R. A. Houze, Jr., U. Romatschke K. L. Rasmussen
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Transcript of R. A. Houze, Jr., U. Romatschke K. L. Rasmussen
R. A. Houze, Jr., R. A. Houze, Jr., U. RomatschkeU. RomatschkeK. L. RasmussenK. L. Rasmussen
R. A. Houze, Jr., R. A. Houze, Jr., U. RomatschkeU. RomatschkeK. L. RasmussenK. L. Rasmussen
AGU Fall Meeting, Remote Sensing of Natural Hazards, San Francisco, 9 Dec 2011AGU Fall Meeting, Remote Sensing of Natural Hazards, San Francisco, 9 Dec 2011
Mesoscale Aspects Mesoscale Aspects of Storms Producing of Storms Producing Floods over Arid Floods over Arid MountainsMountains
University of WashingtonUniversity of Washington
"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-moonAugust 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-moonAugust 2010
2000 lives lost, extensive livestock, household, infrastructure & agricultural ($20B)2000 lives lost, extensive livestock, household, infrastructure & agricultural ($20B)
Recent papers:
• Webster et al. (2011, GRL)• Houze et al. (2011, BAMS)
Synoptic time sequence…
700 mb wind (~3 km)700 mb wind (~3 km)
LL LL LLLL
HH
Water vapor anomaly500 mb windWater vapor anomaly500 mb wind
Rain
ECMWF Ensemble Forecast analyzed by Webster et al. (2011)
• 51 Ensemble members• 50/80 km resolution• Compared to CMORPH
precipitation product
A COMPARISON OF RAINFALL IN 2008 AND 2010:
• 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
Webster et al. 2011
Monsoon Mean Rainfall Climatology
Webster et al. 2011
Webster et al. 2011
Summary of predictions of major July rain events in Pakistan
The type of storm matters…
• TRMM climatology shows different kind of rainstorms in eastern vs western Himalayan region
Deep Convective
Cores
Wide Convective
Cores
BroadStratiform
Regions
Climatology of extreme convective features shown by TRMM for 10 years of data
Broad stratiform precipitation occurred over the mountains of Pakistan
Broad stratiform!
Floods!
Houze et al., BAMS 2011
17:09 UTC15:31UTC
Could the storm type have been anticipated?
Normal
Normal 500 mb anomaly patterns for South Asian storms observed by TRMM
Isolated deep convection
Nor
mal
Normal
Isolated deep convection
Broadstratiform
Normal 500 mb anomaly patterns for South Asian storms observed by TRMM
500 mb pattern 28 July 2010: very abnormal
Nor
mal
Normal
Isolated deep convection
Broadstratiform
500 mb pattern 28 July 2010: very abnormal
500 mb pattern 28 July 2010 was very abnormal
NOT NORMAL
NORMAL
BroadBroadstratiformstratiform
BroadBroadstratiformstratiform
Conclusions from Pakistan
• The probability of major rain periods over The probability of major rain periods over Pakistan was predictable ~7-10 days in Pakistan was predictable ~7-10 days in advanceadvance
• Not every predicted rain event produced Not every predicted rain event produced floodsfloods
• The type of storm mattered—the flooding The type of storm mattered—the flooding storms had mesoscale stratiform storms had mesoscale stratiform characteristics normally seen only in storms characteristics normally seen only in storms far to the eastfar to the east
• The possibility of such cloud systems The possibility of such cloud systems occurring in the west could be seen in the occurring in the west could be seen in the forecast wind pattern and from a knowledge of forecast wind pattern and from a knowledge of the satellite climatologythe satellite climatology
Leh, India, August 2010300 casualties due to flood in a high altitude valley of the Indus River
1200
0200
1200
0200
1200
0200 Flash flood at Leh
Afternoon convective scales grew upscale to form a
mesoscale system that moved off the plateau and fed on low-
level moisture
Rasmussen and Houze 2011
Could remote sensing have identified this as a
flood case?
Deep Convective
Cores
Wide Convective
Cores
BroadStratiform
Regions
Satellite climatology shows occurrence of wide convective systems or systems with broad stratiform regions to be extremely rare
Conclusions from Leh
• The flood producing storms were squall lines The flood producing storms were squall lines of mesoscale proportionsof mesoscale proportions
• The squall lines fed on moisture from low The squall lines fed on moisture from low levels when they moved off the Tibetan levels when they moved off the Tibetan PlateauPlateau
• Such storm are rare over the Tibetan PlateauSuch storm are rare over the Tibetan Plateau
• Again, a satellite climatology of storm type for Again, a satellite climatology of storm type for the region would help to anticipate such an the region would help to anticipate such an event.event.
EndEndThis research was supported byThis research was supported by
NSF grants ATM-0820586 and NASA grant NNX10AH70GNSF grants ATM-0820586 and NASA grant NNX10AH70G