1. Regional, Seasonal, and Diurnal Variations of Convection in the Himalayan Region
Ulrike Romatschke
University of Washington, University of Vienna
Socorro Medina, Robert A. Houze Jr.
University of Washington
13th Conference on Mountain Meteorology, August 2008, Whistler, BC, Canada

2. Ulrike Romatschke, University of Washington, University of Vienna
Objectives
Use 3D reflectivity structure of precipitating systems to document
Regional variability
Role of topography
Seasonal variability
Pre-monsoon vs. monsoon
Diurnal variability
Ulrike Romatschke, University of Washington, University of Vienna

3. Ulrike Romatschke, University of Washington, University of Vienna
Data
Tropical Rainfall Measurement Mission (TRMM) Precipitation Radar (PR)
3D reflectivity
1999 – 2006
Pre-monsoon: May
Monsoon: June – September
NCEP reanalysis
Large-scale environment
Ulrike Romatschke, University of Washington, University of Vienna

4. Classification of radar echoes within convective systems
Deep Convective Cores
Convective 40 dBZ echo  10 km (vertical)
Wide Convective Cores
Convective 40 dBZ area  km² (horizontal)
Broad Stratiform Echoes
Stratiform area  km² (horizontal)
Ulrike Romatschke, University of Washington, University of Vienna

5. Deep Convective Cores

6. Ulrike Romatschke, University of Washington, University of Vienna
Deep Convective Cores
Pre-monsoon (May)
Monsoon (Jun-Sep)
Ulrike Romatschke, University of Washington, University of Vienna

7. Ulrike Romatschke, University of Washington, University of Vienna
Pre-monsoon
Monsoon
Specific Humidity
Ulrike Romatschke, University of Washington, University of Vienna

8. Ulrike Romatschke, University of Washington, University of Vienna
Deep Convective Cores
Monsoon Diurnal Cycle
Mean Solar Time
Ulrike Romatschke, University of Washington, University of Vienna

9. Wide Convective Cores

10. Ulrike Romatschke, University of Washington, University of Vienna
Wide Convective Cores
Pre-monsoon (May)
Monsoon (Jun-Sep)
Ulrike Romatschke, University of Washington, University of Vienna

11. Ulrike Romatschke, University of Washington, University of Vienna
Wide Convective Cores
Monsoon Rain Climatology
Monsoon Wide Convective Cores
Ulrike Romatschke, University of Washington, University of Vienna

12. Land Wide Convective Cores
00 – 12 MST
Monsoon Diurnal Cycle
Early Morning
Evening
Mean Solar Time
12 – 00 MST
Ulrike Romatschke, University of Washington, University of Vienna

13. Wind composites for Wide Convective Cores at the Himalayan foothills
1200 UTC (~ 1730 MST)
0000 UTC (~ 0530 MST)
Ulrike Romatschke, University of Washington, University of Vienna

14. Broad Stratiform Echoes

15. Broad Stratiform Echoes
Monsoon Rain Climatology
Monsoon Broad Stratiform Echoes
Ulrike Romatschke, University of Washington, University of Vienna

16. Ulrike Romatschke, University of Washington, University of Vienna
Conclusions
Monsoon rainfall patterns strongly influenced by convective systems of the following types
Rain maximum over Arabian Sea and Bay of Bengal
Convective systems with Broad Stratiform Echoes
Rain maximum over Himalayan foothills
Convective systems with Wide Convective Cores occurring late night/early morning
Severe convection maximum in northwestern indentation region
Convective systems with Deep Convective Cores
Ulrike Romatschke, University of Washington, University of Vienna 16