南极至北极走航断面海洋-大气水汽稳定同位素分布及分馏过程研究

As one of the most important processes within the hydrological cycle, the evaporation and evapotranspiration in oceanic surface control the global distribution of water stable isotopes in precipitation and snowfall. The fractionation between sea surface and atmosphere, which determined the initial isotopic compositions of vapor/moisture, is the basis to illustrate the imprint in many different natural archives such as ice cores and precipitations, but is still a challenge of simulating the real process happening in sea surface. Based on an improved system for water vapor monitoring, we will carry out in situ observations along the Chinese Antarctic and arctic cruiser traverse. At the same time, the isotopic compositions, salinity and density of sea surface water will be analyzed, the surface meteorological data (wind speed, wind direction, air temperature, sea surface temperature and relative humidity) will also be collected. Then we can study the distribution and its controlling mechanism of stable isotopes in sea surface water and vapor from southern to northern hemisphere. Further studies on the kinetic fractionation process during evaporation will be investigated on a global scale. Finally, the kinetic fractionation model developed by Merlivat and Jouzel, will be examined and improved, based on our observation.

作为水循环最重要的过程之一，海洋表面的水汽蒸发和传输，决定了全球降水和降雪中的氢氧稳定同位素比率的分布，是目前水同位素研究的前沿领域。本项目拟通过改进同位素光谱仪观测系统，依托中国南北极考察，在南极-澳大利亚-上海-北极的走航断面上，开展高分辨率大气水汽稳定同位素实时监测；采集表层海水，带回实验室测定其中的氢氧稳定同位素比率；同时监测海表环境状况，如风速、风向、海表气温、海表温度、相对湿度、海表层水盐度、海表层水密度等。通过这些观测实验，我们可以研究南极至北极经向断面上的海表水稳定同位素分布和近海面大气中水汽稳定同位素分布及其影响机制，进而探讨全球尺度海洋-大气水汽稳定同位素的分馏过程，检验并完善海洋表面的水汽同位素动力分馏模型。本研究集仪器设计改造、野外观测和数理模型研究于一体，有助于诠释海洋与大气之间的相互作用过程，也是研究冰芯、降水和石笋等环境气候记录的基础工作。

氢氧稳定同位素比率的分布研究，是目前水同位素研究的前沿领域。本项目通过改进同位素光谱仪观测系统，依托中国南北极考察，在南极-澳大利亚-上海-北极的走航断面上，开展了高分辨率大气水汽稳定同位素实时监测；采集了表层海水，带回实验室测定其中的氢氧稳定同位素比率；同时监测海表环境状况，如风速、风向、海表气温、海表温度、相对湿度、海表层水盐度、海表层水密度等。通过这些观测实验，我们研究了南极-澳大利亚-上海-北极的走航断面上水汽氢氧稳定同位素的分布特征及其影响机制、新型激光光谱仪测定水样氢氧稳定同位素比率的分析方法与性能、三极降水形态特征差异及其潜在影响机制，并得到了初步结果。