Impact of tropical cyclone winds on ENSO
The impact of tropical cyclone (TC) winds on ENSO is investigated using the fully-coupled Community Earth System model (CESM 1.3). We conduct a suite of experiments where we insert TC winds, extracted from a TC-permitting simulation (0.25˚ atmosphere), into the low-resolution model configuration (1˚ atmosphere) with nearly no intrinsic TCs. Results are compared to a control experiment to diagnose TCs’ impact on ENSO. The added TC winds increased the ENSO power and shifted the ENSO frequency closer to the observations. TCs lead to an increase of strong to extreme El Nino events, and a positive correlation is identified between strong El Nino events and TC wind power. TCs’ impact on El Nino is mainly through enhanced zonal advection feedback and thermocline feedback. Our results suggest that TCs can actively influence ENSO characteristics in a fully coupled comprehensive Earth System model, pointing to an important two-way interaction between TCs and ENSO.