基于TIPEX Ⅲ资料对CLDAS-V2.0和GLDAS-NOAH陆面模式产品在青藏高原地区的适用性评估

Applicability Evaluation of Merged Soil Moisture in GLDAS-NOAH and CLDAS-V2.0 Products over Qinghai-Tibetan Plateau of 2015 Based on TIPEX Ⅲ Observations

利用2015年第三次青藏高原大气科学试验(TIPEX Ⅲ)五层(5,10,20,50和100 cm)土壤的温、湿度观测资料,通过计算全球陆面同化系统(GLDAS-NOAH)和中国气象局陆面同化系统的融合产品(CLDAS-V2. 0)与观测资料之间的相关性和偏差,以及分析降水事件发生后两种模式资料土壤温、湿度的响应,综合评估了融合土壤温、湿度产品在青藏高原的适用性。结果表明,CLDAS-V2. 0土壤温、湿度产品与观测资料的相关性均优于GLDAS-NOAH模式产品,且两模式产品与站点观测资料的相关性在湿季大于干季,相关性随土壤深度增加而减小; CLDAS-V2. 0土壤湿度产品相对站点观测的误差稍大于GLDAS-NOAH,且在浅层土壤两模式产品与站点观测的MRE整体上在干季大于湿季; CLDASV2. 0土壤温度产品与站点观测的RMSE在湿季大于干季,而GLDAS-NOAH产品则相反;两种模式产品均能描述出降水发生后浅层土壤温、湿度对降水的响应,但两种模式产品所描述的深层土壤温、湿度的波动幅度相对观测明显偏大;此外,两种模式产品无法重现观测到的深层土壤温、湿度相对表层土壤温、湿度变化明显"滞后"的特征以及降水后相对降水前土壤温度峰/谷值对应时间存在明显延迟的特征。

In-situ soil temperature and soil moisture observations at five layers（5 cm,10 cm,20 cm,50 cm and100 cm） from the 3 rd Qinghai-Tibetan Plateau Atmospheric Scientific Experiment（TIPEX Ⅲ） were used to verify the applicability of two land surface model products,i.e.Global Land Data Assimilation System-NCEP,OSU,Air Force and Office of Hydrology（GLDAS-NOAH） and CMA（China Meteorological Administration）Land Data Assimilation System Version 2.0（CLDAS-V2.0）.This paper calculated the correlation coefficient and deviation between the two land model products and the in-situ soil temperature and soil moisture observations in 2015.In addition,this paper also analyzed the response of the soil temperature and soil moisture products from CLDAS-V2.0 and GLDAS-NOAH.From the two aspects,this study comprehensively evaluated the soil temperature and soil moisture＇applicability of the two model products over Qinghai-Tibetan Plateau.Through the above analysis,it is discovered that the correlation（both for soil temperature and soil moisture） between the CLDASV2.0 and in-situ observations is better than that of GLDAS-NOAH.The correlation between the land model products（both for CLDAS-V2.0 and GLDAS-NOAH） and in-situ observations in wet season is larger than that in dry season,and shows a decreasing trend with soil depth.The deviation of soil moisture between the CLDASV2.0 and in-situ observations is slightly larger than that of GLDAS-NOAH.In addition,in shallowsoil layers,the mean relative error（MRE） of soil moisture between the model products（both for CLDAS-V2.0 and GLDAS-NOAH） and in-situ observations during dry season is larger than that of the wet season.The root mean square error（RMSE） between CLDAS-V2.0 soil temperature product and in-situ observations in wet season is larger than that of the dry season,while this inclination of RMSE is opposite for GLDAS-NOAH temperature product during the wet and dry season.Both the CLDAS-V2.0 and GLDAS-NOAH model products can relatively accurate grasp that howthe soil temperature and soil moisture response to the precipitation in shallowsoil layers.However,the two model products showa lager fluctuation in deep soil layers relative to in-situ observations both in soil temperature and soil moisture.At last,the two model products（CLDAS-V2.0 and GLDAS-NOAH） cannot reproduce the significantly ＂ lag＂ features that the observed soil temperature and soil moisture showa delayed change with the soil depth.And the daily Peak/valley values appear time of the soil temperature and soil moisture will showa ＂ lag＂ feature after the precipitation happened which the two model products cannot describe it.