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ExUTLS dynamics and global observations Bill Randel, NCAR ACD

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)

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ExUTLS dynamics and global observations Bill Randel, NCAR ACD

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  1. ExUTLS dynamics and global observations Bill Randel, NCAR ACD

  2. ExUTLS dynamics and global observations Bill Randel, NCAR ACD

  3. Two aspects of ExUTLS transport to explore: • Transport above the subtropical jet • (links with double tropopauses) • Tropopause Inversion Layer (TIL) • (coupling between dynamics and chemical mixing)

  4. Extratropical temperature profiles often have multiple tropopauses

  5. Location of double tropopauses for one day (ERA40 data) PV=1-4 (dynamical tropopause)

  6. Cross-section near Charleston (ERA40 data) zonal winds, pot. temp Charleston

  7. Cross-section near Charleston (ERA40 data) zonal winds, pot. temp static stability N2 Charleston

  8. Cross-section near Charleston (ERA40 data) zonal winds, pot. temp static stability N2 Charleston intrusion of tropical tropospheric air above jet core Note: double tropopauses occur frequently even at polar latitudes

  9. Where/how often do multiple tropopauses occur? COSMIC GPS observations for April 2007

  10. Double tropopauses for April 30, 2007 (GFS data) J

  11. Differences in ozone for single vs. double tropopausederived from ozonesondes lower ozone for double tropopause statistics (characteristic of tropics)

  12. Differences in ozone for single vs. double tropopausederived from SAGE II satellite data ~ 2300 soundings NH SH -> consistent pattern of less ozone for double tropopauses

  13. Interpretation: transport of air from tropics above jet core (low stability, low ozone) Randel, Seidel and Pan, JGR, 2006

  14. HIAPER ozone observations during TREX note ozone decrease above 12 km stability derived from GFS ozone Laura Pan HIAPER flight track Andy Weinheimer and Ilana Pollack

  15. 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?)

  16. narrow layer of high stability J This is a climatological feature of the extratropical tropopause Birner, 2006

  17. examples using GPS data in tropopause-based coordinate temp stability layer of high stability height relative to tropopause

  18. April 2007 COSMIC climatology temp stability layer of high stability temp inversion height relative to tropopause

  19. structure of stability in tropopause coordinates shaded: N2 > 4.5 similar results found for all seasons, and both hemispheres 3 height relative to tropopause Randel et al., JAS, 2007

  20. TIL coincides with chemical mixing layer observed profiles in tropopause- based coordinate note water vapor and ozone transitions occur over +/- 1-2 km (tropopause mixing layer, ala Pan et al., 2004)

  21. TIL coincides with chemical mixing layer Pan et al., 2006

  22. 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?

  23. Balanced Structure in Extratropical Cyclone (Hoskins et al. 1985) warm isentropes cold winds low tropopause

  24. strength of the inversion vs. circulation T(ZLRT1+2km) – T(ZLRT1) systematically stronger for anticyclonic flow

  25. Double tropopauses for April 30, 2007

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