滨海新区夏季降水的日变化特征

Diurnal Variation of Summer Rainfall in Tianjin Binhai New Area

利用1970—2015年天津塘沽地面观测站逐小时降水资料,分析了滨海新区夏季降水日变化特征及其长期演变趋势。结果显示滨海新区降水量与降水频次均呈现"昼少夜多"的特征,后半夜到清晨是降水最为活跃的时段。降水量两个高值时段所对应的降水是由不同性质降水构成,清晨出现的降水量的最大峰值是由短时降水与持续性降水共同贡献,后半夜的降水量次大峰值主要由持续性降水贡献。40年来滨海新区的短时降水的降水量呈现增多趋势,长持续性降水的降水量呈现减少趋势,总降水量的减少与长持续性降水总体强度减弱有关。

Based on hourly rain gauge data from 1970 to 2015,the diurnal variation of summer rainfall in Tianjin Binhai New Area was studied.The result shows that both rainfall amount and frequency exhibit their maximum during the night and their minimum in the daytime.The maximum peak of rainfall amount around early morning is contributed to both longduration and short-duration rainfall events while the peak after the midnight accounts for most of the long-duration rainfall events.The total summer rainfall amount of Tianjin Binhai New Area exhibited a downward trend which is related to the decrease of long-duration rainfall amount over the past forty years.