Julia Shates Faculty mentor: Prof. Elizabeth Barnes July 31

Julia Shates
Faculty mentor: Prof. Elizabeth Barnes
July 31, 2014
Introduction
Different atmospheric oscillations lead to storm
development
Southern hemisphere infamous for storminess
-especially hazardous for maritime travelers
New research from Thompson & Woodworth (2013)
and Thompson & Barnes (2014) finds that storm
intensity pulses with 20-30 day cycle
Painting of ship during storm at sea
Newly found cycle: Baroclinic Annular Mode (BAM)
BAM = measure of storminess
EDDY KINETIC ENERGY = signal of the BAM
(A)
Eddy Kinetic Energy (EKE)
-upper atmosphere turbulence – storm development at the surface (where we
experience weather.
HIGH along path of
where storms develop
EKE (m2/s2) at 250mb
GFDL−CM3 GCM; CMIP5
1950−2004
250
−10
200
−20
Latitude
−30
150
−40
−50
100
−60
−70
50
−80
50
100
150
200
Longitude
250
300
350
0
Questions
1.  What is the smallest scale at which the BAM signal
appears?
2.  Do different parts of the Southern Hemisphere
contribute more to the BAM?
Methods
! 
GFDL Aquaplanet GCM
“AQUAPLANET”
Water-world with sunlight
Relatively even band
of high EKE
No continents/land, no chemistry
EKE (m2/s2)at 275mb
Aquaplanet GCM
0
200
−10
180
−20
160
Latitude
−30
140
−40
120
−50
100
−60
80
−70
60
−80
0
50
100
150
200
Longitude
250
300
350
40
Methods Cont’d
! 
GFDL cm3 GCM
Fully coupled global circulation model:
as close to the real world as possible
Sunlight + land + chemistry
EKE (m2/s2) at 250mb
GFDL−CM3 GCM; CMIP5
1950−2004
250
−10
200
−20
Latitude
−30
150
−40
−50
100
−60
−70
50
−80
50
100
150
200
Longitude
250
300
350
0
Methods Cont’d
How was the 20-30 oscillation even
found?
EKE (m2/s2)
GFDLtime
cm3 GCM
EKE
series
daily data
Spectral analysis:
250
Patterns in “noisy” data
How often/at what
frequency
do ofwe
see a
pression
for the time rate of change
the baroclinicity as a function of the heat fluxes
peak in energy?
∂〈b〉
〈b〉
net forcing of the baroclinicity by the wave fluxes
of heat is linearly proportional to the heat fluxes
themselves, and (ii) the damping of the baroclinicity due to both adiabatic and diabatic processes can be modeled as Newtonian cooling. The
resulting equation was subsequently linearized
about the climatological mean state to yield an ex0.045
¼ b〈v* T * 〉 −
ð3Þ
EKE
∂t (m2/s2)
t
GFDL cm3 GCM: 1950−2004
where the regression
coefficient b corresponds to the
°
0−360
lat: 20−60S
amplitude
of the&feedback
between the eddy fluxes
100
22 days
Power spectra of fields averaged 30-70 deg. S
B EKE 300
100
0.04
150
EKE power spectra
Spatial signatures of the BAM
A EKE 300
Power
200
80
60
40
2
0
2
0.03
m /s
−20
0.025
50
1950−2004
−40
−60
0.02
−80
0
0.05
−100
C V*T* 700 0.015
6
4
0
0
0
0.05
−2
−4
K m/s
2
0.005
0.15
Cycles/day
0.2
0.25
Figure
Thompson and
D V*T* from
850
Barnes (2014)
8
0.01
0.1
0.1
0.15
0.2
cycles per day
−6
0
−8
E Precipitation
0..4
This peak shows us:
pulse of EKE every 22 days
Normalized Power
normalized power
20
Normalized Power
0.035
0.05
0.1
0.15
Cycles/day
F Precipitation
ERA-Interim
0.2
0.25
0.25
Results
Aquaplanet GCM width
Max EKE & longitude
lat: 20−60
Max EKE (m2/s2)
1) Scale:
Aquaplanet Model
0.05
EKE
0.045 (m2/s2)
Aquaplanet GCM
°
Anchored at 0
lat: 20−60s
EKE power spectra
Different widths of longitude
0.05
31.25 days
Power spectra
of 360º;
peak
discussed in
Thompson &
Barnes 2014
0.045
0.04
normalized power max
0.04
0.035
0.035
0.03
normalized power
0.03
0.025
0.025
0.02
0.02
0
50
100
150
200
250
range: longitude
0.015
0.01
35−360° Width
0.005
0
0
0.05
0.1
0.15
cycles per day
0.2
0.25
300
350
Max EKE (m2/s2)
GFDL−cm3 GCM; CMIP5: 1950−2004
120° ranges
lat: 20−60S
Results cont’d
2)Geographic distribution of
EKE- fully coupled model
Max EKE at center longitude point
0.034
0.033
EKE power spectra
All 120º width
Different anchors in the Southern
Hemisphere
0.035
EKE0.032
(m2/s2)
GFDL−cm3 GCM; CMIP5: 1950−2004
°
120 ranges
lat: 20−60S
EKE (m2/s2) at 250mb
EKE (m2/s2)
at 250mb
GFDL−CM3
GCM;
CMIP5
GFDL−CM3
GCM;
0.031
1950−2004 CMIP5
1950−2004
max power
20.83 days
−10
0.03
−10
250
200
−20
−20
Latitude
−30
Latitude
normalized power
200
0.029
−30
0.025
0.02
150
−40
0.028
150
−40
−50
100
0.027
−50
−60
100
Indian Ocean
−60
0.026
−70
0.015
Pacific Ocean
50
100
150
Atlantic Ocean
200
250
300
center longitude
50
−70
−80
0.01
50
50
100
100
150
200
Longitude
150
250
200
300
250
300
Longitude
0.005
West to East
0−360° anchor longitude
0
350
50
−80
0
250
0.03
0.05
0.1
0.15
cycles per day
0.2
0.25
0
350
350
0
Conclusion/Summary
1)Scale
Aquaplanet model:
clear signal visible with 35º range
GFDLcm3 model:
signal visible with 120º range
2)
Geographic Distribution
GFDLcm3 model:
Different parts of Southern Hemisphere=different contributions to total signal
->results suggest Indian to W. Pacific Ocean= bigger contribution
Future Questions
!  Statistical Significance at peaks with smaller longitude ranges-
(statistical significance confirmed for 0-360º (lat 30-70) Thompson &
Woodworth and Thompson & Barnes)
EKE (m2/s2)
GFDL−cm3 GCM; CMIP5: 1950−2004
120° ranges
lat: 20−60S
0.035
~20
days
20.83
days
!  Comparison with Observations
->already in process
0.03
!  Frequency/period at peaks
normalized power
0.025
0.02
0.015
0.01
0.005
West to East
0−360° anchor longitude
0
0
0.05
0.1
0.15
cycles per day
0.2
Acknowledgements
Many thanks to Elizabeth Barnes, Marie McGraw, Brian Crow, Melissa Burt and fellow CMMAP interns
References
(A) 
Buttersworth, James E. The American Clipper Ship Flying Cloud, Scudding in a Gale of Wind off Cape Horn. 1854.
Oil on canvas. Bonhams. Web. <http://www.bonhams.com/auctions/21474/lot/132/>.
Thompson, David W. J., Elizabeth A. Barnes, 2014: Periodic Variability in the Large-Scale Southern Hemisphere
Atmospheric Circulation. Science. 343. 641-645.
Thompson, David W.J., Jonathan D. Woodworth, 2013: Barotropic and Baroclinic Annular Variability in the
Southern
Hemisphere. Journal of Atmospheric Science. 71.1480-1493.
GFDL cm3 GCM
Why I picked 120 range
120 degree
range
EKE (m2/s2)
cm3 GCM
EKEgfdl
spectra
GFDLcm3
Anchored at 0
lat: 20−60s
Different longitude widths
°
0.05
0.045
0.04
0.035
normalized power
0.03
0.025
0.02
0.015
0.01
30−360° Width
0.005
0
0
0.05
0.1
0.15
cycles per day
0.2
0.25
Additionally
Max power over fixed latitudes
change in max as function of width
Aquaplanet GCM
0.025
!  EHF & EKE showing max points
verifying relationship
normalized power max
0.02
!  GFDL cm3 GCM
3 ensemble runs
EKE (m2/s2)
GFDL−cm3 GCM; CMIP5
°
360 range; lat: 20−60S
bsmooth3,numchunk 500
0.015
0.025
1
2
3
0.02
EKE; latitude 20−70S; 20−33day cycle; 275mb
EHF; latitude 20−80S; 18.5−23.8day cycle; 850mb
0.01
0
50
normalized power
0.015
0.01
0.005
0
0
0.05
0.1
0.15
cycles per day
0.2
0.25
100
150
200
range: longitude
250
300
350

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