Validation of the STAEBLE lake evaporation model in mountainous terrain

Evaporative loss is a substantial fraction of the water budget of lakes. Quantifying lake evaporation is crucial for water resources management, especially in the face of a changing climate and increasing water demand. The recently developed Surface-Temperature and Available-Energy-Based Lake Evaporation (STAEBLE) model implements a new mass and heat transfer method that does not require locally measured evaporation for calibration and which has potential for deployment in any geographical location. In its original article, STAEBLE was validated for Lake Mead in the southwestern United States. In this work, we assess STAEBLE for Lake Suwa, Japan, which differs significantly from Lake Mead in terms of climate, lake size, and surrounding topography and land cover. We ran STAEBLE for the years 2016-2018 with ERA5 reanalysis and MODIS water surface temperature data, and validated the lake evaporation estimates against in-situ flux observations. We also ran STAEBLE with observed meteorology from automated weather stations in the vicinity of the lake. STAEBLE performed very well at Lake Suwa with the ERA5 data, slightly better than at Lake Mead, compared to flux observations at daily to monthly time scales, with normalized mean bias errors (NMBE) of -4% to -5% and correlations of 0.88 to 0.95 at the monthly scale, depending on the model configuration. When driven by weather station data, the overall model performance further improved. We found that good estimates of net radiation and water surface temperature, both of which are much easier to measure than over-water turbulent fluxes, are important for good model performance.