• Advection of Solenoids

  • a way of estimating the advection by examining the size of areas created where contours of 2 fields intersect.
  • a "solenoid" is Carlson's name for such an area
  • advection is inversely proportional to the solenoid area: large advection for small solenoids
  • alternatively, you could count how many solenoids fit within a given area (the larger the number of solenoids, the greater the advection)
  • if the contours of the 2 fields are parallel: essentially no advection.
  • example shown: geopotential height (to provide the advecting winds) and vorticity contours.
  • could use geopotential height and thickness contours to estimate temperature advection.
  • Some caveats:
    • method breaks down where either field has a weak gradient
    • method breaks down where curvature is strong: gradient wind would differ from geostrophic wind used.
    • method breaks down at the surface: actual wind may differ significantly from geostrophic.
    • only estimates horizontal advection. Other processes can strongly affect movement of vorticity.

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