Developments in Seasonal Atlantic Basin Tropical Cyclone Prediction Phil Klotzbach
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Transcript of Developments in Seasonal Atlantic Basin Tropical Cyclone Prediction Phil Klotzbach
Developments in Seasonal Atlantic Basin Tropical Cyclone Prediction
Phil Klotzbach
Department of Atmospheric Science
Colorado State University
Ph. D. Defense
July 9, 2007
Acknowledgments
Mentor – Dr. Gray
Ph. D. Advisor – Dr. Schubert
Ph. D. Committee Members – Drs. Mielke and Pielke
CSU Student Colleagues – Eric Blake, Matt Eastin, Brian McNoldy, Stacey Seseske, Wes Terwey, Jonathan Vigh
Friends and Family – Especially my parents for providing me with an outstanding home education
National Science Foundation and Lexington Insurance Company
Outline Introduction
Data
Atlantic Basin Multi-Decadal Variability
Seasonal Forecast Developments
2007 Hurricane Forecast
United States Landfalling Hurricane Probability Webpage
Hurricanes and Global Warming
Introduction
The globe’s atmosphere and oceans function as one unit.
Current circulation features have considerable precursor information
regarding the coming month’s or coming season’s amount of
hurricane activity.
OUTGOING LONGWAVE RADIATION
ABSORBED SOLAR RADIATION
LATENT HEAT FLUX
NET ENERGY BALANCE
TEMPERATURE
OCEAN HEAT FLUX
SUBSURFACE HEAT STORAGE
SENSIBLE HEAT AND POTENTIAL ENERGY FLUX
THERMAL INERTIA
Flow diagram for climate modeling, showing feedback loops. From Robock (1985).
Arago’s Admonition:
“Never, no matter what may be the progress
of science, will honest scientific men who
have regard for their reputations venture
to predict the weather.”
So easy a caveman could do it.
Data
• NCEP/NCAR Reanalysis – globally gridded (2.5° x 2.5°) dataset for many surface and upper-level features from 1948-present
• National Hurricane Center “best track” dataset – best estimates of six-hourly location and intensity of tropical cyclones
1 2
3
H
H
Courtesy of John Marshall (MIT)
1860 1900 1940 1980 2020
THC - Strong
(Goldenberg et al. 2001)
Top 20 AMO Years – Bottom 20 AMO Years (1878-2006) - SLP
AMO Index
1.2 2.6 1.5 3.9Major Hurricanes per Year
STRONG THC WEAK THC
gyre - gyre +
+
+
+ –
–
–
SLPA – SLPA +
13
26
10
40
1900-25 1926-69 1970-94 1995-06
Annual Number of 6 Hour Periods for Cat. 3-4-5 Hurricanes in the Atlantic
Date8
Dec.3
Apr.31
May3
Aug.4
Sep. 2
Oct.
Seasonal
ForecastX X X X
Monthly Forecast
X X X
New Forecast Development Methodology
• Use predictors using surface data from the two months prior to the forecast issue date
• Hindcast Net Tropical Cyclone activity metric only
• Develop forecast on data from 1950-1989
• Test forecast on “independent” data from 1990-2004
• New forecast schemes must show comparable skill in both time periods
EQ.
Oct-Nov SLP3
`
2
1
New December Forecast Predictors
Oct-Nov SST
Oct-Nov SLP
Early December Observed versus Hindcast NTC (1950-1989)
0
50
100
150
200
250
1950 1955 1960 1965 1970 1975 1980 1985
NT
C
Observed NTC
Predicted NTC
r2 = 0.51
Developmental
Early December Observed versus "Forecast" NTC (1990-2004)
0
50
100
150
200
250
1990 1992 1994 1996 1998 2000 2002 2004
NT
C
Observed NTC
Predicted NTCr2 = 0.49
Applied
EQ.
Feb-Mar SST
3`
2
1
New April Forecast Predictors
Feb-Mar SLP
Feb-Mar SST
Early April Observed versus Hindcast NTC (1950-1989)
0
50
100
150
200
250
1950 1955 1960 1965 1970 1975 1980 1985
NT
C
Observed NTC
Predicted NTCr2 = 0.53
Developmental
Early April Observed versus "Forecast" NTC (1990-2004)
0
50
100
150
200
250
1990 1992 1994 1996 1998 2000 2002 2004
NT
C
Observed NTC
Predicted NTCr2 = 0.66
Applied
EQ.
Predicted July-Nov AMM
Index2
1
New June Forecast Predictors
April-May SST
3`
April-May SST
Early June Observed versus Hindcast NTC (1950-1989)
0
50
100
150
200
250
1950 1955 1960 1965 1970 1975 1980 1985
NT
C
Hindcast NTC
Observed NTCr2 = 0.42
Early June Observed versus Hindcast NTC (1950-1989)
0
50
100
150
200
250
1950 1955 1960 1965 1970 1975 1980 1985
NT
C
Predicted NTC
Observed NTCr2 = 0.42
Developmental
Early June Observed versus "Forecast" NTC (1990-2004)
0
50
100
150
200
250
1990 1992 1994 1996 1998 2000 2002 2004
NT
C
Forecast NTC
Observed NTCr2 = 0.54
Early June Observed versus "Forecast" NTC (1990-2004)
0
50
100
150
200
250
1990 1992 1994 1996 1998 2000 2002 2004
NT
C
Predicted NTC
Observed NTCr2 = 0.54
Applied
EQ.
12
New August Seasonal Forecast Predictors
June – July SST
3
June – July SST
June – July SLP
Pre 1-August NSD S of 23.5°N,
E of 75°W
4
August Statistical Scheme – Hindcast Skill for NTC (1900-1948)
Observations Hindcasts
Observations Hindcasts
August Statistical Scheme – Hindcast Skill for NTC (1949-2005)
NS NSD H HD MH MHD NTC
Top 10 9.2 57.9 5.2 26.5 2.7 7.5 113.0
Bottom 10 4.3 24.5 2.4 8.2 0.7 1.8 39.2
Ratio (1900-1948)
Ratio (1949-2005)
2.1
2.1
2.4
2.6
2.2
2.5
3.2
3.7
3.9
4.9
4.2
7.3
2.9
3.4
Top 10 – Bottom 10 Atlantic Basin TC Ratios for 1900-1948 Period Using Forecast Equations Developed on 1949-1989
16 Landfalls
3 Landfalls
December April June August
Top 10 7 6 7 6
Bottom 10 2 2 2 2
Ratio 3.50 3.00 3.50 3.00
Top 10 versus Bottom 10 Florida Peninsula and East Coast Major Hurricane Landfalls based on NTC Hindcasts (1949-2005)
Skill of Seasonal Forecasts
Skill of Seasonal Forecasts
Correlation of CSU Forecasts of NTC with Observations
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
December April June August
Skill of Cane and Zebiak Forecast Model for Nino 3 SST
Predicted versus Observed Named Storms (1984-2006) - Issued on 1 August
0
5
10
15
20
25
1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006
Po
st-1
Au
gu
st N
amed
Sto
rms
Predicted NS
Observed NS
r2 = 0.53
2007 Hurricane Predictions2007 Hurricane Predictions
Forecast ParameterStatistical Forecast
Analog Forecast
31 May 2007 Forecast
1950-2000 Climatology
Named Storms (NS) 15.7 12.7 17 9.6
Named Storm Days (NSD) 80.5 71.2 85 49.1
Hurricanes (H) 9.7 7.5 9 5.9
Hurricane Days (HD) 40.2 38.9 40 24.5
Major Hurricanes (MH) 3.7 3.7 5 2.3
Major Hurricane Days (MHD) 8.2 11.4 11 5.0
Accumulated Cyclone Energy (ACE)
158 150 170 96
Net Tropical Cyclone Activity (NTC)
164 158 185 100
2007 FORECAST AS OF 31 MAY 2007
PROBABILITIES FOR AT LEAST ONE MAJOR (CATEGORY 3-4-5) HURRICANE
LANDFALL ON EACH OF THE FOLLOWING COASTAL AREAS FOR 2007
1) Entire U.S. coastline – 74% (average for last century is 52%)
2) U.S. East Coast including Peninsula Florida - 50% (average for last century is 31%)
3) Gulf Coast from the Florida Panhandle westward to Brownsville - 49% (average for last century is 30%)
4) Expected above-average major hurricane landfall risk in the Caribbean
New Landfalling Hurricane Web Application
Currently Available at the following URL:
In partnership with the GeoGraphics Laboratory – Bridgewater State College,
Bridgewater MA
http://www.e-transit.org/hurricane
Areas for which Landfall Probabilities are Issued
U.S. 1
Sub – U.S. 2
Regions 11
Sub – Regions 55
Counties 205
REGION 2 - TEXAS & LOUISIANA
V
AJ
C
C
C
LH
J
O
(a)(c)(b)
Future Work
Monthly Probabilities
User-Selected Probabilities (Daily, Weekly Periods)
Potential Damage
Open AtlanticOcean Differences
1933 Hurricane Season
2005 Hurricane Season
Courtesy of
Chris Landsea (2006)
Figure 4 – From Webster et al. (2005)
Basin 1986-1995 1996-2005 Ratio (1996-2005 / 1986-1995)
North Atlantic 10 25 250%
Northeast Pacific 37 23 62%
N. Atl. + NE Pac. 47 48 102%
Northwest Pacific 75 76 101%
North Indian 3 4 133%
South Indian 26 36 138%
South Pacific 13 16 123%
Northern Hemisphere 125 128 102%
Southern Hemisphere 39 52 133%
Global 164 180 110%
Category 4-5 Hurricanes by Ten-Year Periods
Basin Correlation with ACE Correlation with Cat. 4-5 Hurricanes
North Atlantic 0.57 0.39
Northeast Pacific 0.58 0.59
Northwest Pacific -0.28 -0.11
North Indian -0.07 -0.29
South Indian -0.32 -0.18
South Pacific -0.38 -0.20
Correlation between Boreal Summer Basin-wide Sea Surface Temperatures and Tropical Cyclone Activity
(1986-2005)
y = -9.85x + 928.93
0
200
400
600
800
1000
1200
1400
1990 1993 1996 1999 2002 2005
0.10
0.15
0.20
0.25
0.30
0.35
0.40
Tro
pic
al S
ST
An
om
aly
(°C
)Global ACE
SST
Klotzbach (2006)
Kossin et al. (2007)
ATLANTIC
THC
STRONG
ATLANTIC
THC
WEAK
GLOBE COOLING
GLOBE WARMING
CAT 3-4-5 TRACKS
CAT 3-4-5 TRACKS
PENINSULA FLORIDA LANDFALLING MAJOR HURRICANES
1925-1965 41 Years
1966-2006 41 Years
2050
Background 280 ppm
310 ppm
365 ppm
39
La
nd
falls
22
La
nd
falls
0.95 year
0.54 year
CO 2
zero
Conclusions
• An active hurricane season is predicted in 2007
• The recent increase in Atlantic basin hurricane activity is largely driven by natural multi-decadal variability
Questions???