Oct 27, 2016

How will precipitation change in extratropical cyclones as the planet warms? Insights from a large initial condition climate model ensemble

Vineel Yettella, Jennifer E. Kay
Climate Dynamics
  • Investigates the extratropical precipitation response to global warming within a 30-member initial condition climate model ensemble
  • States that, as in observations, modeled cyclonic precipitation contributes a large fraction of extratropical precipitation, especially over the ocean and in the winter hemisphere
  • When compared to present day, the ensemble projects increased cyclone-associated precipitation under twenty-first century business-as-usual greenhouse gas forcing
  • While the cyclone-associated precipitation response is weaker in the near-future (2016–2035) than in the far-future (2081–2100), both future periods have similar patterns of response
  • Finds that although cyclone frequency changes are important regionally, most of the increased cyclone-associated precipitation results from increased within-cyclone precipitation
  • Finds that cyclone-centric composites show statistically significant precipitation increases in all cyclone sectors
  • Decomposition into thermodynamic (mean cyclone water vapor path) and dynamic (mean cyclone wind speed) contributions shows that thermodynamics explains 92 and 95% of the near-future and far-future within-cyclone precipitation increases respectively
  • Finds the influence of dynamics on future cyclonic precipitation changes is negligible and that the forced response exceeds internal variability in both future time periods
  • Results suggest that future cyclonic precipitation changes will result primarily from increased moisture availability in a warmer world, with secondary contributions from changes in cyclone frequency and cyclone dynamics