Variability of the salinity maximum along 165°E (1984-96)

1. Figures from a paper accepted at JPO
   1. Locations of EPIC CTD profiles along 165°E
   2. Time series of salinity and temperature at 3°-5°S, 165°E
   3. Mean salinity and zonal geostrophic current along 165°E
   4. Salinity on sigma-t=24.5 along 165°E
   5. Top. Depth of sigma-t=24.5; Bot. Salinity on sigma-t=24.5 (Levitus)
   6. Time series of salinity on sigma-t=24.5 at 165°E, 180° and 155°W, 3°-5°S
   7. Salinity difference between 165°E and 180°, averaged over 3°-5°S on sigma-t=24.5.
   8. udS/dx and dS/dt on sigma-t=24.5 at 3°-5°S, 165°E

2. Figures showing observed properties
   1. Locations of 165°E CTD profiles
   2. Count of 165°E CTD profiles by 1°latitude bins

3. Figures made by finding the salinity maximum (or the isopycnal 24.5) at each profile, then gridding these in latitude and time with e-folding scales of 2° latitude and 6 months.
   1. Mean quantities on the salinity maximum layer
   2. Maximum salinity along 165E
   3. Surface salinity along 165E
   4. Depth of the salinity maximum
   5. Temperature at the salinity maximum
   6. Sigma-t at the salinity maximum
   7. Salinity on sigma-t=24.5   (Anomalies)
   8. Temperature on sigma-t=24.5   (Anomalies)   (Overlay)
   9. Depth of the sigma-t=24.5 isopycnal
   10. Zonal geostrophic current on sigma-t=24.5 along 165°E (old G)
   11. Zonal geostrophic current on sigma-t=24.5 along 165°E (normalized by RMS)
   12. Depth anomalies of the sigma-t=24.5 isopycnal
   13. Thickness of the layer between sigma-t=24 and 25
   14. Planetary potential vorticity f/h for the layer between sigma-t=24 and 25
   15. Surface and subsurface salinity at 3°-5°S, 165°E
   16. Surface and subsurface salinity along 165°E
   17. Surface and subsurface salinity along 165°E (demeaned)
   18. Correlation of surface and subsurface salinity along 165°E

4. Figures made by gridding each of the 46 cruises separately in latitude and depth (by linear interpolation) to a grid of 1/2°latitude and 5m. Then the cruises were combined (concatenated) to make fields in (y,z,t). See Fig 1.1 for profile locations.
   1. Time series of T and S at 4°-6°S, 165°E
   2. Time series of salinity at 4°-6°S with overlaid sigma-t
   3. Standard deviation of T and S along 165°E
   4. Time series of depths of salinity maximum and sigma-t=24.5 at 4°-6°S, 165°E
   5. Time series of salinity maximum and density at 4°-6°S, 165°E
   6. Salinity vs density at 4°-6°S, 165°E
   7. Salinity vs temperature at 4°-6°S, 165°E
   8. Salinity vs temperature at the S maximum at 4°-6°S, 165°E
   9. Number of days between cruises along 165°E
   10. Very crude average annual cycle of Smax along 165°E
   11. Mean zonal geostrophic speed (overlaid salt contours) along 165°E
   12. Mean salinity (overlaid Ug contours) along 165°E
   13. Mean salt (top) and zonal geostrophic speed (bottom) along 165°E
   14. Thickness of the layer sigma-t=24 to 25 along 165°E
   15. Demeaned thickness of the layer sigma-t=24 to 25 along 165°E
   16. f/h for the layer sigma-t=24 to 25 along 165°E

5. Salinity sections by individual cruises along 165°E:
   1. Cruises 1-10
   2. Cruises 11-20
   3. Cruises 21-30
   4. Cruises 31-40
   5. Cruises 37-46

      Same sections demeaned by the 1984-97 mean:

   6. Cruises 1-10
   7. Cruises 11-20
   8. Cruises 21-30
   9. Cruises 31-40
   10. Cruises 37-46

6. Figures from the Levitus (1994) World Ocean Atlas.
   1. Depth of the sigma-t = 24.5 surface
   2. Depth of the sigma-t = 24.5 surface with geostrophic streamfunction overlaid
   3. Salinity and Temperature on the sigma-t = 24.5 surface
   4. Salinity, Temperature and Geostrophic currents on the sigma-t = 24.5 surface
   5. Salinity and Geostrophic currents on the sigma-t = 24.5 surface (half of above plot to show detail)
   6. Salinity and geostrophic streamfunction on the sigma-t = 24.5 surface
   7. Ug and sigma-t averaged over 180°-140°W
   8. Thickness of the layer between sigma-t=24 and 25
   9. f/h for the layer between sigma-t=24 and 25
   10. Elements of the MSF
   11. dS/dx on the sigma-t = 24.5 surface
   12. Maximum salinity (over z) in the tropical Pacific
   13. Maximum salinity (over z) in the tropical South Pacific
   14. Properties on the salinity maximum tongue in the South Pacific
       At each depth/longitude the tongue is defined as the maximum salinity over latitude within 21°S to 6°S. Top panel shows this latitude as a function of x and z (colors) with salinity at these latitudes/depths (contours). Bottom panel shows the salinity (colors) with temperature (contours). Both panels have the sigma-t=24.5 line overlaid.

7. Consider the possibility of zonal advection
   1. Mean zonal geostrophic currents along 165°E
   2. Surface zonal geostrophic currents relative to 700m along 165°E
   3. Surface zonal geostrophic currents relative to 150m along 165°E
   4. Zonal geostrophic currents at 150m rel 700m along 165°E
   5. Zonal current on the surface where S is maximum along 165°E
   6. Zonal current on sigma-t=24.5 along 165°E
   7. Ug (150m) and dS/dt at 4°S, 165°E
      
      
   8. dS/dt and udS/dx on sigma-t=24.5 averaged over 3°S-5°S
      
      
   9. S on sigma-t=24.5 at 3°-5°S. Obs and from integral of udS/dx
   10. dS/dt and dT/dt on sigma-t=24.5 at 3°-6°S
   11. dS/dx and dT/dx on sigma-t=24.5 at 3°-6°S
   12. udS/dx and udT/dx on sigma-t=24.5 at 3°-6°S

       Time series comparing Ug along sigma-t=24.5 at 165°E and dS/dx in the salinity maximum between 165°E and 180°.
       Averaged in various latitude bands as indicated.
       

   13. At 3°S
   14. At 4°S
   15. At 5°S
   16. At 6°S
   17. Averaged over 3°-5°S
   18. Averaged over 3°-5°S (omit S-bar)
   19. Correlation of udS/dx and dS/dt on sigma-t=24.5 at 165°E

   20. Salinity at 180° and 165°E, averaged between 3°S-6°S (also Delta-S and Ug)
   21. Salinity 180° and 165°E, averaged between 3°S-6°S with linear trends
   22. Detrended salinity at 180° and 165°E, averaged between 3°S-6°S
   23. Salinity on sigma-t=24.5 at 165°E, 180° and 155°W, averaged between 3°S-5°S
       (Compare the amplitude of variability at 3°S-5°S during the FGGE Shuttle)
   24. Salinity on sigma-t=24.5 at 165°E, 180° and 155°W, averaged between 7°S-10°S
       
   25. Salinity on sigm-t=24.5 at 165°E, 180° and 155°W, averaged between 3°S-5°S (15-month boxcar filter)

8. A few checks
   1. Salinity at 3°S-6°S, 180° at sigma-t=24.5. Individual obs plus mapped time series
   2. As above plus corresponding salinity at 165°E
   3. Comparing Ug time series in the Smax from sections and at 150m from sort
   4. Comparing mean Ug from sections and sort
   5. Steps in finding Ug along 165°E
   6. Compare Ug from smoothed DH or from raw DH, then smoothed
   7. dS/dx at Smax between 165°E and 180°
   8. Components of udS/dx by latitude band
   9. dS/dx binned by latitude band
   10. dS/dx at 3°S-6°S
   11. udS/dx at 3°S-5°S. Overlaid also from dS/dx-bar
   12. udS/dx at 4°S-6°S. Overlaid also from dS/dx-bar
   13. Comparing udS/dx found from sort vs section

9. Z20 time series on the WP track from TOGA XBT data
   1. Depth of 20°C along the WP track (6 month, 2° mapping scales)
   2. Depth of 20°C along the WP track (3 month, 1° mapping scales)
   3. Anomalies of 20°C depth along the WP track (3 month, 1° mapping scales)
      See some more figures from this data set

10. Similar calculations along other sections
    Profile locations:
    
    1. Profile locations along 155°E
    2. Profile locations along 180°
    3. Profile locations along 155°W

       Surface salinity:
       

    4. Surface salinity along 155°E
    5. Surface salinity along 180°

       Salinity maximum:
       

    6. Salinity maximum along 155°E
    7. Salinity maximum along 180°

       Another similar calculation along 5°S.
       Even cruder than the above. Fewer profiles, and gridded by 5° longitude, with scales of 25° longitude and 6 months.
       

    8. Salinity maximum along 5°S
    9. Depth of the salinity maximum along 5°S
    10. Temperature at the salinity maximum along 5°S
    11. Surface salinity along 5°S

11. FGGE Shuttle stuff
    1. Profile locations for FGGE cruises (10°S-10°N only)
    2. Mean salinity during FGGE (overlaid sigma-t)
    3. Mean salinity on sigma-t=24.5 during FGGE
    4. Mean depth of sigma-t=24.5 during FGGE
    5. Salinity on sigma-t=24.5 at 4°S
    6. Surface zonal geostrophic current during FGGE
    7. Zonal geostrophic current on sigma-t=24.5 during FGGE
    8. Mapped and raw salinity on sigma-t=24.5 at 3°S during FGGE

12. Miscellany (SOI)
    1. Salinity on 24.5, WP Z20 and the SOI
    2. Salinity on 24.5, WP Z23 and the SOI
    3. Levitus salinity along 165E (Very crude and over-smoothed!)
    4. T and S at 0°, 165°E
    5. Time series of the SOI, SSS and S on sigma-t=24.5 at 3°-5°S, 165°E
    6. T and S at 0°, 165°E
    7. Mean and RMS difference between depth of Smax and sigma-t=24.5 at 165°E, 180°, 155°W

13. Some things relevant to error estimates. Plots show the results of subsampling. For the period 1984-92 (when the sampling was relatively good), these subsampling tests omitted half the cruises, then recalculated the quantities of interest and compared witht he results of the full record.
    1. Salinity on sigma-t=24.5 along 165°E
    2. Ug on sigma-t=24.5 along 165°E
    3. RMS of subsampled salinity difference on sigma-t=24.5 along 165°E
    4. RMS of subsampled Ug difference on sigma-t=24.5 along 165°E
    5. RMS Signal/Noise ratio of subsampled S and Ug difference on sigma-t=24.5 along 165°E
    6. Compare subsampled dS/dt and udS/dx on sigma-t=24.5 along 165°E

14. Deducing mixed layer salinity (outcrop calculations)
    In these tests, mixed layer salinity near the outcrop of sigma-t=24.5 in the SE Pacific is estimated from an extremely rudimentary mixed layer model with inputs of MSU precipitation and evaporation based on ECMWF winds. The mixed layer "model" assumes an instantly-mixed, constant thickness (50m) surface layer. Each month, fresh water equal to E-P is added or removed and integrated forward to get a crude estimate of salinity. Then this salinity and Reynolds SST is used to find the surface density.
    In these plots, E-P is positive for net evaporation. Units of E and P are cm/month.
    1. Mixed layer salinity deduced from E-P near 20°S, 120°W
    2. 2-meter air temperature and dewpoint near 20°S, 120°W from the ECMWF analysis
    3. Annual average mixed layer quantities P, E, S, T, Sigma (1985-90)
    4. Annual average mixed layer quantities P, E, S, T, Sigma (1991-96)
    5. Annual average mixed layer quantities P, E, S, T, Sigma (1985-90) (Demeaned)
    6. Annual average mixed layer quantities P, E, S, T, Sigma (1991-96) (Demeaned)
    7. Outcrop latitude of sigma-t=24.5 in the SE Pacific (Reynolds SST and ML model)
    8. SSS and SST at the outcrop of sigma-t=24.5 in the SE Pacific (130°-100°W) (time series from model)

15. Outcrop in the SE Pacific (Observations from Levitus)
    1. Mean SST, SSS and surface density in the S Pacific
    2. Mean locations/values of SST and SSS on sigma-t=24,24.5 and 25 in the S Pacific (Levitus)
    3. Mean SST, SSS, Sigma in the SE Pacific
    4. Seasonal RMS of SST, SSS, Sigma in the SE Pacific
    5. Seasonal mean SST, SSS, Sigma in the SE Pacific: JFM  AMJ  JAS  OND  Combined  Combined (summer/winter only)  
    6. Annual cycle of SST and SSS on Sigma-t=24.5   At 120W, the surface isopycnal moves equatorward in the winter due to SST cooling. But since equatorward means higher salinity, SST on the isopycnal warms in winter. When does subduction occur?
    7. Checking SSS data in WOD98: image from EPIC Select web page  Actual locations of SSS data
    8. SSS data on Noumea CD: Mean, std dev, noumber of obs/box