[A-AS15] Progress in dense observation and numerical modeling of micro-scale meteorology

[AAS15-P01] Preliminary consideration of the wind and pressure balance in multigrid assimilation scheme

*weiyu ding¹ (1.Institute of Tropical and Marine Meteorology, CMA, Guangzhou, China)

Keywords: wind and pressure balance, multigrid assimilation scheme

In the variational assimilation system, the statistics of the background error covariance matrix needs a huge amount of computation and storage, the geostrophic balance or linear balance is usually constructed to simplify wind and pressure relationship in the background error covariance matrix during the process of minimizing the cost function. With the improvement of model resolution and the assimilation of dense ground observation data, more and more small-scale information needs to be assimilated into the initial value of the model. Geostrophic balance or linear balance cannot describe the balance of local wind and pressure field. In this study, based on the multi-grid assimilation scheme, the sounding data and Atmosphere Motion Vector data are assimilated in the coarse grid with geostrophic balance, and the automatic weather station data are assimilated in fine grid with no wind pressure balance constraint. In this research, a case of squall line process in Guangdong China is studied, and the impact to 2-meter temperature and precipitation simulation are analyzed.