1958-2006年河西走廊极端天气气候事件变化特征

利用1958-2006年甘肃河西走廊18个观测站大雨、干旱、≥35℃高温、≤-20℃低温、霜冻、大风、沙尘暴、雷暴、冰雹等极端天气气候事件的年发生日数资料,采用多项式法、线性倾向、M ann-Kendall法、滑动t检验及Morlet小波等统计学方法诊断分析其变化特征。结果表明:近49年来,河西走廊大风、沙尘暴、低温、霜冻、雷暴和冰雹呈显著减少趋势,高温呈显著增多趋势,其中大风、沙尘暴、高温和霜冻分别于1996,1989,1996年和1998年前后发生突变;大雨和干旱频数总体变化不显著。20世纪90年代初,低温和霜冻由多趋少,高温、大雨和干旱由少趋多,与河西走廊突变增暖时间基本吻合。干旱和高温存在长期性变化周期,沙尘暴、雷暴存在阶段性变化周期,其余极端天气周期变化不明显。

Change Characteristics of Extreme Weather and Climatic Events over the Hexi Corridor during the Period of 1958 -2006

This paper analyzes the change characteristics of extreme weather and climate events, such as heavy rain, drought, high temperature ≥35 ℃, low temperature≤ -20℃ , frost, gale, sandstorm, thunderstorm and hail over the Hexi Corridor using the data of annual occurring days of extreme weather and climate events from 18 meteorological stations in the corridor during the period of 1958 -2006 and the statistical methods, such as polynomial , linear trend, Mann-Kendall test, Moving T-test and Morlet wavelet analysis. The results show that the annual days of occurring some extreme weather events, such as gale, sandstorm, low temperature ≤ -20℃, frost, thunderstorm and hail, over the Hexi Corridor in recent 49 years have been significantly decreased, but the annual days of occurring high temperature ≥35 ℃ have been obviously increased. Of which the abrupt change of occurrence of gale, sandstorm, high temperature ≥35 ℃ and frost occurred around 1996, 1989, 1996 and 1998 respectively. Generally, the change of the frequencies of heavy rain and drought is not so obvious. In the early 1990s, the annual days of occurring low temperature ≤ -20 ℃ and frost were decreased, but those of high temperature ≥35 ℃ , heavy rain and drought were increased, and these trends met the abrupt warming in the Hexi Corridor. There is a long-term periodical change in high temperature and drought but a staggered one in sandstorm and thunderstorm, and the periodical change of other extreme weather and climate events is not so obvious.