资源环境科技发展态势分析平台

Pan evaporation (E-pan) measurements are used for gauging the atmospheric evaporative demand, and Epan observation networks were established and maintained for a long history. However, due to the replacement of D20 pans with 601B pans across China in 2000, E-pan observation networks in China, which is the largest networks in East Asia, became discontinuous. Thus, it is important to develop a robust method to update and complement Epan of two Chinese pans. PenPan model is a robust model in E-pan estimation, while the previous versions of PenPan are derived for a specific type of pan. This study developed a generalized model, that is, PenPan-V3 model, to simulate E-pan for Chinese pans. The PenPan-V3 model simulated the irradiance of each part of pans; that is, pan water surface, pan rim, side wall and pan bottom, and the simulated E-pan coincided with the observations of D20 and 601B pans. For D20 pans, aerodynamic component (E-pan,E-A) and radiative component (E-pan,E-R) of E-pan were 60% and 40%, respectively. The contributions of pan water surface, inside and outside pan rim, side wall, and pan bottom to E-pan,E-R were 23%, 38%, 26%, 6%, and 7%, respectively. For 601B pans, E-pan,E-A and E-pan,E-R were 42% and 58% of E-pan, respectively. The contributions of pan water surface and inside and outside pan rim to E-pan,E-R were 94%, 5% and 1%, respectively. The PenPan-V3 model benefits establishing the long-term continuous Epan networks in China, which can be used for evaluating the long-term trends of atmospheric evaporative demand in East Asia.