Simulation of the July 2011 Korean Flood with the NCAR

Simulation of the July 2011 Korean Flood with the NCAR

Simulation of the July 2011 Korean Flood
with the NCAR RTFDDA Modeling System
William Y.Y. Cheng1, Yubao Liu1, Yuewei Liu1, Linlin Pan1, Gregory
Roux1, Wanli Wu1, Young-Jean Choi2, Seung-Woo Lee2, Beom-Keun
Seo2, Young-San Park2, Song-Lak Kang3
National Center for Atmospheric Research1
Korean Meteorological Agency2
Texas Tech University3
Acknowledgement: Korean Meteorological Agency
NATIONAL CENTER FOR ATMOSPHERIC RESEARCH
25 – 27 July 2011 Korean Flood
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Motivation
• Heavy rainfall in Korean Peninsula: 25-27 July 2011
– flash floods – more than 70 dead – worst flooding
in 100 years
• Seoul received third highest hourly rain rate (99.5
mm/h) since data collection began in 1907.
• Many power outages – more than 34,500 homes and
numerous roads/highways submerged – more than
125,000 people affected
• Global models, e.g., GFS4, had problems pinpointing
location of convection and underestimated precip
amount
• Study to determine if NCAR WRF-RTFDDA can
simulate some aspects of this flooding event and if
extra data assimilation can help improve simulation
(radar DA not in this talk; waiting for data).
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Infrared Satellite Imagery
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GFS Analysis: 2011-07-26-12
sea-level pressure
500-hPa abs vort/hgt
L
L
500-hPa vort max
low-level southerly
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H
GFS Analysis: 2011-07-26-12
850-hPa temperature
Low-level frontal
boundary in K.P.
900-hPa RH
moist southerly flow
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The Model: NCAR WRF-RTFDDA
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Experimental Design
• Case study: 2011-07-26-06 to 2011-07-27-12; 6 hour
cycling; 24-h fcst: WRF-RTFDDA
• Exp CTL: standard data (NCAR)
• Exp +KMA: standard data + KMA data (extra sfc obs in
Japan and S.K. + AMDAR + ASCAT + sat wind)
• Exp KMA: KMA data + WMO
d01
• Exp NODA: No DA
• Standard Data Ingest:
ü NOAA/MADIS which is GTS/WMO
+ AMDAR
d02
d03
ü Redundant GTS/WMO LDM Ingest:
Radiosondes, Buoy, Ship, METAR,
Special, Synop
ü RTG 1/12 degree global SST
Dx = 24.3, 8.1, 2.7 km
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3-6 h fcst: 3-h precip accum: 26/18
shifted band
inland
CMORPH underestimate
CMORPH
CTL
+KMA
Moved
too fast
GFS4
KMA
NODA
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1-h precip accum and radar: 26/08Z
radar
+KMA shows some
advantage over
other exps. esp for
band near NK/SK
border at this time
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1-h precip accum and radar: 26/17Z
radar
+KMA shifted band
to northeast; NODA
has precip over
east coast of
Korean Pen. but
moved too fast
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1-h precip accum and radar: 27/02Z
radar
except for NODA,
other three exps
similar at this time;
too much precip to
south
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Summary Remarks/Future Work
• Preliminary results are encouraging: RTFDDA
did a much better job than GFS4 in terms of
precipitation for both location and amount.
• DA with KMA extra obs helped to improve
precipitation simulation a bit for certain times.
• Need to look at if SST underestimated.
• Acquiring more observations from KMA to
verify precipitation more closely.
• Plan to assimilate KMA radar data.
• Will test Ensemble-RTFDDA model forecast.
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THE END/LA FIN
Thank You/Merci
Questions?
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