1. Floods in Pakistan and India 2010 Robert A. Houze, Jr. with S. Medina, U. Romatschke, K. Rasmussen, S. Brodzik, D. Niyogi, and A. Kumar Robert A. Houze, Jr. with S. Medina, U. Romatschke, K. Rasmussen, S. Brodzik, D. Niyogi, and A. Kumar Colloquium, University of Vienna, 13 December 2010

2. "Almost 20 million people need shelter, food and emergency care. That is more than the entire population hit by the Indian Ocean tsunami, the Kashmir earthquake, Cyclone Nargis, and the earthquake in Haiti—combined.” Secretary-General Ban Ki-moon August 2010 "Almost 20 million people need shelter, food and emergency care. That is more than the entire population hit by the Indian Ocean tsunami, the Kashmir earthquake, Cyclone Nargis, and the earthquake in Haiti—combined.” Secretary-General Ban Ki-moon August 2010

3. Frontal systems midlatitude winter storms Tropical cyclones hurricanes, typhoons Convective storms local thunderstorms “mesoscale convective systems” Types of rainstorms

4. Example of a local thunderstorm Viewed from the ground

5. 100 km Example of a local thunderstorm Viewed from space Oklahoma

6. Example of a mesoscale convective system Three MCSs

7. 1458GMT 13 May 2004 Convective Precipitation Stratiform Precipitation Radar echoes showing the precipitation in the 3 MCSs

8. Idealized structure of a mesoscale convective system Houze 1989 Stratiform Convective

9. The TRMM Satellite TRM M Precipitation Radar Low altitude, low inclination orbit

10. Kummerow et al, 1998 > TRMM Precipitation Radar Important! Radar measures 3D structure of radar echoes  = 2 cm

11. The Himalayan region A natural laboratory for studying the behavior of extreme convection near a huge mountain range

13. Identify each contiguous 3D echo object seen on radar Convective component Stratiform component Extreme characteristic Contiguous 3D volume of convective echo > 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 with horizontal area > 50 000 km 2 “Broad stratiform region” Radar Identification of Extreme Rainstorms

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

15. Based on 10 years of data for the monsoon season (JJAS) Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of extreme convective features

16. Eastern Himalayan region Rainstorms have -massive stratiform regions -which are enhanced by airflow over the mountains

17. SUMMER MONEX 6 July 1979 850 mb wind Houze and Churchill 1987

18. SUMMER MONEX 6 July 1979 NOAA P3 Aircraft 88E92E 14N 20N 14N 20N 88E92E Houze and Churchill 1987 Microphysics Radar 100 km Extensive stratiform precipitation areas

19. Columns Needles Dendrites   ColumnsPlates & Dendrites Aggregates & Drops Flight Level Temperature (deg C) 0 -5 -10 -15 -20 -25 Relative Frequency of Occurrence Melting Precipitation-sized Ice Particles in MCSs over the Bay of Bengal in MONEX Houze & Churchill 1987

20. Example of a Bay of Bengal depression observed by TRMM & simulated by WRF Surface wind WRF simulation Total Rain Medina et al. 2010

21. TRMM PR WRF Simulation (a) Medina et al. 2010

22. WRF Simulation Summary Black -- 850 mb wind vectors Medina et al. 2010 White -- 850 mb heightWhite -- 850 mb height Yellow -- 500 mb vertical velocity

23. Based on 10 years of data for the monsoon season (JJAS) Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Climatology of extreme convective features RECALLRECALL

24. Western Himalayan region Severe local storms Similarities to the region east of the Rocky Mountains

25. Carlson et al. 1983 moist dry,hot Texas

26. Sawyer 1947

27. Consistent with Sawyer 1947 Backward trajectories (HYSPLIT/NCEP) 2.5 km 1.0 km Medina et al. 2010

28. WRF Simulation Water vapor (mixing ratio at surface) Potential buoyancy (“CAPE”) Medina et al. 2010

29. Hydrometeor mixing ratio just after convection formed (water per mass of air) Isochrones of integrated hydrometeor content Medina et al. 2010 WRF Simulation First cloud formation

30. The Pakistan Floods Storms of the eastern type occur in the west!

31. Normal upper-level wind pattern for Pakistan storms Normal

32. Normal upper-level wind pattern for Pakistan storms Normal

33. Wind pattern 28 July 2010: very abnormal Normal

34. Time sequence…

35. 700 mb wind (~3 km) L L L L L L L L H H Water vapor anomaly 500 mb wind Water vapor anomaly 500 mb wind Rain

36. A humid environment was created in a dry place Typical environment Flood case Bengal case Pressure (mb) 1000 500 200 Relative humidity (%) 501000 Temperature (C) 0 40 -40 1000 500 200

37. Broad stratiform precipitation occurred over the mountains of Pakistan Broad stratiform!  Floods!

38. Monsoon (Jun-Sep) climatology4 Aug 2010 500 mb geopotential height mm

40. Conclusions Large mountain ranges affect extreme convective rainstorms by: Channeling low-level moisture Producing capping of the moist layer Triggering convection Enhancing the stratiform components of mesoscale convective systems Processes occur in different combinations Understanding them can help understand extreme events such as the Pakistan floods

41. End This research was supported by NSF grant ATM-0820586 and NASA grant NNX10AH70G

42. East of the Andes Another region of intense convection… Is it like convection near the Rockies and Himalayas?

43. Extreme mountain ranges Himalayas Andes Rockies

44. The geography

45. Vertical air motions Low-level winds Average airflow conditions for storms with wide convective cores down up moistunstable

46. Example of triggering over the Sierra Cordoba range

47. TRMM PR ObservationsWRF Simulation Medina et al. 2010

48. What the storm looked like on the TRMM radar

49. Pakistan Floods—Summer 2010