| 滇南蒙自地区降水稳定同位素特征及其水汽来源 |
| 摘要点击 4526 全文点击 1840 投稿时间：2015-11-08 修订日期：2015-12-06 |
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| 中文关键词 大气降水 稳定同位素 大气水线 二次蒸发 水汽来源 蒙自地区 |
| 英文关键词 precipitation stable isotopes meteoric water line secondary evaporation moisture sources Mengzi region |
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| 中文摘要 |
| 大气降水中δD、δ18 O值具有规律性变化特征,与诸多气象要素及水汽来源之间存在密切联系. 根据2009年1月至2011年12月对滇南蒙自地区大气降水的连续性采样,结合欧洲中期数值预报中心(ECMWF)以及美国国家环境预报中心/美国国家大气研究中心(NCEP/NCAR)的再分析资料,并利用HYSPLIT_4.8后向轨迹追踪模型,分析了天气尺度下蒙自地区大气降水中δD、δ18 O的变化特征,探究了降水稳定同位素与温度、降水量、风速及水汽来源之间的关系. 结果表明,蒙自地区降水中δD、δ18 O值表现出明显的季节变化,即干季偏高,湿季偏低; 降水中δ18 O与温度、降水量之间存在显著负相关,但与不同气压层(300、500、700、800 hPa)风速之间呈现出显著正相关,表明风速也是影响降水中δ18 O变化的一个重要因素; 随着降雨等级的增加,其大气水线的斜率与截距也增大,说明降水稳定同位素存在一定程度的云底二次蒸发效应; 水汽输送轨迹显示,干季降水的水汽主要来自于西风带输送及局地再蒸发水汽,而湿季降水的水汽主要来源于远源海洋水汽的输送,并且在受台风影响期间,降水中δD、δ18 O值更加偏负. |
| 英文摘要 |
| The δD and δ18 O values in precipitation have disciplinary variations, and they have close connections with meteorological parameters and moisture sources. Based on the continuously collected precipitation samples in Mengzi from Jan. 2009 to Dec. 2011, the reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR), and the Hybrid Single-Particle Lagrangian Integrated Trajectory for 4.8 (HYSPLIT_4.8) model, we analyzed the variations of δD and δ18 O in precipitation at synoptic scale in Mengzi, and the relations between δ18 O in precipitation and air temperature, δ18 O in precipitation and amount, δ18 O in precipitation and wind speed, δ18 O in precipitation and moisture sources. The results showed that the variations of δD and δ18 O values in precipitation exhibited remarkable seasonal variability. The stable isotopic values in precipitation were higher during dry season than those during wet season. The relations between δ18 O in precipitation and air temperature, δ18 O in precipitation and amount indicated significant negative correlations. However, it exhibited significant positive correlation between precipitation δ18 O and wind speed at different pressure levels (300 hPa, 500 hPa, 700 hPa, and 800 hPa), and this result indicated that the wind speed was an important influencing factor for the variations of precipitation δ18 O. With the increasing rainfall levels, the intercept and slope of meteoric water line also increased, and this phenomenon suggested that there was a secondary evaporation effect under sub-cloud in stable isotopes of precipitation. The backward trajectory model showed that the main moisture sources during dry season came from the westerly and the inland. However, during wet season, the remote ocean vapor was the main moisture source in Mengzi, and the δ18 O values in precipitation were much lower during typhoon period. |
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