基于GCM的西北干旱区降水稳定氢氧同位素年际变化模拟

Interannual Variation of Stable Hydrogen and Oxygen Isotopes in Precipitation in Arid Northwest China Based on GCMs

降水中稳定氢氧同位素(18 O)和(D)是水循环过程的重要组成部分,也是气候的天然示踪剂。为了模拟不同时空尺度上降水稳定氢氧同位素的变化,大气环流模式(GCM)已经成为研究全球或区域水循环的有效途径。本文基于全球大汽降水同位素网络(GNIP)提供的实测数据和第2次稳定水同位素比较小组(SWING2)的模拟数据,运用回归分析法和同位素GCM对比分析了西北干旱区1986—2003年大气降水中稳定氢氧同位素的年际变化特征。结果表明:3个同位素监测站点乌鲁木齐、张掖和和田的年均δ18 Ow线性倾向率分别为0.041,0.207,0.915‰/a,δDw线性倾向率分别为0.767,0.026,0.120‰/a;如果只考虑暖季(5—9月),则δ18 Ow线性倾向率分别为-0.008,0.085,0.306‰/a,δDw线性倾向率分别为-0.331,-1.390,-1.503‰/a。同时,采用SWING2中的GISS-E(MERRA),GISS-E(NCEP),isoGSM(NCEP),LMDZ(free),LMDZ(ECMWF)和MIROC(free)共6种同位素GCM模式得出的δ18 Ow和δDw的线性倾向率与回归分析法得到的结果相反。此外,分析了两种模拟方法得到的大气水线,发现各模拟结果中和田的大气水线斜率均高于乌鲁木齐和张掖。

The stable water isotopes in precipitation（18 O and D）are the tracers for climate,which is a crucial part in hydrology.According to simulation of the variation of stable water isotope in precipitation in different temporal scales,general circulation model（GCM）has been an effective way to study global and regional water circulation.Based on GNIP（Isotopic data from the Global Network of isotopes in precipitation）,and isotope-equipped GCM from SWING2（Stable Water Isotope Intercomparison Group,Phase2）,the interannual variation of observed and simulated results in arid Northwest Asia during the period from 1986 to 2003was analyzed by using regression analysis and isotope-equipped GCM.According to temperature effect of isotopes in precipitation,the slopes of weighted average annualδ18 Owfrom GNIP are in Urumqi,Zhangye and Hotan from GNIP are 0.041,0.207,0.915‰/a,respectively.The slopes of weighted average annualδDwfrom GNIP are 0.767,0.026,0.120‰/a,respectively.In warm season（from May to September）,the slopes of weighted average annualδ18Owfrom GNIP are in Urumqi,Zhangye and Hotan from GNIP are-0.008,0.085,0.306‰/a,respectively.The slopes of weighted average annualδDwfrom GNIP are-0.331,-1.390,-1.503‰/a,respectively.The slopes of results inδ18 OwandδDwvalues from GISS-E（MERRA）,GISS-E（NCEP）,isoGSM（NCEP）,LMDZ（free）,LMDZ（ECMWF）and MIROC（free）are different from the results of regression analysis.Considered the local meteoric water line（LMWL）from regression analysis and isotope-equipped GCM,the slope of meteoric water line of Hotan was greater than those of Zhangye and Urumqi.