Transcript Validation of Storm Surge Models for the New York Bight and Long Island Regions and the Impact of Ensembles Tom Di Liberto Dr.

Validation of Storm Surge Models for the New York Bight
and Long Island Regions and the Impact of Ensembles
Tom Di Liberto
Dr. Brian A. Colle
Stony Brook University
Motivation
•
•
•
How well can a surge (ocean) model do
for landfalling hurricanes over the
Northeast U.S.?
What is the skill of the Stony Brook
Storm Surge system over the cool
season? How does it compare with other
models (NOAA and Stevens Institute)?
What are the strengths and current
limitations of ensemble surge modeling?
MM5/WRF Modeling of Gloria /
ADCIRC Modeling of Storm Surge
MM5 / WRF
ADCIRC
36 km
12 km
4 km
• NCAR-AFWA Bogus Method
• YSU PBL, GFS PBL, MY
PBL runs
– NARR initial condition
• 108 K nodes ( 70km to 5 m)
• Ensemble uses 5 MM5 / 3
WRF members
NARR Initial Conditions
Lin Microphysics
YSU PBL
Landfall occurs ~ 1 h
delayed ~30 miles east
of observed landfall
Gloria Tracks
PBL
PBL
PBL
NCAR-NCEP
Global
Reanalysis IC
Hurricane Gloria Wind Verification at JFK
45
YSU 10 m Winds
YSU 30 m Winds
40
GFS 30 m Winds
Wind Speed kts
Observed
35
30
25
20
15
10
5
12
8
4
28 th - 0
20
16
12
8
4
27 th - 0
20
16
12
8
4
26 th - 0
0
Hurricane Gloria Wind Verification at Ambrose Lighthouse
70
YSU 30m Wind
GFS 30m Wind
Observed
50
40
30
20
10
12
8
4
28 th - 0
20
16
12
8
4
27 th - 0
20
16
12
8
4
0
26 th - 0
Wind Speed kts
60
CREATE ANIMATION OF YSU
YSU PBL
10m 1.0x
What if GFS PBL scheme 1 h
shifted?
Observed Landfall
*
Model Landfall
1 h shift of track increases
peak water level by ~.20m
Using 30m wind increases
peak water level by ~.30m
Using different PBL (track)
increases peak water level
by ~.40m
Wave and Surface Stress Impact
SWAN wave model used
to calculate wave radiation
stress
Wave model takes winds
from atmospheric runs to
generate waves
• 5 MM5 / 3 WRF members
• MM5/WRF run at 12 km
resolution, once a day at 00z
and ADCIRC runs out 48 h.
• stormy.msrc.sunysb.edu
Real-time Modeling Systems Compared
• Stevens Institute
– Atmospheric Forcing – 12-km NAM
– Ocean Model – POMS
– http://hudson.dl.stevens-tech.edu/maritimeforecast/
• NOAA ET Surge
– Atmospheric Forcing – GFS
– http://www.weather.gov/mdl/etsurge/
• Stony Brook Storm Surge Model
– Atmospheric Forcing – MM5/WRF
– Ocean Model - ADCIRC Ocean Model
– http://stormy.msrc.sunysb.edu/
Real Time Ensemble
• 36 days during Nov. 2007 – March 2008 with Full
Ensemble
– Nov – 9 days
– Dec – 12 days
– Jan – 15 days
Stony Brook Storm Surge Model Atmospheric Ensemble Members
Members
Model
Microphysics PBL Scheme Radiation
Member #1 MM5
Simple Ice
MRF
Cloud Radiation
Member #2 MM5
Simple Ice
MY
CCM2
Member #3 MM5
Simple Ice
Blackadar
CCM2
Member #4 MM5
Reisner
MRF
Cloud Radiation
Member #5 MM5
Simple Ice
MY
CCM2
Member #6 WRF
Ferrier
YSU
RRTM
Member #7 WRF
Ferrier
YSU
RRTM
Member #8 WRF
WSM3
YSU
RRTM
Initial Condition
WRF-NMM
GFS
NOGAPS
GFS
Canadian Model
WRF-NMM
GFS model
NOGAPS
Cumulus
Grell
Betts Miller
Grell
Kain Fritsch
Kain Fritsch
Kain Fritsch
Grell
Betts Miller
Wave Impacts during Cool Season
• SBSS model member 9a
• Average daily errors from Nov
2007- March 2008
• Correlation Coefficient = -.4711
Stevens Institute
Stevens Institute
1 – GRMRF.NEUS.eta (9a)
2 – 221.YSU.KFE.FERR.RRTM
3 – BMMY-CCM2.NEUS.avn
4 – GFS.YSU.GRE.FERR.RRTM
5 – GRBLK-CCM2.NEUS.nogaps
6 – K2MRF-Reis.NEUS.avn
7 – K2MY-CCM2.NEUS.cmc
8 – NOG.YSU.BMJ.WSM3.RRTM
1 – GRMRF.NEUS.eta (9a)
2 – 221.YSU.KFE.FERR.RRTM
3 – BMMY-CCM2.NEUS.avn
4 – GFS.YSU.GRE.FERR.RRTM
5 – GRBLK-CCM2.NEUS.nogaps
6 – K2MRF-Reis.NEUS.avn
7 – K2MY-CCM2.NEUS.cmc
8 – NOG.YSU.BMJ.WSM3.RRTM
• Gloria:
Conclusions
- WRF-ADCIRC underestimated the surge even after adjusting winds to 30-m ASL.
-
A small change in the track related to a different PBL (GFS rather than
YSU) and a small timing adjustment (1-h) resulted in a better peak water level
forecast.
- There are also relatively large sensitivities to surface stress and
waves in the ocean model.
• Real-time Verification
– Stevens Institute Surge modeling system has smaller mean and root mean
square errors than NOAA ET and Stony Brook surge models. Negative
surge mean errors in the SSBS system may be related to the absence of wave
forcing and/or a low wind bias over the water.
– Stony Brook surge ensemble is under-dispersed and shares many
(negative) biases, even for members that have different wind biases.
Suggests the need for multi-model surge models in operations (not just
different atmospheric forcings) and surge bias corrections.
– Need a larger sample to obtain some probabilistic verification.