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Three Lectures on Tropical Cyclones
Three Lectures on Tropical Cyclones
Kerry EmanuelMassachusetts Institute of Technology
Spring School on Fluid Mechanics of Environmental HazardsSpring School on Fluid Mechanics of Environmental Hazards
Lecture 1:Lecture 1:Observed CharacteristicsObserved Characteristics
What is a Hurricane?What is a Hurricane?
Formal definition: A tropical cyclone with 1-min average winds at 10 m altitude in excess of 32 m/s (64 knots or 74 MPH) occurring over the North Atlantic or eastern North Pacific
The word The word HurricaneHurricane is derived from the is derived from the Mayan word Mayan word HuracanHuracan and the Taino and and the Taino and
Carib word Carib word HunrakenHunraken, a terrible God of Evil, , a terrible God of Evil, and brought to the West by Spanish and brought to the West by Spanish
explorersexplorers
Illustration from Travels in the West Indies, Theodor DeBry
Early historical encounters: The Mongol invasions of Early historical encounters: The Mongol invasions of Japan in 1274 and 1281Japan in 1274 and 1281
Scene from the 13th century Mongol invasion scrolls, based on a narrative written by the Japanese warrior Takezaki Suenaga.
The View from Space
Airborne Radar: Horizontal Map
360 km(220 mi)
120 km
20 km(12 mi)
(75 mi)
Airborne Radar: Vertical Slice
Azimuthal wind
Temperature perturbation at constant altitude
Radial windRadial wind
Vertical velocityVertical velocity
Angular Angular momentum momentum per unit massper unit mass
2sinM rV r
Tracks of all tropical cyclones, 1985-2005Tracks of all tropical cyclones, 1985-2005
Source: Wikipedia
Annual Cycle of Tropical CyclonesAnnual Cycle of Tropical Cyclones
1950 1960 1970 1980 1990 20000
20
40
60
80
100
120
Year
An
nu
al G
lob
al S
torm
Co
un
t
Global Tropical Cyclones, 1949-2006
1950 1960 1970 1980 1990 20000
5
10
15
20
25
30
Year
An
nu
al S
torm
Co
un
t
North Atlantic Tropical Cyclones, 1949-2006
Better Intensity Metric:Better Intensity Metric:
The Power Dissipation IndexThe Power Dissipation Index
0
3maxPDI V dt
A measure of the total frictional dissipation of A measure of the total frictional dissipation of kinetic energy in the hurricane boundary layer kinetic energy in the hurricane boundary layer
over the lifetime of the stormover the lifetime of the storm
Atlantic Storm Maximum Power DissipationAtlantic Storm Maximum Power Dissipation(Smoothed with a 1-3-4-3-1 filter)
Pow
er D
issi
patio
n In
dex
(PD
I)
Years included: 1870-2006
Data Source: NOAA/TPC
Atlantic Sea Surface Temperatures and Atlantic Sea Surface Temperatures and Storm Max Power DissiaptionStorm Max Power Dissiaption
(Smoothed with a 1-3-4-3-1 filter)
Scal
ed T
empe
ratu
re
Pow
er D
issi
patio
n In
dex
(PD
I)
Years included: 1870-2006
Data Sources: NOAA/TPC, UKMO/HADSST1
Socio-Economic Socio-Economic Consequences of HurricanesConsequences of Hurricanes
Windstorms Account for Bulk of Windstorms Account for Bulk of Insured Losses WorldwideInsured Losses Worldwide
Source: Roger Pielke, Jr.
Total U.S. Hurricane Damage by Decade, in 10Total U.S. Hurricane Damage by Decade, in 101010 2004 U.S. Dollars2004 U.S. Dollars
Population of Florida, 1790-2004
Source: Roger Pielke, Jr.
Total Adjusted Damage by Decade, in 1010 2004 U.S. Dollars
Total Number of Landfall Events, by Category, 1870-2004
U.S. Hurricane Damage, 1900-2004,Adjusted for Inflation, Wealth, and Population
Infamous Tropical CyclonesInfamous Tropical Cyclones
Galveston, 1900Galveston, 1900
East Pakistan, 1970East Pakistan, 1970
Hurricane Katrina, 2005Hurricane Katrina, 2005
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