GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien...
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![Page 1: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/1.jpg)
GPS tropical tropopause temperatures
and stratospheric water vapor
William Randel1 and Aurélien Podglajen2
1NCAR Atmospheric Chemistry Division2Pierre and Marie Curie University - Paris
![Page 2: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/2.jpg)
QJRMS, 1949
The stratosphere isextremely dry because
air is dehydratedpassing the cold
tropical tropopause
![Page 3: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/3.jpg)
QJRMS, 1949
17.5 km
Large annual cycle in tropical tropopause temp.
![Page 4: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/4.jpg)
QJRMS, 1949
global climatology
![Page 5: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/5.jpg)
Objective: study correlated behavior of stratospheric H2O and GPS cold point tropopause temps on daily to annual time scales
• Can we understand the large-scale behavior of H2O in a simple way from accurate temperatures?
• When and where does dehydration occur?
• Empirical complement to trajectory studies
![Page 6: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/6.jpg)
Data:
GPS radio occultation temps:
• Daily data from CHAMP, COSMIC, others ~3000 obs/day for middle 2006-present
• High vertical resolution (~ 1 km), well-resolved cold point
• Saturation mixing ratios Qsat (RH=1.0)
MLS water vapor:
• daily gridded fields at 100, 83, 68, … hPa; late 2004 – 2012
![Page 7: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/7.jpg)
GPSmeasurements
gridded
GPS temps
Daily griddeddata set
5o x 20o x 0.2 km2006 - 2012
![Page 8: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/8.jpg)
Large-scale variability at the tropical tropopause (10o N-S)
0 180 360longitude
time
![Page 9: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/9.jpg)
GPS Temperature spectra at 17 km
Mixed Rossby gravity waves
2
5
10
30
3
Antisymmetric
Kelvin waves
MJO
Symmetric 2
5
10
30
3
Perio
d (d
ays)
Zonal wavenumber Zonal wavenumber
westward eastward westward eastward
![Page 10: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/10.jpg)
Temperature spectra at 23 km
Kelvin waves
Symmetric 2
5
10
30
3
Perio
d (d
ays)
Zonal wavenumber
Mixed Rossby gravity waves
Antisymmetric
Zonal wavenumber
2
5
10
30
3
westward eastward westward eastward
![Page 11: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/11.jpg)
MLSorbitaldata
gridded
MLS H2O100 hPa~ 16 km
![Page 12: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/12.jpg)
Temps
H2O
![Page 13: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/13.jpg)
2005 2006 2007 2008 2009 2010 2011 2012
Tropical tape recorder observed by MLS 2004-2012
cold pointtropopause
Cold phase of tropopause annual cycle
![Page 14: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/14.jpg)
100 hPa H2O GPS tropopause temperature Boreal Winter15o N-S
2009-2010
time
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GPS saturation mixing ratioBoreal Winter15o N-S
2009-2010
time
100 hPa H2O
![Page 16: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/16.jpg)
100 hPa H2OBoreal Winter15o N-S
2009-2010
time
GPS saturation mixing ratio
![Page 17: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/17.jpg)
100 hPa H2OBoreal Winter15o N-S
2010-2011
time
GPS saturation mixing ratio
![Page 18: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/18.jpg)
Fractional area of RH>1 for 20o N-S and 100 and 83 hPa
Max duringboreal winter
frac
tion
.30
0
.15
2007 2008 2009 2010 2011
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Winter (DJF) Summer (JJA)
Fraction of RH > 1.0 at 100 hPa locations where dehydration may occur
0.45 0.25
longitude
latit
ude
longitude
Dehydration mainly over ~20o N-S
40 N
40 S
![Page 20: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/20.jpg)
Fraction of RH > 1.0
at 100 hPa
Schoeberl and Dessler 2011
Dehydration locations derived fromLagrangian trajectories
Winter (DJF)
longitude
40 N
40 S
![Page 21: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/21.jpg)
Summer (JJA)
Schoeberl and Dessler 2011
Trajectory dehydration location
longitude
Fraction of RH > 1.0
at 100 hPa
40 N
40 S
![Page 22: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/22.jpg)
Winter (DJF)
longitude
40 N
40 S
Distribution of relative humidityin western Pacific
100% 140%
freq
uenc
y
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Key points:
• MLS and GPS data sets provide opportunity to understand H2O – T coupling on daily to interannual time scales
* links to clouds, dynamics of the TTL
• Dehydration regions (RH > 1.0) occur mainly duringboreal winter. Summertime behavior is less-wellunderstood.
• Observed dehydration patterns compare well with trajectory calculations. Where are the differences?
![Page 24: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/24.jpg)
Thank you
![Page 25: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/25.jpg)
Africa
Lidar cloud observations from CALIPSO
![Page 26: GPS tropical tropopause temperatures and stratospheric water vapor William Randel 1 and Aurélien Podglajen 2 1 NCAR Atmospheric Chemistry Division 2 Pierre.](https://reader035.fdocuments.us/reader035/viewer/2022062805/5697bfbb1a28abf838ca0f45/html5/thumbnails/26.jpg)
100 hPa H2O
83 hPa H2O
Qsat at the cold point
Qsat 15% driest area
Zonal averages 15o N-Spp
mv
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100 hPa H2O15o N-S
GPS saturation mixing ratio at locations where RH > 1.0
H2O vs. Qsat