淮河流域大气降水氢氧稳定同位素变化规律及其气候意义

淮河流域位于我国南北气候过渡带,其复杂多变的降水过程及水汽来源是导致流域洪旱灾害易发、多发的重要因素。以全球降水同位素监测网络(Global Network of Isotope in Precipitation,GNIP)监测的多年降水氢氧稳定同位素数据为基础,探讨了淮河流域大气降水氢氧稳定同位素组成时空变化的驱动因素及其气候指示意义;通过分析氢氧稳定同位素组成(δ¹⁸O、δ²H、氘盈余)、大气降水线特征与流域气温、降水量的响应关系,解析流域不同季节大气降水水汽来源及气团移动路径。结果表明:①淮河流域大气降水氢氧稳定同位素组成能够指示南北气候过渡带特征;②同位素时空变化及异常低的大气降水线斜率、截距与局地降水环境关系不大,主要是由水汽来源差异及降水气团在移动过程中同位素分馏造成的。氘盈余示踪和HYSPLIT模型模拟结果进一步表明流域降水水汽来源及变化受季风活动的控制,冬季风和夏季风的交替进退使得淮河流域的降水氘盈余变化具有明显的“V”型特征。研究成果可为水资源调度管理、极端气候应对决策等提供科学依据。

Variations of Stable Hydrogen and Oxygen Isotopes in Precipitation over the Huaihe River Basin and Their Climatic Implications

Located in China's south-north transitional climatic zone, the Huaihe River Basin is prone to flood and drought disasters because of complex and changing precipitation processes and atmospheric moisture sources.Based on the stable hydrogen and oxygen isotopic data from Global Network of Isotopes in Precipitation (GNIP), we investigated into the driving factors of temporal and spatial variations and their climatic implications.By analyzing the isotopic compositions (δ¹⁸O,δ²H, and deuterium surplus) and Local Meteoric Water Line (LMWL) in response to local temperature and precipitation, we expounded the atmospheric moisture sources in different seasons and air-mass moving processes in the basin.Results demonstrated that the isotopic composition of precipitation can be used to indicate south-north transitional climatic features.The spatio-temporal changes of isotopes and abnormally low slope and intercept of LMWL were mainly caused by different moisture sources and isotopic fractionations in the air-mass moving process rather than local precipitation environment.Deuterium tracing and HYSPLIT simulation results further proved that the sources and variations of atmospheric moisture over the Huaihe River Basin were controlled by monsoon activities, and the alternations between winter and summer monsoons led to V-shaped characteristics of deuterium surplus.