长黄淮海流域雨强变化特征及气象因子影响分析

Characterization of rainfall intensity changes and meteorological factors influence in the Yangtze-Huang-Huai-Hai River Basins

摘要

【目的】近几十年来,全球气候变暖程度加剧,长黄淮海流域降水量等因素明显变化,极端降水事件增多,旱涝灾害频发。为细化降水等级,进一步开展流域内长序列雨强、雨日变化特征以及温度和大气环流等气象因子对雨强的影响分析,【方法】基于流域内417个气象观测站1956—2022年逐日观测资料,使用线性斜率、M-K趋势检验、Sen′s斜率估计等多种趋势分析检验法,以及相关分析法、Morlet小波分析法进行分析。【结果】结果显示:长江流域降水量增加(6.12 mm/10 a),黄淮海流域减少(-14.64 mm/10 a、-3.97 mm/10 a、-6.47 mm/10 a),降水量和降水日数有多类时间尺度主周期。雨强方面:长江流域主要是大雨和暴雨量增加(1.03 mm/10 a、7.00 mm/10 a),黄淮海流域主要是小雨、中雨和大雨量减少。雨日方面:各流域近90%以上站点的各类雨日都呈下降趋势,并且雨强与对应雨日空间相关系数基本在0.88以上。流域内平均温度、最高(低)温度年际变化呈显著上升趋势,与各流域雨强有一定相关性。【结论】结果表明:(1)各流域年降水量在频繁的丰枯交替变化下,长江流域呈增加趋势而黄淮海流域程减少的趋势,全流域降水日数都显著下降,降水量和日数主周期相近。(2)各流域雨强与雨日变化趋势一致,两者的空间相关性较高,长江中下游地区大雨、暴雨量增多加剧极端降水事件的发生,黄淮海流域小雨、中雨量减少导致干旱事件频发。(3)升温对各流域雨强影响效果不同,主要表现为促进长江流域暴雨量增加而加速黄淮海流域小雨量减少,加剧南涝北旱的局面;大气环流因子变化同样影响雨强变化,AMO和EASMI、SCSSI、SASMI和Nino3.4等因子通过影响东亚、南亚和南海季风活动强度等大气环流条件,从而影响流域内极端降水和华北地区干旱事件发生。

Abstract

[Objective] In recent decades, the impact of global warming has intensified, leading to significant changes in precipitation patterns and other climate factors across Yangtze-Huang-Huai-Hai River Basins. This has resulted in a rise in extreme precipitation events and an increase in the frequency of droughts and floods. To refine the understanding of precipitation levels, further analysis is needed to conduct a comprehensive analysis of long-term trends in rainfall intensity, changes in rainy days, and the influence of temperature, atmospheric circulation, and other meteorological factors on rainfall intensity within the basins. [Methods] Based on the daily observation data collected from 417 meteorological stations within the basin spanning from 1956 to 2022, various statistical analyses are employed, including linear slope analysis, the Mann-Kendall(M-K) trend test,Sen′s slope estimation, correlation analysis, and Morlet wavelet analysis, to comprehensively analyze the data. [Results] The results indicate that precipitation increases in the Yangtze River Basin(6. 12 mm/10 a), while decreasing in the Huang-HuaiHai River Basin(with reductions of -14. 64 mm/10 a,-3. 97 mm/10 a, and -6. 47 mm/10 a). Multiple types of time-scale main cycles of precipitation and rainy days exist. Regarding rainfall intensity, heavy rainfall and storm increase in the Yangtze River Basin(1. 03 mm/10 a, 7 mm/10 a), whereas the Huang-Huai-Hai River Basins experience a decrease in light, moderate,and heavy rainfall. Nearly 90% of stations in each basin exhibit a decreasing trend in various types of rainy days, with spatial correlation coefficients of rainfall intensity and corresponding rainy days mostly exceeding 0. 88. The interannual variation of mean and maximum(lowest) temperatures in the basin demonstrates a significant upward trend, correlating with rainfall intensity in each basin. [Conclusion] The results reveal that,(1) annual precipitation in each basin, alternating between abundance and depletion, exhibits an increasing trend in the Yangtze River Basin, while Huang-Huai-Hai River Basins experience decreases.The number of rainy days across the entire basin significantly decreases, with similar main cycles observed in rainfall intensity and rainy days.(2) Rainfall intensity and rainy days trends in each basin are consistent, with a high spatial correlation between them. Extreme precipitation events worsen due to increased heavy and storm rainfall in the middle and lower reaches of the Yangtze River, while decreases in light and moderate rainfall in the Huang-Huai-Hai River Basins lead to frequent drought events.(3) Warming affects rainfall intensity differently in each basin, primarily resulting in increased heavy rainfall in the Yangtze River basin and accelerating the decline of light rainfall in the Huang-Huai-Hai River Basins, exacerbating flooding in the south and drought in the north. Changes in atmospheric circulation factors, including AMO, EASMI, SCSSI, SASMI, and Nino3. 4, also influence extreme precipitation within the basin and drought events in North China by impacting atmospheric circulation, particularly monsoon intensity in East Asia, South Asia, and the South China Sea.

关键词

降水 / 雨强 / 雨日 / 气候变化 / 温度 / 长江流域 / 黄淮海流域

Key words

precipitation / rainfall intensity / rainy days / climate change / temperature / Yangtze River Basin / Huang-Huai-Hai River Basins

基金资助

国家重点研发计划(2021YFC3200204)

基本科研业务费专项项目(HTWR0145B05202100000)