一种新的汛期降水集中期划分方法

A NEW METHOD FOR THE PARTITION OF PRECIPITATION CONCENTRATION PERIOD IN FLOOD SEASON

汛期降水集中期是近期气象学者提出的表征汛期气候的一种新的特征量,它在气候研究中体现了较好的灵活性、客观性,通过对其分析,可为汛期气候的诊断和预测提供依据。但现在普遍使用的降水集中期在计算方法和时间长度上存在缺陷,特别是运用到时间跨度较长时段的气候分析时,特征量表征作用就有所缺失,而且计算方法较为复杂。为更好地使用降水集中期这一特征量,提出了以15天作为时长,用滑动统计来划定汛期降水集中期的新方法,并运用统计方法、天气气候学方法进行了论证,同时在长江下游主雨季降水集中期分析和金华地区汛期分析两个实例中进行了应用检验。结果表明,汛期降水集中期新方法划定的特征量与汛期降水总量存在时间上的相对独立性和总趋势上的显著相关性,且在汛期气候极端灾害事件上有较强的描述能力。因此认为,15天滑动统计新方法划定的汛期降水集中期使用便捷,天气气候意义明确,在实际应用中更为客观有效。

The precipitation concentration period （PCP） is a new characteristic quantity for attributing the climate of flood season. This new quantity was developed by meteorologists and has shown a better flexibility and objectivity in climatic studies. Analysis of PCP can provide basic and useful information for climatic diagnosing and forecasting in flood seasons. While the current used universal indices of precipitation concentration period （PCP） have shortages in computation and time length definition. Specially, this characteristic quantity has a flaw when it is used in the climate analysis with a longer term, moreover the computational method is too complex to use in routine work. In this paper, a new method of PCP with 15-day running mean is developed for the purpose of more effective use of PCP in climate analysis. The authors proved this new method by the use of statistical methods and the synoptic climatological method. Simultaneously, two case studies in the lower Yangtze River and Jinhua area flood season were carried out for the examination of the method. The result indicated that the characteristic quantity of new flood season PCP is time independent with total rainfall in flood season and has remarkable relevance with general trend of precipitation, and it has the strofiger ability in describing extreme disaster event in the flood season. Therefore, the new method of PCP with 15-day running mean has the explicit weather climate significance. It is convenient, objective and more effective in the practical application.