atlantic jet
TRANSCRIPT
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Atlantic Jet:
Stability of jet core
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Thermal winds between 930 and
430 hpa
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Look at cross sections where the
baroclinicity is greatest those
positions are
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Velocity in Cross section-
Northern Hemisphere
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Temperature in cross section-
700hpa
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Modern Stability
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Modern Stability
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LGM Stability
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LGM Stability
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Mid Atlantic Jet Look at jet stability at location of greatest barotropic shear at 800 hpa
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Mid Atlantic Jet Also consider vorticity gradient
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Find location of max shear and
vorticity gradient in LGM
Minnimum vorticity gradient
Maximum Velocity Shear
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Cross sections of zonal velocity at
location of maximum velocity shear
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Mid atlantic modern stability-
structure of eddy
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Mid atlantic modern stability-
Growth by layer
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Mid atlantic LGM stability-
Structure of Eddy
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Mid atlantic LGM stability- Growth
by layer
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Seeding the mid-atlantic
Initialize the mid atlantic mean state jet with
normal modes from the Western Atlantic
Look at growth rates instantaneously whichcan be determined by projection of
tendency onto stream function or finite
differencing of the standard deviation ofperturbation time series (equivalent results)
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Seeding the mid-atlanticModern normal mode growth rates are
Western Atlantic = 3.7 * 10 ^ -6Mid Atlantic = 2.6 *10 ^ -6
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Seeding the mid-atlanticLGM normal mode growth rates are
Western Atlantic = 5.9 * 10 ^ -6Mid Atlantic = 4.65 *10 ^ -6
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2d Atlantic jet -LGM Define a domain over which the thermal wind between
900 hPa and 400 hPa is above a threshold value.
LGM
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2d Atlantic Jet - LGM Transition between this 2d zonal velocity and the zonal mean zonal
velocity, on a rectangular, singly periodic domain
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2d Atlantic Jet - LGM The jet has horizontal divergence which is nearly compensated for by vertical
divergence
Match is not exact because the conversion from the sphere to the rectangle has ageometric factor--- IS THERE SOMETHING ELSE HERE?
LOWER LEVEL
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2d Atlantic Jet- LGM The jet has horizontal divergence which is nearly compensated for by vertical
divergence
Match is not exact because the conversion from the sphere to the rectangle has ageometric factor--- IS THERE SOMETHING ELSE HERE?
UPPER LEVEL
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2d Atlantic Jet - LGM Find the meridional velocity which makes the jet non-divergent and has no flow
through top and bottom boundary
-Doing both is impossible because there is vertical divergence and the conversionfrom the sphere to the rectangle has a geometric factor
LOWER LEVEL
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2d Atlantic Jet - LGM Find the meridional velocity which makes the jet non-divergent and has no flow
through top and bottom boundary
-Doing both is impossible because there is vertical divergence and the conversionfrom the sphere to the rectangle has a geometric factor
UPPER LEVEL
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2d Atlantic Jet - LGM Eddies after 45 day integration
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2d Atlantic Jet - LGM Eddy growth in upper layer- growth rate 3.5 *10^-6 Smaller than zonally invariant
case
E fold in 3.3 days
0 0.5 1 1.5 2 2.5 3
x 106
2
4
6
8
10
12
14
layer 1 data
layer 1 fit s lope = 3.4849e-006layer 3 data
layer 3 fit slope =3.4958e-006
spatial growth == 3.5134e-006+3.537e-006i
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2d Atlantic Jet - LGM Size of eddies by region left half vs right half and middle half vs edge half
0 0.5 1 1.5 2 2.5 3
x 106
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5Ratio of eddy activity in different parts of the domain as a function of time
time (hours)
ration
ofstandard
deviations
Layer 1 ratio of left to right
Layer 1ratio of middle to edge
Layer 3 ratio of left to right
Layer 3 ratio of middle to edge
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2d Atlantic Jet - LGM
Growth by region Projection of tendency onto streamfunction
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2d Atlantic jet - MODERN Define a domain over which the thermal wind between
900 hPa and 400 hPa is above a threshold value.
MODERNMODERN
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2d Atlantic Jet- MODERN Transition between this 2d zonal velocity and the zonal mean zonal
velocity, on a rectangular, singly periodic domain
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2d Atlantic Jet- MODERN The jet has horizontal divergence which is nearly compensated for by vertical
divergence
Match is not exact because the conversion from the sphere to the rectangle has ageometric factor--- IS THERE SOMETHING ELSE HERE?
LOWER LEVEL
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2d Atlantic Jet- MODERN The jet has horizontal divergence which is nearly compensated for by vertical
divergence
Match is not exact because the conversion from the sphere to the rectangle has ageometric factor--- IS THERE SOMETHING ELSE HERE?
UPPER LEVEL
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2d Atlantic Jet - MODERN Find the meridional velocity which makes the jet non-divergent and has no flow
through top and bottom boundary
-Doing both is impossible because there is vertical divergence and the conversionfrom the sphere to the rectangle has a geometric factor
LOWER LEVEL
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2d Atlantic Jet- MODERN Find the meridional velocity which makes the jet non-divergent and has no flow
through top and bottom boundary
-Doing both is impossible because there is vertical divergence and the conversionfrom the sphere to the rectangle has a geometric factor
UPPER LEVEL
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2d Atlantic Jet-MODERN Eddies after 25 day integration- vertical tilt = 53 degrees
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2d Atlantic Jet - MODERN Eddy growth in upper layer- growth rate 2.8 *10^-6 Smaller than zonally invariant cases
E fold in 4 days-
_-Pulses between upper and lower level- NUMERICAL instability?
0 1 2 3 4 5 6
x 106
0
2
4
6
8
10
12
14
16
18
layer 1 data
layer 1 fit slope = 2.8619e-006
layer 3 data
layer 3 fit slope =2.8497e-006
spatial growth == 2.3347e-006+2.7205e-006i
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2d Atlantic Jet - MODERN The eddy size and growth by region oscillates in time
G h b i Edd i b i
0 1 2 3 4 5 6
x 106
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2Ratio of eddy activity in different parts of the domain as a function of time
time (hours)
ration
ofstandard
deviations
Layer 1 ratio of left to right
Layer 1ratio of middle to edge
Layer 3 ratio of left to right
Layer 3 ratio of middle to edge