Past and future changes in extratropical cyclones and their relationships to Arctic warming in the CMIP6 models
Abstract
The influence on the mid-latitudes of Arctic sea-ice loss and the associated amplification of Arctic warming remains unclear. The reduction in the lower tropospheric equator-to-pole temperature gradient effects baroclinicity and therefore, may impact extratropical cyclones. However, changes in mid-latitude cyclones also depend on other aspects of human-induced climate change, such as upper-level temperature gradients, humidity, and static stability. Here, we seek to determine whether an influence of Arctic warming on cyclones is detectable in historical simulations and future projections from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Specifically, we examine trends in mid-latitude cyclone intensity, propagation speed, and lifetime, determined using a Lagrangian objective cyclone tracking algorithm. Over the historical period, Arctic amplification is ubiquitously simulated by the models considered here, however trends in cyclone intensity, speed and lifetime over the Northern Hemisphere are too widely spread to determine a robust change. We assess whether the spread across models in their cyclone responses can be understood in terms of their spread in the magnitude of Arctic amplification. We find that in summertime, models with a faster Arctic warming also depict more pronounced declines in cyclone intensity; equivalent relationships are weaker in wintertime. Finally, we compare the CMIP6 results to dedicated sea-ice loss experiments from the Polar Amplification Intercomparison Project (PAMIP) to isolate the role of sea-ice loss on extratropical cyclones.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.A15L1809H