黄河源区土壤温湿和大气参量变化特征

Variation Characteristics of Soil Temperature & Moisture and Air Parameters in the Source Region of the Yellow River

利用中国科学院西北生态环境资源研究院玛曲土壤温湿观测网2008—2009年、2013—2014年数据验证了3套再分析资料ERA-Interim,CFSR(Climate Forecast System Reanalysis)和JRA-55(Japanese 55-year Reanalysis)在黄河源区的适用性,结合中国气象数据网玛曲气象站1980—2014年观测资料与CLM4.5(Community Land Model4.5)进一步分析了黄河源区近35年气候变迁、土壤温湿分布和变化,结果表明:CFSR能够较好地描绘黄河源区土壤湿度变化,ERA-Interim对于土壤温度刻画能力更强,JRA-55效果较差;35年来气温、土壤温湿总体呈上升趋势且发生突变;近年来10 crm土壤温湿有暖干化趋势,降水量稍有增加,土壤冷季冻结周期变短,暖季持续时间拉长;CLM4.5模拟精度高,能够较好地刻画源区土壤温湿变化细节,两湖及黄河周边暖季为冷湿中心,冷季为暖干中心。

The source region of the Yellow River（SRYR） located in the northeast of the Tibetan Plateau,is the crucial water conservation area.Soil temperature moisture variations and associated climate effects have important implications to the change of runoff.Three kinds of frequently used reanalysis datasets,ERAInterim,CFSR,and JRA-55 are tested using field observations of Maqu Soil Temperature Moisture Network so as to find the optimal one for SRYR.Combining with observations of Maqu Station,the climate changes in recent 35 years and the temporal variation of soil moisture temperature are analyzed.In addition,their spatial variations are depicted by reanalysis datasets and CLM4.5（Community Land Model4.5）.Main results are as follows.CFSR is the best dataset to depict the soil moisture variation,and ERA-Interim is better on soil temperature,while JRA-55 is unsuited.Soil temperature has an indication to the climate change,but its response is less significant than air temperature.Soil moisture has an increasing trend,because freezing time becomes shorter and melting time is extending.Air temperature,soil temperature moisture,except for precipitation,have abruptions in the last 35 years.Air temperature starts to abrupt during 1997-2000,after that it shows significant upward trend.Precipitation decreases from 1987 to 2004 and increases after2005.Abrupt change of soil temperature takes place during 1985-1986,and beyond the belief line after1994 with prominent rising.It means soil temperature is more sensitive than air temperature to climate warming.Soil moisture has an upward abruption in 2002.Soil temperature moisture in 10 cm depth become warm and dry in recent years.Lakes and the Yellow River are the cold and wet centers in warm season,and turn warm and dry in cold season.CLM4.5 has high simulation accuracy,and is capable of describing detailed changes of soil in SRYR.All in all,it is better than reanalysis dataset in simulating the spatial variation of soil temperature moisture,but still has a long way comparing with observations.