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The impact of the January 2013 Stratospheric Sudden Warming on the TTL. Stephanie Evan & Karen Rosenlof. from http:// www.cpc.ncep.noaa.gov /. Warming poleward of 60 o N. Cooling in the tropics (25 o S-25 o N). Wind deceleration = Warming . Warming. SSW onset. - 1 week. Cooling. - PowerPoint PPT Presentation
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The impact of the January 2013 Stratospheric Sudden Warming
on the TTL
Stephanie Evan & Karen Rosenlof
Warmingpoleward of 60oN
from http://www.cpc.ncep.noaa.gov/
Cooling in thetropics (25oS-25oN)
Wind deceleration =
Warming Cooling
Warming
SSW onset
- 3days
- 1 week
+ 3days
Time-seriesof wave activityin the midlatitudes
Cold Point Tropopause T & height from COSMIC
NB: Annual variation in tropopause height ~ 1km (Reid and Gage, 1981)
Dec 2012 Jan 2013
Feb 2013
Cold Point Tropopause from COSMIC
ATTREX
NOAA WV data from Troy Thornberry& Drew Rollins
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Case for SSW in January 2009
Kodera, Eguchi, Lee, Kuroda and Yukimoto (JMSJ, 2010)
January 18th 2009
01/01/09
Changes in deep convection ?
After the SSW
Before the SSW
Changes in high clouds?
Before the SSW
After the SSW
TTL cooling
Equilibrium Level = Top of convection
Altit
ude
Level of freeconvection
Moist Adiabat
T environment
Top of convectionaffected by TTL cooling
dT/dz < dT/dzN2 < N2
(Stability is reduced)
TTL cooling and Convection?
Mean buoyancy frequency(13-17km) and OLRfor the Western Pacific(100 to 180 deg E)
January 6th
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CoolingCooling
Warming
TTL becomes unstable -> higher convectionHigher tropopause -> higher convection
Change in convection with the SSW
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Simplified GCM experiment (Thuburn and Craig , 2000)
Experiment with westward stratospheric force imposed =
Enhances the Brewer-Dobson circulation + stronger dynamical cooling in the tropics.
Cumulus heating
200 hPa
Westward= higher convection
Eastward= lower convection
Tropopausehigher in WSF
experiment
Control
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Summary
• A major stratospheric sudden warming developed in Jan. 2013 and:– Warmed the pole– Cooled the TTL– Had an impact of convection and cirrus
distribution?• The TTL cooling probably resulted in additional
removal of water vapor from the lower stratosphere
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NH warming Jan 2013Easterly QBO
-1K
CHAMP/COSMIC CPT anomalies 15oS-15oN
Evolution of CPT temperature and height for different longitude bands
Tropopause TTropopause height