NOTES AND CORRESPONDENCE Flux Adjustment on Seasonal-Scale Sea Surface Temperature Drift in NICOCO

Abstract

High-resolution atmosphere–ocean coupled models are the primary tool for subseasonal to seasonal-scale (S2S) prediction. However, seasonal-scale sea surface temperature (SST) drift is inevitable due to the imbalance between the model components, which may deteriorate the prediction skill. Here, we investigate the performance of a simple flux adjustment method specifically designed to suppress seasonal-scale SST drift through case studies. The Nonhydrostatic Icosahedral Atmospheric Model (NICAM)–Center for Climate System Research Ocean Component Model (COCO) coupled weather/climate model, referred to as NICOCO, was used for wintertime 40-day integrations with a horizontal resolution of 14 km for the atmosphere and 0.25° for the ocean components. The coupled model with no flux adjustment suffers SST drift of typically −1.5 – 2°C in 40 days over the tropical, sub-tropical, and Antarctic regions. Simple flux adjustment was found to sufficiently suppress the SST drift. Neverthe-less, the lead–lag correlation analysis revealed that air–sea interactions are likely to be appropriately represented under flux adjustment. Thus, high-resolution coupled models with flux adjustment can significantly improve S2S prediction.