This experiment demonstrates the western intensification of ocean gyre by using the analog of topographic vortex stretching an the Beta effect.  We do spin up/down  in a cylindrical basin that is tilted so that the top (North) end is shallow.  Visualization is by thymol blue dye.

The demonstration uses the Rotating Table Facility, and a small cylindrical tank equipped with thymol blue dye wires.  The setup is shown in schematic below.


Image of the cylinder set on-axis.  Lighting is from above and to the side.  Needs white background.

Closeup of the cell.  Tilt the end correlated with the top of the TV camera view up using a 1cm aluminum bar.  This make up North in the camera's view.  Connect the dye wires to the auxiliary AC/DC terminals on the slip-ring terminal strip.  Drive the dye wires from the DC terminals of the gray-box power supply.  Use the banana leads with the trigger button.  Polarity determine which dye wire gets stimulated.  Bigger voltages mean more dye but bubbles can form.  If this happens carefully rub them off the wire with your finger (without breaking the wire please).

  1. Set cylinder on table axis.  Make electrical hookups.  Turn on TV and table lights, etc.
  2. Tilt using bar as above.
  3. Fill with orange thymol to above the top wire.
  4. Set into rotation (period of 6 seconds is fine).
  5. After solid rotation is reached

            a)  stimulate some dye by pulsing the wires

            b)  change the rotation by 10% or so (small Rossby number)

            c)  rotation rate may be changes up or down (anticyclonic or cyclonic gyres)

            d)  observe the resulting asymmetry in the spin up/down

            e)  pulse the wires more during spin up if need be.

    6.   Drain fluid back into supply container when done.


These are made by waiting until the fluid comes into solid rotation on the rotating platform, then initiating a small change in rotation that effectively drives a cyclonic or anticyclonic gyre in the fluid.  The shall end of the tank (a.k.a. North) is towards the top.

  1. f-PLANE  (No Western Intensification) Spin UP  (Big Screen)
  2. b - PLANE  Spin down (Forcing a cyclonic gyre)   (Big Screen)
  3. b - PLANE  Spin Up (Forcing an anti-cyclonic gyre)   (Big Screen)