横断山区极端气候变化的时空格局

Spatial distribution characteristics of extreme climatic events in the hengduan mountains Region

针对全球气候变化下不同区域极端气候事件显著增加问题,为了揭示横断山区极端气候变化的时空演变规律,基于横断山区129个气象站点1970—2019年的逐日降水和气温数据,分析了横断山区27个极端气候指数的时空变化特征,利用广义极值分布揭示了部分极端指数的频率特征,并对比分析与其他地区极端气候指数变化的规律。研究表明:(1)近50年来横断山区大部分区域的各极端降水指数变化趋势不明显,北部极端降水事件的发生频次和强度低于南部。横断山区南部和西部边缘地区发生极端降水事件的频次和强度较大。(2)横断山区内90%以上站点的极端气温暖指数显著上升,极端气温冷指数显著下降。南北气温差异显著,以青藏高原为界,北部气温日较差大,平均在13.83℃,几乎无热夜日数,南部气温日较差小,平均为11.38℃,南部平均的冰冻日数在1 d左右。极端高温较普遍的发生在南部和东部的干旱河谷中,且发生强度有增加的趋势。(3)随着重现期的增加,持续干燥期(CDD)大于110 d的区域逐渐由西部扩大到金沙江下游流域;在不同重现期下,持续降雨期(CWD)和年降水总量(PRCPTOT)的高值区集中在西部和南部的边缘;北部的日最大降水量(RX1day)在不同重现期下变化不显著,在60 mm以下;最低气温极小值(TNn)和最高气温极大值(TXx)在空间分布上北低南高,40℃以上的高温普遍发生在南部的干旱河谷。

Based on daily precipitation and temperature data of 129 meteorological stations in Hengduan mountains region from 1970 to 2019.The spatial and temporal characteristics of 27 extreme climate indices were analyzed in the Hengduan mountains,which aim to reveal the frequency characteristics of extreme climate indices by generalized extreme value distribution.Otherwise,we analyze the extreme climate indices of other regions and compare them with our research.The results are as follows:(1)In recent 50 years,the variation tendency of extreme precipitation indices in most area of Hengduan mountains region is not obvious.The occurrence frequency and intensity of extreme precipitation events in north of Hengduan mountains region is lower than the south,and the frequency and intensity of extreme precipitation events are relatively high in the southern and western marginal areas of Hengduan Mountain.(2)The extreme temperature indices of warmth events in most stations of Hengduan mountains region increased significantly,while the extreme temperature indices of cold events decreased significantly.There was a conspicuous difference in temperature between the north and the south,with a large daily temperature range and no hot nights in the north,and a small daily temperature range and no freezing days in the south and the eastern edge.Extreme high temperatures are more common in the southern and eastern dry valleys,and intensity of extreme high temperatures tends to increase.(3)With the increase of return periods,the high value area of CDD gradually expand from the west to the lower reaches of Jinsha River in the east of Hengduan Mountains.Under the different return periods,the high values of CWD and PRCPTOT were concentrated in the western and southern edges.The high value areas of RX1Day distribute in the southeast,and increase significantly in the southern part with the increase of return period.The spatial distribution pattern of TNN and TXX has little change in different return periods.In the mass,the temperature is low in the north and high in the south,and the high temperature generally occurs in the southern dry valley.