Floods in Pakistan and India 2010 Robert A. Houze, Jr. with K. Rasmussen, U. Romatschke, S. Medina, S. Brodzik, D. Niyogi, A. Kumar, P.Webster, V. Toma, H. Kim Atmospheric Scinences Colloquium, University of Washington, 7 January 2011 "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 Types of rainstorms Frontal systems • midlatitude winter storms Tropical cyclones • hurricanes, typhoons Convective storms • local thunderstorms • “mesoscale convective systems” Example of a local thunderstorm Viewed from the ground Example of a local thunderstorm Viewed from space Oklahoma 100 km Example of a mesoscale convective system Three MCSs Radar echoes showing the precipitation in the 3 MCSs Stratiform Precipitation Convective Precipitation 1458GMT 13 May 2004 Idealized structure of a mesoscale convective system Stratiform Radar echo Convective Stratiform Houze 1989 The TRMM Satellite TRM M Precipitation Radar Low altitude, low inclination orbit TRMM Precipitation Radar = 2 cm Important! Radar measures 3D structure of radar echoes > Kummerow et al, 1998 The Himalayan region A natural laboratory for studying the behavior of extreme convection near a huge mountain range Radar Identification of Extreme Rainstorms Identify each contiguous 3D echo object seen on radar Convective component Stratiform component Extreme characteristic Extreme characteristic Contiguous 3D volume of convective echo > 40 dBZ Contiguous stratiform echo with horizontal area > 50 000 km2 “Broad stratiform region” Top height > 10 km “Deep convective core” Horizontal area > 1 000 km2 “Wide convective core” Examples Deep Convective Core Stratiform Wide Convective Core Convective Broad Stratiform Region Climatology of extreme convective features Based on 10 years of data for the monsoon season (JJAS) Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Eastern Himalayan region Rainstorms are MCSs -massive stratiform regions -which are enhanced by airflow over the mountains SUMMER MONEX 6 July 1979 850 mb wind Houze and Churchill 1987 Microphysics SUMMER MONEX 6 July 1979 20N NOAA P3 Aircraft Extensive stratiform precipitation areas Radar 20N 100 km 100 km 14N 14N 88E 92E 88E 92E Houze and Churchill 1987 Precipitation-sized Ice Particles in MCSs over the Bay of Bengal in MONEX Flight Level Temperature (deg C) -25 -20 Columns Columns Plates & Dendrites Aggregates & Drops Dendrites -15 -10 -5 0 Needles * * Melting Relative Frequency of Occurrence Houze & Churchill 1987 Example of a Bay of Bengal depression observed by TRMM & simulated by WRF WRF simulation Surface wind Total Rain Medina et al. 2010 TRMM PR WRF Simulation (a) Medina et al. 2010 WRF Simulation Summary Black -- 850 mb wind vectors White -- 850 mb height Yellow -- 500 mb vertical velocity Medina et al. 2010 Climatology of extreme convective features Based on 10 years of data for the monsoon season (JJAS) Deep Convective Cores Wide Convective Cores Broad Stratiform Regions Western Himalayan region • Extreme storms are local thunderstorms • Similarities to the region east of the Rocky Mountains Carlson et al. 1983 Texas Backward trajectories (HYSPLIT/NCEP) 2.5 km 1.0 km Consistent with Consistent Sawyer 1947with Sawyer 1947 Medina et al. 2010 WRF Simulation Water vapor mixing ratio at surface Medina et al. 2010 CAPE WRF Simulation Isochrones of integrated hydrometeor content First cloud formation Medina et al. 2010 Hydrometeor mixing ratio (1 g/kg contour) just after convection formed The Pakistan Floods Storms of the eastern type occur in the west! Normal 500 mb anomaly patterns for South Asian rainstorms Normal Normal 500 mb anomaly patterns for South Asian rainstorms Normal 500 mb pattern 28 July 2010: very abnormal Time sequence… 700 mb wind (~3 km) H L Water vapor anomaly 500 mb wind Rain L L L mm A humid environment was created in a dry place 200 200 Pressure (mb) Flood case Bengal case Typical environment 500 1000 0 500 50 Relative humidity (%) 100 1000 -40 0 Temperature (C) 40 ECMWF Ensemble Forecast analyzed by Webster et al. (2011) • 51 Ensemble members • 50/80 km resolution • Compared to CMORPH precipitation product 4-Day ensemble mean forecast Webster et al. 2011 Webster et al. 2011 Broad stratiform precipitation occurred over the mountains of Pakistan Floods! Broad stratiform! Leh, India Ladakh region of Jammu and Kashmir State High altitude cold desert valley 3500 m MSL Near the Indus River August tourist season Leh City After mudslides 4 August 2010 5 August 2010 500 mb 500 mb 850 mb 850 mb 1200 0200 1200 0200 1200 0200 Diurnal cycle of major rain systems in Indian Western Foothills—Climatology Floods Midnight Noon Midnight Conclusions Pakistan Flood: Anomalous southeasterly flow Bay of Bengal type moist conditions MCSs with stratiform regions Leh Flood: Anomalous easterly flow MCSs diurnally generated over Tibet Westward moving squall lines over Leh End This research was supported by NSF grant ATM-0820586 and NASA grant NNX10AH70G End This research was supported by NSF grant ATM-0820586 and NASA grant NNX10AH70G