High Resolution WRF and ADCIRC
Simulations of Hurricane Gloria for the
New York City Metropolitan Region
Tom DiLiberto
Dr. Brian A. Colle
Stony Brook University
United States Coast Guard 1985
Flood areas
for hurricane:
CAT 1
CAT 2
CAT 3
CAT 4
NYC area tracks obtained by
observations and geological survey
(Scileppi and Donnelly 2007)
Hurricane Flooding for NYC (Metro NY
Hurricane Transportation Study 1995)
Lidar image of business district of Manhattan showing seawall locations and
elevation (arrows). The imager is flying above the Hudson River looking east.
Motivational Questions
• How vulnerable is NYC to a landfalling
category 1 hurricane over central Long Island
(Gloria 1985)?
• How well can a coupled atmospheric (WRF)
and ocean (ADCIRC) modeling system
predict the storm surge for Gloria?
• How sensitive are the simulated water levels
to relatively small changes in the track and
timing of hurricanes?
Advanced Circulation Ocean Model
(ADCIRC) Grid (~108 K nodes)
•Run in
barotropic
mode (1-layer
in vertical)
• Use hourly
MM5/WRF
winds and
surface
pressures to
force model
• Tidal forcing
at boundaries
• No wave
forcing (yet)
Detail of gridding in lower Manhattan up to +8 m contour
12-km MM5 Forecast 1200 UTC 11
December 1992
ADCIRC Water-level and Flooding
meters
Colle, B. A., F. Buonaiuto, M. J. Bowman, R.
E. Wilson, et al., 2008: Simulations of past
cyclone events to explore New York City’s
vulnerability to coastal flooding and storm
surge model capabilities , Bull. Amer. Meteor.
Soc.
48-h WRF Hindcast of Hurricane Gloria
36 km
12 km
Steady
4 km
4 km
Moving
• Insert Cyclone Using NCARAFWA Method:
– Davis and Low-Nam (2001)
– Specify Radius of Maximum Wind
Maximum Wind Speed m/s, Radius of
storm, and Wind profile
8PM 25 Sept
– 8 PM 27
Sept 1985
12-km WRF (GFS-PBL) Cloud Top
Temperatures (°C)
*
*
22z Sept. 26th
Hurricane Gloria Central Pressure
990
Observed Central Pressure
GFS-PBL Moving 4km
Pressure
980
970
GFS-PBL Steady 4km
12km
GFS-PBL 12km
960
950
Moving 4km
940
Observed
930
26 00z
2606z
2609z
2612z
2615z
2618z
2621z
27 - 2700z 03z
2706z
2709z
2712z
2715z
2718z
28 00z
2806z
06z Sept 26th – 12z Sept 28th
4-km WRF: surface reflectivity (rain intensity)
and 10-m winds (full barb = 10 kts)
Floyd - 925mb Temp and Wind ; 500mb
Height and Wind at 21z Sept. 16th 1999
Central Pressure - 977 mb
L
Floyd run from Colle MWR Dec 2003
Gloria - 925mb Temp and Wind ; 500mb
Height and Wind at 15z Sept. 27th 1985
Central Pressure - 960 mb
L
Floyd vs Gloria Precip Comparison
Floyd track
Gloria
Gloria – Storm Total Precip - mm
1
2 3 4 5 6 7 8 9 10 11 12 inches
Floyd – MM5 Storm Total Precip
Observed Precipitation (inches)
Gloria (1985)
Floyd
Radar Comparisons Between Observed and Modeled around 06z Sept 27th
06z Sept 27th
538z Sept 27th
L
Central Pressure - 943 mb Central Pressure - 950 mb
Moving 4km
GFS-PBL
Reflectivity at 2.7-km with 2.7-km winds
(full barb = 5 m/s , flag = 25 m/s)
12-km WRF
Central Pressure - 942 mb
Franklin, Lord and Marks Jr. (MWR May, 1988)
Flight Level Winds (full barb = 5 m/s , flag = 25 m/s)
Reflectivity sweep taken at 2.7 km, 21-38dbz = gray scale
4-km WRF Tracks for Gloria
CTL
OBS
1500 UTC
WRF Central Pressure (hPa) for Gloria (1985)
Surface Latent Heat Fluxes (W m-2) for MYJ and YSU PBL
1800 UTC 26 September 1985
MYJ-PBL
L 946
YSU-PBL
L 955
The exchange coefficient of moisture in the MYJ scheme increases linearly with
wind speed at a rate four times larger than the YSU (Hill and Lackmann (2009).
NOAA P-3 Aircraft Obs vs WRF
Observed Winds at 1500-m
CTL Moving 4-km - Winds at 1500-m
x Ambrose
1300 UTC
1300 UTC
Knots
Ambrose Tower 30-m Winds
WRF/ADCIRC Hurricane Gloria Storm Surge
GFS PBL 10m Winds
Moving 4-km Run
The Battery, NYC
06z Sept. 27th – 06z Sept 28th
Storm Surge at Battery, NY
WRF CTL
OBS
GFS PBL 4 km
CTL 10m Winds
15z Sept 27th
L
962 hPa
YSU PBL 4 km
10m Winds
15z Sept 27th
L
954 hPa
Landfall Timing Impact on Water Levels
at High Tide
-1 h
CTL
Flooding at Battery Relative to MLLW
+1h
Gloria Water Level (MSL) if Landfall at High Tide
SWAN Wave Model Forced by WRF Surface Wind Stress
X Battery, NYC
Wave
height (m)
Conclusions
• Current generation of atmospheric and ocean
models can realistically simulate hurricanes and
storm surge in the NYC area.
• However, even a relatively small change in track and
timing can impact the water level forecast
significantly – Need to use ensemble of model
forecasts.
• Significant flooding would have occurred in the NYC
area if Gloria made landfall ~4 h earlier during a high
tide.
• Unlike Floyd (1999), Gloria (1985) did not result in
significant inland freshwater flooding since the
vortex did not merge with the approaching mid-level
trough (weak extratropical transition).
Hurricane
Gloria
Initialization
Used NCAR-AFWA Bogus Scheme described by Davis and Low-Nam (2001)
SLP and Surface Temperatures/Winds plotted
No Bogus
Bogus
Initialized at 00z 26th Sept.