Analyzing the Effect of Tropical Cyclones on the Upper Ocean Using an Ocean General Circulation Model with Varying Horizontal Grid Resolution

Abstract:

Tropical cyclones (TCs) have the potential to influence regional and global climate through their interactions with the upper ocean. Here we present results from a suite of ocean-only model experiments featuring the Community Earth System Model (CESM), in which we analyze the effect of tropical cyclone wind forcing on the global ocean using three different horizontal ocean grid resolutions (3˚, 1˚, and 0.1˚). The ocean simulations are forced with identical atmospheric inputs from the Coordinated Ocean-Ice Reference Experiments version 2 (COREv2) normal year forcing conditions, featuring global blended TC winds from a fully-coupled CESM simulation with a 25 km atmosphere [Small et al., 2014]. The simulated TC climatology shows good agreement with observational estimates of annual TC statistics, including annual frequency, intensity distributions, and geographic distributions. Each simulation is 10 years, which includes a 5-year spin up and 5 years of TC-wind forcing. In addition, we conduct corresponding control simulations for each grid resolution configuration without applied TC forcing. We will discuss the TC-induced ocean responses across a variety of spatial and temporal scales. A key highlight of this work is analyzing the effect of ocean horizontal grid resolution on TC-induced ocean responses, particularly at resolutions capable of simulating mesoscale ocean eddies.