Historical and Projected Tropical Cyclone Characteristics in SPEAR Large Ensemble Simulations
Abstract
This study analyzes the climatology, variability, and key characteristics of tropical cyclones (TC) in future projections from the Seamless System for Prediction and EArth System Research (SPEAR) Large Ensemble, compared with historical simulations. TC genesis numbers are projected to significantly decrease, a trend that is partly explained by the increase in saturation deficit. Spatially, TC genesis generally declines across most basins under warming, except in the central Pacific where SPEAR projects an increase. Correspondingly, accumulated cyclone energy (ACE), landfall frequency, and TC precipitation (TCP) also show decreasing trends. The projected decrease in climatological TCP is driven mainly by reduced TC occurrence, whereas precipitation per TC increases at a scaling of 4.64%/K, comparable to the TCP “climate scaling.” TCP size is projected to expand by approximately 31.5 km in radius by the end of the century. Normalized TC landfall frequency relative to the total number of basin TCs indicates fewer low-latitude landfalls due to a poleward shift in genesis regions. However, the intensity of landfalling TCs shows a slight increase. TC translation speed is projected to slow at higher latitudes due to weakened westerlies and to accelerate at lower latitudes. Standard modes of internal climate variability show no fundamental changes under warming, and the TC responses to these modes remain largely unchanged compared to present conditions.
