Improved simulation of tropical cyclone responses to ENSO in the western north pacific in the high-resolution GFDL HiFLOR coupled climate model

This study aims to assess whether, and the extent to which, an increase in atmospheric resolution of the Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution version of CM2.5 (FLOR) with 50-km resolution and the High-Resolution FLOR (HiFLOR) with 25-km resolution improves the simulation of the El Niño-Southern Oscillation (ENSO)-tropical cyclone (TC) connections in the western North Pacific (WNP). HiFLOR simulates better ENSO-TC connections in theWNP including TC track density, genesis, and landfall than FLORin both long-termcontrol experiments and sea surface temperature (SST)- and sea surface salinity (SSS)-restoring historical runs (1971-2012). Restoring experiments are performed with SSS and SST restored to observational estimates of climatological SSS and interannually varying monthly SST. In the control experiments of HiFLOR, an improved simulation of the Walker circulation arising from more realistic SST and precipitation is largely responsible for its better performance in simulating ENSO-TC connections in theWNP. In the SST-restoring experiments ofHiFLOR, more realisticWalker circulation and steering flow during El Niño and La Niña are responsible for the improved simulation of ENSO-TC connections in the WNP. The improved simulation of ENSO-TC connections with HiFLORarises from a better representation of SST and better responses of environmental large-scale circulation to SST anomalies associatedwithElNiñoorLaNiña.Abetter representation of ENSO-TC connections in HiFLOR can benefit the seasonal forecasting of TC genesis, track, and landfall; improve understanding of the interannual variation of TC activity; and provide better projection of TC activity under climate change.