The Influence of Ocean Coupling on Simulated and Projected Tropical Cyclone Precipitation in the HighResMIP–PRIMAVERA Simulations. Issue 20 (15th October 2021)

• Record Type: Journal Article
• Authors: Huang, Huanping; Patricola, Christina M.; Collins, William D.
• Is Part Of: Geophysical research letters. Volume 48:Issue 20(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-15
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL094801
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: This study aims to quantify the impacts of atmosphere–ocean coupling on simulated and projected tropical cyclone (TC) precipitation globally. We used global climate model (GCM) simulations over 1950–2050 from the High Resolution Model Intercomparison Project (HighResMIP) and compared its fully coupled atmosphere–ocean GCMs (AOGCMs) with atmosphere‐only GCMs (AGCMs). We find that ocean coupling generally leads to decreased TC precipitation over ocean and land. Large‐scale sea surface temperature (SST) biases are critical drivers of the precipitation difference, with secondary contributions from local TC–ocean feedbacks via SST cold wakes. The two driving factors, attributed to ocean coupling in the AOGCMs, influence TC precipitation in association with decreased TC intensity and specific humidity. The AOGCMs and AGCMs consistently project TC precipitation increases in 2015–2050 relative to 1950–2014 over ocean for all basins, and for landfalling TCs in the North Atlantic and western North Pacific. Plain Language Summary: Global climate models (GCMs) are important tools to simulate and project tropical cyclones (TCs) and associated precipitation. Yet there are large uncertainties in simulated TC precipitation, with atmosphere–ocean coupling in GCMs as a major source of uncertainty. In this study, we assess the impacts of ocean coupling on the representation and projection of TC precipitation. We find that the fully coupled atmosphere–ocean GCM simulations generally produce lower TC precipitation than the atmosphere‐only GCM simulations (i.e., sea surface temperatures or SSTs prescribed from observations). The precipitation decrease is associated with large‐scale SST underestimations and local TC–ocean interactions via SST cooling, common features in the GCM simulations with active atmosphere–ocean coupling. The two features influence TC precipitation by reducing TC intensity and specific humidity. During the period 2015–2050, TC precipitation is predicted to increase in most TC basins by both the fully coupled and atmosphere‐only GCM simulations. However, the magnitude can vary by a factor of three depending on ocean coupling. Further research is needed to better understand and characterize the physical mechanisms governing the accurate representations of SSTs, TCs, and TC precipitation. Key Points: Ocean coupling generally leads to decreased tropical cyclone (TC) precipitation over both ocean and land Large‐scale sea surface temperature biases and TC cold wakes, key facets of ocean coupling, drive the precipitation decline Projected future TC precipitation increases in most regions, however the magnitude can vary by a factor of three depending on ocean coupling