New York City Storm Surges: Climatology and An Analysis of the Wind and Cyclone Evolution

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New York City Storm Surges Climatology and An
Analysis of the Wind and Cyclone Evolution

• Dr. Brian A. Colle, Katherine Rojowsky, and F.
  Bounaiuto
• School of Marine and Atmospheric Sciences
• Stony Brook University, SUNY

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Lidar image of business district of Manhattan
showing elevation and seawall locations (arrows).
The imager is flying above the Hudson River
looking east. (Photo Courtesy NOAA/U.S/ Army
JPSD)
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3 September 1821 Only Major hurricane to hit NYC
directly (category 3)
NYC area tracks obtained by observations and
geological survey (Scileppi and Donnelly 2007)
The 1821 hurricane produced a storm surge of
13 feet (4 m) in only one hour at Battery Park.
Manhattan Island was completely flooded to Canal
Street
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Tropical Storm Tracks 1851-2005
Figure provided by J. I. Virmani, 2007
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December 1992 Nor-easter
NARR Analysis
ADCIRC model hindcast of water level ASL (m)
using MM5 winds and pressures at 18 UTC 12 Dec
(Colle et al. 2008)
(18Z 12 Dec 1992)

L
(6Z 13 Dec 1992)

L
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12-13 December 1992 Nor-easter
FDR Drive during the December 1992 noreaster
(Bloomfield, 1999)
Source Metro New York Hurricane Transportation
Study, 1995 Ref Bloomfield, J., M. Smith and N.
Thompson, 1999. Hot Nights in the City.
Environmental Defense Fund, New York.
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Motivational Questions

• What is the variability of minor and moderate
  storm surges and flooding events at NYC during
  the past 50 years?
• How will the number of moderate flooding events
  change as sea level rises during the next 50-100
  years?
• How does the wind speed and direction evolve
  around NYC for minor and moderate surge events?
• What are the cyclone tracks and position at
  maximum surge that favor storm surge events for
  the NYC area?

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Climatological Analysis of NYC Surges A minor and
moderate surge at the Battery that would result
in a coastal flood advisory and warning,
respectively, by the NWS during a high tide (mean
high water). Minor 0.60-1.00 m above
MHW Moderate gt1.00 m above MHW
(Gloria 85)
Donna (60)
(92 Nor-easter)
Maximum daily surge at the Battery, NYC (1959
-2007)
1960s
1970s
1980s
1990s
2000s
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Number of Minor and Moderate Surge Events
Minor Surge
Moderate Surge
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Monthly Minor Surge Events at the Battery, NY
59-07
Monthly Moderate Surge Events at the Battery, NY
59-07
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Minor Surge Events at the Battery, NY 59-07
5 yr running mean
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Monthly Minor Surge Events at the Battery, NY
59-07
Annual Moderate Surge Events at the Battery, NY
59-07
Annual Observed Moderate Flooding Events at the
Battery, NY 59-07
Surge tidal total water level (storm
tide) NWS threshold Mod. Flooding 2.44m above
Mean Low-Low Water (MLLW)
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Impact of Sea-Level Rise on NYC Flood Events IPCC
(2007) 12-50 cm over next 50-100 yrs)
After 12.5 cm Sea-Level Rise
Observed Moderate Flooding Events
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Impact of Sea-Level Rise on NYC Flood Events IPCC
(2007), 12-50 cm over next 50-100 yrs)
After 25 cm Sea-Level Rise
After 50 cm Sea-Level Rise
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Impact of Sea-Level Rise on Minor Flood
Events (rise 2.77 mm/yr at Battery--10-15 cm
over 50 yrs)
Observed Minor Flooding Events
After Sea-Level Rise Correction
NWS threshold 2.04 (minor flooding coastal
flood advisory), 2.44 (moderate flooding)
above Mean Low-Low Water (MLLW)
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Meteorological Analysis

• Datasets
• -- Hourly 10-m wind observations from Bennetts
  Field (1968-1971) and JFK airport (1973-2007).
• -- NCAR-NCEP global (2 degree) reanalysis
  (1959-1978) Regional reanalysis (1979-2006)
• Approach
• -- For 191 minor and 31 moderate events
  after 1968, quantified the average wind evolution
  at JFK and Bennetts Field from 48-h before time
  of maximum surge to 24-h afterwards.
• -- Manually tracked cyclones within reanalysis
  for surge events 0.8-1.0 and gt 1.0 (2mb closed
  contour for cyclone closest to NYC).

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Wind Direction Evolution at JFK/Bennetts
Speed Direction Frequency at Time of Maximum
Surge
Wind Direction -48/24h Surrounding Maximum Surge
Minor
Speed (m/s)
Minor
Moderate
Time of max surge

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Wind Speed Evolution at JFK
Wind Speed -48/24h Surrounding Maximum Surge
Distribution of Wind Speeds at Maximum Surge
Time of max surge

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Minor Surge Cyclone Tracks -48/12h
Position at Time of Max Surge
Cyclone Tracks
0.8-1.0 m events
0.6-1.0 m events

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Moderate Surge Cyclone Tracks -48/12h
Cyclone Tracks
Position at Time of Max Surge
1.0 m events
1.0 m events

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NCEP Reanalysis SLP Composite of 46 gt 1-m Surges
at Battery, NY
-36 h
-24 h
-24h
H
H
H
L
L
-12 h
0 h
H
H
L
L
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NCEP Reanalysis 500Z Composite of 46 gt 1-m Surges
at Battery, NY
-36 h
-24 h
-12 h
0 h
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Tropical Storm Surge Tracks (1959-2007)
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Conclusions

• Large inter-annual inter-decadal variability.
  Minor surge events more prevalent during the
  60s, 70s mid-90s. Only 1 moderate surface
  event since 2000 and no observed moderate
  flooding events since 1996.
• A 10-15 cm sea-level rise over last 50 years has
  increased the number of minor flood events (given
  coastal flood advisory threshold by NWS).
• Flooding (even for nor-easters) will increase
  dramatically as sea level rises 10-50 cm over the
  next 50-100 years.
• Moderate event mean wind speeds 25 greater at
  the time of maximum surge than minor events. Wind
  speeds in isolation not a good predictor of minor
  vs. mod surge.
• Diverse tracks for minor moderate, with
  moderate tending toward the coast (Miller Type A
  track).