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climatology of Alpine precipitation by Schwarb, Daly, Frei and Schär

Terrain and Precipitation Patterns on Southern Side of the Alps in Meso-Beta Scale Jo ž e Rakovec † , Toma ž Vrhovec † , Saša Gaberšek † and G regor Gregori č †‡ † University of Ljubljana, Ljubljana, Slovenia ‡ Present affiliation: Meteorological Office, EARS, Ljubljana, Slovenia.

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climatology of Alpine precipitation by Schwarb, Daly, Frei and Schär

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  1. Terrain and Precipitation Patterns on Southern Side of the Alps in Meso-Beta ScaleJože Rakovec†, Tomaž Vrhovec†, Saša Gaberšek†and Gregor Gregori膇† University of Ljubljana, Ljubljana, Slovenia‡ Present affiliation: Meteorological Office, EARS, Ljubljana, Slovenia

  2. climatology of Alpine precipitation by Schwarb, Daly, Frei and Schär

  3. flow deflection due to rotational effects explains the secondary Alpine precipitation maximum in Ticino

  4. Buzzi and Tibaldi 1977Ro=0.7 full lines: displacements   thin lines: displacements  

  5. Schär and Schneidereit 2000Ro  0.75

  6. Rotunno and Ferretti 2001(the 1994 case) deflection & gradient of potential stability

  7. Rotunno and Ferretti 2001(the 1994 case) deflection & gradient of potential stability

  8. which is the reason for the primary Alpine maximum in Karnic & Julian Alps? what causes the dry area in Trentino & Tyrol? what causes the small scale patches – e.g. the belt of small spots from Monti Lessini to Karnic Alps?

  9. what can we learn from the simpliest kinematic simulation? this si not precipitation field! it is terrain induced vertical velocity in the mass-consistent model

  10. the methodology • terrain characteristics • in 10-km resolution • simple kinematics • with “synthetic” reliefs • and with a “real” relief • some wet MAP cases • simulations

  11. the W-E averaged slope towards North

  12. the S-N averaged height - concavity

  13. synthetic reliefs(similar to the ones of Schär and Schneidereitand of Rotunno and Ferretti)

  14. kinematic vertical velocitiesby uniformSW wind

  15. kinematic vertical velocities by uniform S and SW wind

  16. if Trentino Mts. are removed

  17. if Trentino Mts are removed

  18. if Julian Alpsand Dinarides are removed

  19. if Julian Alpsand Dinarides are removed

  20. 24-h MM5 simulation dry uniform S flow

  21. MM5, dry uniform S flow Trentino Mts. removed

  22. MM5, dry uniform S flow Dinarides removed

  23. MM5 wet simulation MAP IOP5potentially unstable- only Trentino subregion will be presented hereleft: original relief; right:Trentino Mts. removed. top: vertical velocity; bottom: precipitation

  24. IOP 5: vertical velocity at 700 hPa 4 Oct 99 06UTC original relief Trentino Mts. removed

  25. IOP 5: 30hr precipitation accumulat. 4 Oct 99 06UTC original relief Trentino Mts. removed

  26. IOP 9-10: vert. velocity at 700 hPa 24 Oct 99 00UTC original relief Trentino Mts. removed

  27. IOP 9-10: 48hr precipitation accumulation 24 Oct 99 00UTC original relief Trentino Mts. removed

  28. conclusions • convexity/concavity seems to be important • even the simpliest kinematics explains a lot of the climatological precipitation pattern

  29. conclusions • in potentialy unstable MAP IOP 5 case the main role of orograpical lifting was triggering; in Ticino and Trentino it was coupled with frontal processes and “veryintense convective cells”*) developed • in stable MAP IOP 9-10 “a broad southwest current against the windward slopes was dominant feature of the dynamics” *) • *)Robert Houze and Richard Rotunno:POC Science Director Notes • especially in such cases • the details of relief are essential

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