1965～2005年泾河流域极端温度事件变化特征

Trends of Extreme Temperature Events in Jinghe Watershed During 1965-2005

利用18个气象站点1965～2005年的日气温数据,基于Mann-Kendall检验、小波分析等方法,分析黄土高原泾河流域极端温度事件的频次、平均强度、年极值和气温日较差的变化趋势、年代际变化和振荡周期等。结果表明,41a以来泾河流域极端高温事件增多而极端低温事件减少,极端低温平均强度显著降低,年极值呈增长趋势。各变量均发生突变,一般在1990年有明显趋势转变。较1965～1990年,90年代以来各变量的变幅较大,极端高(低)温的发生频次变化+9.5d(-8.6d),极端高(低)温的平均强度变化+0.8℃(-1.3℃),气温年极大(小)值增加1.8℃(0.2℃),日较差增大了0.4℃。极端温度事件有3、8～9和17a的振荡周期。

Based on temperature data during 1965 -2005 in Jinghe watershed and through Mann-Kendall test and morlet wavelet method, this study analyzed the monotonic trend, interdecadal change and period of frequency, intensity, annual extreme value and diurnal range for extreme temperature events. Results showed that in recent 41 years the frequency of extreme high temperature events （EHT） increased while that of extreme low temperature events （ELT） decreased, the intensity of ELT decreased significantly and the annual extreme temperature in- creased. For each variable abrupt change occurred and generally changed in 1990. Compared with 1965 - 1990, each variable changed greatly since 1990s, the frequency of EHT and ELT changed ＋9.5 d and -8.6 d, the intensity of EHT and ELT changed ＋ 0.8℃ and - 1.3 ℃, the annual extreme highest and lowest temperature increased 1.8 ℃ and 0.2 ℃, respectively ; the diurnal range increased 0.4 ℃. The extreme temperature events have several oscillating period such as three years, eight to nine years, seventeen years and twenty eight years.