1. Extreme Convection Near the Himalayas and Andes Gerald R. North Symposium, Texas A&M University, College Station, June 8, 2009 Robert A. Houze, Jr. Ulrike Romatschke, Socorro Medina, Kristen Rasmussen Dev Niyogi, Anil Kumar

2. Sponsored in part by: NSF Award# ATM-0505739 NSF Award# ATM-0820586 NASA Award# NNX07AD59G

3. Data & Models  TRMM PR  3D reflectivity  Sample, 1998-2008  South Asia: March-April, 1999-2006  South America: December-February, 1998-2008  NCEP reanalysis  Large-scale environment  WRF model  Simulation of representative cases

4. Himalayan Region

5. Terrain gradients Land-ocean contrast Land cover differences Snow/Ice Tundra Wetland Forest Irrigated crop Crop Savanna Shrub/Grass Dryland/crop Grass Shrub Barren Thar Desert Ganges Delta

6. Wind & Moisture Climatology SFC 500 hPa 200 hPa SFC 500 hPa 200 hPa

7. Convective systems Convective component Stratiform component Extreme characteristic Contiguous convective echo 3D volume  40 dBZ Top height  10 km “Deep convective core” Horizontal area  1 000 km 2 Horizontal area  1 000 km 2 “Wide convective core” Extreme characteristic Contiguous stratiform echo Horizontal area  50 000 km 2 “Broad stratiform region”

8. Examples Deep Convective Core Wide Convective Core Broad Stratiform Region Convective Stratiform

9. Pre-MonsoonMonsoon Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of Extreme Convective Features

10. Pre-MonsoonMonsoon Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of Extreme Convective Features May July TRMM Rainfall

11. Pre-MonsoonMonsoon Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of Extreme Convective Features

12. Example of a wide convective core system in the western region

13. Backward trajectories (HYSPLIT/NCEP) 2.5 km 1.0 km Sawyer 1947 Houze et a. 2007

14. PakistanIndiaPakistanIndia Observations Infrared satellite temperature (shaded, K) and low-resolution terrain (black contours, km) WRF-simulation Cloud top temperature (shaded, K) and terrain (black contours, m)

15. TRMM PR ObservationsWRF Simulation

16. Mixing ratioCAPE

17. WRF Simulation Hydrometeor mixing ratio just after convection formed Isochrones of integrated hydrometeor content

18. Diurnal Variability in the Himalayan Region

19. Deep convective cores (mostly land) Wide convective cores: Land Wide convective cores: Ocean Broad stratiform regions: Ocean

20. Wide convective cores Nocturnal formation in Himalayan foothills

21. 11301730 23300530 Composite winds Wide convective core cases Nocturnal downslope flow in Himalayan foothills

22. Andes Region

23. Regions of analysis Foothills North La Plata Basin La Plata Basin Foothills South Foothills South

24. Wide convective cores Wide convective cores Precip. climatology Precip. climatology Deep convective Cores Broad stratiform regions Summer Season (DJF)

25. Example of a Wide Convective Core

26. Wide Convective Case (37,901 km 2 40 dBZ echo)

28. 925 mb NCEP/NCAR Reanalysis Air Temperature and Vector Winds 6 UTC (2 LT) 0 UTC (20 LT on the previous day) Time of TRMM Swath is 4:13 UTC (00:13 LT)

29. 500 mb Geopotential Height Anomaly for 11/12/2003 925 mb Geopotential Height Anomaly for 11/12/2003

30. 500 mb geopotential height anomaly Surface pressure anomaly Surface winds (~02 LT) [mb] Composite of NCEP Data For wide convective cores in SOUTH

31. 06 UTC ~02 LT 06 UTC ~02 LT 18 UTC ~14 LT 18 UTC ~14 LT 10 m s -1 Divergence Divergence 06 UTC ~02 LT 06 UTC ~02 LT 18 UTC ~14 LT 18 UTC ~14 LT 10 m s -1 Divergence 500 mb geopotential height anomaly Surface winds & divergence Composites For wide convective cores in SOUTH

32. Region of Eastern Himalayas and Bay of Bengal

33. Pre-MonsoonMonsoon Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of Extreme Convective Features RECALLRECALL

34. Example of a Bay of Bengal Case Surface wind WRF simulation Total Rain

35. TRMM PRWRF Simulation (a)

36. WRF Simulation

38. WRF Simulation Summary Black--850 mb wind vectors

39. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed

40. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux

41. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux Blue--Precipitable water

42. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux Blue--Precipitable water Red--Precip

43. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux Blue--Precipitable water Red--Precip White--850 mb height

44. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux Blue--Precipitable water Red--Precip White--850 mb height Yellow--500 mb vertical velocity

45. WRF Simulation Summary Black--850 mb wind vectors Yellow--850 wind speed White--LH flux Blue--Precipitable water Red--Precip White--850 mb height Orange--500 mb vertical velocity Red--Precip

46. Deep convective cores associated with daytime heating rare over ocean often in arid regions low-level moist jet overrun by dry flow from high terrain Wide convective cores both land and ocean associated with systems that develop broad stratiform regions affected by nocturnal downslope flow line structures common in S. America, not in S. Asia Broad stratiform regions most common over ocean and wetlands likely later stage of MCS over land--strongly reinforced by flow interaction with mountains over ocean--weak diurnal cycle but max in midday over oceans Conclusions

47. End