Global Tropical Cyclone Precipitation Scaling with Sea Surface Temperature
Understanding the relationship between tropical cyclone (TC) precipitation and sea surface temperature (SST) is essential for both TC hazard forecasting and projecting how these hazards will change in the future due to climate change. This work untangles how global TC precipitation is impacted by present-day, short-term SST variability (known as apparent scaling) and by long-term changes in SST caused by climate change (known as climate scaling). A variety of datasets are used, including precipitation and SST observations, realistic climate model simulations, and idealized climate model simulations.
The apparent scaling of TC precipitation with SST in observations and models is greater than the climate scaling estimated from the model simulations. This implies that the apparent scaling should not be used to project how TC precipitation will be impacted by climate change. Scaling rate estimates can depend on methodology choices (e.g., precipitation metric, averaging radius around TC center, etc.), and therefore future studies should use multiple precipitation metrics in their analysis.
The apparent scaling rates depend on precipitation metric; examples shown here have ranges of 6.1% to 9.5% per K versus 5.9% to 9.8% per K for two different metrics. The climate scaling is estimated at about 5% per K, which is slightly less than the atmospheric moisture scaling based on thermodynamic principles of about 7% per K (i.e., the Clausius–Clapeyron scaling). The apparent scaling is greater than the climate scaling, which implies that the relationship between TC precipitation and present-day SST variability should not be used to project the long-term response of TC precipitation to climate change.