Abstract:

Under the severe situation of global warming, regional high temperature and drought events are becoming more frequent, posing a major threat to ecological environment, food security, economic development and life and health. From April to June 2024, high-temperature and drought events occurred again in North China, Northwest China, and Southwest China, causing significant losses in agricultural production. This study utilized various data to preliminarily analyze the characteristics and causes of the high-temperature and drought processes in above three regions. The results show that the drought in southwest China mainly occurred in April, while the drought in North China and Northwest China began to emerge in April, with the intensity gradually increasing and the range expanding from May to June. With the intensification of drought, the abnormal range of regional maximum temperature expanded significantly. The number of hot days in Northwest China reached a new record, and the highest temperature anomaly reached its peak in May, which was one month ahead of the most severe drought period (June) in this region. The high temperatures in southwest China and North China were close to historical extremes. Further analysis indicates that the drought in North China is mainly influenced by the circulation in the Pacific region, while high temperatures are mainly affected by the circulation in the low-latitude Pacific and the Western Pacific Warm Pool. The drought in Northwest China is mainly influenced by the Western Pacific Subtropical High and the Arctic Vortex in the Northern Hemisphere, and the main influence on high temperatures comes from the North Atlantic. The factors affecting high temperatures and drought in the Southwest China are more complex, but mainly concentrated in the Northern Hemisphere Subtropical High and the low-latitude Pacific and Indian Oceans. From the perspective of circulation and water vapor, the main causes of the drought in North China and Northwest China are the development and maintenance of the continental high pressure, while the drought process in Southwest China is affected by the northward shift of the Western Pacific Subtropical High, which allows the dry and hot air currents from the Indian subcontinent to control this area, leading to water vapor divergence and ultimately causing high-temperature drought.

Key words: spring and summer in 2024, heatwave and drought, climate indices, circulation anomalies

摘要：

在全球气候变暖的严峻形势下，区域性高温干旱事件愈发频繁，对生态环境、粮食安全、经济发展和生命健康构成重大威胁。2024年4—6月，我国华北、西北及西南地区再度遭遇高温干旱侵袭，农业生产遭受明显损失。本研究综合多种数据资料剖析上述3个区域高温干旱事件的演变特征及成因。结果表明，西南地区干旱主要发生在4月，而华北和西北地区自4月起旱情显现、5—6月旱情逐渐加剧（强度增强、范围扩大）。伴随旱情加剧，区域最高气温异常范围明显扩展，西北地区高温日数创历史新高，5月最高气温达到峰值，较旱情最为严重的6月提前一个月；西南和华北地区高温接近历史极值。进一步分析表明，华北地区干旱主要受太平洋地区环流调控，而高温则主要受低纬度太平洋环流及西太平洋暖池影响；西北地区的干旱主要与西太平洋副热带高压及北半球极涡密切相关，高温则主要来自北大西洋的影响；西南地区高温干旱的成因更为复杂，但主要聚焦于北半球副热带高压和低纬度太平洋、印度洋。从大气环流和水汽输送的角度审视，华北和西北旱情的主导因素为大陆高压的发展和维持，而西南地区的干旱则受偏北的西太平洋副热带高压引导，致使来自印度大陆的干热气流控制这一区域，造成水汽辐散，进而引发高温干旱灾害。

关键词: 2024年春夏, 高温干旱, 气候指数, 环流异常