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Study of Intense Convection over Taiwan: Some Food for Thought R. Houze

Well defined mountain range near moisture source. Study of Intense Convection over Taiwan: Some Food for Thought R. Houze. Past Observational Studies of Orographic Precipitation. Stable to nearly neutral environments Midlatitude frontal systems passing over mountain ranges

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Study of Intense Convection over Taiwan: Some Food for Thought R. Houze

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  1. Well definedmountainrange nearmoisture source Study of Intense Convection over Taiwan: Some Food for Thought R. Houze

  2. Past Observational Studies of Orographic Precipitation • Stable to nearly neutral environments • Midlatitude frontal systems passing over mountain ranges • Many field projects: CASCADE, SCPP, COAST, CALJET, PACJET, IPEX, MAP, IMPROVE II • Hobbs 1975, Marwitz 1987, Braun et al. 1997, Yu & Smull 2000, Schultz et al. 2002, White et al. 2003, Ralph et al. 2005, Rotunno and Houze 2007, & many others • Mechanisms by which flow over a mountain range modifies the frontal precipitation--microphysical/dynamical interactions • Unstable environments • Deep convection over and near high terrain. • Big Thompson, Rapid City floods: Maddox et al. 1978, Caracena et al. 1979 • But, only two field projects: SPACE, Cotton et al. 1983, and NAME

  3. Dry Dry Moist Moist Synoptic and topographic factors affecting orographically influenced deep convection in other regions Taiwan orographic convection has some similarities to deep convective regimes elsewhere in Asia and elsewhere in the world. Himalayas Taiwan

  4. What could a field project in Taiwan tell us about intense convection? • What processes focus deep convection near the base of a mountain range? • Blocking • Diurnal effects • Juxtaposition of moist and dry flows • Low-level capping of convection near mountains • In addition--Basic convective processes • Boundary layer • Microphysics • Electrification

  5. Why do this project in Taiwan and not in the U.S.? • Good leveraging from Taiwan • Natural laboratory for the orographic convection problem • Highly confined area amenable to setting up field observations • Low-level moist flow • Upper-level dry flow • A region of flat land in front of the mountain range • Few other complicating factors

  6. Lightning frequency based on TRMM satellite observations

  7. Broad stratiform case11 Aug 2002 0252 UTC

  8. Reflectivity data for 2 monsoon seasons

  9. TRMM Data in the Himalayan Region

  10. Western Central Eastern Deep Intense Cores 40 dBZ echo > 10 km in height Wide Intense Cores 40 dBZ echo > 1000 km2 area Broad Stratiform Echo stratiform echo > 50,000 km2

  11. A case of deep isolated 40 dBZ core14 June 2002

  12. Reflectivity data for 2 monsoon seasons Convection is slightly deeper & stronger over the lowlands than the foothills

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