黄河源区近50a极端气候变化趋势分析

Trend Analysis on Extreme Climate Characteristics of the Past Fifty Years in the Source Region of the Yellow River

基于黄河源区及周边15个气象站1961—2012年的气象数据,运用极端气候指数法、距平分析法和Mann-Kendall趋势检验法分析了黄河源区52 a来降水和气温的时空变化趋势,剖析了极端气候指数的变化特点。结果表明:黄河源区各气象站年平均气温、极端高温和极端低温均呈一致性显著上升趋势;年降水量呈西部增大、东部减小的趋势;年最大5 d连续降水量和年无降水日数主要表现为西部减小、东部增大,且最大前十位的无降水日数在1990—2012年频繁出现,这说明近23 a来黄河源区西部湿润化趋势明显,而东部极端暴雨事件日趋严重,干旱化呈加剧趋势。

In this study, routine weather data of fifteen weather stations in the source region of the Yellow River during the period of 1961-- 2012 were collected. The extreme climate index, anomaly analysis and Mann- Kendall trend test methods were used to investigate the spatial - temporal variations of precipitation and air temperature and especially the variation characteristics of extreme climate indices. The results show that the annual mean, extreme high and low air temperature values are in an insistent and significant increase trend in all weath- er stations in the study area. The annual precipitation tends to rise in the western part and to drop in the east. However, both annual maximum 5 - day precipitation amount and annual number of days with no precipitation incline to decrease in the western region and to increase in the east. Meanwhile the top ten annual numbers of days with no precipitation appear frequently in the period of 1990--2012. The above findings indicate that in the past twenty years the western part of the source region of the Yellow River is in an obvious humid trend and the eastern part has experienced more severe extreme storm and drought events.