U.S.-Taiwan Meeting, Boulder, 30 October 2006 Study of Intense Convection over Taiwan: Some Food for Thought R. Houze Study of Intense Convection over Taiwan: Some Food for Thought R. Houze Well defined mountain range near moisture source

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Past Observational Studies of Orographic Precipitation Stable to nearly neutral environments 1)Midlatitude frontal systems passing over mountain ranges 2)Many field projects: CASCADE, SCPP, COAST, CALJET, PACJET, IPEX, MAP, IMPROVE II 3)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 4)Mechanisms by which flow over a mountain range modifies the frontal precipitation--microphysical/dynamical interactions Unstable environments 1)Deep convection over and near high terrain. 2)Big Thompson, Rapid City floods: Maddox et al. 1978, Caracena et al )But, only two field projects: SPACE, Cotton et al. 1983, and NAME Stable to nearly neutral environments 1)Midlatitude frontal systems passing over mountain ranges 2)Many field projects: CASCADE, SCPP, COAST, CALJET, PACJET, IPEX, MAP, IMPROVE II 3)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 4)Mechanisms by which flow over a mountain range modifies the frontal precipitation--microphysical/dynamical interactions Unstable environments 1)Deep convection over and near high terrain. 2)Big Thompson, Rapid City floods: Maddox et al. 1978, Caracena et al )But, only two field projects: SPACE, Cotton et al. 1983, and NAME

U.S.-Taiwan Meeting, Boulder, 30 October 2006DryMoist DryMoist Synoptic and topographic factors affecting orographically influenced deep convection in other regions Himalayas Taiwan Taiwan orographic convection has some similarities to deep convective regimes elsewhere in Asia and elsewhere in the world.

U.S.-Taiwan Meeting, Boulder, 30 October 2006 What could a field project in Taiwan tell us about intense convection? What processes focus deep convection near the base of a mountain range? 1)Blocking 2)Diurnal effects 3)Juxtaposition of moist and dry flows 4)Low-level capping of convection near mountains In addition--Basic convective processes 1)Boundary layer 2)Microphysics 3)Electrification What processes focus deep convection near the base of a mountain range? 1)Blocking 2)Diurnal effects 3)Juxtaposition of moist and dry flows 4)Low-level capping of convection near mountains In addition--Basic convective processes 1)Boundary layer 2)Microphysics 3)Electrification

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Why do this project in Taiwan and not in the U.S.? Good leveraging from Taiwan Natural laboratory for the orographic convection problem 1)Highly confined area amenable to setting up field observations 2)Low-level moist flow 3)Upper-level dry flow 4)A region of flat land in front of the mountain range 5)Few other complicating factors Good leveraging from Taiwan Natural laboratory for the orographic convection problem 1)Highly confined area amenable to setting up field observations 2)Low-level moist flow 3)Upper-level dry flow 4)A region of flat land in front of the mountain range 5)Few other complicating factors

U.S.-Taiwan Meeting, Boulder, 30 October 2006

Lightning frequency based on TRMM satellite observations

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Broad stratiform case 11 Aug UTC

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Reflectivity data for 2 monsoon seasons

U.S.-Taiwan Meeting, Boulder, 30 October 2006 TRMM Data in the Himalayan Region

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Deep Intense Cores 40 dBZ echo 40 dBZ echo > 10 km in height > 10 km in height Deep Intense Cores 40 dBZ echo 40 dBZ echo > 10 km in height > 10 km in height Western Central Eastern Wide Intense Cores 40 dBZ echo 40 dBZ echo > 1000 km 2 area > 1000 km 2 area Wide Intense Cores 40 dBZ echo 40 dBZ echo > 1000 km 2 area > 1000 km 2 area Broad Stratiform Echo stratiform echo stratiform echo > 50,000 km 2 > 50,000 km 2 Broad Stratiform Echo stratiform echo stratiform echo > 50,000 km 2 > 50,000 km 2

U.S.-Taiwan Meeting, Boulder, 30 October 2006 A case of deep isolated 40 dBZ core 14 June 2002

U.S.-Taiwan Meeting, Boulder, 30 October 2006 Reflectivity data for 2 monsoon seasons Convection is slightly deeper & stronger over the lowlands than the foothills