1961—2020年珠江流域极端气温和降水复合事件的时空演变特征分析

Spatiotemporal variations of compound extreme temperature and precipitation events in Pearl River Basin from 1961 to 2020

摘要

【目的】珠江流域是中国重要的经济与人口密集区，然而经常受到极端气温和极端降水事件的影响。仅分析单一变量可能低估这些极端事件对区域的实际影响。因此，研究极端气温和极端降水的复合灾害事件的变化趋势和特征，对准确评估其潜在灾害影响具有重要的科学意义。【方法】基于1961—2020年的气象观测数据，采用相对阈值法和标准化降水蒸散指数(SPEI),识别出热干、热湿、冷干和冷湿四类复合事件，通过趋势分析和空间分布研究，揭示这些复合事件的时空分布特征及其变化趋势。【结果】结果显示：1961—2020年期间，气温与SPEI呈显著负相关，尤其在夏季和冬季，西部和南部地区的相关性尤为突出。珠江流域热湿事件显著增加，冷干事件显著减少，尤其在21世纪初期变化最为明显。热湿事件主要集中在流域东南部及南部沿海地区，热干事件多发于西部和南部，冷湿事件在西北部频繁发生，冷干事件则在东北部较为常见。强度方面，热干事件主要表现为强等级和中等级，其天数远超热湿、冷湿和冷干事件。1991—2020年，热湿和热干事件的发生频数分别增加了24%和99%,而冷湿和冷干事件的频数则分别减少了9%和41%。在区域分布上，热干事件在平原和丘陵地带，尤其是海南岛及南海诸岛区域最为频繁；而冷湿事件在中山和高山地带更为显著。这些变化揭示了区域气候的显著转变。【结论】结果表明：珠江流域内热干和热湿事件的频数显著增加，尤其在南部和西部地区更为明显，反映出这些区域在未来气候变暖背景下面临高风险；相对而言，冷干和冷湿事件的减少趋势表明，区域气候正向暖湿化转变。通过深入分析复合极端事件的时空变化特征及其演变规律，研究成果为珠江流域的气候预估、复合灾害事件应对策略的制定以及防灾减灾能力提升提供了重要的科学依据和参考。

Abstract

[Objective] The Pearl River Basin is an important economic and densely populated area in China, frequently affected by extreme temperature and precipitation events. Studying the spatiotemporal variations of compound extreme events is vital for regional climate adaptation management. [Methods] Based on meteorological observation data from 1961 to 2020, this study employs the relative threshold method and the Standardized Precipitation Evapotranspiration Index(SPEI) to identify four types of compound extreme events: hot-dry, hot-wet, cold-dry, and cold-wet. Trend analysis and spatial distribution studies were conducted to reveal the spatiotemporal distribution characteristics and trends of these compound events. [Results] The result indicate a significant negative correlation between temperature and SPEI in the Pearl River Basin from 1961 to 2020, particularly prominent in the western and southern regions during summer and winter. Notably, there has been a substantial increase in hot-wet events and a significant decrease in cold-dry events, with the most pronounced changes occurring in the early 21st century. Hot-wet events were mainly concentrated in the southeastern and southern coastal areas of the basin, and hot-dry events frequently occur in the western and southern regions. Cold-wet events are common in the northwest, and cold-dry events are most frequent in the northeast. In terms of intensity, hot-dry events are mainly classified as strong or medium, with their duration far exceeding that of hot-wet, cold-wet, and cold-dry events. From 1991 to 2020, the occurrence frequencies of hot-wet and hot-dry events increased by 24% and 99%, respectively, while those of cold-wet and cold-dry events decreased by 9% and 41%. Regionally, hot-dry events are most frequent in plains and hilly areas, particularly in Hainan Island and the South China Sea Islands, whereas cold-wet events are more prominent in mid-altitude and high-altitude areas. The changes reveal a significant transformation in the regional climate. [Conclusion] The findings indicate a notable increase in the frequency of hot-dry and hot-wet events in the Pearl River Basin, especially in the southern and western regions, reflecting high-risk exposure in these areas under future climate warming. Conversely, the decreasing trend of cold-dry and cold-wet events suggests a shift toward a warmer and wetter climate. Through an in-depth analysis of the spatiotemporal characteristics and evolution of compound extreme events, this study provides important scientific evidence and references for climate prediction, response strategies to compound disaster events, and enhancing disaster prevention and mitigation capabilities in the Pearl River Basin.

关键词

复合事件 / 极端气温 / 极端降水 / 珠江流域 / 时空演变 / 气候变化 / 时空分布 / 干旱

Key words

compound events / extreme temperature / extreme precipitation / Pearl River Basin / spatiotemporal variation / climate change / spatiotemporal distribution / drought

基金资助

国家自然科学基金项目(42005126)