金沙江下游地区蒸发皿蒸发量时空变化的东西分异特征

East-west differentiation on spatiotemporal variations of pan evaporation along the lower Jinsha River

摘要

【目的】金沙江下游位于我国西南自然地理分界的过渡区，是重要的水电基地，明确其蒸发皿蒸发量时空变化特征为分析区域水文气候时空变化提供基础，也为估算和分析梯级水库蒸发损失提供支撑。【方法】利用金沙江下游沿线19个气象站1980—2022年D20蒸发皿蒸发量的观测和估算数据，对比分析研究区西部和东部蒸发皿蒸发量时空变化的差异并探讨其驱动因素。【结果】结果表明：东经103.5°以西的13个站点蒸发皿蒸发量(年均值1 997.4 mm)高于东部的6个站点(年均值1 101.4 mm);西部站点春季(3—5月)蒸发皿蒸发量高于夏季(6—8月),峰值主要出现在5月；东部站点夏季蒸发皿蒸发量高于春季，峰值出现在7月或8月，且在6月出现较为明显谷值；西部站点平均的蒸发皿蒸发量以2000年为转折具有显著的先减后增的变化趋势，而东部站点在两个阶段都具有弱增加趋势。【结论】金沙江下游地区蒸发皿蒸发量的时空变化以东经103.5°为界存在显著东西分异，西南季风和东南季风的影响是其主要气候驱动因素，在西南地区蒸发相关研究工作中需要考虑的蒸发皿蒸发量东西分异及其驱动机制。

Abstract

[Objective] The lower reaches of the Jinsha River, situated in the transitional zone of Southwest China′s natural geographical boundary, serve as a significant hydropower base. Understanding the spatiotemporal variations in pan evaporation in this region is crucial. It lays the groundwork for analyzing the patterns of hydrological and climatic changes within the area. Furthermore, it provides essential support for the estimation and analysis of evaporative losses in cascade reservoirs. [Methods] Using observed and estimated data of D20 pan from 19 stations along the lower reaches of the Jinsha River from 1980 to 2022, a comparative analysis of the spatiotemporal differences in pan evaporation between the western and eastern parts of the study area is conducted and the driving factors are explored. [Results] The results indicate that the 13 stations located west of 103.5°E have higher pan evaporation(annual average of 1 997.4 mm) compared to the 6 stations in the eastern part(annual average of 1 101.4 mm). At the western stations, pan evaporation in spring(March-May) exceeds that in summer(June-August), with the peak occurring mainly in May. In contrast, at the eastern stations, summer pan evaporation is higher than in spring, with peaks occurring in July or August and a noticeable trough in June. The average pan evaporation at the western stations shows a non-monotonic change with 2000 being the turning point(first decreasing and then increasing), while the eastern stations exhibit a weak increasing trend in both periods. [Conclusion] The spatiotemporal variations of pan evaporation in the lower reaches of the Jinsha River shows a significant east-west differentiation, with 103.5°E as the boundary, impacted by of the Indian Monsoon and the East Asian Monsoon. In the context of evaporation studies in southwestern China, it is essential to account for the east-west disparity in the spatiotemporal patterns of pan evaporation and to explore the underlying driving mechanisms.

关键词

蒸发皿蒸发量 / 金沙江下游 / 大气环流 / 时空变化 / 气候变化 / 水资源 / 水文循环 / 季风

Key words

pan evaporation / Jinsha River / general circle / spatiotemporal variation / climate change / water resources / hydrological cycle / monsoon

基金资助

中国长江电力股份有限公司资助(Z432302011)

国家自然科学基金项目(52079147)