Thermal responses of a tropical lake over warming climate: insights from 1D hydrodynamic modeling

ABSTRACT We numerically hindcast a 34-year temperature data of a monomictic tropical lake in the Philippines using the one-dimensional General Lake Model (GLM). With minimal calibration, results from GLM closely match field observations with a root-mean-square error (RMSE) of 0.51 °C, reproducing the lake's defining thermal regime. This regime is characterized by brief mixing during the northeast monsoon, followed by prolonged stratification throughout the year. Our simulations reveal pronounced warming trends in both surface and bottom waters, leading to a seven-day lengthening of the stratification period and an increase in internal energy. From perturbation scenarios and correlation analyses, we identify rising air temperature (AT) and declining wind speed (WS) as primary drivers that synergistically affect the lake's thermal stability. Overall, our results show that GLM is suitable for reconstructing precise lake thermal dynamics, introducing a modeling framework for data-scarce tropical regions.