Assimilation of Observational Data in the COSMO-Ru Short-range Numerical Weather Prediction System of the Hydrometcenter of Russia

The paper presents a system of regional data assimilation prepared and functioning at the Hydrometcenter of Russia for the COSMO-Ru short-range weather prediction system. It describes the assimilation methods used: both the nudging and latent heat nudging methods incorporated into the model and the developed surface temperature correction module. An optimal scheme for preparing the analysis fields and the assimilation cycle for obtaining refined initial data is also described. The presented scores of numerical experiments with and without assimilation show that the use of the detailed analysis allows improving the skill of the model very-short-range forecast, including the nowcasting interval, for the fields of temperature, humidity, wind, cloud cover, and precipitation. It is shown that the assimilation of precipitation based on radar data also makes it possible to simulate associated convective phenomena, including severe ones, much more accurately.