由TES反演的大气水汽中δD的时空分布特征

Spatial and temporal distribution characteristics of the δD in the atmospheric vapor as retrieved from the TES data

  • 摘要: 水汽在大气中的输送具有空间上和时间上的连续性。利用水汽同位素可以更全面地分析水汽的来源、路径、水循环中各分量的再分配和补给形式,更深入地了解水循环中各种空间和时间尺度下水汽的连续变化特征和历史。本研究利用对流层发射光谱仪(TES)反演的825—100 hPa层间7个等压面上HDO和H2O数据分析了对流层不同层次大气水汽中δD的时空分布规律以及水汽中δD与大气湿度、大气温度的关系,探讨了水汽同位素与降水同位素的关系以及大尺度水循环过程对水汽同位素的可能影响。结果显示,在空间分布上,对流层大气中水汽δD具有非常明显的带状分布,水汽中δD的分布与可降水量的分布存在很好的对应关系;水汽中δD随垂直气压呈对数型递减,平均递减率由赤道向高纬度减小、陆地向海洋减小。在时间变化上,大气水汽中δD的季节变化存在地域性差别。在中低纬度陆地,水汽中δD的季节变化明显,且与可降水量的季节变化相对应;在中高纬度的许多地区,夏季水汽中δD小于冬季。对流层水汽中δD的空间分布和季节变化具有一致性特点,上对流层和下平流层间水汽中δD的空间分布和季节性变化特点与对流层相反。对流层大气水汽中的δD与层间平均温度和可降水量的相关关系具有相似的分布形势。与降水中的稳定同位素相比,水汽中的稳定同位素在空间分布、季节变化、与温度和湿度的关系上存在某些差异,反映二者在受稳定同位素分馏的影响和水循环中大气环流类型的影响方面存在明显差别。

     

    Abstract: Transport of water vapor in the atmosphere has the continuity in space and time. Using the isotope in water vapor, one can more comprehensively analyze the origins and transport paths of water vapor, and the re distribution and recharge forms of every component in the water cycle, and more in-depth understand the continuous variational characteristics and history of water vapor on the various spatial and temporal scales in the water cycle. This paper analyzes the spatial and temporal distribution of the δD in atmospheric water vapor and the relationship of the δD in water vapor with atmospheric humidity and with temperature at the different levels in the troposphere, and explores the relationship between the stable isotopes in water vapor and in precipitation and the possible impact of the large-scale hydrological cycle on the isotopes in water vapor, using the HDO and H2O data retrieved by Tropospheric Emission Spectrometer (TES), at 7 pressure levels from 825 hPa to 100 hPa. The results show that, in spatial variation, the δD in water vapor has a very obvious zonal distribution in the troposphere and a good correspondence with the precipitable water; the δD in water vapor decreases with vertical pressure as logarithmic type and shows a decreasing tendency in the average decline rate from the equator to high latitudes and from lands to oceans. In temporal variation, the seasonality of the δD in water vapor shows a regional difference. In the low-latitude lands, distinct seasonal variation of the δD in water vapor is corresponding to that of the precipitable water, but the δD in water vapor during summer is lower than that during winter in many parts of the middle and high latitudes. The consistent spatial distribution and the seasonal variation characterize the δD in the troposphere, but an opposite situation appears in the interlayer from the upper troposphere to the lower stratosphere. The correlations of the mean δD in water vapor versus the mean temperature and versus the mean precipitable water in interlayer have a similar distribution in the troposphere. The stable isotope in water vapor, compared with that in precipitation, is of some differences in the spatial distribution, the seasonal variation as well as the relationship with temperature and humidity, showing that the impacts of stable isotopic fractionation and atmospheric circulation types in the water cycle on two types of stable water isotopes have obvious differences.

     

/

返回文章
返回