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.

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. GRASP_pac 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 (β_aer) profiles obtained by GRASP_pac 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 β_aer profiles measured during daytime at the aeroogical station of MeteoSwiss at Payerne (Switzerland) between 2017 and 2019 were used for this comparison.

GRASP_pac 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 GRASP_pac 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 1^ox1^o 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.