动力负熵场及其在短期天气预报中的应用

THE APPLICATION OF DYNAMICAL NEGATIVE DISSIPATION FIELD IN SHORT TERM WEATHER FORECASTING

把纬圈气流虚拟平衡态原理具体应用到短期预报中，因时效短的缘故，决定了虚拟平衡态应在低层大气中寻找，倘若时效达到一定天数（３～５ｄ），则平衡态应在中层大气中定义。按照涡动原理计算出动力负熵值，由动力负熵值构成动力负熵场（图），其由正熵区、负熵区、０值线三部分组成，正熵区为无降水区，负熵区又分为负熵有效区和负熵无效区，前者为未来的降水区域，降水强度与负熵中心值和梯度的大小成正比。

The principle of virtual zonal equilibrium state (VZES) was applicated in short term weather prediction. The VZES may be found in low level of troposphere because of short term. If a forecasting time was longer (3～5 d) the VZES could be defined in middle level of troposphere. According to the principle of eddy motion near the VZES, to calculate dynamical negative dissipation value of every station was necessary in order to form dynamical negative dissipation field (map). The map was mainly consisted of three parts. The first is positive dissipation area, of which significant weather is explained as no precipitation in future. The second is negative dissipation area which should be subdivided into available negative area and ineffective area. The former certainly means that rain will be happening in limited area. The latter equals no any rain. The third is zero isohyet line which separate positive area from negative area. The intensity precipitation in the available negative area is calculated in direct proportion to the value(number) and the gradient of the negative center.