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

LGM Stability

LGM Stability

Mid Atlantic Jet Look at jet stability at location of greatest barotropic shear at 800 hpa

Mid Atlantic Jet Also consider vorticity gradient

Find location of max shear and vorticity gradient in LGM Minnimum vorticity gradient Maximum Velocity Shear

Cross sections of zonal velocity at location of maximum velocity shear

Mid atlantic modern stability- structure of eddy

Mid atlantic modern stability- Growth by layer

Mid atlantic LGM stability- Structure of Eddy

Mid atlantic LGM stability- Growth by layer

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)

Seeding the mid-atlantic Modern normal mode growth rates are Western Atlantic = 3.7 * 10 ^ -6 Mid Atlantic = 2.6 *10 ^ -6

Seeding the mid-atlantic LGM normal mode growth rates are Western Atlantic = 5.9 * 10 ^ -6 Mid Atlantic = 4.65 *10 ^ -6

2d Atlantic jet -LGM Define a domain over which the thermal wind between 900 hPa and 400 hPa is above a threshold value. LGM

2d Atlantic Jet - LGM Transition between this 2d zonal velocity and the zonal mean zonal velocity, on a rectangular, singly periodic domain

2d Atlantic Jet - LGM LOWER LEVEL 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

2d Atlantic Jet- LGM UPPER LEVEL 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

2d Atlantic Jet - LGM LOWER LEVEL 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

2d Atlantic Jet - LGM UPPER LEVEL 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

2d Atlantic Jet - LGM Eddies after 45 day integration

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

2d Atlantic Jet - LGM Size of eddies by region – left half vs right half and middle half vs edge half

2d Atlantic Jet - LGM Growth by region – Projection of tendency onto streamfunction

2d Atlantic jet - MODERN MODERN Define a domain over which the thermal wind between 900 hPa and 400 hPa is above a threshold value. MODERN MODERN

2d Atlantic Jet- MODERN Transition between this 2d zonal velocity and the zonal mean zonal velocity, on a rectangular, singly periodic domain

2d Atlantic Jet- MODERN LOWER LEVEL 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

2d Atlantic Jet- MODERN UPPER LEVEL 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

2d Atlantic Jet - MODERN LOWER LEVEL 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

2d Atlantic Jet- MODERN UPPER LEVEL 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

2d Atlantic Jet-MODERN Eddies after 25 day integration- vertical tilt = 53 degrees

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?

2d Atlantic Jet - MODERN The eddy size and growth by region oscillates in time Growth rate by region Eddy size by region