Using HiFLOR to Understand the Connection Between Tropical Cyclone Intensification Rates and Climate Change

Recent studies have showed that tropical cyclone (TC) intensification rates control forecast performance, the magnitude of financial losses, as well as the lifetime maximum intensity of a storm. As one of the first global coupled climate models to simulate and predict category 4 and 5 (Saffir–Simpson scale) TCs and their interannual variations, the High-Resolution Forecast-Oriented Low Ocean Resolution (HiFLOR) model at the Geophysical Fluid Dynamics Laboratory (GFDL) is uniquely able to provide insight on how the entire TC intensification distribution could be transformed due to climate change.

In this study, three 70-year HiFLOR experiments are performed to identify the effects of radiative forcing on TC intensity change. For each of the experiments, sea surface temperature (SST) and atmospheric radiative forcing are nudged to different targets, allowing us to explore the sensitivity of TCs to these conditions. First, a control experiment, which uses prescribed ocean and atmospheric forcing observed during the years 1986-2005, is compared to two observational records and evaluated for its ability to capture the mean TC intensity behavior during these years. The simulated intensification distribution as well as the percentage of TCs that become major hurricanes agrees well with observations.

The control experiment is then compared to two climate change experiments, which use the same climatological SSTs from the control experiment plus mean SST anomalies and atmospheric radiative forcing from either 2016-2035 or 2081-2100. The frequency, intensity, and intensification distribution of TCs all shift to higher values as the 21st century progresses. Several synoptic variables are investigated as possible pathways for a warming climate to affect TC intensification.