Wind-cloud interactions observed with Aeolus spaceborne Doppler Wind Lidar

Kurzfassung

Model based studies have shown interactions between wind vertical profiles and cloudiness, but few observational studies corroborate them. The unique observations of Aeolus spaceborne Doppler wind lidar can contribute to fill this gap. In this paper, we merged global Aeolus observations of cloud profiles at full horizontal resolution (3 km along orbit track) with co-located profiles of horizontal winds. We first observed wind-cloud interactions at regional scale over the Indian Ocean. Aeolus captures the strengthening of the Tropical Easterly Jet in early June 2020, with wind speeds exceeding 40 ms-1 in its core, and a simultaneous increase of high cloud fraction up to above 30 %, until the decay of the jet during fall. Secondly, we observed wind-cloud interactions at cloud scale (between 3-100 km) in different regions. Over the Indian Ocean as well as over cumulus and stratocumulus dominated regions, we found that the wind shear in cloudy sky is always smaller than the wind shear in the clear sky surrounding the cloud (statistically significant). In addition, we found that the wind speed difference between the cloud and its surrounding clear sky increases with the clear sky wind shear, especially in cumulus (R=0.93) and stratocumulus (R=0.89) dominated regions. This study demonstrated that despite its coarse resolution, Aeolus can capture wind perturbations induced by convective momentum transport.