Evaluation of Applicability and Correction for the CLDAS Temperature and Relative Humidity Products in Guizhou Province

Abstract

Using hourly data from automatic observation stations in Guizhou Province， the China Meteorological Administration Land Data Assimilation System （CLDAS） temperature and relative humidity products have been evaluated and linearly corrected in 2019.The results show that the CLDAS temperature products have a good consistency with the observations， the CLDAS relative humidity products are systematically lower than the observations and using in-situ observations to correct the CLDAS temperature and relative humidity products significantly improves the usability of the products.The mean error （ME） of the whole year CLDAS temperature products in Guizhou Province is 0.2985 ℃， the root mean square error （RMSE） is 1.5578 ℃， and the correlation coefficient （COR） is 0.9822.The annual root mean square error of the temperature products in 12.4% stations exceeds 2 ℃。From 00:00 to 23:00（Beijing Time）， the ME of the temperature products firstly decreases and then increases， while the RMSE has the maximum value around noon.After the correction， both the absolute value of the ME and the RMSE decrease， the COR increases and the RMSE of the whole year CLDAS temperature products is significantly reduced to 1.2369 ℃.When correcting grid products， the smaller the effective distance， the better the corrected effect.The ME of the whole year CLDAS relative humidity products in Guizhou Province is -4.501 %， the RMSE is 9.021 %， the COR is 0.863， while the COR during the nighttime is 0.711.The ME and COR of the relative humidity products reach the maximum around noon， while a maximum of the RMSE exists around dusk and a minimum around dawn.Linear correction has a positive effect on the CLDAS relative humidity products.The RMSE of the whole year CLDAS relative humidity products decreases by 2.317 % and the COR increases by 0.104 during the nighttime after the linear correction conducts.It is shown that the correction has a better improvement on the CLDAS relative humidity products at night.

Keywords

• cldas
• guizhou province
• temperature and relative humidity products
• evaluation