Do Sudden Stratospheric Warmings Boost Convective Activity in the Tropics?

Abstract

Abstract The impact of sudden stratospheric warmings (SSWs) on the tropical troposphere is investigated using 5000‐years scale ensemble simulations with a 60‐km global atmospheric model to detect signals from large natural variability of convection. Stratospheric temperature and static stability decrease in the tropics, and convective activity peaks simultaneously with the tropical upwelling. Tropical cyclone intensity and accumulated cyclone energy (ACE) show a weak but statistically robust enhancement of 5% and 9%, respectively, relative to the December–March climatology. However, the relative probability of the largest 10% of ACE anomalies increases by about 30%. Extratropical waves toward the tropical troposphere, which can alter convective activity, do not show a strong systematic variation during SSWs, and no significant association with convective activity is found if the sample size is large enough.

Keywords

• sudden stratospheric warming
• stratosphere‐troposphere coupling
• tropical convection
• tropical cyclone
• large‐ensemble simulations