1. National Center for Atmospheric Research
Identification of the Tropopause Transition Layer using the Ozone-Water Vapor Relationship

Laura Pan
National Center for Atmospheric Research
Boulder, Colorado USA
To be submitted with Co-authors:
L. Paulik, L. A. Munchak, J. C. Bian, H. Selkirk, and H. Vömel
Laura Pan, October 2012

2. Scientific Issues
TTL boundaries – why different definitions and what are the differences in their physical meanings
Are the boundaries measurable?
Asian monsoon region has been known to behave similarly to the tropical TTL in its very high convectively driven tropopause. How is the transition in this region similar or different from that of equatorial TTL?
Laura Pan, October 2012

3. Two TTL Definitions: FFF vs. GF
Folkins, 2002
Folkins 2002; Fu et al., 2007; Fueglistaler et al. 2009
LB: level of zero net radiative heating ( km)
UB: level of upwelling mass flux decreased to the B-D (18.7 km or 70 hPa)
Gettelman and Forster, 2002
Gettelman and Forster, 2002 ;
LB: level of min stability or main convective outflow ( km, ~345K)
UB: cold point (16-17 km)
Laura Pan, October 2012

4. A Tale of Two TTLs: FFF TTL : “a Tropical Tropopause Layer”
A layer that serves as the boundary for air mass entering the stratosphere
Air mass in this layer ENTERS stratosphere
GF TTL : “a Tropical Transition Layer”
A layer that is transitioning from convective (tropospheric) to radiative (stratospheric) control
Not all air mass in this layer enters stratosphere
Laura Pan, October 2012

5. A Measurable TTL:
If a physical layer, certain properties should change at the boundary
What are the measurable changes? T? composition?
Are there measurable changes in chemical composition ?
Use of tracer correlation to identify the boundaries
Tracer correlation has been a successful method in identifying transition layer in the extratropics
How well would it work for the TTL identification?
Laura Pan, October 2012

6. A Brief Review the use of Tracer-Tracer correlation in characterizing transition layers
Pan et al., 2004, 2007a,b, 2010
Laura Pan, October 2012

7. Tracer-Tracer Correlations
Stratosphere
Tropospheric tracer
Stratospheric tracer
Stratospheric tracer
Tropopause or transition lyr
Altitude TP
Tropospheric tracer
Troposphere
(Pan et al., 2004)
Laura Pan, October 2012

8. START08 Campaign April - June, 2008 operated from Colorado (RAF)
Participated by NCAR, TAMU, Univ. Miami, Univ. Colorado, Harvard U., and NOAA
Principal Investigators:
Laura Pan, Elliot Atlas (Miami U), Kenneth Bowman (TAMU)
Pan et al., 2010
(BAMS)
Laura Pan, October 2012

9. START08/PreHIPPO April-June 2008
> 120 hours of measurements
> 1000 whole air samples
Laura Pan, April 15, 2010

10. Example of ExTL identified using O3-CO tracer-tracer relationship
Stratospheric
Primary TP.
secondary TP.
mixed
Trop.
Laura Pan, October 2012

11. What can we learn about TTL using tracer correlations?
O3-H2O relationship is analyzed
(data from paired ozonesonde and CFH launches)
Laura Pan, October 2012

12. Campaigns: TC4 and KunMing (Asian Monsoon)
July-August 2007
Alajuela, Costa Rica (10°N, 84.2°W)
16 profiles
Kunming
August 2009
KunMing, China (25°N, 102°E )
11 profiles
Laura Pan, October 2012

13. Cryogenic Frost Point Hygrometer (CFH) and ECC ozonesonde data
Upgraded version of NOAA FPH
Total uncertainty of the CFH:
Tropical: 3%–5% in the lower-to-middle troposphere,
5%–8% in the upper troposphere and in the TTL,
and 8%–9.5% in the lower stratosphere up to 28 km altitude
Vömel et al., 2007, Fujiwara et al., 2010, Bian et al., 2012
Laura Pan, October 2012

14. O3 and H2O from TC4:
Laura Pan, October 2012

15. Kunming Profiles
Laura Pan, October 2012

16. Transition Layer in Potential Temperature
“Equatorial TTL”
“Asian Monsoon”
IUGG Melbourne July 2011

17. Relating the transition layer to the dynamic boundaries:
Cold Point Tropopause and the Level of Neutral/Minimum Stability
Laura Pan, October 2012

18. TC4 Temperature Behavior
The cold point tropopause (CPT)
Transitional between convective and radiative control
“Level of minimum Stability” or “neutral stability”
Laura Pan, October 2012

19. Kunming Temperature Behavior
Laura Pan, October 2012

20. Neutral/Minimum Stability Potential Temperature
Cold Point Potential Temperature K K
Neutral/Minimum Stability Potential Temperature
345K
355K
Laura Pan, October 2012

21. Transition Layer Relative to the CPT and to the Level of Minimum Stability
Alt. Rel. to Level of M.S. (km)
Alt. Rel. to CPT (km)
IUGG Melbourne July 2011

22. What produced the “tail” – the example of Kunming 2009-08-07
Laura Pan, October 2012

23. The Outlier Profile : – transition layer from an extratropical intrusion process
Laura Pan, October 2012

24. Summary and Conclusions
TTL as a transition layer is measurable:
O3-H2O Tracer-Tracer correlation confirms: Upper bound by the cold point tropopause, lower bound by the level of minimum stability (near neutral stability)
O3-H2O Tracer-Tracer correlation characterization of TTL:
TC4 case depth: ~ K, ~ 4 km mostly below the cold point tropopause
The transition layer in the Asian Monsoon region show similarity and differences from the equatorial TTL
Smaller depth, higher PT range for both lower and upper boundaries, and with lower C.P. temperatures
The T-T relationship may also identify the effect of “in-mixing”
Laura Pan, October 2012

25. Determination of the background air – TC4 example
Distribution of Stratospheric water vapor
Distribution of Tropospheric ozone
Laura Pan, October 2012

26. Kunming Transition Layer
Laura Pan, October 2012