How much pa is the correlation between precipitation and vertical velocity field generally studied?

Relative humidity ≥70% can be regarded as a necessary condition for the occurrence of rainfall in Yantai. When it rains in Yantai, the divergence of water vapor flux at 700hpa is negative, which is not more than-4×108g cm-2 HPA-1s-1,and the vorticity at 500hpa is ≥ 4× 65438+. In rainy weather, the vertical velocity field has a positive and negative closed center. The greater the gradient between positive and negative vertical velocities, the greater the positive and negative center value of vertical velocity and the greater the rainfall, and vice versa. Through the correlation analysis method, the forecast factors that have great influence on precipitation are screened out, and the multiple regression equation is established by using the model output statistics (MOS) forecast method. Combined with the characteristics of circulation situation, a convenient and practical precipitation forecast discrimination model is proposed, and the forecast accuracy rate is over 75%.