全球大气降水年均氚浓度恢复模型(1960—2014年)

Global model of the annual mean concentration of tritium in precipitation,1960—2014

运用环境同位素氚(3H)建立模型来定量研究地下水运动规律已被广泛应用于水文地质和环境监测领域,大气降水氚浓度是这类模型中必须的输入值.目前已建立的全球大气降水氚浓度模型(MGMTP)为这一领域的研究提供了一种恢复全球范围内年平均氚浓度的新方法,但该氚浓度模型后期恢复数据出现异常负值及面临适用年限等问题.因此,本文选用国际原子能机构和世界气象组织提供的1960—2014年全球氚浓度值实测资料,基于因子分析法拓展了MGMTP模型的适用年份,并对不同的数据预处理及分析方法进行了对比,同时对MGMTP模型提及的"异常负值"问题进行了进一步明确与改进.最后把模型应用于南北半球的典型站点,将恢复得到的数据与实测数据进行对比,发现拓展后的MGMTP模型结果能较好地拟合实测数据.研究表明,该模型具有简单易用、时间序列长、全球性适用等优点,尤其对缺少大气降水氚浓度实测数据的地区具有重要参考价值.

The use of environmental isotope of tritium to establish the quantitative model of groundwater flow has been widely applied in the field of hydrogeology and environmental monitoring. Zhang Yanhong et al. developed‘MGMTP＇（ modified global model of tritium in precipitation） to provide a new method for the quantitative study of tritium concentration in the global scale,but the tritium model is now facing a problem of limit period and predicts negative values for the year after 1990. In this paper,we used the dataset over the period from 1960 to 2014 provided by the International Atomic Energy Agency and World Meteorological Organization（ IAEAWMO） to extend the time period of MGMTP model based on factor analysis. At the same time,we also compared the difference between data preprocessing and analysis methods. The problem of negative values predicted by MGMTP model mentioned by Zhang et al. was further clarified and fixed. This extended MGMTP model was applied to the typical stations of the northern and southern hemispheres. The results showed that it can well calculate the annual mean tritium concentration in precipitation over the world from 1960 to 2014,which is especially necessary and valuable for the area with few or without the monitoring data.