The satellite mission EarthCARE (Earth Cloud, Aerosol, and Radiation Explorer) of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) was successfully launched in May 2024. The satellite has four instruments on board, namely a high-spectral-resolution lidar called ATLID, a Cloud Profiling Doppler Radar (CPR), a Multi-Spectral Imager (MSI), and a Broad-Band Radiometer (BBR). ATLID provides for the first time directly measured profiles of the extinction and backscatter coefficient (and thus lidar ratio) together with the depolarization ratio at 355 nm from space. Since the start of the measurements, several updates in the ESA's processing chain have been made resulting in different baselines of the products. A first homogenized data set for the entire mission duration processed with one algorithm version, namely Baseline BA, was accomplished in September 2025. We used ground-based multiwavelength-Raman-polarization lidars of PollyNET operating in the framework of the Aerosol, Clouds and Trace gases Research Infrastructure (ACTRIS) to discuss the quality of ATLID profiling products based on golden case studies. The PollyNET lidars measure the same geophysical parameter as EarthCARE, namely profiles of the particle backscatter coefficient, the particle extinction coefficient, and the particle linear depolarization ratio at 355 nm. Seven dedicated cases, for which EarthCARE and the ground-based reference system observed the same atmospheric scene, were selected, spanning several atmospheric conditions (ice clouds, high aerosol load, pristine conditions) and geographic locations (Tropical Atlantic, Europe, Central Asia, and the pristine Southern Hemisphere). Our investigations revealed that ATLID has remarkable profiling capabilities with good signal strength and high vertical resolution. The ATLID profiling product of ESA's processing chain, A-EBD, could resolve the vertical structure of the targeted atmospheric features very well so that the A-EBD backscatter and extinction profiles (at low resolution) matched qualitatively (and mostly quantitatively) with the ground-based reference observations for most investigated atmospheric conditions. The intensive particle quantity lidar ratio is retrieved layer-wise and thus not in the same resolution as the backscatter and extinction products. It matches in many cases with the ground-based reference, but we also detected occasions when the lidar ratio in certain atmospheric regions was significantly deviating from the reference, which then affects either the extinction or backscatter coefficient values. Especially edge effects at the transition of particle layers to clean air seem to be problematic. Concerning ATLID's depolarization ratio, fair agreement was found for strongly scattering and depolarizing features, like ice clouds - especially during nighttime. For the aerosol regime, however, we confirm significant deviations from the ground reference and consider the depolarization ratio in Baselines BA and BB as quantitatively not reliable, especially during daytime. Thus, ATLID's depolarization ratio of Baselines B can be used to discriminate but not to type atmospheric features.In conclusion, we can state that ATLID's optical profiles of Baselines B are ready for scientific exploitation keeping in mind the reported drawbacks (e.g., depolarization ratio offsets, edge effects, occasional retrieval errors, non-complete quality flags). EarthCARE data should therefore be intensively quality checked before using for scientific studies. As EarthCARE's lifetime was recently foreseen to last for more than 10 years and algorithm development continues, such validation efforts stay important and complement other respective validation approaches.

In this paper we discuss about the design, construction and working of two different experimental setups to measure the depolarization ratio of natural mineral dust samples in the laboratory in the exact back-scattering direction. The first setup involves a 50:50 beam splitter and the second setup involves a Faraday rotator to achieve the 180˚ backscattering angle. Both the experimental setups will be first tested at 532 nm wavelength. Later, the setup with better results will be extended to cover the full triple-wavelength (355, 532 and 1064 nm) capabilities for linear polarization and circular polarization, enabling ellipsometry measurements of mineral dust particles.

Residential wood combustion is a major contributor to wintertime air pollution, releasing high concentrations of fine particulate matter and altering aerosol optical properties. Understanding the optical characteristics of wood-burning aerosols is crucial for improving air quality monitoring and refining atmospheric models. In this study, we examined the aerosol optical characteristics in Tirana, Albania, using Polly lidar observations at 532 nm during 2022-2023. For the first time, a lidar campaign was conducted in Albania, enabling long-term profiling of aerosol optical properties up to the tropopause. Our results indicate a dominant contribution of residential wood burning to winter air pollution by measuring exceptionally high extinction-to-backscatter ratios (lidar ratios) within the planetary boundary layer. Significant contributions from controlled biomass burning were identified in winter, with lidar ratios around 100 +/- 20 sr measured predominantly in December and January. We analyzed lidar ratios during winter and spring and retrieved intensive and extensive optical properties for selected cases. Lidar-derived particle mass concentration of the emissions ranged from 20-80 mu g m-3 in the lowermost heavily polluted smoke layer with a vertical depth of usually 200 to 300 m. The smoke-related AOD, measured with Polly at 532 nm, was typically between 0.05 and 0.1 in the 1200-1700 m deep boundary layer during the main winter months. To provide a regional perspective, lidar ratios and aerosol optical depth (AOD) data from the AERONET (AErosol RObotic NETwork) and 1 km MODIS (Moderate Resolution Imaging Spectroradiometer) were included in the analyses. HYSPLIT back-trajectory analysis of three contrasting cases revealed diverse air mass pathways and aerosol transport mechanisms affecting Tirana. These results enhance understanding of aerosol dynamics in urban and regional environments.

This study investigates the relationship between lidar-measured intensive optical properties of Saharan dust and simulated hematite content, using data collected during the Joint Aeolus Tropical Atlantic Campaign (JATAC) in 2021 and 2022. Measurements were taken in Mindelo, S & atilde;o Vicente, Cabo Verde. The study aims to determine how changes in hematite content influence the intensive optical properties of dust particles, particularly in the ultraviolet-visible (UV-Vis) spectrum. Given the well-documented impact of hematite on the absorption properties of dust, especially in the UV-Vis range, our hypothesis is that these effects will be detectable in lidar measurements. Specifically, this study focuses on the lidar ratio, particle depolarization ratio, and backscatter- and extinction-related & Aring;ngstr & ouml;m exponents at 355 and 532 nm wavelengths. By analyzing dust plume cases separately regarding their size differences, the strongest positive correlation was identified between the backscatter-related & Aring;ngstr & ouml;m exponent and hematite fraction (R2=0.63). These findings contribute to improving the representation of dust in atmospheric models, which often overlook the variability in mineralogical composition in their dust descriptions, and refining calculations of its direct radiative effect.

A mineralogical database is included in the simulation of mineral dust atmospheric life cycle for the chemistry and transport model COSMO5.05-MUSCAT. Evaluation of the ability of the model to reproduce the atmospheric drivers and the spatial-temporal resolution of mineral dust in the atmosphere is done through comparisons with remote sensing measurements in the Sahara Desert region for January-February 2022. Results show simultaneously good agreements and suggest that discrepancies could be explained due to the methods used for calculating mineral dust in the atmosphere not considering compositional differences.

Mineral dust aerosols are composed of a complex assemblage of various minerals depending on the region in which they originated. Given the different mineral composition of desert dust aerosols, different physicochemical properties and therefore varying climate effects are expected.Despite the known regional variations in mineral composition, chemical transport models typically assume that mineral dust aerosols have uniform composition. This study adds, for the first time, mineralogical information to the mineral dust emission scheme used in the chemical transport model COSMO-MUSCAT. We provide a detailed description of the implementation of the mineralogical database, GMINER (), together with a specific set of physical parameterizations in the model's mineral dust emission module, which led to a general improvement of the model performance when comparing the simulated mineral dust aerosols with measurements over the Sahara region for January-February 2022.The simulated mineral dust aerosol vertical distribution is tested by a comparison with aerosol lidar measurements from the lidar system Polly XT , located at Cape Verde. For a lofted mineral dust aerosol layer on 2 February at 05:00 UTC the lidar retrievals yield a dust mass concentration peak of 156 mu g m - 3 , while the model calculates the mineral dust peak at 136 mu g m - 3 . The results highlight the possibility of using the model with resolved mineral dust composition for interpretation of the lidar measurements since a higher absorption in the UV-Vis wavelengths is correlated with particles having a higher hematite content. Additionally, the comparison with in situ mineralogical measurements of dust aerosol particles shows that more of them are needed for model evaluation.

Aerosol optical properties retrieved from PollyXT lidar located in Mindelo, Cabo Verde. The time frame for the retrieval is between 4:30 - 5:29 UTC. More informantion about the lidar network and data availablitiy at: polly.tropos.de

In the framework of the Joint Aeolus Tropical Atlantic Campaign (JATAC), a temporary ground-based ACTRIS aerosol remote sensing station has been setup by TROPOS at the Ocean Science Center Mindelo (OSCM) in June 2021. The instrumental capabilities for aerosol profiling at the OSCM comprise a multiwavelength-Raman-polarization lidar Polly XT and an AERONET sun photometer. Furthermore, a scanning HALO photonics Doppler lidar is utilized to study the dynamics near the observational site. Continuous 24/7 observations have been performed since June 2021, thus covering the four intensive observational periods of JATAC (July 2021, September 2021, June 2022, September 2022).In this presentation, we want to discuss the capabilities of Aeolus to observe the aerosol conditions including the Saharan dust layer (SAL) above the Cabo Verdean islands. The time series of the ground-based PollyXT lidar from June 2021 until today has shown, that dust is omnipresent above the local boundary layer in the summer months. The maximum dust layer top height has been observed in July with 7 km. The SAL top height has then decreased to 3 km in November. Some rainy periods were observed in September/October, especially in the year 2022 for the fourth intensive JATAC campaign.We will utilize the direct Aeolus overpasses over Mindelo each Friday during these four periods (and for other seasons) to make a long(er)-term assessment of the Aeolus aerosol capabilities (L2A) involving also products from the most recent algorithm versions (Baselines). Due to the capabilities of the ground-based PollyXT lidar, we can directly compare the 2 main products of Aeolus: The extinction coefficient and the co-polar backscatter coefficient. Doing so, we can also quantify the influence of the missing polarization component in the Aeolus aerosol products which is important for the planning of the potential Aeolus follow-on mission, for which the polarization capabilities are still under discussion.Finally, the lessons learnt from the current Aeolus Cal/Val on Cabo Verde can be also used for the upcoming EarthCARE mission as TROPOS has started to setup a permanent ACTRIS aerosol and cloud remote sensing supersite at Mindelo.

DeLiAn is a collection of lidar-derived aerosol intensive optical properties for several aerosol types. The intensive parameters are the particle linear depolarization ratio, the extinction-to-backscatter ratio (lidar ratio) and the Ångström exponent. The data collection is based on globally distributed, long-term, ground-based, multiwavelength, Raman and polarisation lidar measurements. DeLiAn is available in two data formats: NetCDF and excel workbook. The intensive optical properties are presented at the typical lidar wavelengths, 355, 532 and 1064 nm, for 13 aerosol categories in total. The variables included in the datafiles are listed below. For each variable, a full description is provided in the long_name attribute (applicable for the netCDF file only). The same information is provided in the first excel sheet (“List of variables”). ScienceData angstrom_exponent_backscatter_355_532 angstrom_exponent_backscatter_532_1064 angstrom_exponent_extinction_355_532 campaign_rv date error_angstrom_exponent_backscatter_355_532 error_angstrom_exponent_backscatter_532_1064 error_angstrom_exponent_extinction_355_532 error_lidar_ratio_355 error_lidar_ratio_532 error_particle_linear_depolarization_ratio_355 error_particle_linear_depolarization_ratio_532 lidar_ratio_355 lidar_ratio_532 location measurement_type number_samples particle_linear_depolarization_ratio_355 particle_linear_depolarization_ratio_532 reference system For any further information or expression of interest with respect to DeLiAn, please contact Athena Augusta Floutsi (floutsi@tropos.de) and/or Holger Baars (baars@tropos.de).

Methods based on statistical learning have become prevalent in various signal processing disciplines and have recently gained traction in atmospheric lidar studies. Nonetheless, such methods often require large quantities of annotated or resolved data. Such data are rare and require effort, especially when exploring evolving phenomena. Existing simulators and databases primarily focus on atmospheric vertical profiles. We propose the Atmospheric Lidar Data Augmentation (ALiDAn) framework to fill this gap. ALiDAn serves as an end-to-end generation and augmentation framework of spatiotemporal and multiwavelength resolved lidar simulated data. ALiDAn employs a hybrid approach of physical models, data statistics, and sampling processes. In addition, it takes into account geographical and seasonal characteristics of aerosols and meteorological conditions along with short- and long-term phenomena that affect lidar measurements. This approach can provide diversified data and robust benchmarks to assist in developing and validating new lidar processing algorithms. We demonstrate simulations compatible with a pulsed time-of-flight lidar. Our approach leverages a broader use of existing databases and can inspire similar data augmentation to other types of lidars and active sensors.

For the first time, vertically resolved long-term lidar measurements of the aerosol distribution were conducted in Haifa, Israel. The measurements were performed by a PollyXT multi–wavelength Raman and polarization lidar. The lidar was measuring continuously over a 2-year period from March 2017 to May 2019. The resulting data set is a series of manually evaluated lidar optical property profiles. To identify the aerosol types in the observed layers, a novel aerosol typing method that was developed at TROPOS is used. This method applies optimal estimation to a combination of lidar-derived intensive aerosol properties to determine the statistically most-likely contribution per aerosol component in terms of relative volume. A case study that shows several elevated aerosol layers illustrates this method and shows, for example, that coarse dust particles are observed up to 5 km height over Israel. From the whole data set, the seasonal distribution of the observed aerosol components over Israel is derived. Throughout all seasons, coarse spherical particles like sea salt and hygroscopically grown continental aerosol were observed. These particles originate from continental Europe and were transported over the Mediterranean Sea. Sea-salt particles were observed frequently due to the coastal site of Haifa. The highest contributions of coarse spherical particles are present in summer, autumn, and winter. During spring, mostly coarse non-spherical particles that are attributed to desert dust were observed. This is consistent with the distinct dust season in spring in Israel. An automated time–height-resolved air mass source attribution method identifies the origin of the dust in the Sahara and the Arabian deserts. Fine-mode spherical particles contribute significantly to the observed aerosol mixture during all seasons. These particles originate mainly from the industrial region at the bay of Haifa.

Calibration of an atmospheric lidar is often required due to variations in the electro-optical system. Rayleigh fitting commonly performed may fail under various conditions. Temporal and spatial variations both affect lidar signals. We hence opt for spatiotemporal analysis. We present a novel deep-learning (DL) lidar calibration model based on convolutional neural networks (CNN). We demonstrate our method on simulated data that mimics natural ground-based pulsed time-of-flight lidar signals. Such an approach can better address measurements with a poor signal-to-noise ratio (SNR) and provide a more frequent calibration.

The long-range transport of desert dust over the area of the temperate climate zone is associated with the influx of hot air masses due to the location of the sources of this aerosol in the tropical climate zone. Between 24–26 February 2021, such an aerosol outbreak took place and reached Central Europe. The mean temperature of +11.7 °C was recorded during the event. A comparison of this value to the 20-year (2000–2020) average February temperature for Warsaw (−0.2 °C) indicates the uniqueness of the meteorological conditions. It was the first wintertime inflow of Saharan dust over Warsaw, the presence of which was confirmed by lidar and sun-photometer measurements. The properties of the desert dust layers were obtained; the mean values of the particle depolarization for the fully developed mineral dust layer were 13 ± 3% and 22 ± 4% for 355 and 532 nm, respectively. The aerosol optical thickness was high with average values >0.36 for all wavelengths smaller than 500 nm. The three-modal, aerosol size distribution was dominated by coarse-mode particles, with a visible contribution of accumulation-mode particles. It suggests the possible presence of other aerosol types.

Knowledge of the vertical distribution and layering of aerosols and identification of the corresponding aerosol sources are needed to improve our understanding of the spatial and temporal variability of aerosol pollution. To achieve this goal, we combined both passive and active remote-sensing techniques to provide a 3D view of local aerosol levels and regional to long-range pollution transport. We studied aerosol optical depth (AOD) data from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm at 1-km spatial resolution along with active multiwavelength polarization lidar observations of vertical aerosol profiles in Haifa, Israel, Aerosol Robotic Network (AERONET) sun photometer observations at the lidar site, and local-network observations of aerosol concentrations (PM2.5). This comprehensive dataset enabled analyzing the performance of the MAIAC AOD retrieval in cases of complex aerosol layering and mixing states which are typical of the Eastern Mediterranean. While satellite-derived and ground-based AOD measurements generally showed good agreement, 35 out of 100 measurements showed low correspondence. Analysis of those cases revealed that overestimation of AOD was mostly related to cloud-contaminated pixels and aerosol water-uptake effects in moist, cloud-free air at cloud level. Furthermore, AOD over- and underestimations were related to the presence of complex aerosol mixture and layering conditions, especially when dust was mixed with aged anthropogenic aerosol pollution and marine aerosols with lofted anthropogenic pollution. In these cases 50–70% of measurements were outside of the expected error limit. Perhaps these conditions are not considered in the MAIAC retrieval. Finally, we investigated the link between AOD spatial variability and the MAIAC AOD bias, and performed a cluster analysis corroborating the strong impact of cloud contamination on MAIAC AOD quality. Our observation-based results raise the importance of carefully analyzing the uncertainties in satellite AOD measurements that are used as an important input variable in numerous health-related exposure studies and climate models.

The large number of unsolved questions concerning the interaction between aerosol particles and clouds and corresponding indirect effects on precipitation and radiative transfer demand new measurement strategies and systems to resolve the atmospheric processes involved. Obtaining synergistic information about cloud and aerosol properties from multi–instrument and hence multi–sensor observations is a key approach to overcome the current lack of knowledge. Motivated by these needs, the mobile multi–instrument platform Leipzig Aerosol and Cloud Remote Observations System LACROS was set-up in 2011 by Leibniz Institute for Tropospheric Research (TROPOS). LACROS nowadays is the central component of a sophisticated framework of synergistic state-of-the-art measurement techniques and methodologies, embedded into an environment of comprehensive data management. The current setup of LACROS comprises a set of state-of-the-art remote-sensing instruments such as a 35-GHz scanning polarimetric cloud radar, multi-wavelength polarization Raman lidars, Doppler lidar, micro rain radar, microwave radiometer, laser disdrometer, as well as sensors for direct and diffuse downwelling solar and terrestrial radiation. All instruments are installed within customized sea-freight containers. This ensures a highest-possible mobility of the whole set of instruments. LACROS is a central mobile exploratory platform of the European Union Aerosol, Clouds, and Trace Gases Research Infrastructure (ACTRIS, http://www.actris.net). A variety of ways for physical, remote, and virtual access to the LACROS capabilities are provided via the European Union project ATMO-ACCESS (https://www.atmo-access.eu). LACROS measurements focus on three main tasks: (1) Investigation of mixed-phase cloud processes by exploiting co‐located remote-sensing observations of microphysical properties and radiative effects of aerosols and clouds and their interactions. (2) Instrument validation and development of algorithms and new measurement techniques for cloud and aerosol microphysics retrievals such as, i.e., dual‐field‐of‐view lidar to derive cloud droplet size information, or retrievals of aerosol microphysical properties from combined lidar and Sun photometer measurements. (3) Field deployments in key regions of atmospheric research, where the processes under investigation are already naturally constrained and observations can ideally be combined with in-situ observations or model simulations. This contribution will present the current setup of LACROS and its recent deployments in Leipzig, the Netherlands, Cyprus and southern Chile, results of aerosol-cloud-interaction studies by means of both, case studies and multi-site long-term statistics, as well as an overview on the current and future involvement of LACROS in cal/val activities of new methods and satellite missions.

In September 2020, extremely strong wildfires in the western United States of America (i.e., mainly in California) produced large amounts of smoke, which was lifted into the free troposphere. These biomass‐burning‐aerosol (BBA) layers were transported from the US west coast toward central Europe within 3–4 days turning the sky milky and receiving high media attention. The present study characterizes this pronounced smoke plume above Leipzig, Germany, using a ground‐based multiwavelength‐Raman‐polarization lidar and the aerosol/cloud product of ESA’s wind lidar mission Aeolus. An exceptional high smoke‐AOT >0.4 was measured, yielding to a mean mass concentration of 8 μg m −3 . The 355 nm lidar ratio was moderate at around 40–50 sr. The Aeolus‐derived backscatter, extinction and lidar ratio profiles agree well with the observations of the ground‐based lidar PollyXT considering the fact that Aeolus’ aerosol and cloud products are still preliminary and subject to ongoing algorithm improvements.

Atmospheric boundary layer height (ABLH) was observed by the CHM15k ceilometer (January 2008 to October 2013) and the PollyXT lidar (July 2013 to December 2018) over the European Aerosol Research LIdar NETwork to Establish an Aerosol Climatology (EARLINET) site at the Remote Sensing Laboratory (RS-Lab) in Warsaw, Poland. Out of a maximum number of 4017 observational days within this period, a subset of quasi-continuous measurements conducted with these instruments at the same wavelength (1064 nm) was carefully chosen. This provided a data sample of 1841 diurnal cycle ABLH observations. The ABLHs were derived from ceilometer and lidar signals using the wavelet covariance transform method (WCT), gradient method (GDT), and standard deviation method (STD). For comparisons, the rawinsondes of the World Meteorological Organization (WMO 12374 site in Legionowo, 25 km distance to the RS-Lab) were used. The ABLHs derived from rawinsondes by the skew-T-log-p method and the bulk Richardson (bulk-Ri) method had a linear correlation coefficient (R2) of 0.9 and standard deviation (SD) of 0.32 km. A comparison of the ABLHs obtained for different methods and instruments indicated a relatively good agreement. The ABLHs estimated from the rawinsondes with the bulk-Ri method had the highest correlations, R2 of 0.80 and 0.70 with the ABLHs determined using the WCT method on ceilometer and lidar signals, respectively. The three methods applied to the simultaneous, collocated lidar, and ceilometer observations (July to October 2013) showed good agreement, especially for the WCT method (R2 of 0.94, SD of 0.19 km). A scaling threshold-based algorithm was proposed to homogenize ceilometer and lidar datasets, which were applied on the lidar data, and significantly improved the coherence of the results (R2 of 0.98, SD of 0.11 km). The difference of ABLH between clear-sky and cloudy conditions was on average below 230 m for the ceilometer and below 70 m for the lidar retrievals. The statistical analysis of the long-term observations indicated that the monthly mean ABLHs varied throughout the year between 0.6 and 1.8 km. The seasonal mean ABLH was of 1.16 ± 0.16 km in spring, 1.34 ± 0.15 km in summer, 0.99 ± 0.11 km in autumn, and 0.73 ± 0.08 km in winter. In spring and summer, the daytime and nighttime ABLHs appeared mainly in a frequency distribution range of 0.6 to 1.0 km. In winter, the distribution was common between 0.2 and 0.6 km. In autumn, it was relatively balanced between 0.2 and 1.2 km. The annual mean ABLHs maintained between 0.77 and 1.16 km, whereby the mean heights of the well-mixed, residual, and nocturnal layer were 1.14 ± 0.11, 1.27 ± 0.09, and 0.71 ± 0.06 km, respectively (for clear-sky conditions). For the whole observation period, the ABLHs below 1 km constituted more than 60% of the retrievals. A strong seasonal change of the monthly mean ABLH diurnal cycle was evident; a mild weakly defined autumn diurnal cycle, followed by a somewhat flat winter diurnal cycle, then a sharp transition to a spring diurnal cycle, and a high bell-like summer diurnal cycle. A prolonged summertime was manifested by the September cycle being more similar to the summer than autumn cycles.

The European Space Agency (ESA) has launched the Earth Explorer Mission Aeolus on 22 August 2018. Within the German initiative EVAA (Experimental Validation and Assimilation of Aeolus observations), Cal/Val activities for Aeolus started immediately after the instrument was turned on in space. The aim is to validate the wind and aerosol products of Aeolus and to quantify the benefits of these new measurements for weather forecasting and aerosol and cloud research.For this purpose, ground-based aerosol and wind lidar observations have been performed at the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig, Germany, and at Punta Arenas (53.13 S, 70.88 W), Chile, in the frame of the DACAPO-PESO campaign (dacapo.tropos.de). Radiosondes have been launched during the Aeolus overpasses each Friday at Leipzig in addition since mid of May 2019. In Punta Arenas, we also used Doppler cloud radar observations with respect to the validation of Mie and Rayleigh winds of Aeolus.Aerosol-only observations with multiwavelength-Raman polarization lidar were made at the PollyNET (Baars 2016) stations in Haifa (Israel), Dushanbe (Tajikistan), Tel Aviv (Israel), and in the United Arab Emirates (UAE) - the latter two are hosted by PollyNET partner institutions (Baars, 2016). These locations are close to the desert with frequent dense, lofted aerosol layers and are thus of particular interest for Aeolus Cal/Val. Considering the long averaging length of Aeolus (87 km) and the distance to the lidars (max. 100 km), a good agreement with respect to the co-polar backscatter coefficient is found between Aeolus and the ground-based lidars at these locations.We will present results from the above-mentioned Cal/Val activities with respect to, both, wind and aerosol products of Aeolus. It will be shown, that one of the mission goals, namely the demonstration that wind observations from space by active remote sensing are possible, have been already achieved. Furthermore, it will be demonstrated that the spaceborne HSRL (high spectral resolution lidar) technique applied for Aeolus can provide independent backscatter and extinction measurements of aerosols – a spaceborne novelty as well. Since September 2019, also an aerosol-optimized range resolution, the so-called Mediterranean range-bin setting (MARS), is operational for Aeolus in the Eastern Mediterranean. First results show a significantly improved aerosol retrieval for this adapted instrumental setting and will be presented as well.Reference:Baars, H., et al. (2016), An overview of the first decade of PollyNET: An emerging network of automated Raman-polarization lidars for continuous aerosol profiling, Atmos. Chem. Phys., 16(8), 5111-5137, doi:10.5194/acp-16-5111-2016.

In August 2018, the first Doppler wind lidar in space called Atmospheric Laser Doppler Instrument (ALADIN) was launched on board the satellite Aeolus by the European Space Agency (ESA). Aeolus measures profiles of one horizontal wind component (i.e., mainly the west–east direction) in the troposphere and lower stratosphere on a global basis. Furthermore, profiles of aerosol and cloud properties can be retrieved via the high spectral resolution lidar (HSRL) technique. The Aeolus mission is supposed to improve the quality of weather forecasts and the understanding of atmospheric processes. We used the opportunity to perform a unique validation of the wind products of Aeolus by utilizing the RV Polarstern cruise PS116 from Bremerhaven to Cape Town in November/December 2018. Due to concerted course modifications, six direct intersections with the Aeolus ground track could be achieved in the Atlantic Ocean west of the African continent. For the validation of the Aeolus wind products, we launched additional radiosondes and used the EARLINET/ACTRIS lidar PollyXT for atmospheric scene analysis. The six analyzed cases prove that Aeolus is able to measure horizontal wind speeds in the nearly west–east direction. Good agreements with the radiosonde observations could be achieved for both Aeolus wind products – the winds observed in clean atmospheric regions called Rayleigh winds and the winds obtained in cloud layers called Mie winds (according to the responsible scattering regime). Systematic and statistical errors of the Rayleigh winds were less than 1.5 and 3.3 m s−1, respectively, when compared to radiosonde values averaged to the vertical resolution of Aeolus. For the Mie winds, a systematic and random error of about 1 m s−1 was obtained from the six comparisons in different climate zones. However, it is also shown that the coarse vertical resolution of 2 km in the upper troposphere, which was set in this early mission phase 2 months after launch, led to an underestimation of the maximum wind speed in the jet stream regions. In summary, promising first results of the first wind lidar space mission are shown and prove the concept of Aeolus for global wind observations.

Monthly mean vertical profiles of aerosol type occurrences are determined from multiwavelength Raman and polarization lidar measurements above Haifa, Israel, in 2017. This contribution presents the applied methods and threshold values. The results are discussed for one example, May 2017. This month shows more often large, non-spherical particles in lofted layers than within the planetary boundary layer. Small particles are observed at higher altitudes only when they are observed in lower altitudes, too.