1901～2010年青藏高原土壤温度变化的模拟研究

摘要

Frozen ground change is a hot issue in the research regarding climate change,and soil temperature is an important parameter for research on frozen ground change.However,the change in soil temperature at deep layer has not be well understood on a centenary time-scale.This study investigates the change in soil temperature on the Tibetan Plateau (25° ～40.5°N,75°～ 105°E) from 1901 to 2010 using the latest version of Community Land Model (CLM),CLM4.5,driven by the default forcing dataset of CRUNCEP in the model.The in situ observations from both 20 meteorological stations and 4 field borehole monitoring sites were collected to validate the simulated results.The results show that (1) the CLM can reproduce the observed changes in soil temperature (the correlation coefficient is 0.92 and the Nash-Sutcliffe efficiency is 0.82),and the results are superior to reanalysis data.(2) Soil temperature at 15m depth increased by 0.05 (0.27) ℃/decade on the Tibetan Plateau during 1901～2010 (1979～2010).The increase in the soil temperature is larger in winter than summer.Increase in soil temperature decreased along with increasing depth and longitude and first increased and then slightly decreased along with increasing latitude.(3) Change in soil temperature on the Tibetan Plateau is mostly influenced by air temperature.Sensitivity of soil temperature at 1m (15m) depth to air temperature change is 0.79 (0.37)℃/ ℃.Soil temperature at shallow layer is more sensitive than those at deep layer and permafrost temperature is more sensitive than seasonally frozen ground temperature.These results are useful for in-depth understanding the change in soil temperature on the Tibetan Plateau on a centenary time-scale.%冻土变化是气候变化研究领域的热点问题之一,而土壤温度是冻土变化研究的重要参量.但目前对百年尺度土壤温度,特别是深层土壤温度变化的认识还存在不足.本研究利用CRUNCEP大气强迫资料驱动最新版本的通用陆面模式(CLM4.5)对过去百年的青藏高原土壤温度变化进行了模拟研究.利用来自气象站和野外钻孔监测站的土壤温度观测资料对模拟结果进行了验证,结果显示:1)通用陆面模式能合理地模拟出观测的青藏高原土壤温度变化,模拟和观测结果的相关系数为0.92,纳什效率系数为0.82,趋势分别为0.27℃/10年和0.28℃/10年.模拟结果明显优于再分析资料;2)1901 ～ 2010(1979～ 2010)年青藏高原15m土壤温度增加率为0.05(0.27)℃/10年,冬季增温高于夏季,土壤增温随深度增加而减弱、随经度增加而减小、随纬度的增加呈先增加后略减小的变化;3)青藏高原土壤温度变化主要受气温控制,1m(15m)深度土壤温度对气温变化的敏感性为0.79(0.37)℃/℃,浅层土壤温度对气候变化较深层敏感,多年冻土温度对气候变化较季节冻土敏感.这些结果从百年时间尺度上深化了对青藏高原土壤温度变化的认识.