atlantic jet: stability of jet core
DESCRIPTION
Atlantic Jet: Stability of jet core. Thermal winds between 930 and 430 hpa. Look at cross sections where the baroclinicity is greatest – those positions are. Velocity in Cross section- Northern Hemisphere. Temperature in cross section- 700hpa. Modern Stability. Modern Stability. - PowerPoint PPT PresentationTRANSCRIPT
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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 which can be determined by projection of tendency onto stream function or finite differencing of the standard deviation of perturbation time series (equivalent results)
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Seeding the mid-atlanticModern normal mode growth rates areWestern Atlantic = 3.7 * 10 ^ -6Mid Atlantic = 2.6 *10 ^ -6
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Seeding the mid-atlanticLGM normal mode growth rates areWestern 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 a
geometric 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 a
geometric 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 conversion
from 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 conversion
from 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 datalayer 1 fit slope = 3.4849e-006layer 3 datalayer 3 fit slope =3.4958e-006spatial 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)
ratio
n of
sta
ndar
d de
viat
ions
Layer 1 ratio of left to rightLayer 1ratio of middle to edgeLayer 3 ratio of left to rightLayer 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 a
geometric factor--- IS THERE SOMETHING ELSE HERE?
LOWER LEVEL
![Page 34: Atlantic Jet: Stability of jet core](https://reader033.vdocuments.site/reader033/viewer/2022061614/56813e5a550346895da8525e/html5/thumbnails/34.jpg)
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 a
geometric factor--- IS THERE SOMETHING ELSE HERE?
UPPER LEVEL
![Page 35: Atlantic Jet: Stability of jet core](https://reader033.vdocuments.site/reader033/viewer/2022061614/56813e5a550346895da8525e/html5/thumbnails/35.jpg)
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 conversion
from the sphere to the rectangle has a geometric factor
LOWER LEVEL
![Page 36: Atlantic Jet: Stability of jet core](https://reader033.vdocuments.site/reader033/viewer/2022061614/56813e5a550346895da8525e/html5/thumbnails/36.jpg)
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 conversion
from 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 datalayer 1 fit slope = 2.8619e-006layer 3 datalayer 3 fit slope =2.8497e-006spatial 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
Growth rate by region Eddy size by region
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)
ratio
n of
sta
ndar
d de
viat
ions
Layer 1 ratio of left to rightLayer 1ratio of middle to edgeLayer 3 ratio of left to rightLayer 3 ratio of middle to edge