Back to Search
Start Over
Increase in the skewness of extratropical vertical velocities with climate warming: fully nonlinear simulations versus moist baroclinic instability
- Source :
- Prof. O'Gorman via Chris Sherrstt
- Publication Year :
- 2017
- Publisher :
- Wiley Blackwell, 2017.
-
Abstract
- The distribution of vertical velocities in the extratropical troposphere is skewed such that upward motions are faster than downward motions. This skewness is important for the intensity distribution of precipitation and for the effective static stability experienced by moist eddies. We show here that the skewness of the vertical velocity increases in magnitude as the climate warms in simulations with an idealized general circulation model (GCM), except in very warm climates. That the skewness increases with warming is consistent with studies of moist baroclinic instability which suggest that the area of updraughts should contract as the stratification approaches moist neutrality in warm climates. However, the increase in skewness with warming is much weaker in the fully nonlinear simulations as compared to what is found for unstable modes of moist baroclinic instability in the same GCM. Nonlinear equilibration to a macroturbulent state leads to a reduction in skewness in warm climates. Therefore, while the unstable modes may be relevant for some cases of cyclogenesis, they overestimate the effect of warming on the skewness of the overall distribution of the vertical velocity. Remarkably, the most unstable mode transitions from a quasi‐periodic wave to an isolated diabatic Rossby vortex at sufficiently high temperatures, with possible implications for fast‐growing disturbances in warm climates. Keywords: skewness, vertical velocity, non‐Gaussian,moist baroclinic instability, diabatic Rossby vortex, diabatic Rossby wave, effective static stability, climate change<br />National Science Foundation (U.S.) (Grant AGS 1148594)
- Subjects :
- Physics
Atmospheric Science
010504 meteorology & atmospheric sciences
Baroclinity
Global warming
Diabatic
Stratification (water)
010502 geochemistry & geophysics
Atmospheric sciences
01 natural sciences
Physics::Geophysics
Eddy
13. Climate action
Skewness
Climatology
Cyclogenesis
Extratropical cyclone
Physics::Atmospheric and Oceanic Physics
0105 earth and related environmental sciences
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Prof. O'Gorman via Chris Sherrstt
- Accession number :
- edsair.doi.dedup.....6589a5314d23426e6d2ffc91916acea9