Intercomparison of wind observations from ESA’s satellite mission Aeolus, ERA5 reanalysis and radiosonde over China

The European Space Agency (ESA) Earth Explorer Atmospheric Dynamics Mission Aeolus is the first satellite mission providing wind profile information on a global scale, and its wind products have been released on 12 May 2020. Here we verify and intercompare the wind observations from ESA’s satellite mission Aeolus and the European Centre for Medium-Range Weather Forecasts (ECMWF) fifth generation atmospheric reanalyses (ERA5) with radiosonde (RS) observations over China, to allow a fitting application of Aeolus winds. Aeolus provides wind observations in aerosol-free (referred to as Rayleigh-clear winds) and cloudy atmospheres (Mie-cloudy winds). In terms of Aeolus and RS winds, the correlation coefficient (R) and mean difference of Rayleigh-clear (Mie-cloudy) vs RS winds are 0.94 (0.97) and −0.24 ± 7.01 (0.18 ± 4.42) m/s, respectively. The vertical profiles of wind speed differences between Aeolus and RS winds are similar to each other during ascending and descending orbits. The comparison of ECMWF winds relative to Aeolus winds provides the R and mean difference of Rayleigh-clear (Mie-cloudy) winds, which are 0.95 (0.97) and −0.16 ± 6.78 (−0.21 ± 3.91) m/s, respectively. The Rayleigh-clear and Mie-cloudy winds are very consistent with the ECMWF winds, likely due to the assimilation of Aeolus wind observations into the ECMWF analysis. Moreover, we find that among the results of comparing Aeolus with RS and ECMWF winds, a small difference between Rayleigh-clear winds relative to RS winds is appeared in the height range of 2–3 km during descending orbits. This result may be due to the high vertical velocity during the descending orbits. The mean differences between Rayleigh-clear (Mie-cloudy) winds and RS winds during the ascending and descending orbit phase are −0.07 ± 0.69 (−0.72 ± 1.48) and 0.3 ± 1.25 (0.1 ± 1.32) m/s. These small deviations indicate that the performance of Aeolus wind products may be unaffected by the orbit phase or HLOS wind conditions. In addition, the R and mean difference between ERA5 and RS zonal wind components are 0.97 and −0.46 ± 3.12 m/s, respectively. Overall, the Aeolus winds over China are similar to the RS and ECMWF winds. The findings give us sufficient confidence and information to apply Aeolus wind products in numerical weather prediction in China and in climate change research.