25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics...
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![Page 1: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/1.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
Potential vorticity dynamics of a tropopause polar vortex
Steven M. Cavallo
and Gregory J. Hakim
University of Washington
Department of Atmospheric Sciences
![Page 2: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/2.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
Outline
• Tropopause polar vortices (TPVs)
• Ertel Potential Vorticity (EPV)
• Mechanisms for vortex intensity changes
• November 2005 TPV
Overview and observations
Potential vorticity analysis
PV budget
![Page 3: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/3.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What are tropopause polar vortices (TPVs)?
• Vortices that occur north and away from jet stream
• Based on tropopause
• Cold core
Vortices defined by closed contours of a materially conserved field such as PV
Changes in strength equivalent to changes in fluid properties within closed contours
Disturbances wave-like along jet stream
![Page 4: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/4.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
Why do we care about TPVs?
• Formation and intensity changes are not well understood
• Are often long-lived
Can have lifetimes > 1 month
• Trigger surface cyclones, such as in the image above
Eventually drift into midlatitudes and jet stream, impacting the weather
![Page 5: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/5.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
Ertel Potential Vorticity (EPV)
![Page 6: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/6.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Latent heating Heating rate
![Page 7: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/7.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Latent heating EPV changes
![Page 8: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/8.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Radiation Heating rate
![Page 9: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/9.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Latent heating EPV changes
![Page 10: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/10.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Radiation + Latent heating
Net EPV changes (radiation > latent heating)
![Page 11: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/11.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What EPV changes can we expect with a cloud?
Radiation + Latent heating
Net EPV changes (radiation < latent heating)
![Page 12: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/12.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Observations
GFS analysis tropopause pressure Coral Harbour, NT sounding
21 November 2005 at 00 UTC
![Page 13: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/13.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Observations
GFS analysis tropopause pressure Coral Harbour, NT sounding
22 November 2005 at 00 UTC
![Page 14: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/14.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV
WRF (V. 2.1.2) simulations:
• X = 30 km, Nz = 31
• 5-class microphysics, RRTM longwave radiation
• GFS initial conditions, boundaries updated every 3 hours
GFS Tropopause Analysis
![Page 15: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/15.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV
WRF (V. 2.1.2) simulations:
• X = 30 km, Nz = 31
• 5-class microphysics, RRTM longwave radiation
• GFS initial conditions, boundaries updated every 3 hours
GFS Tropopause Analysis
![Page 16: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/16.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Strengthening
PV Budget: Time mean vertical profiles for Siberia segment
All EPV components Diabatic components
![Page 17: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/17.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Strengthening
Time-height: Diabatic components Diabatic components
PV Budget
![Page 18: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/18.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Strengthening
Time-height: Radiation and cloud Diabatic components
PV Budget
![Page 19: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/19.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Strengthening
Time-height: Latent heat + Radiation Diabatic components
PV Budget
![Page 20: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/20.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
November 2005 TPV: Weakening
PV Budget: Time mean vertical profiles for Hudson Bay segment
All EPV components Diabatic components
![Page 21: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/21.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
Summary
•TPV strengthening from cloud-top radiational cooling in November 2005 TPV
•TPV weakening processes not clear, but strengthening no longer appears to occur when latent heating effects dominate the radiational effects.
• Is radiation always the key driver? What dynamics control weakening?
Work is underway involving idealized experiments to isolate the dynamics responsible for TPV intensity changes.
![Page 22: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/22.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
![Page 23: 25 June 200716th Conference on Atmospheric and Oceanic Fluid Dynamics Potential vorticity dynamics of a tropopause polar vortex Steven M. Cavallo and Gregory.](https://reader035.fdocuments.net/reader035/viewer/2022062714/56649d555503460f94a31fde/html5/thumbnails/23.jpg)
25 June 2007 16th Conference on Atmospheric and Oceanic Fluid Dynamics
What can we expect from a cloud?