DataSheet1_The Seasonally Altered Atmosphere Moisture Circulations With Rainfall and Rainfall Isotopes in Southwest China.pdf

To interpret the climatic signals of precipitation/speleothem δ18O, it is critical to identify the importance of the factors affecting the precipitation δ18O. This study presents new stable isotope data for precipitation δ18O and δD in the site of Shenqi cave, southwest China, from November-2015 to October-2016 (the “Super-El Niño” event), to investigate the regional-scale climate forcing on precipitation δ18O. The precipitation δ18O, δD and d-excess have an obvious seasonality, relatively low values in the wet season and high in the dry season. The further analysis of seasonally altered LMWL and moisture circulations suggested that changes in atmosphere moisture circulations would be the key factor underlying the precipitation/speleothem δ18O fluctuations in our study area at least on seasonal timescales. Combined with the seasonal-monthly variations of the IsoGSM δ18O, GPCP/CRU rainfall and NCEP/NCAR moisture fluxes, we detected that the super-El Niño of 2016 have changed the distributions of monthly rainfall in wet season through the Western Pacific Subtropical High, but not mainly the precipitation isotopic compositions and moisture circulations in our study area.

为解读降水/洞穴石笋δ¹⁸O的气候信号，明确影响降水δ¹⁸O的各类因素的重要性至关关键。本研究获取了中国西南地区申齐洞穴2015年11月至2016年10月（即"Super-El Niño"事件期间）的降水δ¹⁸O与δD稳定同位素新数据，以探究区域尺度气候强迫对降水δ¹⁸O的影响机制。降水δ¹⁸O、δD及氘盈余（d-excess）呈现显著的季节变化特征：湿季数值偏低，干季数值偏高。对季节变化的局地大气水线（Local Meteoric Water Line, LMWL）与水汽循环的进一步分析表明，至少在季节尺度上，大气水汽循环的变化是本研究区降水/洞穴石笋δ¹⁸O波动的核心驱动因素。结合同位素通用循环模型（IsoGSM）δ¹⁸O、全球降水气候学项目（Global Precipitation Climatology Project, GPCP）/气候研究单位（Climatic Research Unit, CRU）降水数据以及美国国家环境预报中心/国家大气研究中心（National Centers for Environmental Prediction/National Center for Atmospheric Research, NCEP/NCAR）水汽通量的季节-月际变化，本研究发现2016年超级厄尔尼诺事件通过西太平洋副热带高压改变了湿季的月降水分布，但并未显著改变本研究区的降水同位素组成与水汽循环。