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Observations of Mesoscale * Ocean Circulation: Present and Future

Observations of Mesoscale * Ocean Circulation: Present and Future. Bo Qiu Dept of Oceanography University of Hawaii. Schematic of Satellite Altimetry. * mesoscale = 10s~100s km. A UH profiling float was being deployed from R/V Revelle in Kuroshio Extension, May ‘05.

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Observations of Mesoscale * Ocean Circulation: Present and Future

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  1. Observations of Mesoscale* Ocean Circulation: Present and Future Bo Qiu Dept of Oceanography University of Hawaii Schematic of Satellite Altimetry * mesoscale = 10s~100s km A UH profiling float was being deployed from R/V Revelle in Kuroshio Extension, May ‘05

  2. Altimeter-derived rms sea surface height variability (cm) Abundant mesoscale eddies Eddy “desert”

  3. Altimeter-derived rms sea surface height variability (cm) Schematic of NW Pacific Ocean Circulation

  4. Semi-monthly Kuroshio Extension paths (1.7m SSH contours) Stable yrs: 1993-94, 2002-04 Unstable yrs: 1996-2001, 2006-07

  5. (a) Upstream KE path length (141-153°E) (b) Eddy kinetic energy (141-153°E, 32-38°N) Stable yrs: 1993-94, 2002-04 Unstable yrs: 1996-2001, 2006-07

  6. Pacific Decadal Oscillations(Mantua et al. 1997) • Center of action of wind forcing is in the eastern half of the N Pacific basin • Positive (negative) phase of PDO generates – (+) local SSH through Ekman divergence (convergence)

  7. Yearly SSH anomaly field in the North Pacific Ocean + -

  8. 2004 stable Kuroshio Extension System Study Observing Array/Timeline 20 floats 28 floats UH-KESS profiling float measurements 2005 unstable 1500db 5 days

  9. Distributions of semi-monthly profiling float T/S data (contours: SSH from satellite altimeters)

  10. T(z) and PV(z) evolution in the KE recirculation gyre mixed layer depth subtropical mode water KESS period

  11. PV values on 25.4 σθ surface (~250m)

  12. What’s Next ? from mesoscale to submesoscale … SSH snapshot from the NLOM model for 04/10/2006 Right: from the original 1/32°-resolution output Left: reduced to 1/2°-resolution (observable by current nadir-looking satellite altimeters)

  13. SSH vs vorticity snapshot from the NLOM model for 04/10/2006 reduced 1/2°-resolution original 1/32°-resolution

  14. PDF of modeled vorticity as a function of intensity anticyclonic vorticity cyclonic vorticity Ratio of anticycl./cyclonic vorticities original 1/32°-resolution

  15. “Surface Water and Ocean Topography (SWOT)” Mission Point vs 200km-wide swath measurements Repeat cycle: 10 days vs 3~5 days (at mid-high lat.) Recommended to NASA by the NRC Decadal Survey for Oceanographic and Hydrological Applications: http://bprc.osu.edu/water

  16. Approximate Time and Space Scales of Oceanic Variability Chelton (2001)

  17. EKE level SSH field SSHA along 34°N PDO index L H L center of PDO forcing 135E 145E 155E 165E

  18. Yearly-mean sea surface height field

  19. Kuroshio Extension System Study (KESS) is designed to study KE’s transition/impact from a stable to unstable state KESS period

  20. T(z), S(z) and PV(z) evolution in the KE recirculation gyre mixed layer depth subtropical mode water

  21. Altimeter-derived rms sea surface height variability (cm) Schematic of NW Pacific Ocean Circulation Eddy “desert” Abundant eddies

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