黑龙江省水稻生育阶段极端降水事件时空特征

利用百分位相对指数法,基于1971-2016年历史长序列的日降水资料,分析研究黑龙江省水稻生长季极端降水事件的阈值、频数和强度的时空特征。结果表明:黑龙江省极端降水事件阈值的高值区主要位于松嫩平原中南大部;极端降水事件主要集中于水稻生长季的5-9月,尤其是在水稻生殖生长的关键阶段,发生了大部分的极端降水事件;46年中,水稻种植区极端降水事件频数在18～72 d,极端降水事件频数总体呈经向分布特征,自东向西逐渐减少。7月下旬为中西部地区极端降水事件发生的高频时段,东部地区极端降水事件发生的高频时间段为5和9月,6月为极端降水事件发生的低频时段。近6年为极端降水事件频数最高、强度最大的一段时期,20世纪70年代则反之;极端降水事件频数和强度存在高度的相关性;在有雨量观测的小区域内,洪涝灾害事件基本可以被极端降水事件捕捉到,同时极端降水事件对洪涝灾害的指示性也较高。

Spatio-Temporal Distribution of Extreme Precipitation Events During Growing Season of Rice in Heilongjiang Province

The extreme precipitation event (EPE) is defined by relative index method of percent. This paper analyzes spatio-temporal characteristics by the indicators of threshold, frequency and intensity based on the daily rainfall data during growing season of rice in Heilongjiang from 1971 to 2016. The results show that high value of EPE threshold appears mainly in Central South Songnen Plain. The EPE happens mainly from May to September during growing season of rice, especially in the key reproductive growth stage of rice. During the 46 years, frequency of the EPE ranges from 18 to 72 days, showing the characteristics of meridional distribution and decreasing gradually from the east to the west. Usually, frequency of the EPE is the highest in late July over central and western regions, and that is the highest in May and September for the eastern regions. The lowest frequency of EPE is in June, so June is a safe period for rice production. As for the interdecadal difference from 1971 to 2016, the frequency is the most in recent 6 years, and the intensity is the largest for EPE, but in 1970s the situation is opposite. Thus, there is a high correlation between frequency and intensity of EPE. For small regions with rainfall observation, flood di-saster can mostly be designated with EPE, and emergence of EPE possibly indicate flood disaster.