Optimising the Exploitation of Aeolus Winds in Regional NWP
The first results from a project focused on optimizing the use of Aeolus HLOS winds in regional Numerical Weather Prediction (NWP) models will be presented. In this study the regional NWP model Harmonie-Arome is used with a four-dimensional variational data assimilation scheme. The initial part of this study is focused on a period with Polar Lows in Nov-Dec 2019 over the Arome-Arctic domain, which covers Northern Scandinavia and the Svalbard region. The impact of different settings for the assimilation of Aeolus HLOS winds, using Rayleigh clear air and Mie cloudy observations, are investigated. Both the impact on the analysis and the forecasts will be evaluated. Moreover, the impact of assimilating the Aeolus wind in the global ECMWF model used as boundary conditions for the Arome-Arctic will be assessed. There are many Aeolus overpasses over the Arctic domain and at the same time rather few other observations, which makes the evaluation challenging. We also expect a larger impact from the Aeolus winds here than we would see in a domain with fewer overpasses. For this reason, we plan to study the impact of Aeolus observations over a more typical limited area NWP domain, UWC-west covering western Europe, where there are more other types of observations available. Here, we plan to study the impact of Aeolus data for the winter storms Ciara and Dennis in Feb. 2020.
