Representativeness of gridded evapotranspiration observations for VIC calibration

Determine whether a monthly gridded evapotranspiration product adequately constrains the roughly 10,000 km² Xixian catchment at the spatial and temporal resolution of the VIC model.

Background

In the multivariable VIC calibration at Xixian, discharge performance was retained or improved, but evapotranspiration validation performance deteriorated: validation NSE fell from 0.05 to −0.29 and absolute bias increased from 25% to 31%.

The authors identify the representativeness of the monthly GLEAM evapotranspiration product for the catchment and model resolution as a specific unresolved issue requiring further investigation.

References

For VIC, the questions are whether a monthly gridded evapotranspiration product constrains a catchment of about 10,000 km² at the resolution of the model, whether the active parameters govern the evaporative partition, and whether a discharge-dominated objective should trade against it;

— Delegating Earth science model calibration to knowledge-guided LLM agents  (2610.18378 - Zhu et al., 13 Oct 2026) in Section 4, Discussion and conclusion