Geostrophic currents page

Geostrophic currents from combined TOPEX and XBT datasets

Currents are found from TOPEX anomalies, and added to means from the Kessler (1990) XBT dataset. XBT currents are estimated from the mean depth of the 20°C isotherm: Ug = -(g/f)(delta-rho/rho)d(Z20)/dy. This requires choosing a value for delta-rho/rho. Here I use 4x10^-3, which was found to give the best estimate of the transport of the NECC (Kessler and Taft 1987).
    Preliminaries
  1. Climatology of TOPEX Ug anomalies
  2. Climatology of XBT Ug annual cycle
  3. Climatology of XBT Ug annual cycle anomalies

    Meridional sections of Ug from XBT means plus TOPEX anomalies:

  4. 95°W
  5. 110°W
  6. 125°W
  7. 140°W
  8. 155°W
  9. 170°W
  10. 180°
  11. 165°E

  12. Time series of Ug averaged over 10°S-10°N
  13. Time series of Ug anomalies averaged over 10°S-10°N

    Some model comparisons (NSCAT winds):

  14. Ug from XBT means plus TOPEX anomalies during the NSCAT period: 16°S-16°N. 2°N-16°N
  15. Surface zonal current from the Gent/Cane model forced by NSCAT winds
  16. Surface zonal current from the NOVA4.5 model forced by NSCAT winds (Zuojun Yu)
  17. y-t sections at 140°W from XBT+TOPEX and the Gent/Cane model
  18. Mean NECC above 20°C from XBTs and the Gent/Cane model
    (time average after calculation) (finer vertical resolution)

    Monthly comparisons XBT and TOPEX current climatologies.

  19. Full fields (use XBT mean for TOPEX): Feb-May;   Jun-Sep;   Oct-Jan
  20. Anomalies: Feb-May;   Jun-Sep;   Oct-Jan
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