1 / 39

Atlantic Jet: Stability of jet core

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.

dirk
Download Presentation

Atlantic Jet: Stability of jet core

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Atlantic Jet:Stability of jet core

  2. Thermal winds between 930 and 430 hpa

  3. Look at cross sections where the baroclinicity is greatest – those positions are

  4. Velocity in Cross section-Northern Hemisphere

  5. Temperature in cross section-700hpa

  6. Modern Stability

  7. Modern Stability

  8. LGM Stability

  9. LGM Stability

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

  11. Mid Atlantic Jet • Also consider vorticity gradient

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

  13. Cross sections of zonal velocity at location of maximum velocity shear

  14. Mid atlantic modern stability- structure of eddy

  15. Mid atlantic modern stability- Growth by layer

  16. Mid atlantic LGM stability- Structure of Eddy

  17. Mid atlantic LGM stability- Growth by layer

  18. 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)

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

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

  21. 2d Atlantic jet -LGM • Define a domain over which the thermal wind between 900 hPa and 400 hPa is above a threshold value. LGM

  22. 2d Atlantic Jet - LGM • Transition between this 2d zonal velocity and the zonal mean zonal velocity, on a rectangular, singly periodic domain

  23. 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

  24. 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

  25. 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

  26. 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

  27. 2d Atlantic Jet - LGM • Eddies after 45 day integration

  28. 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

  29. 2d Atlantic Jet - LGM • Size of eddies by region – left half vs right half and middle half vs edge half

  30. 2d Atlantic Jet - LGM • Growth by region – Projection of tendency onto streamfunction

  31. 2d Atlantic jet - MODERN • Define a domain over which the thermal wind between 900 hPa and 400 hPa is above a threshold value. MODERN MODERN

  32. 2d Atlantic Jet- MODERN • Transition between this 2d zonal velocity and the zonal mean zonal velocity, on a rectangular, singly periodic domain

  33. 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

  34. 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

  35. 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

  36. 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

  37. 2d Atlantic Jet-MODERN • Eddies after 25 day integration- vertical tilt = 53 degrees

  38. 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?

  39. 2d Atlantic Jet - MODERN • The eddy size and growth by region oscillates in time Growth rate by region Eddy size by region

More Related