Expected NWP Impact of Continuous Mode Aeolus Wind Data
Horanyi, Andras; Rennie, Michael; Isaksen, Lars
European Centre for Medium-Range Weather Forecasts (ECMWF), UNITED KINGDOM

This poster gives an overview about studies performed at the European Centre for Medium-Range Weather Forecasts (ECMWF) to investigate the expected NWP impact of Continuous Mode Aeolus wind data. For the impact assessments real, good quality wind observations were used for a number of Observing System Experiments (OSE) and advanced assimilation diagnostics experiments. The denial studies used aircraft and wind profiler observations to investigate the impact of thinning the wind data. In addition the wind observations from radiosondes, aircraft and profilers were used to define single component (HLOS: Horizontal Line-of-Sight) wind data for various Aeolus related impact studies, where the impact of HLOS data was investigated. Additional experimentation was conducted to investigate the impact of degraded quality observations, representative for the decreased laser pulse energy expected to be used for the first phase of the Aeolus mission. The NWP impact results confirm that wind observations are very beneficial. It is shown that wind data is more important than mass (temperature and humidity) data, so new wind observations like Aeolus wind data would be welcome from the global data assimilation and forecast point of view. Particularly, most benefit is expected in the tropics and in the upper troposphere and lower stratosphere. Furthermore it is shown that a slight increase in random observation error does not severely reduce the impact of the Aeolus data. However even relatively small biases can have very detrimental effect on the impact. All in all the impact studies at ECMWF concludes that Aeolus wind data is expected to provide valuable impact in global numerical weather prediction. The poster will give an overview of the main methodologies applied and it will summarise the most important results of the impact studies.