Cyprus is strategically located in the region of the Eastern Mediterranean, the Middle East and North Africa (EMMENA). As a crossroad between Europe, Asia and Africa, it is representative of meteorological conditions and coastal areas in the EMMENA region. Therefore, Cyprus, and especially Limassol as a coastal city, can be considered an ideal natural laboratory for advanced and comprehensive field studies on climate change, aerosol-cloud-dynamics-precipitation interaction, and the weather-precipitation-dryness complex.
Incomplete coverage with ground monitoring stations is the main limitation to make fast and significant progress in understanding the complex climate-relevant atmospheric processes around the globe and thus to improve atmospheric models used for climate change projections. Although satellites can continuously monitor the atmosphere on a regional to global scale, they must be ground-calibrated in order to incorporate satellite data into atmospheric models that are necessary for validation purposes.
A modern observational super site in Cyprus is of fundamental importance to understand the atmospheric and environmental system in the fast growing and developing EMMENA region with increasing urbanization and pollution problems which cannot be separated from the climate-change issue. Modern efforts of weather, climate, and environmental prediction are based on sophisticated modeling in close connection with state-of-the-art observations. A modern supersite of atmospheric monitoring is totally missing in the Eastern Mediterranean, in one of the hot spots of climate change with high pollution, frequent dust storms, and diminishing amounts of precipitation.
This contribution reports on recent progress regarding the buildup of a permanent, state-of-the-art atmospheric remote sensing station in Limassol, Cyprus. As a demonstration initiative, an 18-month field campaign (Cy-CARE (Cyprus Cloud Aerosol and pRecipitation Experiment)) has been designed by the Leibniz Institute for Tropospheric Research (TROPOS) and was implemented by the ERATOSTHENES group at Cyprus University of Technology (CUT) between October 2016 and March 2018, with the main focus on lidar/radar-based studies of aerosol-cloud-precipitation relationships. The vision of the ERATOSTHENES Research Centre (ERC) in Cyprus is to become a Centre of Excellence for Earth Surveillance and Space-Based Monitoring of the Environment, in the framework of the EU H2020 Teaming project EXCELSIOR. Within this vision, a modern observational super site in Cyprus is of fundamental importance and shall be set up for long-term profiling of the atmosphere (wind, humidity, aerosol and cloud properties, precipitation fields).
The ERATOSTHENES station in Limassol, Cyprus with the current instrumentation (EARLINET Raman depolarization lidar) follows the CAL/VAL activities of the AEOLUS satellite launched last August through the participation to the VADAM project. Selected cases that demonstrate the complex aerosol conditions over Eastern Mediterranean will be presented as well as the first lidar observations during AEOLUS overpasses over Cyprus.

Acknowledgements
The authors acknowledge the EXCELSIOR H2020-WIDESPREAD-04-2017: Teaming Phase1 project under grant agreement No 763643, (www.excelsior2020.eu). CUT team acknowledges ACTRIS-2 project that received funding from the European Union (H2020-INFRAIA-2014-2015) under grant agreement no. 654109 and the ESA AEOLUS CAL/VAL VADAM project (27409).

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Scene classification is an important component of the Level-2B processor (L2Bp). Its main objective is to detect cloud and aerosol layers along the Aeolus track. The result is a binary map, also denoted feature mask, used in the L2Bp classification procedure as input for the accumulation of Mie and Rayleigh signals from measurement (2.88 km along track) to observation level (87 km along track).

Two options for scene classification have been implemented in the L2Bp, (i) based on the application of a threshold value to the scattering ratio estimate calculated by the Level-1B processor and (ii) from the Optical Properties Code (OPC), which is part of the L2Bp. Both options are operated on measurement level, which poses a challenge because of the high levels of measurement noise on top of the atmospheric return signal.

Both options are complementary because the L1B scattering ratio is inferred from the Mie channel signal only, while OPC uses the Rayleigh channel signal only. OPC also contributes to a mission risk reduction in case the Mie channel performs less than anticipated. Since scene classification is a crucial procedure in the L2Bp, the quality of produced winds strongly relies on the performance of the classification procedure.

Results of the performance of both options for scene classification with real Aeolus data will be presented and the pros and cons discussed. The ultimate goal of the L2Bp is to provide wind observation profiles of the highest quality. Resulting L2B wind observations using both options for scene classification will be presented.

In addition to the binary map, the OPC provides for each measurement profile estimates of (i) aerosol backscatter and extinction, (ii) the scattering ratio, (iii) the positioning of particle layers inside the Aeolus bins and (iv) the cross-talk correction factor. The quality of these additional geophysical parameters will be compared against the corresponding products obtained from the Level-2A processor, whose main objective is to provide estimates of aerosol and cloud backscatter and extinction. First results of this intercomparison will be presented.

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In Autumn 2018, a transatlantic cruise with the German research vessel Polarstern will take place from Bremerhaven (Germany) to Cape Town (Republic of South Africa). During this cruise, Polarstern is equipped with the OCEANET facility of TROPOS which includes the multiwavelength Raman polarization lidar PollyXT (Engelmann 2016).
This ship cruise offers a unique opportunity to perform Cal/Val of Aeolus level 2a products above the Atlantic Ocean, and thus in a marine environment. Of special interest will be observations in the outflow region of the Saharan desert, west of Africa, for which we expect thick, lofted layers of Saharan dust and mixtures of biomass burning smoke (Bohlmann, 2018). During the cruise, we expect to obtain 3-5 possibilities to evaluate Aeolus’ products, for which the ship will be directly steered to the ground track location of Aeolus. These events will be complemented by additional radio sonde launches onboard the ship to also validate the Aeolus wind products (Level 1b and 2b).
In this contribution, we will present first results from the direct overpasses of Aeolus during the ship cruise.



References:
Engelmann, R., Kanitz, T., Baars, H., Heese, B., Althausen, D., Skupin, A., Wandinger, U., Komppula, M., Stachlewska, I. S., Amiridis, V., Marinou, E., Mattis, I., Linné, H., and Ansmann, A.: The automated multiwavelength Raman polarization and water-vapor lidar PollyXT: the neXT generation, Atmos. Meas. Tech., 9, 1767-1784, https://doi.org/10.5194/amt-9-1767-2016, 2016

Bohlmann, S., Baars, H., Radenz, M., Engelmann, R., and Macke, A.: Ship-borne aerosol profiling with lidar over the Atlantic Ocean: from pure marine conditions to complex dust–smoke mixtures, Atmos. Chem. Phys., 18, 9661-9679, https://doi.org/10.5194/acp-18-9661-2018, 2018.

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VirES is a highly interactive data manipulation and retrieval interface for the ESA Earth Explorer mission products. It is under evolutionary/operational maintenance by EOX since 2016 for the Swarm geomagnetic mission and has now implemented a new service supporting ESA's Earth Explorer Aeolus wind mission.

The goal of this service is twofold, to provide quick first hand easy access to the data during commissioning phase as well as allowing further users intuitive open access in the future.
In order to be able to understand, manage, work and visualize the new and exotic data produced by the satellite a close collaboration between experts in the field and project partners DLR and DoRIT and EOX as Industry partner was necessary.

VirES Aeolus provides an intuitive easy to use web interface for the official Aeolus archives. It includes multi-dimensional visualization, interactive plotting and analysis. VirES stands for a modern concept of extended access to Earth Observation (EO) data. It supports novel ways of data discovery, visualization, filtering, selection, analysis, snapshotting and downloading. The service was designed having following areas in mind:
Quality Analysis, Calibration and Validation, Scientific Exploitation, Modeling and Prediction

Specialized solutions have been developed to be able to visualize the amount of data in an interactive and intuitive way. The tool has been actively used since the first data has been made available and initial feedback has been very positive. It was important to find a balance between simplifying the interface for intuitive use with enough room for complexity through configuration was found. Having easy access to data without need of specialized software from the beginning of the mission has been a major achievement as it usually takes some time for solutions to become available. This has been possible through the foresight of ESA and the good collaboration of the project partners.

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In the framework of its Earth Observation Programmes the European Space Agency (ESA) carries out ground based and airborne campaigns to support geophysical algorithm developments, calibration/validation activities, simulation of future space-borne Earth Observation missions, as well as application developments related to atmosphere, land, oceans, solid Earth and cryosphere. For Aeolus, campaign activities have covered almost all phases of the mission, including the consolidation of mission specific requirements, implementation of the instrument, commissioning phase after launch, as well as the operational Calibration and Validation activities using airborne and balloon observations.

Since 2007, a series of ESA supported airborne campaigns have been essential to the development of the Aeolus Doppler Wind Lidar satellite mission, which was successfully launched on 22 September 2018. At the core of these activities is DLR’s A2D wind lidar (Lux et al. 2018, Reitebuch et al. 2009, Paffrath et al. 2009) on-board the DLR Falcon aircraft, an airborne demonstrator for the Aeolus ALADIN satellite instrument. A2D is working with the same laser frequency and has an almost identical optical and electronic design as the space-borne instrument, which is ideal for supporting the development of the hardware, calibration procedures and retrieval algorithms.

Following the WindVal campaigns in 2015, 2016 and 2018, two airborne campaigns are planned for 2019 in Central Europe and the Arctic, with operations centres at DLR in Southern Germany and Iceland, respectively, with the target to provide key correlative observation between Aeolus and the airborne A2D and 2μm Doppler Wind Lidar (Weissmann et al. 2005) systems. The campaign data will have a significant impact on the in-flight calibration of the space instrument and provide critical validation data for both wind and aerosol products. Currently there are around 30 flight hours foreseen in Central European and 50 hours from Iceland, focussing on satellite underpasses and including overpasses of ground based Aeolus validation sites, providing important Aeolus Cal/Val opportunities. The campaigns are also extending the high quality wind and aerosol datasets for dynamically complex scenes from the previous projects, providing important input for scientific investigations in processes related to atmospheric dynamics and microphysics.

The contribution of wind profiles in the Tropics, and in particular the tropical oceans, is currently not provided by other space-based systems than Aeolus and there is only a limited number of ground based observations from radiosondes and wind profile radars. Therefore, the largest impact of the Aeolus observations is expected in the tropics where direct wind observations are of importance to correctly determining the flow. To provide in-depth insight in the quality of Aeolus products in this region, a dedicated tropical airborne campaign is planned. In addition to the Cal/Val objectives, the campaign plans to address the understanding of tropical dynamics such as Kelvin and gravity waves, intensive storm development (e.g. hurricanes), heat exchange with the ocean its impact on tropical weather and intense storm development. While undergoing further consolidation, the airborne campaign base is planned on the Cape Verde Islands in June/July 2020, providing opportunities to study the dynamics and microphysics related to the Saharan Air Layer, African Easterly Waves and Jets, Tropical Easterly Jet and deep convection in the ITCZ. With foreseen 100 flight hours, potential support by mobile ground based observing systems for wind and aerosols and possible international contributions, ESA is reaching out to the science community to participate to the tropical campaign.

Extending the Aeolus validation capacities to the tropical UTLS, ESA is cooperating with the CNES Stratéole-2 (see https://strateole2.cnes.fr/ for detailed information) stratospheric balloon activities in the frame of the ESA TAPAPA project. During the campaign several long-duration, superpressure balloons to study the upper troposphere and lower stratosphere in the deep tropics are launched providing unique upper level wind data for the Aeolus validation. Around six long-duration balloon flights will be performed from Seychelles islands early 2019, each staying for about 2 to 3 months between 15°N and 20°S providing in total several 100 co-locations with Aeolus. The core of the Stratéole-2 flights will take place in 2020/21 and November 2023/24 with 20 balloon flights planned for each campaign, with the potential for providing future Aeolus validation opportunities.

References:
Lux, O., Lemmerz, C., Weiler, F., Marksteiner, U., Witschas, B., Rahm, S., Schäfler, A., and Reitebuch, O. (2018): Airborne wind lidar observations over the North Atlantic in 2016 for the pre-launch validation of the satellite mission Aeolus, Atmos. Meas. Tech., 11, 3297–3322.
Reitebuch, O., Lemmerz, C., Nagel, E., Paffrath, U., Durand, Y., Endemann, M., Fabre, F., and Chaloupy, M. (2009): The airborne demonstrator for the direct-detection Doppler wind lidar ALADIN on ADM-Aeolus: I. Instrument design and comparison to satellite instrument. J. Atmos. Ocean. Tech., 26, 2501-2515.
Weissmann, M., Busen, R., Dörnbrack, A., Rahm, S., and Reitebuch, O. (2005): Targeted Observations with an Airborne Wind Lidar. J. Atmos. Ocean. Tech., 22, 1706-1719.

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The purpose of the poster is to provide an overview of the early Aeolus operations conducted at ESOC, the European Space Operations Centre. After touching the most important operational aspects for Earth Observation satellites in general, it will depict more in detail the implications for Aeolus as an especially low-orbiting satellite at 320 km. In this context the most relevant components such as the orbit maintenance concept and the process of changing it from one reference orbit to another one according to the science needs will be explained.
In addition to operations at satellite level, it will be presented how ALADIN operations are performed at ESOC. The focus lies on the operations not covered by the routine phase mission planning, in particular the commissioning phase. It will cover the milestones of the first phase of the mission, e.g. the switch-on of ALADIN including both the transitions through the different instrument modes and raising the laser energy stepwise from the lowest to the highest level. Also the timeline until the completion of the first round of repetitive operations and calibrations will be shortly mentioned.
Furthermore, the process of implementing special operations requests (SORs) that were deemed necessary by the Project Support group during commissioning, for instance due to thermal or power adjustments, is described as part of the poster. Some statistics and examples will be selected to illustrate this process, which is based on a smooth cooperation between Industry, Project and the Flight Operations Segment (FOS). In view of this aspect it is worth pointing out the challenge for all parties to generate, exchange and process the needed input taking into account the short pass durations that restrict visibility and time to uplink the required commands to the spacecraft.
As it is important to prepare in advance for these situations and the considerable stress they cause, the poster will complete the topic of operations by emphasising the value of the simulations campaign that took place at ESOC during the last three months before launch and that allowed the involved teams to get prepared for the ALADIN activities in flight.

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ESA’s Doppler Wind Lidar Mission, Aeolus, was successfully launched on 22 August 2018. It is the first mission in space measuring vertical profiles of the tropospheric and lower stratospheric wind field on a global scale, aiming to improve numerical weather prediction (NWP) and to advance our understanding of atmospheric dynamics and processes relevant to climate variability. In addition, Aeolus provides valuable profile information of aerosol and cloud layer optical properties, which are relevant for air quality modeling and the atmospheric radiation budget. Calibration and Validation (Cal/Val) are fundamental aspects to assure the missions best possible product quality.

ESA’s Sensor Performance, Products and Algorithms (SPPA) section has the function to assure that ESA mission product users are provided with best possible product quality. For Aeolus, this includes the coordination of several Cal/Val activities worldwide, providing independent wind, aerosol and cloud products from dedicated Cal/Val campaigns, ground-based, airborne, ship and satellite observations in order to assess and improve the Aeolus data quality during its exploitation phase. These activities include also a number of data impact studies to assess the potential impact of Aeolus data on NWP.

This presentation will provide initial Aeolus data quality results as well as an overview of most recent Cal/Val activities from the first Aeolus in-orbit Cal/Val and Science Workshop, which took place in March 2019. An assessment of the L2A aerosol and cloud and the L2B wind error statistics based on the first Cal/Val results will be presented. Furthermore, the presentation will give a brief overview of first results from NWP impact assessment studies and scientific studies presented at the March workshop. The next Cal/Val steps as well as possible implications of these first data quality findings on the Aeolus exploitation phase will be finally discussed.

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We propose to apply the statistically based stability control methodology developed in the framework of preparation of two space borne lidar missions, ATLID/EarthCare and MESCAL, to the ALADIN Level 1 data.

Namely, we propose a set of parameters, which would characterize the behavior of the ALADIN lidar system on a day-to-day basis using the L1 data as an input. With the help of this set one can trace:

(a) the stability of the detection chain for ALADIN channels (Rayleigh, Mie);
(b) the drift of cross-talk coefficients;
(c) the stability of day- and nighttime noise;
(d) the stability of the radiation detection for all atmospheric scenarios and over the whole globe using a clustering algorithm applied to the scattering ratio (SR) histograms.

We define 11 parameters: 3 related to surface reflection, 6 related to stratospheric day- and nighttime noise, and 2 related to the SR histogram analysis. We demonstrate the feasibility of the approach using CALIOP L1 data for polarized and cross-polarized attenuated backscatter (ATB) components in 2008-2015.

(i) The stability control using surface backscatter takes advantage of a stable scattering scene providing thousands of measurements per day, namely, a clear sky ocean surface at a fixed surface temperature (300±1K). Using CALIOP data, we show that the ATB histograms built over this subset demonstrate a clear maximum, the behaviour of which over the years is coherent with laser power degradation. Applied to the ALADIN channels, this approach will track the performance of laser, the absolute calibration for each channel, and the cross-talk coefficients.

(ii) For the stratospheric noise analysis, we build histograms of the day- and nighttime r.m.s. values of the stratospheric “noise” (35-40 km layer) and analyze them in the same manner as above. For ALADIN, this will help tracking issues in the detection path, in the signal treatment chain, and in the crosstalk estimates. Using CALIOP as a reference and knowing the ALADIN technical specifications, we define “safe limits” for the day-to-day variability of histogram centre values for surface and stratospheric ATB separately for its Rayleigh and Mie channels.

(iii) To address the whole range of the detected molecular and particular ATBs, we use an advanced SR histogram approach based on our previous studies. We take advantage of the day-to-day similarity of physical processes in the atmosphere and quantify the deviation of the SR histograms built for typical scenes from the “reference” ones. To identify these scenes, we use a clustering approach. Using 8 years of CALIOP data, we show that the “clustered SR histograms” do not change dramatically over time for a well-calibrated instrument and that they are sensitive to calibration issues.

Figure caption: Examples of height-intensity SR clustered histograms calculated for CALIOP: a) clear sky; b) multi-layer middle-level cloud; c) high semi-transparent cloud; d) thick high cloud.

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Improved global wind observations are of major interest to NOAA. An internal Satellite Observing Systems Architecture Study (NSOSA) examining NOAA operational advancements needed to meet defined requirements in the post 2028 time frame ranked 3-dimensional winds as the highest priority geophysical observation. Atmospheric motion vector winds derived from 2-dimensional images or 3-dimensional sounders offer one technique for increasing the number of wind observations available for assimilation; however, the product is subject to spatial limitations and placement errors. Space-based Doppler lidar is perhaps the most promising methodology for obtaining full global wind profiles which can be assimilated into forecast models as well as be used to potentially improve the AMV product. Because the Aeolus mission provides an opportunity to investigate the performance of a space-based Doppler wind lidar instrument and to estimate impact of lidar wind measurements assimilated into numerical forecast models, the mission is important to NOAA and as a result the agency is supporting a broad internal effort associated with Aeolus calibration, validation, analysis and assessment.

The NOAA investigations using Aeolus data encompass a range of important topics, including direct inter-comparison of remote and in situ wind measurements with Aeolus observations, Observing System Experiments (OSEs), Observing System Simulation Experiments (OSSEs), impact of data assimilation of Aeolus measurements into forecast models, and examination of how Aeolus data can augment and improve AMV-derived wind data. Inter-comparison data sources will include ground and airborne Doppler lidar, sondes, airborne Doppler radar, and atmospheric motion vectors. Field campaigns focused on tropical cyclone research will utilize the NOAA P-3 aircraft to investigate Aeolus representation of winds in the tropical cyclone environment, including the impacts of cloudy regions on Aeolus observation and the utility of Aeolus measurements to probe winds and aerosols in the Saharan Aerosol layer (SAL). The tropical-cyclone-based field campaign study will be augmented by a long-term investigation to compare Aeolus observations with measurements obtained by surface-based Doppler wind measurements in the boundary layer and lower troposphere at several locations where the lidars are being deployed for scientific studies.

In order to investigate the impact of Aeolus observations, OSEs will be conducted to evaluate the potential enhancement of Aeolus data assimilation on both global and regional weather prediction, including the impact on tropical cyclone prediction. We also intend to employ Aeolus measurements in OSSE studies to investigate the benefits of enhanced future Doppler instrument capabilities, with a focus on single versus multiple line-of-sight observations and multiple versus single track observations, in order to prepare for follow-on Doppler lidar instruments.

Atmospheric Motion Vectors represent a significant component of the present-day space-based wind data set. Therefore, the NOAA team will investigate differences and synergisms between Aeolus wind measurements and those computed from conventional AMVs, which are produced using state-of-the-art algorithms from several geostationary satellites and polar orbiters. Aeolus Level 2C wind profiles will be compared with the global AMV data set to document differences in vector coverage, quality and impact on forecasts. The team will also study how Aeolus wind profiles can be used to assess uncertainties that are introduced into AMV wind measurements by the assumption that cloud and water features are ideal tracers and will interpret how Aeolus cloud tip heights and cloud-dependent AMV assigned altitudes correlate. Finally, the team will investigate how Aeolus wind data can be used to make variational bias corrections (VarBC) of AMV data sets.

More details on these studies, progress and first results will be presented at the symposium.

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Several uncertainties remain in assessments of long-term trends of global properties of aerosols, mainly due to lack of observations and the difficult in measurements of important aerosol parameters. In order to solve these issues and reduce the sources of aerosol uncertainties, it is necessary to increase the number of observational stations and experimental field campaigns to improve the global observations of aerosol and its optical and physical properties, therefore, helping to improve the climate numeric model validations. An important step further to increase the accuracy of aerosol measurements is to develop the capability of aerosol measurement networks, implementing rigorous and systematic protocols of measurements. In this context, the Latin America Lidar network (LALINET) has been monitoring the vertical distribution of particle optical properties since 2001, and started to be operative with systematic measurements since 2013. LALINET has the purpose to develop a database of vertical distribution of aerosols over South America, and also from other atmospheric components such as water vapour and clouds, and provide quality assurance data for atmospheric satellite missions such as CALIPSO, and the ESA’s mission ADM-AEOLUS and EarthCARE. In order to prepare the most suitable strategy for calibration and validation (CAL/VAL) processes of ESA’s satellite missions, Quality Assurance and Quality Control (QA/QC) program based on the EARLINET standards were implemented in the SPU lidar station to provide quality assured particle backscatter and extinction profiles, and to identify possible improvements for this system. Standard procedures and protocol of QA tests were implemented in order pinpoint hardware problems and consequential optimization of the lidar system.
Using the LALINET stations measurements it will be possible to derive the aerosol backscatter and extinction profiles applying the Klett-Fernald-Sasano inversion method. Raman measurements does not have bias and it can provides the backscatter and extinction profiles with any priori assumption. The Raman lidar products can be used as basis for error budget estimations for Aeolus. Since L2A AEOLUS product will be delivery as a mixture of aerosol and clouds return, we can provide the Aeolus-like backscatter and extinction profiles from the ground-based stations in order to avoid any distortion or bias on the validation process. As a rough and preliminary estimate, we can provide the backscatter and extinction atmospheric profiles on the same basis of the image product provided on the ESA Aeolus Online Catalogue website. LALINET expected to contribute to the AEOLUS CAL/VAL processes to quantify the cloud and aerosol physical, geometrical and optical parameters using several ground-based aerosol lidars. Compare L2A backscatter and extinction products data from AEOLUS and LALINET stations in order to validate the space and ground-based measurements. As overall activity during phase E1 and E2 work-tasks (WT) are proposed in this document. We will present the improvements results and the future methodology to participate at the AEOLUS CAL/VAL process.

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ESA deployed the first Doppler Wind lidar in space within its Earth Explorer Mission Aeolus on 22 August 2018. The objective of Aeolus is to provide tropospheric and lower stratospheric wind profiles globally for the improvement of weather forecasts on short and medium term. Spin-off products are profiles of atmospheric backscatter and extinction coefficients and lidar ratio.
The measurements are performed with the single payload ALADIN (Atmospheric LAser Doppler INstrument), which is a direct-detection Doppler wind lidar (DWL) operating at an ultraviolet (UV) wavelength of 354.8 nm. It has a mono-static configuration where the emitted and received light share the large (1.5m Cassegrain) telescope and part of the optical bench optics. The optical receiver consists of two spectrometers to determine the Doppler shift from the spectrally broad Rayleigh-Brillouin molecular backscatter and the spectrally narrow Mie backscatter from aerosols and cloud particles. Accumulation charge coupled device (ACCD) detectors are used for both the Mie and Rayleigh channels.
Since the start of the mission the system is monitored by special means of its internal calibration path and maintenance sequence. Permanent Monitoring and Maintenance of Aeolus (MAMA) is considered a mandatory need to continue the acquisition of a unique data set on atmospheric dynamics, but also to learn for follow on missions. The activities of MAMA will be presented starting with the activities during the laser switch on process, the telescope focus characterization, and a timeline of results during the InOrbit Commissioning and Verification (IOCV) phase will be shown. In addition, based on MAMA and the results from ESA Data Analysis From Expert Core teamS (EDAFECS) recommendation for instrument operation are provided and new methods for instrument characterization are developed, which be explained by case studies.

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The purpose of this presentation is to assess the accuracy of the ADM-Aeolus wind profile measurements based on comparisons with data collected from the National Research Council (NRC) Convair580 aircraft. The Convair580 measurements were conducted in the frame of the ESA RadSnowExp project in the Iqaluit region (Nunavut, Canada) (>63N). The NRC Convair580 was equipped with state-the-of-art instrumentation for in-situ aerosol, cloud microphysical and remote sensing. The Convair580 was instrumented by NRC in collaboration with Environment and Climate Change Canada (ECCC).
The Aeolus velocity is calculated from the measurements of the Doppler shift of the light scattered either by interaction with aerosol or cloud particles (Mie scattering) or by interaction with air molecules (Rayleigh scattering). The two scattering mechanisms may exhibit an effect on the accuracy of the Aeolus Doppler wind calculations depending on the aerosol load and presence of cloud particles. In order to address this question the in-situ wind, aerosol and cloud particle size distributions were measured during porpoise profiling of the Convair580 at the location of the ADM-Aeolus overpass. The measured in-situ wind speed and wind direction was averaged to the vertical resolution of the Aeolus and compared to the Aeolus measurements. The accuracy of the Aeolus measurements was analyzed based on the type of scattering and natural variability of the wind on different levels.

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Up to 7 long-duration balloons able to fly for several months in the lower stratosphere at ~18 and 20 km will be launched from Seychelles Islands (5°S) in early 2019, within the Strateole 2 project. These balloons drift with the wind on constant-density surfaces. Monitoring their displacements therefore provide very accurate observations of the horizontal wind. Since the balloons are launched from an equatorial site, they will be embedded in the QBO-induced circulation, and sample the whole tropical band, including oceans and continents, clear skies and convection. The equatorial winds provided by those balloon-borne observations will thus provide a unique opportunity to validate Aeolus observations in a region where the impact of spaceborne wind-lidar mission on weather predictions is expected to maximize, and where classical observations are very scarce, especially over the oceans. Previous low-latitude long-duration balloon flights have indeed revealed that analyzed winds in the tropical lower stratosphere prior to Aeolus exhibited significant deficiencies.
The time resolution of Strateole 2 balloon-borne observations allows us to resolve the whole spectrum of waves in the tropical stratosphere: from the large-scale planetary waves trapped in the equatorial wave guide (Kelvin, Yanai and Rossby waves) down to the smaller gravity waves. These waves are responsible for most of the wind variability in the tropical lower stratosphere, and may induce disturbances on both the zonal and meridional velocities. Their vertical wavelengths vary during their propagation from the troposphere (where they are primarily generated by deep convection) to the stratosphere and above where they eventually break, and may become as small as 1-2 km as they approach their critical level.
The first results from the comparison between Strateole 2 and Aeolus winds will therefore be presented, with an emphasis on wave activity during the Strateole 2 campaign. The effect of Aeolus wind assimilation in numerical weather prediction systems will be also investigated.

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The satellite Atmospheric Dynamics Mission Aeolus was successfully launched in August 2018. It is an ESA Earth Explorer Core Mission. The expected lifetime is around 4 years. The instrument on-board, the Atmospheric Laser Doppler Instrument (ALADIN), emits light pulses in the UV spectral region (355 nm). It is an incoherent direct detection lidar with a fringe-imaging receiver for analyzing aerosol and cloud backscatter (Mie scattering) and a double-edge receiver for analyzing molecular backscatter (Rayleigh scattering). The basic principle of observing wind is the Doppler shift of the return signal, backscattered at different levels in the atmosphere. The frequency shift results from the relative motion of the scatter elements along the sensor line of sight. The pointing is 35° offset from nadir in the anti-sun direction. During observations, 7 s are actively been used for sampling, which are then integrated within a 50 km along-track distance. The across-track resolution is narrower. After an observation cycle, there is a gap of 21 s (150 km) before next active observation.

The study focuses on the comparison of wind speed retrievals between a ground-based WLS70 lidar with Aeolus. The collection of WLS70 data started in August 2018. The WLS70 from Leosphere is a pulsed wind lidar that measures the line-of-sight velocity at four azimuthal positions separated 90 deg with an inclination of 15 deg. The instrument is capable of reconstruct the horizontal wind vector from 100 m up to 2000 m every 100 m with a sampling rate of 6 s, depending on the amount of aerosols in the atmosphere. The WLS70 is positioned near Pamplona in Spain as part of the Alaiz measurement campaign within the New European Wind Atlas project (http://www.neweuropeanwindatlas.eu/). Prior work with WLS70 includes analysis onshore at the Høvsøre test site in Denmark, at Hamburg, Germany, offshore at FINO3 in the North Sea, Kassel in Germany as well as in forested terrain in Hornamossen, Sweden.

The planned work includes the comparison of Aeolus with WLS70 wind retrievals, and, particularly in finding the ways to compare winds from two instruments that retrieve the wind speed very differently The presentation will focus on the first results of such inter-comparison.

At a later stage, Aeolus data are expected to be useful for wind energy resource mapping when data assimilation of Aeolus wind retrievals becomes possible. The Aeolus mission shall improve numerical weather forecasts, air quality and climate modelling. In addition, at DTU Wind Energy, we foresee improvements in our capabilities for wind resource mapping globally. Currently, DTU Wind Energy is responsible for the third version of the global wind atlas (Global Wind Atlas https://globalwindatlas.info/). The possibility to assimilate Aeolus winds in numerical modelling is expected to improve wind resource mapping, particularly particular in regions with limited or non-existing data such as oceans, tropics, arctic and the southern hemisphere.

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We present a first part of the project which will be jointly performed by Swedish Institute of Space Physics (IRF) in Kiruna and the Swedish Meteorological and Hydrological Institute (SMHI). Aeolus winds will be validated by comparison with winds measured by two atmospheric radars, ESRAD and MARA, located at Esrange in Arctic Sweden and at Antarctic station Maitri, respectively. Scarcity of data at high latitudes makes our radar observations very valuable for validation of Aeolus wind products in these regions. Because Aeolus will have a polar orbit, the measurement tracks will be more densely distributed at high latitudes and hence, there will be relatively many collocations with the radars. Validation will be done for one year of satellite operation, and, as a result, Aeolus wind errors will be evaluated. We will accumulate data for all collocation events and compare a climatology for the Aeolus HLOS wind component (L2B) and the corresponding component of radar winds both in total and as a function of height. The comparison will result in various statistical products such as a mean wind speed and root-mean-squared wind speed difference that describes bias (systematic error) and accuracy of Aeolus HLOS winds. Statistics will be provided for the validation period as a whole as well as when considering certain criteria, e.g. season, wind speed and wind direction. We will present first results of our validation project covering several months of satellite operation. For certain cases (e.g. high likelihood for significant vertical winds, jet streams, broken clouds) the comparison will be done in more detail using a km-scale Numerical Weather Prediction (NWP) model. In all cases that we will examine, the averaging of Aeolus observations over 87 km could contribute to deviations of Aeolus wind profiles from locally measured ones. We therefore also aim to test whether Aeolus higher resolution data (up to 3 km horizontal averages) would agree better with ESRAD data under certain conditions. We will show several examples of comparison Aeolus winds with those from the ESRAD observations and regional NWP model for various atmospheric conditions.

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The European Space Agency (ESA) Aeolus mission launched a Doppler Wind Lidar(DWL) on 22 August 2018, following a well-expressed need for wind profile observations to initialize Numerical Weather Prediction (NWP) models and better depict atmospheric circulation. Currently, wind profile observations are obtained operationally from radiosondes, aircraft ascends/descends and profilers, but leaving a large volume of the troposphere and lower stratosphere void of wind profile observations, particularly over the oceans, tropics and southern hemisphere. Aeolus' objective is to demonstrate the beneficial impact of partially filling this gap and several observation impact and sensitivity experiments in NWP have confirmed this expectation. In addition, Aeolus winds are expected to inform and improve atmospheric circulation modelling and thus benefit climate research. After the Aeolus launch, the Aeolus Mission Advisory Group considered it is high time to look forward to future vertical wind profiling capability to fulfil the rolling requirements in operational meteorology. The following considerations will be illustrated and presented at the symposium.

Requirements for wind profiles and information on vertical wind shear have evolved, since the need for wind information to capture and initialize small-amplitude, fast-evolving and mesoscale dynamical structures increases as the resolution of global NWP improved well into the 3D turbulence regime on horizontal scales smaller than 500 km. In addition, advanced requirements to describe the transport and dispersion of atmospheric constituents and better depict the circulation on climate scales are eminent. These requirements are generally well captured by the WMO OSCAR and Rolling Requirements Review.

The increasing demand for well-resolved wind information may be met by a number of different techniques. Wind scatterometers and microwave radiometers provide information on ocean surface winds in a growing virtual constellation (CEOS), but do not provide information on vertical shear or the upper air. Moreover, research missions are studied with satellite Doppler cloud radars or tandem (stereo) multi-angle imagers to provide vector winds near clouds. Since clouds constitute only about 30% of the tropospheric volume and represent a dynamically and optically heterogeneous environment, the development of these techniques to fulfil the global demand for 3D wind information can only be partial. Also, research in obtaining winds from tandem IASI profiles, e.g., by employing optical flow techniques, may not meet the requirement to obtain high-resolution wind and shear.

Operational wind profiles exist in radiosondes and airplane ascends and descends, which generally do not cover areas over the oceans, tropics and southern hemisphere, which were currently void of such profiles before Aeolus. AMVs do fill this gap partially, as they may be obtained at high temporal resolution and at several heights. However, height assignment and vertical sampling will remain an issue for this class of winds.

Therefore, an Aeolus-like follow-on mission, obtaining wind profiles in clear air by exploiting molecular scattering appears worthwhile. However, several technological and scientific aspects of such mission need further consideration by the wind lidar community. These considerations on evolving lidar technology for winds, clouds and aerosol will be further presented at the symposium.


The figure shows an orbit of Aeolus molecular winds.

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