A Generalized Evaporation Model for Chinese Pans

Abstract

AbstractPan evaporation (Epan) 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, Epan 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 Epan 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 Epan 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 Epan coincided with the observations of D20 and 601B pans. For D20 pans, aerodynamic component (Epan,A) and radiative component (Epan,R) of Epan were 60% and 40%, respectively. The contributions of pan water surface, inside and outside pan rim, side wall, and pan bottom to Epan,R were 23%, 38%, 26%, 6%, and 7%, respectively. For 601B pans, Epan,A and Epan,R were 42% and 58% of Epan, respectively. The contributions of pan water surface and inside and outside pan rim to Epan,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.