GLDAS和CLDAS融合土壤水分产品在青藏高原地区的适用性评估

Applicability Evaluation of Merged Soil Moisture in GLDAS and CLDAS Products over Qinghai-Tibetan Plateau

利用第三次青藏高原(下称高原)大气科学试验(TIPEXⅢ)和高原周边自动土壤水分观测站0~10 cm层次土壤湿度观测资料,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-V1.0)与观测资料之间的相关性和偏差,综合评估了融合土壤水分产品在高原的适用性。结果表明,两种融合资料在安多、那曲、聂荣、Sta-ave区域(小嵩草高寒草甸)4个站点表现较优,而融合资料在班戈(禾草高寒草原)、嘉黎(亚高山常绿叶灌丛)和比如(亚高山常绿叶灌丛)质量较差,阿里站(矮半灌木荒漠)是融合资料与观测相差最大的站点;融合土壤湿度产品的质量存在明显的日变化,并在14:00-20:00(北京时)表现为最差;融合资料的质量2014年整体上优于2013年,其中2013年8月中下旬和10月中旬两种资料质量较差,进一步分析发现当降水强度急剧增强时,融合资料的质量变差;融合产品质量在高原地区由东南向西北方向递减,相对于GLDAS资料,CLDAS在对四川东南地区和新疆地区大部分站点的土壤湿度描述能力上有了较大的改善,两种资料在四川东北部地区有较好的一致性。

The temporal and spatial variations in soil moisture play an important role in the water and energy cy- cle on the Qinghai-Tibetan Plateau （QTP）. In-situ soil moisture observation at 0- 10 cm layer from the automatic soil moisture monitoring stations around the QTP and the 3rd QTP Atmospheric Scientific Experiment （ TIPEX HI ） were firstly put into use to test and verify two land surface model products, i. e. GLDAS-NOAH （Global Land Data Assimilation System） and CLDAS-V1.0（ CMA Land Data Assimilation System Versionl. 0 ） by cal- culating the correlation coefficient and bias between model product and in-situ soil moisture observation. The two merged products were better in the four sites of Ando, Nagqu, Nierong and Sta-ave （ Kobayashi alpine mead- ow）, while in Bangor （Grassy alpine grassland）, Jiali （Subalpine evergreen leaves Shrub） and Biru （Subalpine evergreen leaf shrubs）, the quality of the merged data performed less well, and the Ali station （ Dwarf shrub des- ert） was the site with the largest deviation between the merged data and the in-situ soil moisture data. There was a significant diurnal variation of the quality of soil moisture products and the worst performance of model prod- ucts shows during 14：00 to 20：00 （Beijing Time）. And their performances on simulating the temporal distribution in 2014 were all superior to that in 2013. From June to August, the two models had a good consistency with the in-situ soil moisture data. The quality in 2014 of the two merged products had an advantage over the quality of 2013, and the quality of the two merged products had the lowest score in the middle and the late of August and mid-October in 2013. By further analysis, it is found that when the precipitation intensity increased sharply, the quality of the two merged data became worse. For the two merged products, the quality in the QTP decreased from southeast region to northwest region. Compared with GLDAS, the quality of CLDAS was raised more re- markable improvement in southeastern Sichuan province and Xinjiang region. In addition, the two merged prod- ucts were in good agreement in northeast Sichuan province.