Improvement of dynamic balance for a hotstart analysis for short-range forecast

Yuanfu Xie

A hotstart scheme is crucial for short range forecast or nowcasting.

It usually initiates a cloud vertical velocity field by analyzing

various data sources, including satellite, metar and radar data. A

dynamic balance is required to be consistent with the cloud analysis.

A variational balance has been proposed and used for decades in Local

Analysis and Prediction System (LAPS). When it is applied to high

resolution analysis in km scales, the balance does not show expected

impact on short range forecast sometimes. Some interesting numerical

issues have been investigated and a new simplified scheme is tested.

Some numerical results will be shown.