Land-Atmosphere Coupling Simulation and Its Role in Subseasonal-to-Seasonal Prediction

Land-atmosphere (L-A) coupling can significantly contribute to the subseasonal-to-seasonal (S2S) prediction. A pivotal element within this coupling is the interaction between the evapotranspiration (ET) and 2-m surface air temperature (T2M). During periods of strong L-A coupling, an increase in evaporative cooling induces reduced temperatures, resulting in a larger negative correlation between the two variables. This study aims to better understand S2S predictions of ambient surface air temperatures by investigating the L-A coupling present within forecasts produced with NASA’s state-of-the-art GEOS S2S forecast system. In our preliminary results, strong L-A coupling during boreal summer is found to be connected to enhanced prediction skill of surface air temperature across the Great Plains and Mexico. When L-A coupling is strong in the forecasts, these hot spot regions are characterized by warm and dry anomalies, signals that are well simulated in the model. Overall, this study provides insight on how better capturing relevant L-A coupling processes might improve predictions on subseasonal-to-seasonal timescales.