DOWNSTREAM EFFECTS OF NORTHERN HEMISPHERE EXTRATROPICAL TRANSITION IN A FUTURE CLIMATE

Abstract

When a Tropical Cyclone (TC) encounters a more baroclinic environment, the structure of the TC can change to an asymmetric cold core cyclone in a process known as extratropical transition (ET). Transport of warm air from the tropics and latent heat release from precipitation associated with ET can modify the jet and downstream environment through the initiation and propagation of Rossby wave packets, which have been linked to atmospheric blocking and extreme weather. Changes in jet latitude and strength as well as the antecedent cyclone in a future climate may modify this process and change downstream development. A consensus on how ET is expected to change in a future environment has not been reached. The change in downstream effects of ET is the least studied and understood. This study makes use of high-resolution CMIP6 climate datasets to assess projected future changes in ET and its associated downstream impacts in the Northern Hemisphere. Models disagree over the evolution and strength of the mid-latitude sinuosity in both present and future climates, though this is very likely due to the limited sample size in the EC-Earth model.