Impact of the distribution of sea surface temperature on the maintenance of storm tracks

Moist diabatic processes significantly impact storm track variability, position, and intensity. The distribution of atmospheric moisture is closely linked to sea surface temperatures (SSTs) through the Clausius-Clapeyron relation. Therefore, midlatitude atmospheric circulation is affected by the spatial distribution of SSTs, especially midlatitude SST fronts associated with oceanic western boundary currents.

We quantify the storm track’s response to moisture availability by performing idealised aqua-planet simulations where we modify the distribution of SST by changing the position, intensity, and width of midlatitude SST fronts. We assess the sensitivity of atmospheric circulation by comparing the water cycle and climatological mean energy cycle resulting from each simulation. Specifically, we find that storm tracks tend to align with SST fronts when these are located in midlatitudes, and that stronger SST gradients enhance storm track activity by increasing baroclinicity and moisture fluxes. The storm track’s latitudinal variability is strongly dependent on the latitude of the SST front, while its amplitude and maximum gradient primarily affect storm track intensity. Two additional experiments where we uniformly increase and decrease absolute temperature highlight the response of storm tracks to climate change: the water cycle intensifies in a warmer climate, but storm track activity appears more sensitive to the total meridional temperature contrast than to absolute temperature. 

Finally, we present preliminary results from ongoing work exploring the synoptic drivers of storm track response, including changes in cyclone distribution, baroclinicity, and the role of moist diabatic processes, which significantly impact storm track variability, position, and intensity.