ong>Usingong> ong>Atmosphericong> ong>Modelsong> ong>andong> ong>Ensemblesong> on a
Variety of Time ong>andong> Spatial Scales to Improve
Predictions of Song>andong>y, Storm Surge, ong>andong> Future
Changes in Coastal Storms
Dr. Brian A. Colle
School of Marine ong>andong> ong>Atmosphericong> Sciences
• What was unusual about Song>andong>y from a
• Storm Surge Forecast Issues – Motivation for
ensembles ong>andong> multi-model approaches
• Collaboration with Penn State on simulations
of Song>andong>y using Ensemble Kalman Filter
(EnKF) data assimilation
• Future (next 100 years) changes East coast
storms (Oct-March) from an ensemble of
global climate models
Upper-Level Flow Differences
1938 Long Islong>andong> Express Hurricane Song>andong>y 2012
How Rare Was Song>andong>y??
(Hall ong>andong> Sobel (GRL 2013) – 1 in 700 yr storm??
Scileppi ong>andong> Donnelly, 2007, Geochem. Geophys. Geosys.
Courtesy of Mel Shapiro
at 0600 UTC 29
1200 UTC 29
NOAA ong>andong> Stevens
Inst 46-h forecast
Stony Brook (ADCIRC) Surge Forecasts using 12-km MM5
Benefits of Multi-Model Surge Predictions (Brier
Skill relative to SBSS CTL – DiLiberto et al. 2011)
ENS 3 (Best SBSS
member , NWS, Stevens)
ALL (5 SBSS, NWS,
To Better Estimate of ong>Atmosphericong> Forcing
ong>andong> Uncertainty: Ensemble WRF Simulations
ong>Usingong> 60-member EnKF (Assimilates Aircraft
Doppler ong>andong> In Situ-- Zhang et al. 2011)
Courtesy of Dr. Fuqing Zhang
Wind speed in kts
WRF Model Simulation (3-km grid spacing)
Observed Surface Wind Comparison vs 3-km WRF
Simulation of Hurricane Song>andong>y at Long>andong>fall.
at 1200 UTC 29 October 2012
But how will coastal flooding
events change as we go into the
-As the climate changes, the frequency, intensity ong>andong> track of cyclones will must
-We can use general circulation models (GCM's) as part of the Coupled Model
Intercomparison Project (CMIP5) to determine long term variability in the weather
using grid spacing of 0.5 to 3 degrees.
Cyclone frequency ong>andong> intensity (Oct-March) were tracked within 13 GCM's
along the East Coast of the U.S. (Colle et al. 2013)
East Coast Region Future
Change in 6-h Deepening Rates
Number change per cool season in EC-L
% Change in the number of 850
hPa wind bins for MPI ong>andong> MRI
models (10 deg around cyclone)
% change per cool season in EC-L
• A blocking high to the northeast helped steer
Song>andong>y to the coast. This pattern is not that
unusual during the Fall season, but it is rare to be
coupled with a tropical/hybrid storm.
• Song>andong>y’s wind field was highly asymmetric – can
not use a simplified or deterministic wind field.
• Large surge forecast uncertainty with Song>andong>y’s
track. ong>Usingong> multi-model surge predictions can
improve accuracy of water levels.
• Global CMIP5 models suggest there may be a
period during the mid-21 st century with more
intense Fall-Spring storms.