The study of three mathematical and physical models on the pan evaporations

• 1、Key Laboratory for Semi-Arid Climate Change of PRC Ministry of Education,College of Atmospheric Sciences of Lanzhou University,lanzhou 730000
• 2、Unit of 94195 of the Chinese Pepoles’s Liberation Army , Lintao 730500

Abstract：Using the designed wild observation Experiment, based on the energy conservation principle and the boundary layer gradient transport theory, this paper built three evaporation pan models. In the three models, both sensible and latent heat fluxes of the evaporation pan were calculated by eddy-covariance technique. Meanwhile, the heat transport of the lateral wall of 20cm and CLASS-A was parameterized. Following, the three models were verified by the 51days hourly measurements which were from "Microclimate and Evaporation Experiment". Analysis results showed that the three models could reflect the non-uniformity between water surface and land surface, and summarized interaction and physical process between three evaporation pans and local environment very well. In addition, the results indicated that day performance of the model was good, 20cm evaporation pan with a root-mean-square error (RMSE) of 0.09(mm/h), a mean relative error ratio (MRER) of 27.1%. CLASS-A evaporation pan with RMSE and MRER were 0.02(mm/h) and 25.8%, E601B evaporation pan with RMSE and MRER were 0.019(mm/h) and 27.4%. The results of the day pan evaporate rate of model，20cm evaporation pan with a root-mean-square error (RMSE) of 1.42(mm/d), a mean relative error ratio (MRER) of 10.0%. CLASS-A evaporation pan with RMSE and MRER were 1.37(mm/d) and 13.1%, E601B evaporation pan with RMSE and MRER were1.22(mm/d) and 16.6%, the correlation coefficient of three pans were all more than 0.95.

Keywords： evaporation pan；Non-uniform underlying surface；Energy conservation；numerical simulation