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- Title
Potential Evaporation and the Complementary Relationship.
- Authors
Tu, Zhuoyi; Yang, Yuting; Roderick, Michael L.; McVicar, Tim R.
- Abstract
The complementary relationship (CR) provides a framework for estimating land surface evaporation with basic meteorological observations by acknowledging the relationship between actual evaporation, apparent potential evaporation and potential evaporation (Epo). As a key variable in the CR, Epo estimates by conventional models have a long‐standing problem in practical applications. That is, the meteorological forcings (i.e., radiation and temperature) employed in conventional Epo models are observed under actual conditions that are generally not saturated. Hence, conventional Epo models do not conform to the original definition of Epo (i.e., the evaporation that would occur with an unlimited water supply). Here, we estimate Epo using the maximum evaporation approach (Epo_max) that does follow the original Epo definition. We find that adopting Epo_max considerably reduces the asymmetry of the CR compared to when the conventional Priestley‐Taylor Epo is used. We then employ Epo_max and develop a new physically based, calibration‐free CR model, which shows an overall good performance in estimating actual evaporation in 705 catchments at the mean annual scale and 64 flux sites at monthly and mean annual scales (R2 ranges from 0.73 to 0.75 and root‐mean‐squared error ranges from 9.8 to 18.8 W m−2).Both the 705 catchments and 64 flux sites cover a wide range of climates. More importantly, the use of Epo_max leads to a new physical interpretation of the CR. Key Points: Adopting a measure of potential evaporation that conforms to its physical definition reduces the asymmetry of the complementary relationship (CR)A new physically based, calibration‐free CR model is developedThe developed model performs well across catchments at mean annual scale and flux sites at mean annual and month scales
- Subjects
EVAPORATIVE power; METEOROLOGICAL observations; WATER supply
- Publication
Water Resources Research, 2023, Vol 59, Issue 3, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2022WR033763