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ExUTLS dynamics and global observations Bill Randel, NCAR ACD. ExUTLS dynamics and global observations Bill Randel, NCAR ACD. Two aspects of ExUTLS transport to explore: Transport above the subtropical jet (links with double tropopauses ) Tropopause Inversion Layer (TIL) - PowerPoint PPT Presentation
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ExUTLS dynamics and global observations
Bill Randel, NCAR ACD
ExUTLS dynamics and global observations
Bill Randel, NCAR ACD
Two aspects of ExUTLS transport to explore:
1)Transport above the subtropical jet (links with double tropopauses)
2)Tropopause Inversion Layer (TIL) (coupling between dynamics and chemical
mixing)
Extratropical temperature profiles often have multiple tropopauses
Location of double tropopauses for one day (ERA40 data)
PV=1-4(dynamicaltropopause)
Cross-section near Charleston (ERA40 data)
zonal winds, pot. temp
Charleston
Cross-section near Charleston (ERA40 data)
static stability N2zonal winds, pot. temp
Charleston
Cross-section near Charleston (ERA40 data)
static stability N2zonal winds, pot. temp
intrusion of tropical tropospheric air above jet core
Charleston
Note: double tropopauses occur frequently even at polar latitudes
Where/how often do multiple tropopauses occur?
COSMIC GPS observations for April 2007
Double tropopauses for April 30, 2007 (GFS data)
J
Differences in ozone for single vs. double tropopause
derived from ozonesondes
lower ozonefor doubletropopausestatistics
(characteristicof tropics)
Differences in ozone for single vs. double tropopause
derived from SAGE II satellite data
NH SH
-> consistent pattern of less ozone for double tropopauses
~ 2300 soundings
transport ofair from tropicsabove jet core
(low stability, low ozone)
Interpretation:
Randel, Seidel and Pan, JGR, 2006
HIAPER ozone observations during TREX
stability derived from GFS
HIAPER flight track
ozone
note ozone decrease above 12 km
Andy Weinheimerand Ilana Pollack
Laura Pan
Some Questions:
Why is the transport above the jet mostly poleward rather than equatorward?
How does transport above jet contribute to ventilation of LS? (when and how much?)
What is the origin / age spectrum of air above STJ ? (are there short-lived species in this region?)
J
narrow layer ofhigh stability
This is a climatological feature of theextratropical tropopause
Birner, 2006
examples using GPS data in tropopause-based coordinate
heightrelative totropopause
temp stability
layer ofhigh
stability
April 2007 COSMIC climatology
heightrelative totropopause
temp stability
layer ofhigh
stability
tempinversion
structure of stability in tropopause coordinates
similar resultsfound for
all seasons, andboth hemispheres
shaded:N2 > 4.5
Randel et al., JAS, 2007
heightrelative totropopause
3
observedprofiles in
tropopause-based
coordinate
note water vapor andozone transitions occur
over +/- 1-2 km
(tropopause mixing layer, ala Pan et al., 2004)
TIL coincides with chemical mixing layer
TIL coincides with chemical mixing layer
Pan et al., 2006
Summary:
Tropopause inversion layer is ubiquitous in extratropics and coincides with the chemical mixing layer.
Radiative forcing may help maintain the TIL.
* Detailed structure of ozone and water vapor across the tropopause is important.
-> What determines thickness of the chemical mixing layer?
-> Is this important to get correct in models?
Balanced Structure in Extratropical Cyclone (Hoskins et al. 1985)
cold
warm
low tropopause
isentropes
winds
strength of the inversion vs. circulation
T(ZLRT1+2km) – T(ZLRT1)
systematically stronger for anticyclonic flow
Double tropopauses for April 30, 2007