CLDAS融合土壤湿度产品在东北地区的适用性评估及订正

Applicability Evaluation of CLDAS Merged Soil Relative Moisture in Northeast of China and Its Correction Research

通过计算CLDAS的0-20cm土壤相对湿度融合产品与农业气象观测站逐旬10cm土壤相对湿度观测值的相关性和偏差,综合分析CLDAS在东北地区的适用性。结果表明:CLDAS融合土壤相对湿度能较合理地反映东北地区10cm深度土壤相对湿度的空间分布,但是在对极值的描述上有所欠缺,其中CLDAS对辽宁西部和黑龙江西南部的土壤相对湿度模拟偏高较明显,而在黑龙江的东北部地区对实际土壤相对湿度的模拟偏低;总体上,CLDAS融合土壤相对湿度资料在东北地区的适用性由西南向东北方向递减,在吉林和辽宁省的适用性更好。回归订正和7旬滑动平均订正法对CLDAS产品的误差订正表明,订正结果大大提高了CLDAS产品的精度,其订正后产品可以应用于土壤湿度干旱监测业务。

Using observed soil relative moisture data at 10cm layer, the applicability of CLDAS(CMA Land Data Assimilation System)merged soil relative moisture at 0-20cm layer was tested and verified by calculating the correlation coefficient and bias between the CLDAS product and in-situ soil moisture observation in Northeast of China during 2008-2017. The results showed that CLDAS merged soil relative moisture data could reasonably reflect the actual spatial distribution of soil moisture at a depth of 10cm in Northeast of China, however, it was not very excellent at the extreme values’ performance. CLDAS merged soil relative moisture data was obviously higher than actual site observations in western of Liaoning province and southwestern of Heilongjiang province, while the simulation was lower than the actual soil relative moisture in northeastern of Heilongjiang province. The applicability of CLDAS product in Northeast of China decreases from southwest to northeast and was better in Jilin and Liaoning provinces. Furthermore, further analysis found that the poor applicability was mainly caused by the low correlation between CLDAS and site observation in Heilongjiang province. Finally, the error of CLDAS product was corrected by regression correction method and 7 ten-day sliding average correction method. The result greatly improves the accuracy of CLDAS product, and the revised products could be applied to soil moisture drought monitoring business.