1. The PV-perspective Part I Based partly on: Weather analysis and forecasting: Applying Satellite Water Vapor Imagery and Potential Vorticity Analysis By Patrick Santurette and Christo Georgiev Elsevier Academic Press

2. Storyline: Why is PV weather relevant? How can you read a PV chart Link between WV imagery and PV Certain “extreme” weather phenomena and their PV signature

3. vertical stability of the atmosphere Ertel Potential Vorticity   vertical component of rel. vorticity  potential temperature f planetary vorticity p pressure g gravitational constant A measure of the rotation of an air mass 1 PV = *

4. A measure of the rotation of an air mass + PV anomalies are associated with a cyclonic wind field Ertel potential vorticity f planetary vorticity   vertical component of rel. vorticity  potential temperature p pressure g gravitational constant 19

5. PV anomalies and the wind field PV and wind - 12 Nov 1996 12UTC 2 0 PVU 6 Figures courtesy Linda Schlemmer PVU Alps

6. vertical stability of the atmosphere + PV anomalies indicate areas of reduced vertical Stability underneath Ertel potential vorticity f planetary vorticity   vertical component of rel. vorticity  potential temperature p pressure g gravitational constant 22

7. Stability / CAPE (convective available potential energy) 100 200 500 1000 J/kg © NERC Satellite Receiving Station Dundee figures courtesy Linda Schlemmer PV streamer 23 Alps

8. Cross-section Vertical cross-section shading: PV contours: potential temperature hPa 100 200 300 400 500 600 700 -40 -30 -20 -10 0 10 lon Static stability > 0 stable < 0 unstable colder less stable stable CF

9. Funatsu and Waugh 2008 Santurette and Georgiev2005 2D Jet EW 3D

10. 0 0.25 1 2 4 6 8 10 PVU stratospheric air (high PV) tropospheric air (low PV) Pole Alps tropopause MotivationA first look at instantaneous PV 2 wind > 25m/s

11. WinterSummer X X -height of isentropes varies with season -latitude of intersection of dyn. TP with isentropes varies with season -daily plots might differ substantially from these zonal and seasonal mean plots 320K good in winter, 335K good in summer for mid-latitudes

12. 310K Nov. 1996

13. 320K Nov. 1996

14. 330K Nov. 1996 ! Some features are cut-off on one level and connected on an other

15. 340K Nov. 1996

16. 350K Nov. 1996

17. WinterSummer -theta on PV2 maps e.g. from the University of Reading ! Problems in the tropics, not always uniquely defined -> tropopause folds

18. Theta on PV2 K

19. Tropopause height 30000 45000 60000 75000 90000 10500 12000 135000 [m2/s2]

20. [10 3 m] 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 Geopotential height [m] Comparison to geopotential height 3 0 0.25 1 2 4 6 8 10 Potential vorticity [PVU] [PVU] wind vectors vel > 25 m/s

21. Cross-section Vertical cross-section shading: PV contours: potential temperature hPa 100 200 300 400 500 600 700 -40 -30 -20 -10 0 10 lon Static stability > 0 stable < 0 unstable colder less stable stable CF

22. 0 0.25 1 2 4 6 8 10 Potential vorticity wind vectors vel > 25 m/s Thetae on 850 hPa L L LL 2 10 18 26 34 42 50 58 66 [K] SLP < 1005hPa, 5hPa contours Link to surface fields 4 cold and dry air

23. There is a clear relation between PV and water vapour imagery: A low tropopause can be identified in the WV imagery as a dark zone. As a first approximation, the tropopause can be regarded as a layer with high relative humidity, whereas the stratosphere is very dry, with low values of relative humidity. The measured radiation temperature will increase if the tropopause lowers. This is because the radiation, which is measured by the satellite, comes as a first approximation from the top of the moist troposphere. High radiation temperatures will result in dark areas in the WV imagery. http://www.zamg.ac.at/docu/Manual/SatManu/main.htm

24. tropopause stratosphere (dry) troposphere (moist) tropopause WV signal cross-section through a trough cross-section through the jet http://www.zamg.ac.at/docu/Manual/SatManu/main.htm

25. Geopotential Tropopause height

26. Concept TP height blue

28. Upper-level PV signature of several (extreme) weather events

29. Schlans November 2002Gondo October 2000 Heavy precipitation along the Alpine south-side

30. Example case: Schlans November 2002 IR 850hPa vel + rain 320K PV 16.11.2002 figures courtesy Evelyn Zenklusen

31. PV on 320K SLP strong convective activity along eastern flank formation of low pressure systems L Floods in Algeria November 2001 cyclonic windfield which can reach the surface wind on 850hPa precipitation IR meteosat

32. Kona lows occurrence: from October until March in the subtropical central- and north Pacific weather impact: strong rain fall, hail showers, land slides, flooding, storm winds, high surf, waterspouts and severe thunderstorms Hawaii as a kona low reaches maui (John Fischer, 2002) Slide courtesy Michael Graf

33. „kona low“ November 1996 figures courtesy Michael Graf PV on 330K, SLP GOES-9 IR HI

34. „kona low“ November 1996 PV on 330K, SLPGOES-9 IR L L L L

35. blocks identified as persistent upper-level low PV anomalies (Schwierz et al. 2004) Blocking from a PV persepctive TP Z block

36. January 2007 Atlantic Blocking PVU

37. PV anomalies and polar lows 290 K 05 Feb 2001 18 UTC25 Dec 1995 06 UTC18 Jan 1998 00 UTC PV on 290K isentropic surface

38. Links - PV loops on the web: University of Washington: http://www.atmos.washington.edu/~hakim/tropo/trop_theta.html University of Reading: http://www.met.rdg.ac.uk/Data/CurrentWeather/index.html DLR (analysis) http://www.pa.op.dlr.de/arctic/ At ETH see course website Satellite pictures and PV manual: http://www.zamg.ac.at/docu/Manual/SatManu/main.htm