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Pakistan Flood 2010:

Pakistan Flood 2010:. P. J. Webster R. A. Houze, Jr. Could it have been predicted?. with V. Toma , H. Kim, K. Rasmussen, U. Romatschke, S. Medina, S. Brodzik , D. Niyogi , and A. Kumar,. International Weather & Climate Events of 2010, AMS Annual Meeting, Seattle, 25 January 2011.

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Pakistan Flood 2010:

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  1. Pakistan Flood 2010: P. J. Webster R. A. Houze, Jr. Could it have been predicted? with V. Toma, H. Kim, K. Rasmussen, U. Romatschke, S. Medina, S. Brodzik, D. Niyogi, and A. Kumar, International Weather & Climate Events of 2010, AMS Annual Meeting, Seattle, 25 January 2011

  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

  3. 2000 lives lost, extensive livestock, household, infrastructure & agricultural ($20B)

  4. Upcoming papers: • Webster et al. (2011, GRL) • Houze et al. (2011, BAMS)

  5. Monsoon Mean Rainfall Climatology Webster et al. 2011

  6. A COMPARISON OF RAINFALL IN 2008 AND 2010: Webster et al. 2011 • 2010 produced devastating floods but was not an outlier meteorologically • The hydrological uniqueness came because of the number of prior extreme events over the mountainous north, run-off due to drought in 2009, deforestation, and the TYPE OF STORM

  7. ECMWF Ensemble Forecast analyzed by Webster et al. (2011) • 51 Ensemble members • 50/80 km resolution • Compared to CMORPH precipitation product

  8. 4-Day ensemble mean forecast Webster et al. 2011

  9. Summary of predictions of major July rain events in Pakistan Webster et al. 2011

  10. Does the type of storm matter? • TRMM climatology shows different kind of rainstorms in eastern vs western Himalayan region

  11. Climatology of extreme convective features shown by TRMM for 10 years of data Deep Convective Cores Wide Convective Cores BroadStratiformRegions

  12. Normal 500 mb anomaly patterns for South Asian rainstorms Normal

  13. Normal 500 mb anomaly patterns for South Asian rainstorms Normal Normal

  14. 500 mb pattern 28 July 2010: very abnormal Normal Normal

  15. Time sequence…

  16. 700 mb wind (~3 km) H L L L L Water vapor anomaly 500 mb wind Rain

  17.  Floods! Broad stratiform precipitation occurred over the mountains of Pakistan Broad stratiform! Houze et al., BAMS 2011

  18. Conclusions • What was predictable about the Pakistan floods? • 2010 was not an abnormally rainy year in Pakistan • The probability of major rain periods over Pakistan was predicable ~7-10 days in events • Could floods have been anticipated? • Not every predicted major rain event produced floods • The July 28 storms occurred over deforested mountains • And they had mesoscale stratiform characteristics normally seen only in storms far to the east • The possibility of such cloud systems occurring in the west could be seen in the forecast wind pattern

  19. What can be done in the future?

  20. Proof of concept in Bangladesh Webster et al., BAMS November 2010 • Could be applied to other basins • Need downscaling for type of storm and topography

  21. End This research was supported by NSF grants ATM-0820586 and ATM-0965610 and NASA grant NNX10AH70G

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