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The impact of the January 2013 Stratospheric Sudden Warming on the TTL

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.

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The impact of the January 2013 Stratospheric Sudden Warming on the TTL

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  1. The impact of the January 2013 Stratospheric Sudden Warming on the TTL Stephanie Evan & Karen Rosenlof

  2. from http://www.cpc.ncep.noaa.gov/ Warming poleward of 60oN Cooling in the tropics (25oS-25oN)

  3. Wind deceleration = Warming Warming SSW onset - 1 week Cooling - 3days + 3days

  4. Time-series of wave activity in the midlatitudes

  5. Cold Point Tropopause T & height from COSMIC NB: Annual variation in tropopause height ~ 1km (Reid and Gage, 1981)

  6. Cold Point Tropopause from COSMIC Jan 2013 Dec 2012 Feb 2013

  7. ATTREX NOAA WV data from Troy Thornberry & Drew Rollins

  8. Case for SSW in January 2009 01/01/09 January 18th 2009 Kodera, Eguchi, Lee, Kuroda and Yukimoto (JMSJ, 2010)

  9. Changes in deep convection ? Before the SSW After the SSW

  10. Changes in high clouds? Before the SSW After the SSW

  11. TTL cooling and Convection? TTL cooling Top of convection affected by TTL cooling Equilibrium Level = Top of convection dT/dz< dT/dz N2 < N2 (Stability is reduced) Altitude Moist Adiabat Level of free convection T environment

  12. Mean buoyancy frequency (13-17km) and OLR for the Western Pacific (100 to 180 deg E) January 6th

  13. Change in convection with the SSW Warming Cooling Cooling TTL becomes unstable -> higher convection Higher tropopause -> higher convection

  14. Simplified GCM experiment (Thuburn and Craig , 2000) Experiment with westward stratospheric force imposed = Enhances the Brewer-Dobson circulation + stronger dynamical cooling in the tropics. Westward = higher convection Control Eastward = lower convection Tropopause higher in WSF experiment Cumulus heating 200 hPa

  15. 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

  16. CHAMP/COSMIC CPT anomalies 15oS-15oN NH warming Jan 2013 Easterly QBO -1K

  17. Evolution of CPT temperature and height for different longitude bands Tropopause T Tropopause height

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