The ESA-funded Aeolus/EarthCARE Aerosol Assimilation Study (A3S)

<pre class="aLF-aPX-K0-aPE">In recent years, aerosol prediction has become more skillful thanks also to advances in aerosol observability. Several centres with forecasting capabilities now offer forecasts of aerosol fields up to five days ahead. At ECMWF, the Copernicus Atmospheric Monitoring Service (CAMS) delivers aerosol products based on analysis of Aerosol Optical Depth (AOD) from various sensors. Recent reasearch efforts have also shown the potential of lidar backscatter to extract aerosol information, providing also important insight on the aerosol vertical structure. In preparation to the launch of the Aeolus mission, ESA funded a collaboration between ECMWF and MeteoFrance, the Aeolus/EarthCARE Aerosol Assimilation Study (A3), to look at the potential of lidar data from the ALADIN lidar instrument on board of Aeolus. While this instrument is designed for wind retrieval and not specifically for aerosol science, some useful information can be extracted through a combination of post-processing and assimilation. This is also preparatory work for the EarthCARE mission which will operate a UV lidar at the wavelength of 355nm, designed to study aerosols and clouds. The A3S project demonstrated the technical feasibility of assimilating lidar backscatter signal at that frequency usingdemonstration datasets built on model and CALIPSO data. Following the successfull launch of Aeolus in 2018, ESA has funded a continuation of the A3S project with the goal to assimilate in-orbit data of particle backscatter (L2A) from the ALADIN instruments. In this presentation, preliminary results from this activity will be discussed, focusing in particular on the post-processing of the L2A particle backscatter product using a model-dependent cloud screening to ensure that only aerosol signal is allowed into the 4D-Var analysis.<br /><br /></pre>