Ocean Meanders Modulate Extratropical Cyclone Energetics

Extratropical cyclones primarily develop over the western parts of ocean basins, where strong sea surface temperature (SST) contrasts form along western boundary currents. While previous studies have highlighted the influence of the mean SST and SST gradient on cyclones developing over these currents, they have generally disregarded their meandering nature. Here, we use idealized simulations to examine the sensitivity of cyclone development to SST meanders of varying size. Each crossing from the cold to the warm side of a meander locally enhances moisture supply into the troposphere, triggering peaks in diabatic heating a few hours later. This, in turn, amplifies the conversion from eddy potential to kinetic energy throughout the troposphere within hours. Both the size and phase of meanders relative to the cyclone modulate this energetic response. Such results reveal that not only the SST gradient but also the SST front geometry affect the life cycle of extratropical cyclones.