analyse_secalis2_ctd

CTD-Geostrophy and SADCP Secalis-2

A. Ganachaud

Cruise map

CTD-Geostrophy

1. Default treatment:

• data were filtered with a 7-points (7-meters) median to remove most spikes before integration in 20m bins and insure static stability

• missing data in the first 60db are copied all the way up

• missing data in the last 10db are copied all the way down

• holes or larger extrapolations are done visually (horiz/vertical interpolation)

2.South Leg

1. T/S diagrams

2. Theta, S, sigma, Vgeo_1000m;

3. Zoom 0-1000m: Theta, S, sigma, vgeo_1000m, (Ferret version)

4. transports by depth range cumulative from north (NC reef)

3. South Leg Return trip (Two stations at 2000db)

1. T/S diagrams

2. 0-2000m: Theta, S, sigma, vgeo_2000m

3. see also CARS from Billy (http://www.pmel.noaa.gov/people/kessler/noumea/cars/surface-dh-ug-nc-detail.gif)

4. East Leg Havannah-Vanuatu: (without station 26)

1. T/S diagrams

2. Theta, S, sigma, Vgeo_2000m

3. zoom 0-1000m: Theta, S, sigma, vgeo_2000m (positive to East); without station 26

4. transports (!positive to the east but positive to the south towards New Caledonia) by depth range cumulative from north (Vanuatu)

5. Topography Stations 26 (-16.1, 166.8) or  (-16°06, 166°48) to 27 (-15.75, 166.683) or (-15°45, 166°41) from along track (separation is 40km)

6. Geostrophic velocity Stats 26-27

7. Geostrophic velocity field, with sill depth at 700m for sts 26-27

5. North Leg Huon-Vanuatu:

1. T/S diagrams

2. Theta, S, sigma, Vgeo_2000m

3. Zoom 0-1000m: Theta, S, sigma, vgeo_2000m (ferret version) (positive to North; Station Huon stops at about 350m; had bottom depth set at this level rather than the true one (670m) to avoid spurious geostrophic velocity calculations)

4. detail NCJ , transports by depth range cumulative from east (Vanuatu)

5. Comparison of vgeo2000 with the P21data

6. Grand Passage (North NC) :

1. T/S diagrams

2. Theta, S, sigma, vgeo_520m (positive to East)

3. transports by depth range

Nice Ferret plots

1. North Box Theta and S (Four quadrans); South Theta and S

2. North and South TS diagram (Blue=Huon-Vanuatu; Red=Vanuatu-Havannah;Green=South). The lower salinity maximum corresponds to two stations near Huon. Detail Grand Passage.

3. TS diagram with ROMS
1. Comparison with P21 between NC and Vanuatu

Comparison with CARS (Dec climatology)

• North leg Huon-Vanuatu: CARS, december Theta, S ,Vg_2000, Vg_2000 on Z-V

SADCP

• Technical notes, projection used at each station pair (positive to left of the section)
• Uncertainties: Used Huon-Vanuatu variance of profiles at stations (station averaging option) to get a statistics of the deviation during a station.
• South Leg (345.7128 to 346.8308): Arrows at 206m from 0.25d averaging; 0.5d averaging (weight on stations); hourly
• Found out that error on station averaging is much reduced (and found bugs in output files of contadcp) for stations
• Compare Geost and ADCP in the range 150-206m from 0.5 d avg (Chereskin and Roemmich, 1991; Wijffels et al. 1995) and from 0.25d avg (almost no difference)
• south leg does not work for station averaging option (only gets 3 stations starting at 23°S)
• Inertial period:  28h at 25°S; 46h at 15°S
• South Leg Return Trip (Fig from Seca2 report)
• One point only: SADCP=+4cm/s ; gvel=+5.9cm/s
• North Leg NC (Havannah)-Vanuatu (Fig from Seca2 report)
• Compare 150-200m ADCP velocities
• Compare 150-200m ADCP velocities with sill at 700m for station 27
• North Leg Huon-Vanatu (fig from Seca2 report): station averaging does not work very well. 0.25d averaging gives about 6cm/s rms codas uncertainty in 150-206m
• Compare Geost and ADCP interpolated on stations then on pairs in the range (geost referenced at 1000m here!) 150-206m from 25.5 d avg
• Compare Geost and ADCP interpolated directly on pairs in the range 150-206m from 25.5 d avg (with 3 point running mean= thick line)
• Grand Passage (fig from Seca2 report)
  

• Note that ADCP data started only at -18.8 while first station at -18.6 because ADCP was not on between 18.6 and 18.8.Lots of shear in both: eastward flow in SADCP near the surface, near zero at 100-200m. Gvel shows close to zero at 200m and bulk flow occuring at 300m. Compare Geost and ADCP 150-206m: geostrophy: +2.5cm/s; SADCP:+6.5cm/s assign +/10cm/s.

• section 1: transboulari     2004/12/08 05:00:40 (342.2088) to 2004/12/09 11:54:49 (343.4964)
  section 2: transboulari_ret    2004/12/09 10:19:48 (343.4304) to 2004/12/09 19:39:48 (343.8193)
  section 3: transmato        2004/12/09 17:49:48 (343.7429) to 2004/12/10 06:34:50 (344.2742)
  section 4: zonalmato        2004/12/10  9:29:48 (344.3957) to 2004/12/10 19:54:50 (344.8297)
  section 5: longdurecif        2004/12/11 00:22:51 (344.0159) to 2004/12/11 01:57:51 (345.0818)
  section 5: transSud        2004/12/11 11:31:21 (345.4801) to 2004/12/12 19:56:22 (346.8308)
  section 6: transSud_ret        2004/12/12 21:51:23 (346.9107) to 2004/12/13 18:26:23 (347.7683)