibration of the sun photometers.
References:
Barreto et al.: Evaluation of night-time aerosols measurements and lunar irradiance models in the frame of the first multi-instrument nocturnal intercomparison campaign, Atmospheric Environment, Volume 202, Pages 190-211, ISSN 1352-2310, https://doi.org/10.1016/j.atmosenv.2019.01.006, 2019.
Uchiyama et al.: Nocturnal aerosol optical depth measurements with modified sky radiometer POM-02 using the moon as a light source, Atmos. Meas. Tech., 12, 6465–6488, https://doi.org/10.5194/amt-12-6465-2019, 2019.
Román et al.: Correction of a lunar-irradiance model for aerosol optical depth retrieval and comparison with a star photometer,, Atmos. Meas. Tech., 13, 6293–6310, https://doi.org/10.5194/amt-13-6293-2020, 2020.
How to cite: Barreto, Á., Román, R., Balotti, A., Frangipani, C., Gamonal, M. Á., González-Fernández, D., González-Sicilia, P., Karanikolas, A., Pulimeno, S., Busschots, C., and Kazadzis, S.: Nocturnal Aerosol Monitoring at Roque de los Muchachos high-altitude station: Lunar Product Comparison, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-1045, https://doi.org/10.5194/ems2024-1045, 2024.
The improved Langley method (ILP) is an in-situ calibration method developed for Prede POM Sun/sky radiometers. The so-obtained calibration is used to retrieve the aerosol optical depth (AOD) in SKYNET from direct irradiance data, and other optical properties. As opposed to the standard Langley method where we need a pristine high-altitude site to calculate calibration value, ILP is used at any site with varying aerosol optical depth. In the ILP, the Skyrad pack 4.2 version has been used for years to invert the radiance data, followed by strict screening criteria to derive the calibration. In the process of performing ILP, radiance data between the scattering angle of 3o-30o is selected. From the previous studies, it is well established that the ILP has weak dependence on imaginary refractive index and Single Scattering Albedo (SSA) in this range, whereas ILP has major dependence on real refractive index. Apart from this, it is also assumed that the refractive index remains almost constant during the period of observation.However, this assumption is not always respected in real conditions. With the change of seasons, the observation sites can face different weather and atmospheric situations. For sites like Valencia (Spain), which is affected by urban pollution but also dust intrusions during summer, the type of dominant aerosol can change during the observation time. In the present study, we aim to check the dependencies of ILP method, by using multiyear data of POM01 and POM02 instruments located at Valencia. The idea behind this is to use different assumptions of real, imaginary refractive index instead of fixed values. In previous analysis of this kind, assumed values were changed keeping the other inputs constant. However, we plan to do this sensitivity analysis by using different combinations of the input values. Other strategies will be also explored in order to estimate more accurate calibrations, as calibration transfers from pre and post calibrated Cimel instruments, belonging to AERONET, to be used as reference. Improving the accuracy in calibration value will help us in reducing the uncertainity associated with the calculation of aerosol properties in the SKYNET network.
Keywords: Improved Langley Plot, Calibration, SKYNET
Acknowledgements: The current analysis has been done in the frame of the COST Action CA21119 HARMONIA, supported by COST (European Cooperation in Science and Technology). The Spanish Ministry of Economy and Competitiveness also fund the research through project PID2022-138730OB-I00, PID2021-123881OB-I00, TED2021-129185B-I00 and the Valencian Autonomous Government project AICO/2021/341. The participation of G. Kumar has been supported by the Santiago Grisolia program fellowship GRISOLIAP/2021/048. We thank AERONET, PHOTONS and SKYNET for their scientific and technical support
How to cite: Kumar, G., Momoi, M., Campanelli, M., Estellés, V., and Garcia, M.: Upgrade and assessment of the on-site calibration methods used in SKYNET, EMS Annual Meeting 2024, Barcelona, Spain, 1–6 Sep 2024, EMS2024-998, https://doi.org/10.5194/ems2024-998, 2024.
