EGU21-3554, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-3554
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Two parameters are required for a Budyko function to describe the land-atmosphere interaction

Daeha Kim1 and Jong Ahn Chun2
Daeha Kim and Jong Ahn Chun
  • 1Department of Civil Engineering, Jeonbuk National University, Jeonju-si, Jeollabuk-do, Korea, Republic of (daeha.kim@jbnu.ac.kr)
  • 2Prediction Research Department, APEC Climate Center, Busan, Korea, Republic of (jachun@apcc21.org)

While the Budyko framework has been a simple and convenient tool to assess runoff (Q) responses to climatic and surface changes, it has been unclear how parameters of a Budyko function represent the vertical land-atmosphere interactions. Here, we explicitly derived a two-parameter equation by correcting a boundary condition of the Budyko hypothesis. The correction enabled for the Budyko function to reflect the evaporative demand (Ep) that actively responds to soil moisture deficiency. The derived two-parameter function suggests that four physical variables control surface runoff; namely, precipitation (P), potential evaporation (Ep), wet-environment evaporation (Ew), and the catchment properties (n). We linked the derived Budyko function to a definitive complementary evaporation principle, and assessed the relative elasticities of Q to climatic and land surface changes. Results showed that P is the primary control of runoff changes in most of river basins across the world, but its importance declined with climatological aridity. In arid river basins, the catchment properties play a major role in changing runoff, while changes in Ep and Ew seem to exert minor influences on Q changes. It was also found that the two-parameter Budyko function can capture unusual negative correlation between the mean annual Q and Ep. This work suggests that at least two parameters are required for a Budyko function to properly describe the vertical interactions between the land and the atmosphere.

How to cite: Kim, D. and Chun, J. A.: Two parameters are required for a Budyko function to describe the land-atmosphere interaction, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3554, https://doi.org/10.5194/egusphere-egu21-3554, 2021.

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