Effects of Global Warming, El Nino and other Climate Variations on Typhoon Activity in Asia
Johnny ChanGuy Carpenter Asia-Pacific Climate Impact Centre
School of Energy and Environment
City University of Hong Kong
1Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Outline
Crash course on global warming, El Niño and the Pacific Decadal Oscillation
Crash course on typhoons
Possible effects on typhoon activity
Summary
2Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Global warming – current temperatures
3Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Global warming – future projections
4Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Global warming – temperatures in the late 21st century
5Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Global warming – rainfall in the late 21st century
WINTER
SUMMER
6Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño/Southern Oscillation (ENSO)
7Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño/Southern Oscillation (ENSO)
8Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño/Southern Oscillation (ENSO)
NINO1+2NINO3NINO4 NINO3.4
9Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño/Southern Oscillation (ENSO)
10Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño Modoki
11Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño – Southern Oscillation
12Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño/Southern Oscillation (ENSO)
13Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Pacific Decadal Oscillation
warm phase cold phase
14Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Pacific Decadal Oscillation – PDO index
warm warmcold cold cold
15Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Tropical Cyclones – Structure
16Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
1.sea-surface temperature > 26.5oC - to provide
enough moisture and thermal buoyancy for deep
convection to occur
2.conditionally unstable atmosphere - to allow
moist air to rise through a deep layer of the
atmosphere
3.moist lower to mid troposphere - so that the
condensed water will not evaporate and will
continue its ascent
Tropical Cyclone formation: Thermodynamic Conditions
17Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
May-Oct
Nov-Apr
Tropical Cyclone formation: Ocean surface temperature
18Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
1. strong anticlockwise rotation near the
ocean surface and clockwise rotation in the
higher atmosphere - to provide the
necessary rotation in the low levels and
allow outflow in the upper levels
2. small vertical wind shear near the centre of
the disturbance - so that the convection
will not be sheared off
Tropical Cyclone formation: Dynamic Conditions
19Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Tropical Cyclone formation: East-west Winds and Shear
flow near
ocean surface
flow in the
upper
atmosphere
20Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Annual Number of TCs and intense TCs in WNPAnnual number of TSs and Cat45 TCs over the WNP
15
20
25
30
35
40
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
0
2
4
6
8
10
12
14
TS
10-yr filtered TS
Cat45
10-yr filtered Cat45
21Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
ACE vs. May-Nov SSTA (5-30oN, 120-180oE)
-1.5
-1
-0.5
0
0.5
1
1.5
1964 1969 1974 1979 1984 1989 1994 1999
ACE
SSTA
correlation = 0.23
22Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
ACE vs. VORT, SHEAR and MSE
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
ACE
VORT EOF1
SHEAR EOF1
MSE EOF2
0.580.72 0.67
23Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Variations of Landfall in Each Area at Various Oscillation PeriodsSTC
-3
-2
-1
0
1
2
3
4
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Standa
rdized
anoma
lies
-1.5
-1
-0.5
0
0.5
1
1.5
2
Standardized anomalies
original
2-8 yr
8-16 yr
16-32 yr
sta
nd
ard
ize
d a
no
ma
lie
ss
tan
da
rdiz
ed
an
om
alie
s
MTC
-3
-2
-1
0
1
2
3
4
1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
Year
Stand
ardize
d ano
malies
-1.5
-1
-0.5
0
0.5
1
1.5
2
Standardized anomalies
original
2-8 yr
8-16 yr
16-32 yr
sta
nd
ard
ize
d a
no
ma
lies
sta
nd
ard
ize
d a
no
ma
lies
sta
nd
ard
ize
d a
no
ma
lie
ss
tan
da
rdiz
ed
an
om
ali
es
South China, Philippines and
Vietnam
East China
Japan/Korea
24Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño effects on tropical cyclone activity
Year before
El Niño
El Niño Year
Year after
El Niño
25Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
La Niña effects on tropical cyclone activity
Year before
La Niña
La Niña Year
Year after
La Niña
26Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño effects on tropical cyclone activity
27Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño effects on tropical cyclone activity
28Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
July-Dec Mean Life Span (Days)El Niño effects on tropical cyclone activity
29Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño effects on tropical cyclone intensityIntensity vs. Nino3.4 SST
30Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
El Niño effects on tropical cyclone intensityTyphoon Days vs. Nino3.4 SST
31Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
PDO effects on tropical cyclone intensity
32Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Summary
Global warming does not cause changes in
typhoon activity (frequency of occurrence,
intensity, landfall locations) in Asia.
El Niño has a significant effect on typhoon
activity through modifications of the
atmospheric flow patterns that
subsequently lead to changes in location
of formation, and hence frequency of
occurrence, intensity and locations of
landfall.
33Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Summary
Effects of the Pacific Decadal Oscillation
apparently either collaborates with or
modifies those of El Niño on a decadal or
longer time scales. However, more
research is necessary.
34Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Conclusion and take-home message
In assessing typhoon risk on an annual
time scale, the most important factor is El
Niño. Better predictions of typhoon activity
come from better predictions of the
occurrence of El Niño.
On longer time scales such as decades,
other climate oscillations such as the
Pacific Decadal Oscillation need to be
considered. More research is necessary.
35Guy Carpenter Asia-Pacific Climate Impact Centre, School of Energy and Environment, City University of Hong Kong
Conclusion and take-home message
The effect of global warming on typhoon
activity is not obvious unless it can be
shown that global warming will lead to
changes in the frequency of occurrence of
El Niño or other climate oscillations. The
simple idea of an increase in ocean
temperature due to global warming will
enhance typhoon activity is incorrect.
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