北上台风暴雨过程涡散场的能量收支和转换特征

DIVERGENT AND ROTATIONAL WIND KINETIC ENERGY BUDGET AND CONVERSION DURING A TORRENTIAL RAIN PROCESS CAUSED BY TYPHOON LOW PRESSURE TROUGH

利用辐散风和旋转风的动能收支方程，对北方一次北上台风倒槽暴雨过程暴雨区内的涡散场能量收支和转换进行了计算。结果表明：暴雨区内动能的增加是暴雨增幅的一个主要原因。暴雨发展时，就旋转风动能（ Ｋ Ｒ） 而言，旋转风动能通量（ Ｈ Ｆ Ｒ） 辐合是主要能源，而旋转风的动能产生项（ Ｇ Ｒ） 是主要能汇；就辐散风动能（ Ｋ Ｄ） 而言，辐散风的动能产生项（ Ｇ Ｄ） 是主要能源，辐散风动能通量（ Ｈ Ｆ Ｄ） 辐散是主要能汇；总动能水平通量（ Ｈ Ｆ） 提供的辐合主要表现于对流层中、低层，这就使得低层辐合加强，上升运动加强，有利于暴雨的增幅。在暴雨过程中次网格尺度效应由能源转变为能汇，在暴雨发展之时能汇减小；能量的转换项 Ｃ（ Ｋ Ｄ， Ｋ Ｒ）总为正值，在转换项中，地转效应项的贡献很大。说明暴雨过程能量均由 Ｋ Ｄ 向 Ｋ Ｒ 转换，也就是说有效位能经 Ｋ Ｄ 向 Ｋ Ｒ 转换， 充分说明了在整个暴雨过程中， 尽管辐散风动能变化（ Ｋ Ｄ／ｔ） 很小，但是它在其中充当“桥梁”作用， Ｃ（ Ｋ Ｄ， Ｋ Ｒ） 在暴雨发展时达到最大，此时能量转换最为旺盛；对流层低层辐散风动能向旋转风动能的转换是暴雨产生和发展的重要条件。此次暴雨过程，在暴雨区内表现为斜压?

Divergent and rotational wind kinetic energy budget and conversion during a torrential rain process caused by typhoon low pressure trough are calculated using the complete equations of budget of divergent and rotational wind kinetic energy. The results show that the increment of the kinetic energy in the torrential rain area is one of the main contributions to the amplification of the torrential rain, while the rotational wind kinetic energy generation GK is the principle energy source, the horizontal flux HF provide convergence, especially in the lower troposphere, the sub grid scale kinetic energy generation term change from the energy sink into the energy source in the torrential rain process. The energy conversion term C(K D, K R) is always positive which show that energy transformed from K D to K R ,with the maximum in the lower troposphere as the torrential rain enhancement, and the term AF has the most important role during the energy conversion. It is also denoted that there is the enhancement of the baroclinic instability and the decrement of the barotropic stability during the torrential rain process, and the enhancement of the baroclinic instability in the lower troposphere is an important reason for the amplification of the torrential rain.