Assimilation of Aeolus Horizontal Line of Sight Wind Speed at the Met Office
As members of the Calibration and Validation community, the Met Office began assessment of Aeolus Horizontal Line of Sight (HLOS) wind in January 2019. Using the Met Office global Numerical Weather Prediction (NWP) Model background to generate Observation minus Background (O-B) statistics, we have investigated the bias characteristics of Aeolus HLOS winds, on a routine basis, both to contribute to the Cal/Val effort and to help inform our own assimilation strategy.
We made an initial assessment of the impact of assimilating Aeolus HLOS wind speed from laser A, into our global NWP model using 4D-VAR, using a 1-month period during the early part of the mission. These experiments show Aeolus to have an impact on forecasts which is similar to the magnitude of assimilating surface winds from scatterometers. Improvements to the O-B standard deviation of most other observation types were seen in these experiments.
The Met Office started assimilating Mie channel winds from Aeolus in December 2020, and is preparing for assimilation of the Rayleigh channel in 2021. Results from our assimilation experiments will be presented, and the impact as measured by FSOI in our operational model.
