Baroclinic Energy Conversion Drives the Poleward Stronger Storm Tracks in a Warming Climate

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Storm tracks play a vital role in modulating midlatitude weather and global heat, momentum, and moisture transport. Under global warming, their position and intensity are projected to undergo substantial changes. Using Coupled Model Intercomparison Project Phase 6 simulations, this study examines future storm track responses and the underlying dynamics. Storm tracks are diagnosed using a classical Eulerian metric—synoptic-band (2.5- to 6-d) band-pass-filtered geopotential-height variance—while the mechanisms are quantified through a full-form local eddy kinetic energy budget that partitions baroclinic conversion, barotropic conversion, energy redistribution, and geopotential (pressure) flux convergence. Results show a weakening tendency of Northern Hemisphere storm tracks in June–July–August, consistent with recent evidence of boreal-summer storm track weakening, but a more regionally structured intensification accompanied by a poleward displacement in December–January–February. In the Southern Hemisphere, storm tracks intensify in June–July–August and shift poleward in December–January–February. These changes are linked to enhanced background baroclinicity measured by the Eady growth rate, arising mainly from strengthened meridional temperature gradients with a secondary contribution from changes in static stability. Interpreted through the eddy kinetic energy budget, strengthened high-latitude baroclinic conversion, together with weakened barotropic damping and energy redistribution by flux convergence, supports an upper-tropospheric increase and poleward displacement of transient eddy activity, highlighting the central role of eddy energy conversion and redistribution processes in shaping storm tracks in a warming climate.