analyse_secalis2_ctd
CTD-Geostrophy and SADCP Secalis-2
A. Ganachaud
Cruise map
CTD-Geostrophy
1. Default treatment:
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data were filtered with a 7-points (7-meters) median to remove most spikes before integration in 20m bins and insure static stability
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missing data in the first 60db are copied all the way up
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missing data in the last 10db are copied all the way down
- holes or larger extrapolations are done visually (horiz/vertical interpolation)
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T/S diagrams
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0-2000m: Theta, S, sigma, vgeo_2000m
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see also CARS from Billy (http://www.pmel.noaa.gov/people/kessler/noumea/cars/surface-dh-ug-nc-detail.gif)
3. South Leg Return trip (Two stations at 2000db)
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T/S diagrams
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zoom 0-1000m: Theta, S, sigma, vgeo_2000m (positive to East); without station 26
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transports (!positive to the east but positive to the south towards New Caledonia) by depth range cumulative from north (Vanuatu)
- 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)
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Geostrophic velocity Stats 26-27
- Geostrophic velocity field, with sill depth at 700m for sts 26-27
4. East Leg Havannah-Vanuatu: (without station 26)
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T/S diagrams
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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)
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detail NCJ , transports by depth range cumulative from east (Vanuatu)
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Comparison of vgeo2000 with the P21data
5. North Leg Huon-Vanuatu:
6. Grand Passage (North NC) :
Nice Ferret plots
- North Box Theta and S (Four quadrans); South Theta and S
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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.
- TS diagram with ROMS
- 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)
- 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)