Conference Agenda

The global wind profile has a significant impact on the atmospheric circulation, the atmospheric carbon cycle, marine–atmosphere circulation, and aerosol activities. On the other hand, aerosols in the whole troposphere play a key role in the climate change and the air quality because of its direct, semi-direct, and indirect effects on the radiation budget. ESA decided to implement the Atmospheric Dynamics Mission ADM-Aeolus and the Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) to provide global profiles of wind, clouds, aerosols, and properties together with derived radiative fluxes and heating rates. ADM-Aeolus carried the first wind lidar in space (ALADIN) and launched in August 2018. EarthCARE will carry cloud profiling radar, HSRL (High Spectral Resolution Lidar) and multispectral imager and is scheduled for launch in 2021. TROPOS developed several multiwavelengths and polarization Raman lidar systems (about 10 PollyXTs, MARTHA and BERTHA) and is using these systems at different continents. The recent and ongoing campaigns are atmospheric measurement at Cape Verde, the Central Asian Dust Experiment (CADEX), the Widefield Sky Scatterer Tomography by Lidar Anchor together with Technion Haifa, the Atlantic atmospheric observation experiment (OCEANET), and the Cyprus Clouds and Aerosol and precipitation experiment (CyCARE). The measurement results will support the CAL/VAL of the Aeolus. Ground-based WACAL (WAter vapor, Cloud and Aerosol Lidar) was developed by the lidar group at OUC (Ocean University of China) and deployed during several field campaigns, including the third Tibetan Plateau Experiment of Atmospheric Sciences (TIPEX III) in Naqu (31.5°N, 92.05°E) with a mean elevation of more than 4500 m above MSL in summer of 2014. HSRL and CDL (Coherent Doppler Wind Lidar) developed by OUC were also deployed in several field campaigns in the coastal zone and China Seas. These devices were deployed for the CAL/VAL field campaigns. The ground-based co-located and simultaneous measurements with lidars and sun photometer during overpasses of Aeolus are foreseen over Qingdao (for example: 17:37 LT on 18 November 2018 and 06:10 LT 19 November 2018). The CAL/VAL campaigns will contribute to exploit the Aeolus wind observations for the study of atmospheric dynamics. Lanzhou University (LZU) established a Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) and conducted lidar observations of dust aerosol physical optical characteristics near the resource area in the northwest of China. To investigate the characterization of atmospheric bioaerosols along transported pathways of dust aerosols, a multi-channel lidar spectrometer system was developed to observe Mie, Raman scattering and laser-induced fluorescence excitation at 355 nm from the atmosphere. Long-range transport of Asian dust from the Taklimakan and Gobi deserts was studied based on CALIPSO lidar measurements. German Aerospace Center's (Deutsches Zentrum für Luft- und Raumfahrt; DLR) Institute of Atmospheric Physicsa (IAP) is a member of ESA´s ADM-Aeolus Mission Advisory Group, Head of ESA funded pre-launch campaign study and contributor to algorithm and processor studies for Aeolus data products. DLR-IAP conducted several flights in the Mediterranean area which aimed at aerosol (incl. Saharan dust) detection using the ALADIN Airborne Demonstrator (A2D). DLR leads the Aeolus Data Innovation and Science Cluster (DISC) after launch to provide recommendations for the Aeolus instrument operation, retrieval algorithms as well as the calibration and validation procedures. The campaigns including airborne rehearsal campaign, airborne CAL/VAL campaigns and Tropical airborne campaign are ongoing/scheduled for 2018-2020.

The project objective is to validate the ADM-Aeolus and EarthCARE wind, cloud and aerosol data products. Ground-based co-located measurements with PollyXT, BERTHA, WACAL, CDL and HSRL lidars during overpasses of Aeolus and EarthCARE are foreseen in China (Costal cities, China Seas, inland cities, Tibetan Plateau, Taklimakan desert) and in Central Europe. An overview of the field campaigns will be presented in this report together with observation results from the ongoing data analysis. As an outlook, combing the aerosol data from other atmospheric lidar mission with the wind/aerosol products from ADM-Aeolus, the comprehensive observations of vertical profiles of optical properties, flux and the deposition of dust during the long-range transport over continents of Europe and Asia can be implemented. Furthermore, by means of the back trajectories model, it is possible to determine the long range transportation of dust and to reveal its impact on marine ecosystem.

Launched on 22 August 2018, Aeolus is the first satellite mission to measure atmospheric wind profiles on a global scale. The wind observations contribute to the improvement in numerical weather prediction (NWP), as they help to close the gap in wind data coverage, especially over the oceans and in the tropics, which has been identified as one of the major deficiencies in the current Global Observing System. For this purpose, it provides profiles of one line-of-sight (LOS) component of the horizontal wind vector from ground throughout the troposphere up to the lower stratosphere with a vertical resolution of 0.25 km to 2 km depending on altitude and precision of 2 m/s to 4 m/s. The obtained near-real-time data allow for greater accuracy of the initial atmospheric state in NWP models and thus improve the quality of weather forecasts as well as the understanding of atmospheric dynamics and climate processes.

At the heart of Aeolus is the Atmospheric Laser Doppler Instrument, ALADIN, which is composed of a frequency-stabilized, ultraviolet laser, a 1.5 m-diameter telescope and a highly sensitive receiver. The revolutionary instrument works by emitting short, powerful laser pulses through the atmosphere and collecting the backscattered light from air molecules, particles and hydrometeors which move with the ambient wind. The wind speed is then derived from the frequency difference between emitted and backscattered pulses, which is caused by the Doppler effect, while the travel time of the pulses contains the altitude information. The algorithms and processors needed to derive wind profiles from ALADIN's raw data were developed by a European team of DLR institutes, the software company DoRIT as well as several European meteorological services (ECMWF, Météo-France and the Dutch weather service KNMI).

After a four-month commissioning phase dedicated to the initial in-orbit characterization and optimization of the instrument, its data processing, and as such the improvement of the wind data quality, the mission is currently in the transition to its operational phase. During this transition phase, data is released to an extended group of calibration/validation teams in order to receive important data quality assessments and further feedback, e.g. from co-located measurements. This allows for the necessary refinements of the data processing and mission operation in preparation of the official data release which is scheduled for 2019.

This presentation will provide an overview and status report of the Aeolus mission and present first impressive results obtained with the first wind lidar in space.

Since the successful launch of ESA’s Earth Explorer mission Aeolus in August 2018, atmospheric wind profiles from the ground to the lower stratosphere are being acquired on a global scale deploying the first-ever satellite-borne wind lidar system ALADIN (Atmospheric LAser Doppler INstrument). ALADIN provides one component of the wind vector along the instrument’s line-of-sight (LOS) with a vertical resolution of 0.25 km to 2 km depending on altitude, while the precision in wind speed is between 2 m/s to 4 m/s. The near-real-time wind observations contribute to improving the accuracy of numerical weather prediction and advance the understanding of tropical dynamics and processes relevant to climate variability.

Already several years before the satellite launch, an airborne prototype of the Aeolus payload, the ALADIN Airborne Demonstrator (A2D), was developed at DLR (German Aerospace Center). Due to its representative design and operating principle, the A2D has since delivered valuable information on the wind measurement strategies of the satellite instrument as well as on the optimization of the wind retrieval and related quality-control algorithms. Broad vertical and horizontal coverage across the troposphere is achieved thanks to the complementary design of the A2D receiver, which, like ALADIN, comprises a Rayleigh and Mie channel for analysing both molecular and particulate backscatter signals. In addition to the A2D, DLR’s research aircraft carries a well-established coherent Doppler wind lidar (2-µm DWL) which allows determining the wind vector with accuracy of better than 0.1 m/s and precision of better than 1 m/s. Hence, both instruments represent key instruments for the calibration and validation activities during the Aeolus mission.

Over the past years, the A2D and 2-µm DWL were deployed in several field experiments for the purpose of pre-launch validation of the satellite instrument and of performing wind lidar observations under various atmospheric conditions. In autumn of 2018, the first airborne campaign after the launch of Aeolus was carried out from the airbase in Oberpfaffenhofen, Germany. Aside from extending the existing dataset of wind observations, this field experiment aimed to perform several underflights of Aeolus in Central Europe in order to provide first comparative results between the two airborne wind lidars (A2D and 2-µm DWL) and the satellite instrument. At the same time, the campaign served to optimize the operational procedures, particularly in terms of flight planning, to be applied during the forthcoming Cal/Val campaigns in the operational phase of Aeolus. In particular, two campaigns are scheduled for May 2019 in Central and Southern Europe and September 2019 in the North Atlantic region.

This work will provide an overview of the most recent airborne wind lidar campaigns and present their results both from an instrument and a meteorological point-of-view. Furthermore, an outlook on the upcoming Aeolus Cal/Val campaigns will be presented.