Transport Processes in the Tropical Tropopause Region – Observations

1. Transport Processes in the Tropical Tropopause Region – Observations C. Michael Volk + the HAGAR Team With contributions by S. Viciani, A. Ulanovsky, F. Ravegnani, P. Konopka G-SPARC Workshop, Berlin, 4 December 2006

2. Cold Point TP ~380K clear-sky heating = 0 ~360-370K TTL Secondary TP ~345K max. conv. outflow Goal: Diagnose transport with ozone and tracer observations Isentropic mixing across the subtropical barrier and the tropopause Mixing of overshooting air with the background TTL Transport Processes in the Tropical Tropopause Region Isolated tropical stratosphere Stratospheric Subtropical barrier Subtropics Troposphere latitude

3. SPARC Relevance: Key role of TTL in Climate-Chemistry Interaction (Theme 1) • H2O: TTL transport details intimately linked to dehydration mechanisms • Chemistry: TTL transport time scales determine abundances of short- lived and/or water soluble substances entering the stratosphere => influences stratospheric Cl, Br, I, and S budgets e.g. recent SPARC TTL sessions and workshops: Modelling of Deep Convection and of Chemistry and their Roles in the Tropical Tropopause Layer, Victoria, June 12-15, 2006 TTL session at General SPARC 3d General Assembly 2004 Basic Open Question: Quantitative understanding of the balance between the dominant transport processes in the TTL as function of time and space

4. Use of Tracers for tropical UTLS Transport • Horizontal mixing from extratropical stratosphere (above or below tropopause): • identified by stratospheric tracers: N2O, CH4, CFCs (& correlations w/ O3) • Large-scale diabatic ascent: • estimate using CO2, CO or O3 „clock“ (if other processes are weak) • Convective uplift: • boundary layer tracers: O3 (marine), CO, CO2 (continental) • Vertical mixing of overshooting air: • Mixing lines in CO2, CO, O3 vs q and their correlations • Interhemispheric mixing in TTL (need measurements on both sides of ITCZ) • tracers with large interhemispheric gradients (CO, CO2, SF6, H-1211)

5. Observations by Multi-Tracer Instrument: HAGAR (High Altitude Gas Analyzer) • Techniques: • 2-channel-gas chromatograph • LI-COR 6251 CO2-sensor(IR-absorption) • Molecules: nom. precision frequency • N2O 0.2% 90 s • CH4, F12, F11 0.5% 90 s • SF6 , H2 1.5% 90 s • H-1211 2.5% 90 s • CO 3% 110 s • CO2 0.1% 5-10 s

6. M55 Geophysica In situ Tracer Measurements FOZAN (CAO, Russia): O3 COLD (INOA, Italy): CO HAGAR (Univ. Frankfurt) N2O, F11, F12, H1211, SF6, CO2 (CH4, CO, H2)

7. M55 Geophysica Observations in the Tropical UTLS Total # of tropical flights: 48

8. Horizontal mixing into tropical LS: Vertical N2O distribution APE-THESEO: mostly inside tropical pipe

9. Horizontal mixing into tropical LS: Vertical N2O distribution TROCCINOX: outside tropical pipe, mixing region

10. Horizontal mixing into tropical LS: Vertical N2O distribution SCOUT-O3: somewhere in between

11. Horizontal mixing into tropical LS: O3-N2O correlation APE-THESEO: mostly inside tropical pipe

12. Horizontal mixing into tropical LS: O3-N2O correlation TROCCINOX: outside tropical pipe, mixing region

13. Horizontal mixing into tropical LS: O3-N2O correlation SCOUT-O3: somewhere in between

14. APE-THESEO Climatological Context of campaigns: Tropical Pipe (@ 500K) Meridional PV gradient is a measure for inhibition of isentropic mixing THESEO SCOUT TROC.

15. No significant negative O3-N2O correlation in TTL No Evidence TTL: Stratospheric (horizontal) inmixing during APE-THESEO ? Mean tropopause

16. No low N2O values in TTL No significant negative O3-N2O correlation in TTL No Evidence TTL: Stratospheric (horizontal) inmixing during SCOUT-O3 ?

17. TTL: Stratospheric inmixing during TROCCINOX? Significant correlations (confidence level > 99%) at q > 340 K FOZAN O3 Yes, significant stratospheric influence in TTL

18. Slow Ascent in upper TTL and tropical lower LS => can be studied with propagation of CO2 seasonal cycle

19. ~18 km Highest level of convective outflow ~ 18 km Slow ascent versus convection: CO and CO2 (AMMA 2006) ~15 km

20. SCOUT-O3 051130b 355 K Max. outflow level ~ 355 K Convective uplift of boundary layer air into the TTL: CO2 TroCCiNOx

21. Linear mixing of CO and q Vertical mixing of overshooting air in the TTL: TroCCiNOx CO Mixing of overshooting air: CO profiles

22. Mixing of convected air Mixing of overshooting air in the TTL: TroCCiNOx correlations

23. Mixing of overshooting air in the TTL: SCOUT-O3 ozone

24. Mixing of overshooting air in the TTL: SCOUT-O3 ozone

25. SCOUT-O3 „background TTL“ O3 Profiles

26. Elevated TTL O3 due to horizontal stratospheric inmixing SCOUT-O3 background and TROCCINOX O3 profiles

27. Elevated TTL O3 due to: - Descent below Q=0 level ? - Vertical mixing ? - O3 production ? SCOUT-O3 background and APE-THESEO O3 profiles

28. At the TP and above still interhemispheric gradients Interhemispheric mixing in the TTL: APE-THESEO

29. TTL NH SH ITCZ Interhemispheric mixing in the TTL: SCOUT-O3 Transfer Flights Darwin Bangkok

30. Proposed Research for G-SPARC: Model-aided analysis of transport processes in the tropical UTLS • Observations: • CO2, CO, O3, CH4, SF6, potentially other tracers from all 5 tropical M55 campaigns since 1999. • Tropical O3 profiles from the SHADOZ programme • Model: Close Co-operation w/ FZ Jülich (P. Konopka) • CLaMS long-term runs with simplified chemistry for CO, CH4, O3 • CO2, CO, SF6 surface fields from NOAA CMDL global observations • Goals: • Quantitative interpretation of tracer data in terms of transport processes • Validation and improvement of CLaMS transport and mixing • => Quantitative understanding of transport and its impact on chemical budgets • => Determine which processes need particular attention in CCMs • Approach: • Model-observation comparisons of both mean features (profiles, correlations) and specific episodes • Additional model runs to test sensitivity to mixing strength, radiative ascent • Model runs with origin of air tracers to facilitate interpretation