淮河流域暖季极端高温干旱复合事件的演变特征及其与气候和植被的关系

使用淮河流域1981年至2020年的149个气象站点的气温和相对湿度数据,分析了流域暖季极端高温干旱复合事件(Compound Drought and Heat Events,CDHEs)的时空演变特征,并通过趋势分析和相关分析法探讨了CDHEs与气候和植被的关系。结果表明:①CDHEs的发生日数在年代际尺度上呈现明显的增加趋势,并且范围扩大,频发区逐渐向淮河流域中西部移动;②在年际尺度上,CDHEs随时间序列呈显著的波动上升趋势,空间分布上以西北部为中心向四周递减。连续CDHEs事件呈年际变化,最大2至4天的连续事件存在波动,2019年达到高峰,并且在流域内零散或成片出现;③在月际尺度上,CDHEs的发生日数在6月最多,其次是5月、7月、9月和8月。淮河流域入汛前的旱情和入汛后的旱涝急转都容易导致CDHEs发生,而且随着月际变化向南移动;④CDHEs对水热条件和大气环流具有特别的敏感性。在850hPa反气旋和500hPa显著高压异常的控制下,高温、低湿、高蒸发和降水少的气候背景有利于淮河地区CDHEs的形成,尤其是在淮河中西部地区。因此,CDHEs的发生与气候变化密切相关;⑤CDHEs与植被生长也存在显著关系。CDHEs与GPP呈显著的负相关,而与NDVI呈显著的正相关,显著地区的土地类型以耕地和城乡、工矿、居民用地为主。GPP和NDVI的不同步可能是因为多种因素的非线性相互作用,而不仅仅是单一因素的影响。此外,对于GPP和NDVI来说,土壤含水量至关重要。总之,本文对淮河流域CDHEs的时空分布特征进行了深入研究,并探讨了其与气候和植被的关系。研究结果可以为该地区的气象灾害防御和生态环境保护提供科学依据和参考。

Evolution characteristics of compound drought and heat events during the warm season in the Huaihe River Basin and their relationship with climate and vegetation

This article analyzed the spatiotemporal characteristics of Compound Drought and Heat Events (CDHEs) during the warm season in the Huaihe River Basin from 1981 to 2020, using temperature and relative humidity data from 149 meteorological stations in the basin. Through trend analysis and correlation analysis, the relationship between CDHEs and climate and vegetation is explored. The results show that: ① The number of CDHEs has a significant increasing trend on a decade scale, with an expanding range. The frequent has shifted towards the central and western regions of the Huaihe River Basin, indicating a significant trend. ② At the interannual scale, CDHEs show a significant fluctuating upward trend over time, with a spatial distribution centered in the northwest and decreasing towards the periphery. Continuous CDHEs events display interannual variability, with fluctuations in the occurrence of 2 to 4-day consecutive events, peaking in 2019 and scattered or clustered appearances throughout the basin. ③ At the monthly scale, CDHEs occur most frequently in June, followed by May, July, September, and August. These events are often triggered by pre-monsoon droughts and sudden shifts from drought to flood postmonsoon. The southward migration during monthly variations contributes to the occurrence of CDHEs. ④ CDHEs are particularly sensitive to hydrothermal conditions and atmospheric circulation. Under the control of significant anti-cyclones at 850 hPa and significant high-pressure anomalies at 500 hPa, the climate background of high temperature, low humidity, high evaporation, and low precipitation is conducive to the formation of CDHEs in the central and western parts of the Huaihe River Basin. Therefore, the occurrence of CDHEs is closely related to climate change. ⑤ CDHEs have a substantial connection to the growth of vegetation. CDHEs are negatively correlated with gross primary productivity (GPP) and positively correlated with normalized differnce vegetation index (NDVI). The significant areas are mainly cultivated land and urban and rural areas, industrial and mining areas, and residential land. The asynchrony between GPP and NDVI may result from complex nonlinear interactions among various factors, rather than the influence of a single factor. Additionally, soil moisture plays a crucial role in both GPP and NDVI dynamics. In summary, this article provides an in-depth study of the spatiotemporal distribution characteristics of CDHEs in the Huaihe River Basin and explores their relationship with climate and vegetation. It also delves into the intricate interplay between CDHEs, climate patterns, and vegetation in the region. The results can serve as a scientific basis and reference for meteorological disaster prevention and ecological environmental protection in the region.