2023年河西走廊中部异常高温干旱特征及其成因

Characteristics and causes of abnormally high temperature and drought in the central Hexi corridor in 2023

  • 摘要: 2023年河西走廊中部出现了60 a一遇的极端高温干旱,给当地农业生产和生态环境带来不利影响,造成严重经济损失。利用河西走廊中部6个国家基本气象站1951—2023年逐月降水和气温资料,黑河上游莺落峡水文站黑河径流量资料,FY-3D/MERSI卫星资料,GF-1卫星资料,NCEP/NCAR 月平均再分析资料,NCC提供的88项大气环流指数和26项海温指数,对2023年河西走廊中部高温干旱从气象、水文、生态、农业等多角度探讨了高温干旱特征及影响,重点分析了降水对大气环流和关键区海温的异常响应。结果表明:2023年5—9月河西走廊中部降水和平均气温均突破历史极值,降水量创历史新低,气温创历史新高,高温叠加效应,使干旱强度明显加重,引发祁连山中段积雪面积减少45.8%,黑河年径流偏枯15%,主要水库面积减少25.8%—66.0%。干旱的传递特征是气象干旱—水文干旱—生态和农业干旱。河西走廊中部5—9月降水量存在5、11、17、32 a显著多尺度振荡,多个时间尺度显示2023年均处于偏少期。河西走廊中部干旱的异常环流特征是西太平洋副高脊线偏南、西伸脊点偏东、南亚高压脊点偏东、印度低压偏弱、北半球和亚洲区极涡面积偏小、亚洲中高纬阻塞高压偏强、欧亚和亚洲地区西风环流经向度加大、Nino3区和西风漂流区海温偏暖、黑潮区海温偏冷。

     

    Abstract: In 2023, the central part of the Hexi corridor experienced an extreme high temperature and drought that would occur once every 60 years, which adversely affected local agricultural production and ecological environment, causing serious economic losses. This study uses various observational datasets to discuss the characteristics and effects of the high-temperature and drought in the central Hexi corridor in 2023 from perspectives of meteorology, hydrology, ecology and agriculture. We further examine the responses of summer precipitation in the central Hexi corridor to anomalous atmospheric circulation and sea surface temperature (SST). The datasets used in this study include monthly precipitation and temperature data during 1951—2023 from six national basic stations in the central Hexi corridor, the Heihe river runoff data from Yingluoxia hydrological Station in the upper reaches of the Heihe river, the FY-3D/MERSI satellite data, the GF-1 satellite data, and the NCEP/NCAR monthly mean reanalysis data, and 88 atmospheric circulation indexes and 26 SST indexes provided by NCC. The results show that precipitation and average temperature in the central part of the Hexi corridor from May to September 2023 both exceeded historical extremes, with precipitation reached a new historical low and temperature reached a new historical high. The combined effect of high temperature and low precipitation significantly exacerbated the intensity of drought. In the middle Qilian mountains, the average snow cover area decreased by 45.8%, the annual runoff decreased by 15%, the main reservoir area decreased by 25.8%—66.0%. The characteristics of drought spread are meteorological drought—hydrological drought—ecological and agricultural drought. We find that precipitation in the central Hexi corridor from May to September had significant multi-scale oscillations in 5, 11, 17 and 32 a, and multiple time scales showed that 2023 was in a period of less oscillation. When the drought in the central Hexi corridor was observed, the atmospheric circulation anomalies included a southward shifted ridge line of the subtropical high in the Western Pacific Ocean, an eastward shifted ridge point of the western extension, a westward shifted ridge point of the South Asian high pressure, a weaker than normal Indian low, a smaller polar vortex area in the northern hemisphere and Asia, a stronger blocking high in the middle and high latitudes of Asia, and increased longitudinal coverage of the westerly circulation in Eurasia and Asia. Meanwhile, positive SST anomalies occurred in the Nino3 area and the west wind drift region, while negative SST anomalies occurred in the Kuroshio region.

     

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