中文摘要：

采用新一代中尺度数值模式WRFv3.2版本,模拟研究了前期（秋季）土壤湿度异常对云南冬季降水的影响。数值模拟试验结果和一系列分析清楚表明,前期（秋季）土壤湿度的异常偏低,会导致云南地区冬季（12月1日~2月28日）降水的显著减少;前期土壤湿度减少一半,可以使云南冬季的降水量平均减少30%以上,小部分区域减少达50%以上,影响十分明显。大气环流及其主要参量模拟结果的对比分析清楚表明,持续的西偏北气流和干气团的控制以及云南地区大气散度场和垂直运动场等的异常是导致降水量减少的直接原因。对降水过程的分析表明,前期土壤湿度减少对降水过程的频次和发生时间的影响较小,但对各次过程的降水强度影响明显。这是前期土壤湿度减少所导致的包括区域性蒸发量和热通量等大气物理过程的改变决定的。本研究数值模拟结果与关于区域性土壤湿度异常影响机理的已有结论基本一致。

英文摘要：

The impact of anomalous antecedent soil moisture （in autumn） on the winter precipitation in Yunnan Province is investigated using the latest version of the mesoscale numerical model WRFv3.2. The simulated and analyzed results clearly show that the precipitation in Yunnan Province in winter （December 1-February 28） can be significantly reduced by unusually low antecedent soil moisture. The impact of the reduced antecedent soil moisture is so dramatic that the average reduction in precipitation is greater than 30% when the antecedent soil moisture is reduced to half that under normal conditions. In some regions, this number can even exceed 50%. Comparative analyses of the atmospheric circulation and major variable fields clearly indicate that a persistent northwest flow （dry air mass）, an anomalousdivergence, and the vertical velocity fields over Yunnan Province contribute directly to the reduced precipitation. By analyzing the precipitation events, the authors find that the precipitation intensity of every event is strongly influenced by the reduced antecedent soil moisture, whereas the frequency and timing of the precipitation events are affected less. This is related to the variability of physical processes in the atmosphere, including regional evaporation and thermal flux, that is caused by the reduced antecedent soil moisture. The simulation results of this study are consistent with previous results on the climatic impact of anomalous regional soil moisture.