Pan Evaporation as Local Potential Evaporation

Role of pan evaporation in the study on evapotranspiration (II)

Abstract

In the previous paper, studies based mainly on the measurement of pan evaporation (Epan) aiming at scrutinizing (1) evapotranspiration (ET) formula and (2) reference evaporation for estimating ET were outlined. In the present paper, we summarize the studies on (3) the characteristics of pan evaporimeter as they are the characteristics of radiation and heat balance of pan caused by local advection from the surroundings and its structure. Then, the studies on (4) the advection effect are outlined and it is emphasized that the characteristics can be utilized as they reflect the local meteorological conditions of the spot where the pan is placed. Namely, Epan has a role as local potential evaporation. Further, the concept of complementary relationship is shown to integrate the role of Epan as reference evaporation and local potential evaporation. Finally, it is emphasized that in future studies on evapotranspiration, Epan can play an important role in scrutinizing meteorological environment in a small area.