GI4.2 | Lidar remote sensing of the atmosphere
EDI

This session invites contributions on the latest developments and results in lidar remote sensing of the atmosphere, covering • new lidar techniques as well as applications of lidar data for model verification and assimilation, • ground-based, airborne, and space-borne lidar systems, • unique research systems as well as networks of instruments, • lidar observations of aerosols and clouds, thermodynamic parameters and wind, and trace-gases. Atmospheric lidar technologies have shown significant progress in recent years. While, some years ago, there were only a few research systems, mostly quite complex and difficult to operate on a longer-term basis because a team of experts was continuously required for their operation, advancements in laser transmitter and receiver technologies have resulted in much more rugged systems nowadays, many of which are already operated routinely in networks and several even being fully automated and commercially available. Consequently, also more and more data sets with very high resolution in range and time are becoming available for atmospheric science, which makes it attractive to consider lidar data not only for case studies but also for extended model comparison statistics and data assimilation. Here, ceilometers provide not only information on the cloud bottom height but also profiles of aerosol and cloud backscatter signals. Scanning Doppler lidars extend the data to horizontal and vertical wind profiles. Raman lidars and high-spectral resolution lidars provide more details than ceilometers and measure particle extinction and backscatter coefficients at multiple wavelengths. Other Raman lidars measure water vapor mixing ratio and temperature profiles. Differential absorption lidars give profiles of absolute humidity or other trace gases (like ozone, NOx, SO2, CO2, methane etc.). Depolarization lidars provide information on the shapes of aerosol and cloud particles. In addition to instruments on the ground, lidars are operated from airborne platforms in different altitudes. Even the first space-borne missions are now in orbit while more are currently in preparation. All these aspects of lidar remote sensing in the atmosphere will be part of this session.

Co-organized by AS5/CL5
Convener: Andreas Behrendt | Co-conveners: Paolo Di Girolamo, Silke GrossECSECS, Joelle BuxmannECSECS
Orals
| Thu, 27 Apr, 08:30–12:30 (CEST)
 
Room G2
Posters on site
| Attendance Thu, 27 Apr, 14:00–15:45 (CEST)
 
Hall X4
Orals |
Thu, 08:30
Thu, 14:00

Orals: Thu, 27 Apr | Room G2

Chairpersons: Andreas Behrendt, Paolo Di Girolamo, Silke Gross
08:30–08:35
WaLiNeAs - Assimilation of Water Vapor Lidar Data
08:35–08:55
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EGU23-14747
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GI4.2
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solicited
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On-site presentation
Cyrille Flamant and the WaLiNeAs Team

Extreme heavy precipitation events (HPEs) pose a threat to human life but, despite regular improvement, remain difficult to predict because of the lack of adequate high frequency and high-resolution water vapor (WV) observations in the low troposphere (below 3 km). To fill this observational gap, The Water vapor Lidar Network Assimilation (WaLiNeAs) initiative aims at implementing an integrated prediction tool (IPT), coupling network measurements of WV profiles, and a numerical weather prediction system to try to improve the  forecasts of  the amount, timing, and location of rainfall associated with HPEs in southern France (struck by ~ 7 HPEs per year on average during the fall).

In the fall/winter of 2022-2023, a network of 6 mobile Raman WV lidars was specifically implemented in Southern France (Aude, Gard, Var and Bouche du Rhone) and in Corsica. The network was complemented by 2 fixed Raman WV lidars in Barcelona and Valencia with the aim to provide measurements with high vertical resolution and accuracy to be assimilated in the French Application of Research to Operations at Mesoscale (AROME-France) model, using a four-dimensional ensemble-variational approach with 15-min updates in addition to the observations operationally assimilated (radar, satellites, …). This innovative IPT is expected to enhance the model capability for kilometer-scale prediction of HPEs over southern France up to 48 h in advance.

The field campaign was conducted from October of 2022 to January 2023, to cover the period most propitious to heavy precipitation events in southern France. A consortium of French, German, Italian, and Spanish research groups operated the Raman WV lidar network

In this presentation, we will provide an overview of the precipitation events in southern France during the WaLiNeAs campaign, as well as an outline of the operations period of the different Raman WV lidars and the lidar data monitoring procedure implemented during the experiment. We will highlight the cases of interest and provide an outlook at next steps towards lidar data assimilation in AROME.

How to cite: Flamant, C. and the WaLiNeAs Team: A network of water vapor Raman lidars for improving heavy precipitation forecasting in southern France: introducing the WaLiNeAs initiative and first highlights from the 2022 field campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14747, https://doi.org/10.5194/egusphere-egu23-14747, 2023.

08:55–09:05
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EGU23-8149
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GI4.2
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ECS
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On-site presentation
Frédéric Laly, Patrick Chazette, Julien Totems, and Jérémy Lagarrigue

The Mediterranean Rim, and more particularly the western Mediterranean area, is one of the most sensitive regions to climate change. The associated environmental changes are already evident through periods of drought and intense rainfall. The predictions of these phenomena are a major societal issue, which led us to use lidar systems to constrain regional modelling. The Raman lidars HORUS-1 and -2 are each composed of two telescopes of 15 cm diameter.  For each telescope N2 and H2O channels are associated. Lidars components have been specifically defined for this task and put into operation during the international Water vapor Lidar Network Assimilation (WaLiNeAs) campaign led by French research teams. Among the three stations managed by the LSCE team, two of them were equipped with HORUS lidar systems at the Port Camargue (43.52 N 4.13 E) and Coursan (43.23 N 3.06 E) sites. The main difference between the two HORUS lidars is the laser used. For HORUS-1 we used an ULTRA laser (optimally pumped by a flash lamp at 30 mJ/20Hz) which showed a good reliability since the beginning of the lidar installation. However, the MERION-C laser (optimally pumped by diodes at 30 mJ/100 Hz) installed in HORUS-2 did not live up to our expectations with several failures, to the point of stopping the measurements in Coursan. We will nevertheless discuss the relative interest of these two lasers in projection of future Raman lidar networks. Observations available from these two lidar systems will be presented and discussed with respect to the meteorological processes encountered during their operating periods.

We give a special acknowledgment to the ANR grant #ANR-20-CE04-0001 for the contribution to the WaLiNeAs program and a special acknowledgment to Meteo France and to the CNRS INSU national LEFE program for their financial contribution for this project. The CEA is acknowledged for the provision of its staff and facilities.

How to cite: Laly, F., Chazette, P., Totems, J., and Lagarrigue, J.: Water vapor retrieval from mini Raman lidar HORUS in the framework of the WaLiNeAs campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8149, https://doi.org/10.5194/egusphere-egu23-8149, 2023.

09:05–09:15
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EGU23-10606
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GI4.2
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On-site presentation
Diego Lange, Andreas Behrendt, and Volker Wulfmeyer

Since there are only a very few suitable remote sensing measurements, the thermodynamic field of the atmospheric boundary layer and lower free troposphere is largely still Terra Incognita. To close this gap, we developed an automated thermodynamic profiler based on the Raman lidar technique, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS) (Lange et al. 2019).

It uses only the ice-safe 355-nm radiation of an injection-seeded Nd:YAG laser as transmitter. The laser power is about 20 W at 200 Hz. The diameter of the receiving telescope is 40 cm. Four receiving channels (elastic, water vapor, two rotational Raman signals) allow for four independently measured parameters: temperature (T), water vapor mixing ratio (WVMR), particle extinction coefficient, and particle backscatter coefficient.

With these data, ARTHUS resolves, e.g., the strength of the inversion layer at the atmospheric boundary layer (ABL) top, elevated lids in the free troposphere, and turbulent fluctuations. Furthermore, in combination with Doppler lidars, sensible and latent heat flux profiles in the convective ABL and thus flux-gradient relationships can be studied (Behrendt et al. 2020). Consequently, ARTHUS can be applied for process studies of land-atmosphere feedback, weather and climate monitoring, model verification, and data assimilation.

Resolutions of the measurements are a few seconds and meters in the lower troposphere. With the data, also the statistical uncertainties of the measured parameters are derived. Continuous operations over long periods were achieved not only at the Land Atmosphere Feedback Observatory (LAFO) at University of Hohenheim but also during several field campaigns elsewhere covering a large variety of atmospheric conditions.

During the EUREC4A field campaign (Stevens et al, 2020), ARTHUS was deployed onboard the research vessel Maria S Merian between 18 January and 18 February 2020 to study ocean-atmosphere interaction. Here, ARTHUS was collocated with two Doppler lidars: one in vertically pointing mode and one in a 6-beam scanning mode.

Between 15 July and 20 September 2021, ARTHUS was deployed at the Lindenberg Observatory of the German Weather Service (DWD). The objective of the campaign was to investigate the long-term stability of ARTHUS by comparisons with four local radiosondes. Indeed, the very high accuracy during day and night were verified.

ARTHUS participated in WaLiNeAs (Water Vapor Lidar Network Assimilation) between 15 September and 10 December 2022. For this campaign, ARTHUS was deployed at the west coast of Corsica. The objective was to implement an integrated prediction tool to enhance the forecast of heavy precipitation events in southern France, primarily demonstrating the benefit of assimilating vertically resolved WVMR lidar data in the new version of the French operational AROME numerical weather prediction system.

At the conference, highlights of ARTHUS’ measurements during WaLiNeAs will be shown.

References:

Behrendt et al. 2020, https://doi.org/10.5194/amt-13-3221-2020

Lange et al. 2019, https://doi.org/10.1029/2019GL085774

Stevens et. al. 2021, https://doi.org/10.5194/essd-2021-18

How to cite: Lange, D., Behrendt, A., and Wulfmeyer, V.: The Atmospheric Raman Temperature and Humidity Sounder: Highlights of Four Years of Automated Measurements of the Atmospheric Boundary Layer and Free Troposphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10606, https://doi.org/10.5194/egusphere-egu23-10606, 2023.

09:15–09:20
Water Vapor & Temperature
09:20–09:30
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EGU23-13101
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GI4.2
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On-site presentation
Hannes Vogelmann, Maria Federer, Johannes Speidel, and Alexander Gohm

A newly available Raman lidar (Purple Pulse Lidar Systems) for vertical profiling of atmospheric water vapor, temperature and aerosols was evaluated during the TEAMx pre-campaign (TEAMx-PC22) in summer 2022 in the Inn Valley (Austria). TEAMx (Multi-scale transport and exchange processes in the atmosphere over mountains – programme and experiment) is an international research program addressing exchange processes in the atmosphere over mountains and their parametrization in numerical weather models and climate models. Prior to the multi disciplinary measurement campaign, planned in 2024/2025, the pre-campaign 2022 was rather performed for testing (new) instruments and measurement sites and finding synergies between certain devices.

The Raman lidar system is capable of profiling water vapor and temperature throughout the entire planetary boundary layer (typically 3 km to 4 km agl. on summer days) continuously with a basic temporal resolution of 10 s and a reasonable vertical resolution of 30 m to 100 m. Depending on conditions and temporal averaging, water vapor profiles could even be obtained up to ~7.5 km agl. during nighttime. The lidar system was located at the University of Innsbruck (downtown). It was operated side by side with a vertically staring Doppler wind lidar and a nearby (50 m) scanning Doppler wind lidar on the rooftop of the university building, which provide vertical profiles of the vertical wind component at a 1-s interval and vertical profiles of the three-dimensional wind vector at a 10-min interval, respectively. During the measurement period (Aug 2022 to Sep 2022), operational radiosondes were launched in close proximity, at Innsbruck Airport, roughly 3 km to the west of the lidar site. In addition to the daily ascent at 2 UTC, radiosondes were launched at about 8, 14 and 20 UTC on selected days with potentially complex meteorological conditions. We present a first assessment of the Raman lidar measurements through comparisons with the radiosonde data. Together with data from the wind lidars, we also present an interpretation for significant meteorological situations and events, such as foehn, a passing front, a thunderstorm and the formation of a convective boundary layer during a warm period.

How to cite: Vogelmann, H., Federer, M., Speidel, J., and Gohm, A.: Assessing the performance of a Combined Water Vapor / Temperature / Aerosol Raman Lidar within the TEAMx pre-campaign in the Inn Valley (Innsbruck, Austria) during Summer 2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13101, https://doi.org/10.5194/egusphere-egu23-13101, 2023.

09:30–09:40
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EGU23-2024
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GI4.2
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On-site presentation
Martin Wirth and Silke Groß

Ice clouds in the Arctic are expected to have different radiative properties compared to mid latitude cirrus, because of the different humidity and temperature profile and also the prevalent aerosol loading in northern latitudes which govern their formation. During the late winter and early spring 2022 the HALO-(AC)3 campaign was conducted out of Kiruna (Sweden) to probe artic clouds with an airborne remote sensing payload. For this purpose, the German research aircraft HALO was equipped with a water vapor Differential Absorption Lidar (DIAL), a cloud radar, micro-wave radiometers, radiation measurements in the visible, near infrared and thermal region and a drop-sonde dispenser. A total of 25 flights where performed mainly over the sea between Svalbard and Greenland and up to nearly 90°N.

The primary observable to study ice cloud formation is the relative humidity, which is not directly measurable by lidar, but can only be computed with the aid of additional temperature information. By comparison with a large number of dropsondes launched during flight, we will show that the temperature field from ECMWF IFS analyses and short-term forecasts provides sufficient accuracy to retrieve the relative humidity for ice cloud studies. Using this method we will analyse different scenarios of arctic cirrus formation: under stable artic conditions, during a warm air intrusion and while a cold air outbreak. An interesting special case is the modification of cirrus properties by the presence of an aerosol layer which is most probably composed of long range transported Sharan dust. 

How to cite: Wirth, M. and Groß, S.: Characterisation of Arctic Cirrus by Airborne Water Vapor and High Spectral Resolution Lidar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2024, https://doi.org/10.5194/egusphere-egu23-2024, 2023.

Mixing Layer Height Determination
09:40–09:50
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EGU23-135
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GI4.2
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ECS
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On-site presentation
Jasper Wijnands, Arnoud Apituley, Diego Alves Gouveia, and Jan Willem Noteboom

The mixing layer height (MLH) indicates the change between vertical mixing of air near the surface and less turbulent air above. MLH is important for the dispersion of air pollutants and greenhouse gases, and assessing the performance of numerical weather prediction systems. Existing lidar-based MLH detection algorithms typically do not use the full resolution of the ceilometer, require manual feature engineering, and often do not enforce temporal consistency of the MLH profile. Given the large-scale availability of lidar remote sensing data and the high temporal and spatial resolution at which it is recorded, this domain is very suitable for machine learning approaches such as deep learning. This presentation introduces a completely new approach to estimate MLH: the Deep-Pathfinder algorithm, based on deep learning techniques for image segmentation.

The concept of Deep-Pathfinder is to represent the 24-hour MLH profile as a mask (i.e., black indicating the mixing layer, white indicating the non-turbulent atmosphere above) and directly predict the mask from an image with lidar observations. Range-corrected signal (RCS) data at 12-second temporal and 10-meter vertical resolution was obtained from Lufft CHM 15k ceilometers at five locations in the Netherlands (2020–2022). High-resolution annotations were created for 50 days, informed by a visual inspection of the RCS image, the manufacturer's layer detection algorithm, gradient fields, thermodynamic MLH estimates, and humidity profiles of the 213-meter mast at Cabauw.

Our model is based on a customised U-Net architecture with MobileNetV2 encoder to ensure fast inference times. A nighttime variable indicated whether the sample occurred between sunset and sunrise and hence, whether an estimate of the stable or convective boundary layer was required. Model calibration was performed on the Dutch National Supercomputer Snellius. First, input samples were randomly cropped to 224x224 pixels, covering a 45-minute period and maximum altitude of 2240 meters. Then, the model was pre-trained on 19.4 million samples of unlabelled data. Finally, the labelled data was used to fine-tune the model for the task of mask prediction. Performance on a test set was compared to MLH estimates from ceilometer manufacturer Lufft and the STRATfinder algorithm.

Results showed that days with a clear convective boundary layer were captured well by all three methods, with minimal differences between them. The Lufft wavelet covariance transform algorithm contained a slight temporal shift in MLH estimates. Further, it had more missing data in complex atmospheric conditions. STRATfinder estimates for the nocturnal boundary layer were consistently low due to guiding restrictions in the algorithm. In contrast, Deep-Pathfinder followed short-term fluctuations in MLH more closely due to the use of high-resolution input data. Path optimisation algorithms like STRATfinder have good temporal consistency but can only be evaluated after a full day of ceilometer data has been recorded. Deep-Pathfinder retains the advantages of temporal consistency by assessing MLH evolution in 45-minute samples, however, it can also provide real-time estimates. This makes a deep learning approach as presented here valuable for operational use, as real-time MLH detection better meets the requirements of users in aviation, weather forecasting and air quality monitoring.

How to cite: Wijnands, J., Apituley, A., Alves Gouveia, D., and Noteboom, J. W.: Deep-Pathfinder: A machine learning algorithm for mixing layer height detection based on lidar remote sensing data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-135, https://doi.org/10.5194/egusphere-egu23-135, 2023.

Aerosols
09:50–10:00
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EGU23-4339
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GI4.2
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On-site presentation
Simone Lolli, Adolfo Comeron, Cristina Gíl-Diaz, Tony Landi, Constantin Munoz-Porcar, Daniel Oliveira, Alejandro Rodriguez-Gomez, Michael Sïcard, Andrés Alastuey, Xavier Querol, and Cristina Reche

In the last two decades, several scientific studies have highlighted the adverse effects, primarily on population health, transportation, and climate, of urban atmospheric particulate due to anthropogenic emissions. For these reasons, aerosols have been monitored through both, remote sensing and in-situ observation platforms, also to establish if the reduction emission policies implemented at the government level have had positive outcomes. In this study, for the first time, we assess how the vertically resolved properties of the atmospheric particulate have changed and consequently their radiative effect during the last twenty years in Barcelona, Spain, one of the largest metropolitan areas of the Mediterranean basin. This study is carried out in the frame of the ACTRIS project through synergy between lidar measurements and the meteorological variables, e.g. wind, temperature, and humidity at the surface. This research, thanks to twenty-year measurements, can shed some light on the meteorological processes and conditions that can lead to haze formation and can help decision-makers to adopt mitigation strategies to preserve large marine Mediterranean metropolitan regions.

How to cite: Lolli, S., Comeron, A., Gíl-Diaz, C., Landi, T., Munoz-Porcar, C., Oliveira, D., Rodriguez-Gomez, A., Sïcard, M., Alastuey, A., Querol, X., and Reche, C.: Climatological assessment of the vertically resolved optical aerosol properties by lidar measurements and their influence on radiative budget over the last two decades at UPC Barcelona, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4339, https://doi.org/10.5194/egusphere-egu23-4339, 2023.

10:00–10:10
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EGU23-7093
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GI4.2
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ECS
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On-site presentation
Marcus Müller, Ulrich Löhnert, and Birger Bohn

In recent years there is a growing interest in real-time aerosol profiling and in this context, the use of automated lidars and ceilometers (ALC) for aerosol remote sensing increased. Ceilometers were originally developed to measure cloud-base height automatically. Apart from this, they also provide vertically resolved backscatter information. Several algorithms have been developed to calibrate this signal and to derive aerosol concentration from it, bringing up new opportunities in air quality monitoring and boundary layer research.

The quality of ALCs is often evaluated by comparing the attenuated backscatter to measurements from high-power lidars. This approach is suitable to validate the backscatter signal. However, for the validation of the aerosol concentration, a direct comparison with an in-situ, optical aerosol measurement is more significant.

In this work, a comparison study was performed using the Jülich Observatory for Cloud Evolution. Data were processed and calibrated with algorithms by E-Profile (https://www.eumetnet.eu/activities/observations-programme/current-activities/e-profile/alc-network/). The aerosol retrieval was performed using a Klett inversion algorithm. Close to the JOYCE site a 120 m meteorological tower is located. This tower was used as a platform for the in-situ aerosol measurement, where an optical particle sizer was mounted 100 m above the ceilometer position.

We will show the setup and data processing of the in-situ measurements as well as an approach how ceilometer raw data can be processed, calibrated and used to retrieve aerosol concentration. First results of the comparison will be presented to evaluate the quality of ALC aerosol-measurement.

How to cite: Müller, M., Löhnert, U., and Bohn, B.: Ceilometer aerosol retrieval and comparison with in-situ tower-measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7093, https://doi.org/10.5194/egusphere-egu23-7093, 2023.

10:10–10:15
Coffee break
Chairpersons: Paolo Di Girolamo, Silke Gross, Andreas Behrendt
10:45–10:55
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EGU23-13218
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GI4.2
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ECS
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On-site presentation
Nikolaos Siomos, Ioannis Binietoglou, Peristera Paschou, Mariana Adam, Giuseppe D'Amico, Benedikt Gast, Moritz Haarig, and Volker Freudenthaler

We present newly developed software for the data analysis and quality assurance of lidar systems operated in the ACTRIS (Aerosol Clouds and Trace Gases Research Infrastructure) research infrastructure. The software development is coordinated by the Meteorological Institute of Munich (MIM), which operates as one of the central facilities of the Center of Aerosol Remote Sensing (CARS) of ACTRIS. In the frame of ACTRIS, a large number of national facilities (NF) are operating lidar systems for aerosol remote sensing. In order to ensure homogeneously high data quality, CARS is developing appropriate common software tools to assist data processing, system intercomparison, and routine quality assurance of lidar data. Here, we present two such software tools, developed and tested using the long experience of the EARLINET (European Aerosol Research Lidar Network) community.

The ARC (Algorithm for Rayleigh Calculations) has been designed to calculate the cross-section and depolarization ratio of molecular back-scattering. The effect of Rotational Raman (RR) scattering is included line-by-line in ARC considering especially the partial blocking of the RR spectrum due to transmission through narrow-band interference filters. The algorithm supports calculation in variable meteorological conditions for an atmosphere that consists of up to five major gas components (N2, O2, CO2, Ar, H2O). Such a tool is needed in order to properly take into account the effect of air temperature in the molecular depolarization ratio measured by the NF lidar systems. It is also crucial for designing lidars that rely on RR scattering such as temperature and RR aerosol lidars and can even be applied for the algorithmic correction of unwanted effects introduced by the interference filter in such systems.

The second software package developed by CARS-MIM is ATLAS (AuTomated Lidar Analysis Software). It has been designed for the operational analysis of the quality assurance tests that should be regularly performed and submitted to CARS by the NF for the ACTRIS labeling process. ATLAS currently supports the analysis of all main CARS test procedures, that is, the Rayleigh fit, the Telecover, and the Polarization Calibration. It can also be used to directly compare signals from two lidar systems; It has already been applied in the first intercomparison campaign of CARS reference systems, organized in September 2022 in Magurele, Romania. The software takes raw lidar data as input so the user can detect otherwise-hidden issues in the preprocessing steps. At the time of writing, ATLAS is compatible with all ACTRIS lidar systems. Future updates will include automated syncing of the system metadata from the handbook of instruments of the network, currently hosted by the Single Calculus Chain (SCC), and a graphical user interface that will facilitate its adoption by the NF users. Both software packages are written in python and are open-source projects.

How to cite: Siomos, N., Binietoglou, I., Paschou, P., Adam, M., D'Amico, G., Gast, B., Haarig, M., and Freudenthaler, V.: ARC and ATLAS: CARS software tools for the data analysis and quality assurance of lidar measurements performed within ACTRIS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13218, https://doi.org/10.5194/egusphere-egu23-13218, 2023.

10:55–11:05
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EGU23-13419
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GI4.2
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ECS
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Virtual presentation
Benedetto De Rosa, Lucia Mona, Simone Lolli, Aldo Amodeo, and Michalis Mytilinaios

The uncertainties of the Earth-atmosphere energy budget are associated with a poor understanding of direct and indirect aerosol effects. Dust is a mixture of different minerals, and its chemical and microphysical properties change during transport. Therefore, the influence of dust aerosols on radiative effects is characterized by great uncertainty. Due to meteorological atmospheric patterns, aerosol intrusions are very frequent in the Mediterranean, which is a climatic hot spot and where climate change is much stronger than in other parts of the world. In this study, we analyzed and assessed long-term trends of the surface and columnar heating rate and the radiative effects of dust aerosols using lidar observations. These measurements were taken in the framework of the European Aerosol Research Lidar Network (EARLINET) at Istituto di Metodologie per l'Analisi Ambientale (IMAA) with the Raman/elastic lidar MUSA (40°36′N, 15°44′E). The radiative transfer model Fu–Liou–Gu (FLG) was used to solve aerosol (no clouds) radiative fluxes, with aerosol extinction coefficient profiles from lidar observations as input data. All the cases of dust intrusion that occurred in the last twenty years were selected to understand how they affected the Earth-atmosphere radiative budget, both at the surface and at the top-of-the-atmosphere. In the future, these studies will be important for improving the accuracy of climate predictions.

How to cite: De Rosa, B., Mona, L., Lolli, S., Amodeo, A., and Mytilinaios, M.: Columnar heating rate and  radiative effects of dust aerosols using 20 years of lidar observations., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13419, https://doi.org/10.5194/egusphere-egu23-13419, 2023.

11:05–11:15
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EGU23-13643
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GI4.2
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ECS
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On-site presentation
Johannes Speidel and Hannes Vogelmann

Precise knowledge about the prevailing aerosol content in the atmosphere is very important for several reasons, as aerosols are involved in multiple important processes that not only have a direct impact on air quality, but also influence cloud formation and the earth's radiation budget. Besides that, continuous aerosol observations provide valuable information on atmospheric transport dynamics.
Aerosol backscatter coefficient measurements with elastic backscatter lidars are conducted since multiple decades [1], while the implemented retrieval algorithms predominantly refer to the seminal publications by Klett 1985, Fernald 1984 and Sasano 1985 [2,3,4]. The respective inversion algorithm is often simply called the 'Klett inversion', being a main reason why this algorithm is most often adapted. While more sophisticated aerosol lidars (e.g. Raman lidars, HSRL, ...) have been developed since, simple elastic backscatter lidar measurements are still very frequently conducted as they are technically easy to implement, often as a byproduct. In most cases, the corresponding retrieval algorithms still refer to the 'Klett inversion'.
Unfortunately, the inversion algorithm by Klett 1985 is afflicted by a sign error. In his publication, the sign error is hidden within a substitute, making it very hard to be recognized, representing a major pitfall. A comprehensive literature review revealed, that large parts of the aerosol lidar community are aware of this problem and have tacitly corrected it or, to a much smaller amount, even referred to an erratum which was published by Kaestner in 1986 [5].
However, at the same time and up to this date, a considerable error propagation can be found in literature as well, using and referring to the incorrect algorithm with the sign error included.
Therefore, we want to renew the awareness towards this sign error and show a corrected and slightly improved Klett inversion algorithm. In addition, we present the overall implication resulting from the uncorrected inversion algorithm by using exemplary case studies. Depending on the lidar location and prevailing atmospheric conditions, potential errors reach from marginal to major, often preventing error detection solely based on the magnitude of the calculated results. Simple a posteriori corrections are not possible, as the error magnitude depends on multiple factors.

[1] T. Trickl, H. Giehl, H. Jäger, and H. Vogelmann. 35 yr of stratospheric aerosol measurements at Garmisch-Partenkirchen: From Fuego to Eyjafjalla-   jökull, and beyond. Atmospheric Chemistry and Physics, 13(10):5205–5225, 2013.
[2] James D. Klett. Lidar inversion with variable backscatter/extinction ratios. Appl. Opt., 24(11):1638–1643, June 1985.
[3] Frederick G. Fernald. Analysis of atmospheric lidar observations: Some comments. Appl. Opt., 1984.
[4] Yasuhiro Sasano, Edward V. Browell, and Syed Ismail. Error caused by using a constant extinction/backscattering ratio in the lidar solution. Appl. Opt., 24(22):3929–3932, November 1985.
[5] Martina Kaestner. Lidar inversion with variable backscatter/extinction ratios: Comment. Applied Optics, 25(6):833–835, March 1986.

How to cite: Speidel, J. and Vogelmann, H.: Is your aerosol backscatter retrieval afflicted by a sign error?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13643, https://doi.org/10.5194/egusphere-egu23-13643, 2023.

11:15–11:25
Nitrous Oxide & Carbon Dioxide
11:25–11:35
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EGU23-7065
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GI4.2
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On-site presentation
Christoph Kiemle, Christian Fruck, and Andreas Fix

Nitrous Oxide, N2O, is the third most important GHG contributing to human-induced global warming, after carbon dioxide and methane. Its growth rate is constantly increasing and its global warming potential is estimated to be 273 times higher than that of CO2 over 100 years. The major anthropogenic source is nitrogen fertilization in croplands. Soil N2O emissions are increasing due to interactions between nitrogen inputs and global warming, constituting an emerging positive N2O-climate feedback. The recent increase in global N2O emissions exceeds even the most pessimistic emission trend scenarios developed by the IPCC, underscoring the urgency of mitigating N2O emissions (Global Carbon Project, 2020). Estimating N2O emissions from agriculture is inherently complex and comes with a high degree of uncertainty, due to variability in weather and soil characteristics, in agricultural management options and in the interaction of field management with environmental variables. Further sources of N2O are processes in the chemical industry and combustion processes. The sink of N2O in the stratosphere increases the NOx concentration which catalytically depletes ozone. Better N2O measurements thus are urgently needed, particularly by means of remote sensing.

Airborne or satellite based N2O lidar remote sensing combines the advantages of high measurement accuracy, large-area coverage and nighttime measurement capability. Past initial feasibility studies revealed that Integrated-Path Differential-Absorption (IPDA) lidar providing vertical column concentrations of N2O would be the method of choice. In this current study we use the latest HITRAN spectroscopic data in order to identify appropriate N2O absorption lines in the wavelength region between 2.9 and 4.6 µm. The infrared spectral region challenges both lidar transmission and detection options. On the transmitter side, the use of optical parametric conversion schemes looks promising, while HgCdTe avalanche photodiode (APD), superconducting nanowire single-photon (SNSPD) or upconversion detectors (UCD) could offer high-efficiency low-noise signal detection. These options are implemented into a lidar simulation model in order to identify the optimal lidar system configuration for measuring N2O from aircraft or satellite using state-of-the-art technology.

How to cite: Kiemle, C., Fruck, C., and Fix, A.: Nitrous Oxide, N2O: Spectroscopic Investigations for Future Lidar Applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7065, https://doi.org/10.5194/egusphere-egu23-7065, 2023.

11:35–11:45
|
EGU23-16149
|
GI4.2
|
ECS
|
On-site presentation
Marco Di Paolantonio, Paolo Di Girolamo, Davide Dionisi, Annalisa Di Bernardino, Tatiana Di Iorio, Noemi Franco, Giovanni Giuliano, Anna Maria Iannarelli, Gian Luigi Liberti, and Donato Summa

Within the frame of the project CONCERNING (COmpact RamaN lidar for Atmospheric CO2 and ThERmodyNamic ProfilING), we investigated the feasibility and the limits of a ground-based Raman lidar system dedicated to the measurement of CO2 profiles. The performance of the lidar system was evaluated through a set of numerical simulations. The possibility of exploiting both CO2 Raman lines of the ν1:2ν2 resonance was explored. An accurate quantification of the contribution of the Raman O2 lines on the signal and other (e.g., aerosol, absorbing gases) disturbance sources was carried out. The signal integration over the vertical and over time required to reach a useful signal to noise ratio both in day-time and night-time needed for a quantitative analysis of carbon dioxide sources and sinks was evaluated. The above objectives were obtained developing an instrument simulator software consisting of a radiative transfer model able to simulate, in a spectrally resolved manner, all laser light interaction mechanisms with atmospheric constituents, a consistent background signal, and all the devices present in the considered Raman lidar experimental setup. The results indicate that the simulated lidar system, provided to have a low overlap height, could perform measurements on the low troposphere (<1 km) gradients (1-5 ppm) with sufficient precision both in day-time and night-time with an integration time of 1-3 h and a vertical resolution of 75 m. The selected Raman lidar setup is currently being tested and we aim to present preliminary results during the conference.

How to cite: Di Paolantonio, M., Di Girolamo, P., Dionisi, D., Di Bernardino, A., Di Iorio, T., Franco, N., Giuliano, G., Iannarelli, A. M., Liberti, G. L., and Summa, D.: Performance Simulation and Preliminary Measurements of a Raman Lidar for the Retrieval of CO2 Atmospheric Profiles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16149, https://doi.org/10.5194/egusphere-egu23-16149, 2023.

11:45–11:50
Satellite Lidars
11:50–12:00
|
EGU23-11893
|
GI4.2
|
On-site presentation
Qiang Li and Silke Groß

Cirrus clouds, forming in the cold upper troposphere, are composed of ice crystals with various sizes and nonspherical shapes. They are observed at all latitudes covering over 30% of the Earth’s surface. Studies reveal that they have a significant impact on the radiation balance of our planet and, consequently, on the climate evolution. The radiative effect of cirrus clouds is strongly determined by the cloud microphysical, thermal, and optical properties. Furthermore, global aviation affects the Earth’s radiation balance by inducing contrails and exerting an indirect effect on the microphysical properties of naturally-formed cirrus clouds. In the last decades, the Arctic surface has been warming faster than other regions of the globe, which is known as Arctic Amplification. The thin and small-coverage cirrus clouds over the Arctic are presumed to largely contribute to it. Unfortunately, however, the optical and microphysical properties of cirrus clouds over the Arctic and the exact role they play in the elevated warming of the Arctic are far from understanding. Compared with the intensive studies of cirrus clouds in the tropics and midlatitude regions, cirrus cloud measurements and model studies at high latitudes are sparse. In this study, we present the comparisons of the particle linear depolarization ratio (PLDR) and occurrence rates of cirrus clouds at midlatitudes (35–60 oN; 30 oW–30 oE) and high latitudes (60–80 oN; 30 oW–30 oE) based on the analysis of lidar measurements of CALIPSO in the years 2018–2021. The results show that cirrus clouds at high latitudes appear at lower altitudes than the midlatitude cirrus clouds. The PLDR and occurrence rates of cirrus clouds at high latitudes are smaller than the midlatitude cirrus clouds. Furthermore, air traffic over Europe was significantly reduced in 2020 (starting from March) and only moderately reduced in 2021 due to the COVID-19 pandemic. Under this condition we are able to study the difference in the aviation impacts on the cirrus cloud properties at high latitudes and midlatitudes.

How to cite: Li, Q. and Groß, S.: CALIPSO observations of cirrus cloud properties: investigation of latitude differences and possible aviation impacts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11893, https://doi.org/10.5194/egusphere-egu23-11893, 2023.

12:00–12:10
|
EGU23-13416
|
GI4.2
|
On-site presentation
Artem Feofilov, Hélène Chepfer, and Vincent Noël

Clouds play an important role for the energy budget of Earth. But, when it comes to predicting the climate's future, their behavior in response to climate change is a major source of uncertainty. To understand and accurately predict the Earth's energy budget and climate, it is necessary to have a thorough understanding of the cloud variability, including their vertical distribution and optical properties.

Satellite observations have been able to provide ongoing monitoring of clouds all around the globe. Among them, active sounders hold a special place thanks to their capability of measuring the vertical position of the cloud with an accuracy of about 100 meters and with a typical horizontal sampling on the order of hundreds of meters. However, clouds retrieved from two spaceborne lidars are different, because the instruments use different wavelengths, pulse energies, pulse repetition frequencies, telescopes, and detectors. In addition, they do not overpass the atmosphere at the same local time.

In this work, we discuss the approach to merging the clouds retrieved from the space-borne lidar ALADIN/Aeolus, which has been orbiting the Earth since August 2018 and operating at 355nm wavelength with the clouds measured since 2006 by CALIPSO lidar, which operates at 532nm.

We demonstrate how to compensate for the existing instrumental differences to get an almost comparable cloud dataset and we discuss the importance of the aforementioned differences between the instruments. The method developed in this study sets the path for adding future lidars (e.g. ATLID/EarthCare) to the global climate lidar cloud record.

How to cite: Feofilov, A., Chepfer, H., and Noël, V.: Merging clouds retrieved from ALADIN/Aeolus and CALIOP/CALIPSO spaceborne lidars, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13416, https://doi.org/10.5194/egusphere-egu23-13416, 2023.

12:10–12:20
|
EGU23-16695
|
GI4.2
|
ECS
|
On-site presentation
Noemi Franco, Paolo Di Girolamo, Donato Summa, Marco Di Paolantonio, and Davide Dionisi

CALIGOLA (Cloud Aerosol Lidar for Global Scale Observations of the Ocean-Land-Atmosphere System) is a mission funded by the Italian Space Agency (ASI), aimed at the development of a space-borne Raman Lidar. A Phase A study to assess the technological feasibility of the laser source and receiver system is currently underway at the Leonardo S.p.A., while scientific studies in support of the mission are conducted by the University of Basilicata. Scientific and technical studies are furthermore supported by other Italian institutions (CNR-ISMAR, CNR-IMAA), with NASA also having expressed an interest in contributing to the mission .

Mission objectives include the observation of the Earth atmosphere, surface (ocean and land). Among the atmospheric objectives, the characterization of the global scale distribution of natural and anthropogenic aerosols, their radiative properties and interactions with clouds, and the measurements of ocean color, suspended particulate matter and marine chlorophyll.

The expected performance of CALIGOLA has been assessed based on the application of an end-to-end lidar simulator. Specifically, sensitivity studies have been carried out to define the technical specifications for the laser source, the telescope, the optics of transceiver, the detectors and the acquisition system. Simulations reveal that the system can measure Rotational Raman echoes from nitrogen and oxygen molecules stimulated at the three lengths wavelength of 355, 532 and 1064 nm. Simulations also reveal that elastic signals are strong enough to meet the requirements under different environmental conditions. As reference signal, several options have been considered. Among others, a temperature-insensitive rotational Raman signal including rotational lines from nitrogen and oxygen molecules.

A careful analysis of different potential orbits is ongoing, with the goal to identify solutions which maximize performance and scientific impact of both atmospheric and oceanic measurements. Near noon-midnight equatorial crossing times are preferable on the ocean side for diel vertical migration and phytoplankton observations, but degrade significantly the performances of atmospheric measurements due to the high solar background. For this reason is essential to find an orbit in which the solar contribution is low enough to obtain acceptable atmospheric results and at the same time the oceanic measurements are far enough from the night-day transitions for as many days a year as possible to assure correct interpretation of phytoplankton physiology. To counterbalance the degraded signal performances also lower obit height are considered, as well as the use of polarized filters to reduce the amount of solar radiation. The estimated performances under different conditions and considering different orbits will be showed during the presentation.

How to cite: Franco, N., Di Girolamo, P., Summa, D., Di Paolantonio, M., and Dionisi, D.: Preliminary Studies and Performance Simulations in support of the mission “CALIGOLA”, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16695, https://doi.org/10.5194/egusphere-egu23-16695, 2023.

12:20–12:30

Posters on site: Thu, 27 Apr, 14:00–15:45 | Hall X4

Chairpersons: Silke Gross, Andreas Behrendt, Paolo Di Girolamo
Aerosols
X4.185
|
EGU23-1387
|
GI4.2
|
ECS
Maria Filioglou, Ari Leskinen, Ville Vakkari, Minttu Tuononen, Xiaoxia Shang, and Mika Komppula

Pollen has important implications for health, but also for the climate as it can act as cloud condensation nuclei or ice nuclei in cloud processing. Active remote sensing instruments equipped with polarization capability can extend the detection of pollen from the surface up to several kilometres in the atmosphere maintaining continuous and high time resolution operation. In this study, we use a synergy of three lidars, namely, a multi-wavelength PollyXT lidar, a Vaisala CL61 ceilometer and a Halo Photonics StreamLine Doppler lidar, to investigate the optical properties of birch pollen particles. All three lidars are equipped with polarization channels enabling the investigation of the wavelength dependence at 355, 532, 910 and 1565 nm. Together with pollen observations from a Hirst-type spore sampler and aerosol in situ observations, we were able to characterize the linear particle depolarization ratio (PDR) and backscatter-related Angstrom exponents of the pollen particles. Both optical properties have been extensively used in aerosol classification algorithms and they are therefore highly desired in the lidar community. We found that birch pollen exhibits a spectral dependence in the PDR, and its classification is feasible when, preferably, two or more polarization wavelengths are available.

How to cite: Filioglou, M., Leskinen, A., Vakkari, V., Tuononen, M., Shang, X., and Komppula, M.: Optical properties of birch pollen using a synergy of three lidar instruments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1387, https://doi.org/10.5194/egusphere-egu23-1387, 2023.

X4.186
|
EGU23-3042
|
GI4.2
Kang-chan Choi and Chang-keun Song

The atmospheric boundary layer is a layer that directly responds to energy emitted or absorbed from the ground into the atmosphere, and is greatly affected by various meteorological factors, which change the concentration of air pollutants. There is generally an inversion layer above the atmospheric boundary layer, so most of the air pollutants emitted by humans cannot escape to the outside of the atmospheric boundary layer and remain there. Ulsan Metropolitan City in Korea is known as the largest industrial city in Korea. These industrial cities generally emit more air pollutants than other cities. Since these air pollutants are greatly affected by the boundary layer, it is important to accurately calculate the height of the boundary layer. In this study, we compare the height of the atmospheric boundary layer based on LiDAR and the height of the atmospheric boundary layer in the Weather Research and Forecasting numerical model, and examine how the height of the atmospheric boundary layer affects the change in the concentration of air pollutants.

How to cite: Choi, K. and Song, C.: Effect of air pollutant concentration according to the height of the Planetary boundary layer in Ulsan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3042, https://doi.org/10.5194/egusphere-egu23-3042, 2023.

X4.187
|
EGU23-12585
|
GI4.2
Rodanthi-Elisavet Mamouri, Dragos Ene, Holger Baars, Ronny Engelmann, Argyro Nisantzi, Maria Prodromou, Diofantos Hadjimitsis, and Albert Ansmann

In the summer of 2021, several wildfires were reported in the south of Turkey, fires that are considered one of the worst in the history of Turkey. Due to atmospheric conditions, the smoke plume travelled south between 27 July to 5 August 2021, and smoke layers arrived above Cyprus. 

In this work, the capabilities of the newly established ERATOSTHENES Centre of Excellence (CoE), to study large-scale atmospheric events is presented. The study is based on the synergistic use of different datasets of remote sensing techniques both from ground and space. The EARLINET multiwavelength-Raman-polarization lidar PollyXT-CYP hosted by the ERATOSTHENES CoE is continuously running since October 2020 in Limassol, and during summer 2021, the lidar observed smoke plumes from these extreme wildfires on the south coast of Turkey.  

The PollyXT-CYP is a key research infrastructure of the Cyprus Atmospheric Remote Sensing Observatory (CARO) of the ERATOSTHENES CoE established through the EXCELSIOR H2020 EU Teaming project coordinated by the Cyprus University of Technology. CARO will consist of two high-tech containers housing the PollyXT-CYP lidar and state-of-the art doppler lidar, cloud radar and radiometric equipment which will be used to measure the air quality, the dust transport, and the cloud properties over Cyprus. The CARO is a planning National Facility of the Republic of Cyprus for Aerosol and Cloud Remote Sensing Observations.

Land cover information which shows the type of burned vegetation is used together with satellite products to capture additionally the burned area and to investigate the carbon monoxide of the smoke plume. The study is focusing on the optical characteristics of the plume, as it was detected by the PollyXT-CYP lidar at Limassol. An intense fresh smoke layer was detected on 28-29 July 2021, at an altitude between 2.5 to 4.0 km, having a volume depolarization ratio of ~15% at 355n and ~20% at 532nm, and lidar ratio of 75-80sr at 355nm and 65-70sr at 532nm.

 

Acknowledgements

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. The PollyXT-CYP was funded by the German Federal Ministry of Education and Research (BMBF) via the PoLiCyTa project (grant no. 01LK1603A). The study is supported by “ACCEPT” project (Prot. No: LOCALDEV-0008) co-financed by the Financial Mechanism of Norway (85%) and the Republic of Cyprus (15%) in the framework of the programming period 2014 - 2021.

How to cite: Mamouri, R.-E., Ene, D., Baars, H., Engelmann, R., Nisantzi, A., Prodromou, M., Hadjimitsis, D., and Ansmann, A.: Investigation of 2021 summer wildfires in the Eastern Mediterranean: The ERATOSTHENES Centre of Excellence capabilities for atmospheric studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12585, https://doi.org/10.5194/egusphere-egu23-12585, 2023.

X4.188
|
EGU23-16192
|
GI4.2
|
ECS
Osama Alnayef, Andreas Behrendt, Diego Lange, Florian Späth, Volker Wulfmeyer, and Syed Abbas

Our research focuses on the vertical transport of aerosol particles, and the properties of these aerosol particles in dependence on relative humidity. For this, we use the synergy of Raman and Doppler lidar systems operated during the Land-Atmosphere Feedback Experiment (LAFE) (see https://www.arm.gov/research/campaigns/sgp2017lafe).

We will present our first results of investigating the aerosol flux. For this, we use the aerosols backscatter coefficient and vertical wind velocity collected with Raman lidar and Doppler lidar.

The LAFE project was executed at the Southern Great Plains (SGP) site of the Atmospheric Radiation Measurement (ARM) program in August 2017 in the USA.  In addition, data collected at the Land-Atmosphere Feedback Observatory (LAFO) at the University of Hohenheim, Germany is used. Results of the combined aerosol backscatter measurements with water-vapor and temperature lidar measurements to detail insights into the relative humidity dependencies on the growth of aerosols.

How to cite: Alnayef, O., Behrendt, A., Lange, D., Späth, F., Wulfmeyer, V., and Abbas, S.: Investigation of Boundary Layer Aerosol Processes with Turbulence-Resolving Lidar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16192, https://doi.org/10.5194/egusphere-egu23-16192, 2023.

Carbon Dioxide
X4.189
|
EGU23-3054
|
GI4.2
|
ECS
Application of the Raman lidar for remote sensing of CO2 VMRs at several CO2 emission source areas.
(withdrawn)
Daewon Kim and Hanlim Lee
X4.190
|
EGU23-11104
|
GI4.2
|
ECS
Luojia Hu, Zhitong Yu, Yan Huang, and Rong Ma

The increasing atmospheric carbon dioxide (CO2) is the most important factor forcing climate change. However, due to lack of observation data about large-scale range-resolved CO2, there remains substantial uncertainty in current global atmospheric CO2 budget, which hinders giving insight into CO2 cycle and modeling its forcing to climate change. Space-based range-resolved differential absorption lidar (range-resolved DIAL), is a promising and powerful means for obtaining large-scale range-resolved CO2 data, but has been rarely studied. Prior to developing spaceborne range-resolved DIAL, a preliminary study on optimization of on/off-line wavelengths must be performed to ensure high signal-to-noise (SNR), high sensitivity to near surface region and minimize the interference of atmospheric factors. This study aims to find the optimum wavelength scenarios in terms of random errors determined by SNR, weighting functions used to assess sensitivity to near-surface region, and systematic errors affected by atmospheric factors. Firstly, we find the optimal on/off-line wavelengths at 1.57μm and 2.05μm, which are widely used and show good results for measuring CO2 concentration, after estimating on-line and off-line wavenumbers separately using evaluation indexes called  and . Furthermore, we get the optimum wavelength scenarios of spaceborne range-resolved DIAL by comparing the random, systematic errors and weighting functions of optimal on-line and off-line wavelengths at 1.57μm and 2.05μm. Results show that the wavelength scenario at 2.05μm is the optimal for spaceborne range-resolved CO2 detection. To satisfy the requirement that the relative random errors are smaller than 0.01 (<1%), systems at 2.05μm wavelength scenario with vertical resolution of 0.5 km, 0.7 km, 0.8 km, 0.9 km separately require that SNR values of on-line wavelength at 0 km height are larger than 10, 9, 8, 7.

How to cite: Hu, L., Yu, Z., Huang, Y., and Ma, R.: Performance Simulation of Spaceborne Range-resolved Differential Absorption Lidar System For CO2 Profile Detection At 1.57μm and 2.05μm Wavelength Scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11104, https://doi.org/10.5194/egusphere-egu23-11104, 2023.

X4.191
|
EGU23-13823
|
GI4.2
|
ECS
Moritz Schumacher, Andreas Behrendt, Diego Lange, and Volker Wulfmeyer

Carbon dioxide (CO2) is one of the most important greenhouse gases and therefore its detailed measurement is of high interest. As the concentration varies significantly with altitude and time, it is desirable to be able to measure vertical CO2 profiles with high temporal resolution. Profiles of high resolution will improve our understanding of atmospheric systems and the impact of the local environment, e.g., due to natural and anthropogenic sources and sinks. The use of these data in data assimilation provides the potential of improving climate models.

For water vapor and temperature the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS) system has proven to be able to provide profiles with high resolution (10-60 s in time and 7.5-100 m vertically) and accuracy in the lower troposphere. Now this successful system will be expanded with a CO2 Raman channel, which is currently in development. After successful integration it will be possible to simultaneously measure CO2, water vapor and temperature profiles. Challenges are the weak signal of the backscattered light due to the low concentration and the small Raman backscatter cross section of CO2.

Further information on the CO2 Raman lidar will be given at the conference.

How to cite: Schumacher, M., Behrendt, A., Lange, D., and Wulfmeyer, V.: Development of a Carbon Dioxide Raman Lidar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13823, https://doi.org/10.5194/egusphere-egu23-13823, 2023.

Wind
X4.192
|
EGU23-3068
|
GI4.2
|
ECS
Yujin Kim, Byung Hyuk Kwon, Jiwoo Seo, Geon Myeong Lee, and KyungHun Lee

Representative meteorological instruments that utilize the Doppler effect include Doppler radar, wind profiler, and wind lidar. The latter two instruments produce a vertical profile of winds in high spatio-temporal resolution, in the atmospheric boundary layer. Wind lidar observes with a vertical resolution of 50 m or less and a temporal resolution in minutes, so it fills the observation gap in the lower layer where the wind profiler misses meteorological data. The wind lidar makes the wind vector using DBS (Doppler Beam Swinging) and VAD (Velocity Azimuth Display) methods. It is known that the wind by the VAD method is more accurate than the wind by the DBS method. The DBS method has the advantage of obtaining a wind profile with a fast scan time. On the other hand, there is a restriction that requires at least two beams including vertical beams (one of the east and west beams, and one of the south and north beams), which causes a decrease in the data acquisition rate. The VAD method was improved to produce more wind vector of the wind profiler as well as the wind lidar, which generally uses 5 beams. First, the Fourier series was estimated with the radial velocity by the DBS method. Next, the wind vector was determined by setting the azimuth interval and applying the radial velocity by the Fourier series to the VAD method. The wind vectors were retrieved at the altitude where the wind was not calculated by the DBS method, and the results of the two methods were consistent at the altitude where the wind was calculated by the DBS and the improved VAD method. In this study, we propose a method to increase the data acquisition rate even if the vertical beam or one of the inclined beams is insufficient.

How to cite: Kim, Y., Kwon, B. H., Seo, J., Lee, G. M., and Lee, K.: Improvement of wind vector retrieval method for increasing data acquisition rate of the wind profiler and the wind lidar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3068, https://doi.org/10.5194/egusphere-egu23-3068, 2023.

X4.193
|
EGU23-8014
|
GI4.2
|
ECS
Jan Froh, Josef Höffner, Alsu Mauer, Thorben Mense, Ronald Eixmann, Gerd Baumgarten, Franz-Josef Lübken, Alexander Munk, Sarah Scheuer, Michael Strotkamp, and Bernd Jungbluth

We present the state of the VAHCOLI (Vertical and Horizontal COverage by Lidar) project for investigating small- to large-scale processes in the atmosphere. In the future, an array of compact lidars with multiple fields of view will allow for measurements of temperatures, winds and aerosols with high temporal and vertical resolution.

Doppler lidars, in particular resonance Doppler lidars, with daylight capability are challenging systems because of the small field of view, spectral filtering and other additional subsystems required compared to observations at night. We developed a universal Doppler lidar platform (~1m3, ~500kg) with all required technologies for automatic operation. The system is capable of studying Mie scattering (aerosols), Rayleigh scattering (air molecules), and resonance fluorescence on free potassium atoms in the middle atmosphere from 5 km to 100 km. Unique spectral methods and narrowband optical components allow precise wind, temperature, and aerosol measurements by studying the Doppler shift and broadening of the scattered signals. The combination of cost-efficient design and fast assembling of such a system allows the construction of a Doppler lidar network with identical units

We will show the latest results and discuss the next scientific and technical steps for network operation and transferring the technology into industry.

How to cite: Froh, J., Höffner, J., Mauer, A., Mense, T., Eixmann, R., Baumgarten, G., Lübken, F.-J., Munk, A., Scheuer, S., Strotkamp, M., and Jungbluth, B.: A compact general-purpose Doppler Lidar for lidar networks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8014, https://doi.org/10.5194/egusphere-egu23-8014, 2023.

X4.194
|
EGU23-15696
|
GI4.2
|
Kevin Wolz, Christopher Holst, Frank Beyrich, and Matthias Mauder

We compare the wind measurements of a virtual tower triple Doppler Lidar setup to those of a sonic anemometer located at a height of 90 m above ground on an instrumented tower and with those of a single Doppler Lidar. The instruments were set up at the boundary-layer field site of the German Meteorological Service (DWD) in July and August of 2020 during the FESST@MOL (Field Experiment on sub-mesoscale spatio-temporal variability at the Meteorological Observatory Lindenberg) 2020 campaign.  The triple Lidar setup was operated in a stare and in a step/stare mode at six heights between 90 and 500 m above ground, while the single Lidar was operated in a continuous scan Velocity-Azimuth-Display (VAD) mode with an azimuthal resolution of around 1.5 ° and a zenith angle of 55.5 °. Overall, both Lidar methods showed a good agreement for the whole study period for different averaging times and scan modes compared to the sonic anemometer. Additionally, we developed and show a new filtering approach based on a Median Absolute Deviation (MAD) filter for the virtual tower setup and compare it to a filtering approach based on a signal-to-noise ratio SNR threshold. The advantage of the MAD filter is that it is not based on a strict threshold but on the MAD of each 30-second period and can, therefore, better adapt to changing atmospheric conditions. In the comparison the MAD filter leads to a greater data availability while upholding similar comparability and bias values between the triple Lidar and sonic anemometer setups. Our results also show that a single Doppler Lidar is a viable method for measuring wind speed and direction with only small disadvantages, at least for measurement heights similar to our investigation and for comparable heterogeneous but flat landscapes.

How to cite: Wolz, K., Holst, C., Beyrich, F., and Mauder, M.: A new filtering approach for multiple Doppler Lidar setups, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15696, https://doi.org/10.5194/egusphere-egu23-15696, 2023.

Water Vapor & Temperature
X4.195
|
EGU23-7775
|
GI4.2
Paolo Di Girolamo, Noemi Franco, Marco Di Paolantonio, Donato Summa, Davide Dionisi, Annalisa Di Bernardino, Anna Maria Iannarelli, and Tatiana Di Iorio

The University of Basilicata, in cooperation with ISMAR-CNR, deployed two compact Raman lidars, namely the system CONCERNING and the system MARCO, in Southern France in the frame of the “Water Vapor Lidar Network Assimilation (WaLiNeAs)” experiment. WaLiNeAs, primarily funded by the “French National Research Agency” (ANR), is an international field experiment aimed at studying extreme precipitation events and improving their predictability through the assimilation of water vapour profile measurements from a network of Raman lidar systems into mesoscale numerical models. The experiment has a specific geographical focus on Southern France. The measurement strategy implies the exploitation of seven Raman lidars along the Mediterranean coasts of Spain and France, capable to provide real-time measurements of water vapour mixing ratio profiles over a three-month period starting on October 1st, 2022.

CONCERNING (COmpact RamaN lidar for Atmospheric CO2 and ThERmodyNamic ProfilING), developed in the frame of a cooperation between University of Basilicata, ISMAR-CNR and University of Rome, is a compact and transportable Raman lidar system designed for long-term all-weather continuous operation, capable to perform high-resolution and accurate carbon dioxide and water vapour mixing ratio profile measurements, together with temperature and multi-wavelength (355, 532 and 1064 nm) particle backscattering/extinction/depolarization profile measurements. The system relies on a 45-cm diameter Newtonian telescope and on a diode-pumped Nd:Yag laser source, capable of emitting pulses at the three traditional wavelengths of this laser source(355, 532 and 1064 nm), with a single pulse energy at 355 nm of 110 mJ and an average emitted power of 11 watts, based on a pulse repetition frequency of 100 Hz.

MARCO (Micropulse Atmospheric Optical Radar for Climate Observations) is also a compact and easily transportable Raman lidar system, developed around a high- frequency laser source (20 kHz), capable to perform 24/7 high-resolution and accurate CO2 and water vapour mixing ratio profile measurements, together with temperature and single-wavelength (355 nm) particle backscattering/extinction/depolarization measurements. In the frame of WaLiNeAs, as a result of the restrictions imposed by air traffic authority in the use of the visible and infrared laser radiation, only the 355 wavelength was exploited in CONCERNING, the temperature channel was not available in MARCO, while the CO2 channels, not needed for the purposes of WaLiNeAs, were temporarily deactivated in both systems.

Both systems have been recently designed and developed and WaLiNeAs represents the first international field deployment for both. CONCERNING was deployed at the University of Toulon in La Garde (Lat.: 43.136040 N, Long.: 6.011650 E, Elev.: 65 m, with continuous measurements since 29 September 2022, i.e. over more than 100 days up to now), while MARCO, was deployed at the Direction de Services Techniques in Port-Saint-Louis-du-Rhône, Camargue (Lat.: 43.392570 N, Long.: 4.813480 E, Elev.: 5 m, with continuous measurements since 19 October 2022, i.e. over more than 80 days up to now). At the time of the submission of this abstract, both system are still operational with a tbc date for the stop of the operation of 31 January 2023. Preliminary results from these two systems will be illustrated and discussed during the Conference.

How to cite: Di Girolamo, P., Franco, N., Di Paolantonio, M., Summa, D., Dionisi, D., Di Bernardino, A., Iannarelli, A. M., and Di Iorio, T.: Several months of continuous operation of two thermodynamic Raman lidars in the frame of WaLiNeAs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7775, https://doi.org/10.5194/egusphere-egu23-7775, 2023.

X4.196
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EGU23-15605
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GI4.2
Andreas Behrendt, Diego Lange, and Volker Wulfmeyer

In this contribution, we will discuss the performance of state-of-the-art automatic temperature and humidity lidar (e.g., Wulfmeyer and Behrendt 2022). As example, we will investigate ARTHUS (Lange et al., 2019), a lidar system developed at University of Hohenheim. This automatic mobile instrument participated in recent years in a number of field campaigns.

ARTHUS technical configuration is the following: A strong diode-pumped Nd:YAG laser is used as transmitter. It produces 200 Hz laser pulses with up to 20 W average power at 355 nm. Only this UV light is sent after beam expansion into the atmosphere so that the system remains eye safe. The atmospheric backscatter signals are collected with a 40 cm telescope. A polychromator extracts the elastic backscatter signal and three inelastic signals, namely the vibrational Raman signal of water vapor, and two pure rotational Raman signals. The detection resolution of these backscatter signals are 1 to 10 s and 3.75 to 7.5 m. All four signals are simultaneously analyzed and stored in both photon-counting (PC) mode and voltage (so-called “analog” mode) in order to make optimum use of the large intensity range of the backscatter signals covering several orders of magnitude.

From these eight primary signals measured by ARTHUS, four independent atmospheric parameters are calculated merging the PC and analog signals: temperature, water vapor mixing ratio, particle backscatter coefficient, and particle extinction coefficient. The temporal resolution of these data is also 1 to 10 s, allowing studies of boundary layer turbulence (Behrendt et al, 2015) and - in combination with a vertical pointing Doppler lidar - sensible and latent heat fluxes (Behrendt et al, 2020).

From the measured number of photon counts in each range bin, the statistical uncertainty of the measured data due to so-called shot-noise can directly be calculated. This value, however, while determining the major part of the uncertainty, does not cover the total uncertainty because additional noise of the analog signals is not included. So the shot-noise uncertainty alone underestimates the uncertainties in the near range where the analog data is used. To solve with this problem, higher-order analyses of the turbulent fluctuations can be performed which allow to determine the total statistical uncertainty of the measurements (Behrendt et al, 2020).

Finally, to investigate the stability of the calibration and thus the accuracy of the measured data, we decided to compare averaged ARTHUS data with local radiosondes. In order to cope with the unavoidable sampling of different air masses between these different instruments, we are investigating the average of a larger number of profiles.  We found that the performance of the measured data of ARTHUS reaches even the stringent requirements of WMO.

The results will be presented at the conference.

 

References:

Behrendt et al. 2015, https://doi.org/10.5194/acp-15-5485-2015

Behrendt et al. 2020, https://doi.org/10.5194/amt-13-3221-2020

Lange et al. 2019, https://doi.org/10.1029/2019GL085774

Wulfmeyer and Behrendt 2022, https://doi.org/10.1007/978-3-030-52171-4_25

How to cite: Behrendt, A., Lange, D., and Wulfmeyer, V.: How good are temperature and humidity measurements with lidar?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15605, https://doi.org/10.5194/egusphere-egu23-15605, 2023.

Turbulent Fluxes
X4.197
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EGU23-15538
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GI4.2
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ECS
Manuel Gutleben and Silke Groß

Each year, during both boreal winter and summer, large amounts of Saharan mineral dust particles get carried westwards over the Atlantic Ocean towards the Caribbean. During their transport, Saharan dust particles can affect the Earth’s radiation budget in different ways. They can either directly scatter, absorb and emit radiation or have an indirect effect by modifying cloud properties through their interactions as cloud condensation nuclei or ice nucleating particles. While during the summer months – the peak season of transatlantic mineral dust transport – the particles are mostly advected in elevated Saharan Air Layers at altitudes of up to 6 km and at latitudes around 15°N, wintertime transport takes place at lower atmospheric levels (<3 km altitude) and lower latitudes. Our recent studies have shown that, during both boreal winter and summer, transported Saharan dust layers are characterized by enhanced concentrations of water vapor compared to the surrounding atmosphere. In this way the dust layers have to potential to modify the radiation budget not only through particle-radiation-interactions, but also through the absorption and emission of radiation by water vapor. This in turn may affect the atmospheric stability and stratification in and around the aerosol layers.

In this study, the turbulent structure as well as the atmospheric stability in and around transported Saharan mineral dust is analyzed and possible differences between summer and wintertime are investigated. Therefore, measurements by both the water vapor and aerosol lidar WALES as well as by dropsondes are studied. They were collected upstream the Caribbean island of Barbados aboard the German research aircraft HALO (High Altitude and Long Range). To identify possible seasonal differences, not only data collected in boreal summer in the framework of the NARVAL-II campaign (August 2016), but also data collected in winter during the EUREC4A research campaign (January & February 2020) are analyzed. During both campaigns several research flights were designed to lead over long-range-transported Saharan mineral dust, thus allowing and in-depth investigation of their properties. The analysis shows that dust layers are highly turbulent and therefore help dust particles to stay airborne for a longer time. Additionally, the dust layers modify the atmospheric stability in a way that the evolution of marine clouds can be affected.

In our presentation, we will give an overview of the performed measurements over long-range-transported Saharan dust layers and present the conducted analyses on atmospheric stability and turbulence from dropsonde measurements and calculated power spectra from lidar data.

How to cite: Gutleben, M. and Groß, S.: Atmospheric turbulence and stability in and around long-range-transported Saharan dust layers as observed by airborne lidar and dropsondes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15538, https://doi.org/10.5194/egusphere-egu23-15538, 2023.

X4.198
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EGU23-15942
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GI4.2
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ECS
Syed Abbas, Andreas Behrendt, Florian Späth, Diego Lange, Osama Alnayef, and Volker Wulfmeyer

Investigating the dynamics of the atmospheric boundary layer (ABL) is essential for studies of air quality, the energy and water cycles and for the improvement of weather and climate models. During daytime in convective conditions, the convective boundary layer (CBL) is formed. Here, we present our approach of how to continuously study CBL characteristics with an improved algorithm including fuzzy logic. The Land-Atmosphere Feedback Observatory (LAFO) of University of Hohenheim consists of two Doppler lidars, a Doppler Cloud Radar, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS), and Eddy covariance stations. These are excellent tools for observing high resolution atmospheric wind profiles, clouds and precipitation events, as well as thermodynamic profiles and surface fluxes. The data are collected at LAFO by operating continuously two Doppler lidars, one in vertical and one in six-beam scanning mode, to obtain vertical and horizontal wind profiles. Both Doppler lidars are operated with resolutions of 1 s and 30 m. The six-beam staring Doppler lidar is used for obtaining time series of turbulent kinetic energy (TKE), momentum flux, TKE dissipation rate and horizontal wind profiles statistics. The vertically staring Doppler lidar is used to compute statistics of higher-order moments of vertical wind fluctuations, the CBL height, and cloud base height. With these data, the land-atmosphere coupling processes and the associated nonlinear feedbacks are investigated as well as their impact on the turbulent structure of the CBL.

We will present analyses of two three-month periods covering different weather conditions: 1 May to 31 July 2021 and 2022.

How to cite: Abbas, S., Behrendt, A., Späth, F., Lange, D., Alnayef, O., and Wulfmeyer, V.: Study of the Atmospheric Boundary Layer and Land-Atmosphere Interaction with Lidars, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15942, https://doi.org/10.5194/egusphere-egu23-15942, 2023.

X4.199
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EGU23-5753
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GI4.2
Donato Summa, Paolo Di Girolamo, Noemi Franco, Ilaria Gandolfi, Marco Di Paolantonio, Marco Rosoldi, Fabio Madonna, Aldo Giunta, and Davide Dionisi

A network of water vapor Raman lidars  WaLiNeas (Lidar Network Assimilation) for improving heavy precipitation forecasting in the Mediterranean Sea has been designed among with the aim of providing water vapor measurements with high spatial-temporal resolution and accuracy, in order to be assimilated into AROME mesoscale models using a four-dimensional ensemble-variational approach with 15-min updates. The CONCERNIG Lidar from University of Basilicata and a Wind Lidar form CNR–IMAA are co-located in the University of Toulone between October 2022 and January 2023 in order to reach the campaign objective. For this scope a of vertical profiles of latent heat flux were obtained  as a  Covariance matrices from vertical wind component (w') and mixing ratio (q') are estimated as a retrieval of a Wind Lidar and Raman Lidar UV respectively.

In this way, a time series of vertical wind profiles from the selected case (31 Oct to 03 Nov) are computed. with temporal resolution Δt = 15 min and vertical resolution Δz = 90 m.  The specific humidity flux < w’ · q’>  [g/kg · m/s] is converted into the flux of latent heat (W/m2) by multiplication with the air density ρ obtained from the radiosonde and the latent heat of vaporization of water Lv. A flux comparison with ground-based water vapour Raman and wind lidar shows agreement within the instruments and the results will be presented during the conference

How to cite: Summa, D., Di Girolamo, P., Franco, N., Gandolfi, I., Di Paolantonio, M., Rosoldi, M., Madonna, F., Giunta, A., and Dionisi, D.: Latent flow measurement by Wind Lidar and Raman Lidar during WaLiNeas campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5753, https://doi.org/10.5194/egusphere-egu23-5753, 2023.