基于LMDZ模型的蒙古高原降水氢氧稳定同位素特征及水汽来源分析

基于LMDZ（Laboratoire de Météorologie Dynamique-Zoom）模型的模拟数据、NCEP/ NCAR格点气象数据和北极涛动指数（Arctic Oscillation Index，AOI)，验证了LMDZ模型在蒙古高原的适用性，分析了局地大气水线（Local Meteoric Water Line，LMWL）、降水中δ¹⁸O与环境因子的关系，探索了降水中δ¹⁸O、氘盈余（d-excess）的时空变化，并结合HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model)模型对蒙古高原气团运输轨迹进行了模拟。结果表明：在LMDZ模型的2种结果中，LMDZ-nudged模拟蒙古高原降水稳定同位素效果较好；计算得到的蒙古高原LMWL为δD=7.78δ¹⁸O+3.31(R²=0.995)，其斜率和截距均小于全球大气水线( Global Meteoric Water Line，GMWL)斜率和截距，表明该区域雨滴下落中受云下二次蒸发影响较大；降水中δ¹⁸O夏高冬低，与温度、北极涛动指数呈正相关，而与相对湿度呈负相关。降水中d-excess呈现夏低冬高的特点；对蒙古高原后向轨迹追踪并对其进行聚类分析发现，研究区主要有3条水汽路径：西风带水汽（约88.39%）、东亚季风水汽（约5.73%）与极地水汽（约5.88%），其中西风带水汽为主控水汽。

Hydrogen and Oxygen Stable Isotope Characteristics and Water Vapor Sources of Precipitation over Mongolian Plateau Based on LMDZ Model

Based on the simulation data of the LMDZ (Laboratoire de Météorologie Dynamique-Zoom) model, the NCEP/NCAR grid meteorological data and the AOI (Arctic Oscillation Index), we verified the applicability of the LMDZ model in the Mongolian Plateau, analyzed the relationship between environmental factors and the LWML (Local Meteoric Water Line) as well as δ¹⁸O in precipitation, explored the temporal and spatial variations of δ¹⁸O and deuterium excess (d-excess) in precipitation, and simulated the transportation trajectory of air mass in the Mongolian Plateau using HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model). The results show that among the two results of LMDZ, LMDZ-nudged has a better effect in simulating stable isotopes of precipitation in the Mongolian Plateau. The LMWL in Mongolian Plateau is δD=7.78δ¹⁸O+3.31 (R²=0.995), and its slope and intercept are less than those of GMWL (Global Meteoric Water Line), indicating the falling raindrops of this region are greatly affected by the below-cloud evaporation. The δ¹⁸O in precipitation is higher in summer than that in winter, with obvious latitudinal effect, and is positively correlated with temperature as well as AOI, but is negatively correlated with relative humidity. The d-excess in precipitation tends to be low in summer and high in winter. Westerly water vapor (about 88.39%), East Asian monsoon water vapor (about 5.73%) and Polar water vapor (about 5.88%) are three main water vapor paths in the study area by tracing the backward trajectory and clustering analysis, and westerly water vapor is the main control water vapor.