A study on a wind field when a cold air flow which causes snow fall on Sapporo city appears

Abstract

Sapporo has a heavy snowfall when a cold air flow appears on Ishikari Bay against the monsoon. Predicting a wind field is important to predict a snowfall. First, we study on horizontal convection by numerical analysis which is caused by temparature difference between the sea and the cold air flow which is about 20°C. On the other way, convction on the tip of the cold air flow is confirmed by doppler radar observations. Second, we analyze the wind field and derive a release rate of the latent heat between the convection area and the compensation area by convection model.
As a result, it was found that the horizontal convection is weak on an actual condition and that the vertical profile of the vertical velocity in convection model is similar to actual one. The change from the convection to a little low pressure around Ishikari Bay can be estimated with the release rate of the latent heat.