Initial Impact Assessment of ADM-Aeolus Wind Observations on NCEP Global Analysis and Forecast

The Atmospheric Dynamic Mission (ADM)-Aeolus satellite was launched by the European Space Agency (ESA) on August 22, 2018, as the first Doppler wind lidar providing horizontal line of sight (HLOS) wind profiles from space. This study presents the preliminary results for the impact of Aeolus wind-profile assimilation into the NOAA operational Global Data Assimilation System (FV3GDAS/GFS). To assimilate the Aeolus Level-2B (L2B) wind profiles, the existing wind-assimilation capacity is extended in the FV3GDAS/GFS. The Aeolus L2B Rayleigh and Mie wind retrievals are verified by the collocated analysis and background of ERA5 and GDAS for the period of September 12 to October 16, 2018 as recommended by ESA. The Observation-minus-Background/Analysis (OmB/A) statistics shows that the Aeolus data have reasonable quality, with some eminent biases depending on ascending/descending orbits. In this initial impact assessment, these biases are removed by a stand-alone Bias Correction (BC). Various physics-based Quality Controls (QCs) are applied. Assimilation experiments are performed using a low-resolution version of the GDAS with or without assimilating the Aeolus L2B data. The analysis and forecast impacts are evaluated and validated in comparison with independent observations from radiosonde, Atmospheric Motion Vectors (AMVs), and aircraft flight level winds. Development of more advanced QC and BC processes and turning of the parameters, e.g., accumulation length, will be also discussed.