Two YSI Inc. dissolved oxygen probes (#13341 and #13251) were used in a dual-sensor configuration during the 1997 cruises. Both sensors had electrolyte added before HOT-80. Sensor #13251 started showing large values in its temperature channel during HOT-79, this problem was aggravated after the CTD hit the bottom during the deep cast of HOT-80. The sensor was repaired and calibrated at Sea-Bird on 24 April 1997. Sensor #13341 was also calibrated and inspected on 24 March 1997. This sensor was not affected by the CTD hitting the bottom during HOT-80.

     The sensors were empirically calibrated Three sets of parameters were usually obtained per HOT cruise, corresponding to the casts at Stations 1, 2 and 8. Casts from HA-1A and 2A were calibrated with bottle data obtained during these cruises. HA-3A did not have enough bottles for a calibration and was calibrated with coefficients from the following HOT-88 cruise. One set of calibration coefficients was obtained to calibrate the 5 stations of AC-2 cruise. Tables 4.9a and 4.9b give the means and standard deviations for the final calibrated CTD oxygen minus water sample values from the various CTD stations.

Table 4.9a: CTD-Bottle dissolved oxygen per cruise (µmol kg-1)

 

 

 

Station 1, Kahe Point

Station 2, ALOHA

 

 

0 to 1500 dbar

0 to 4700 dbar

500 to 4700 dbar

Cruise

Sensor #

Mean

SD

Mean

SD

Mean

SD

79

13251

0.00

1.22

0.07

1.07

0.21

1.07

80

13341

0.00

1.61

0.02

1.64

0.15

1.26

81

13341

0.00

0.00

    -0.05

1.51

0.02

1.15

82

13341

0.03

1.62

0.07

1.77

0.18

1.57

83

13341

0.02

1.81

0.00

1.92

0.17

1.67

84

13251

0.00

0.51

0.05

1.29

0.06

0.75

85

13251

0.01

1.42

0.13

1.10

0.28

1.00

86

13251

0.00

1.08

0.11

1.28

0.40

1.14

87

13251

No Data

No Data

0.08

1.32

0.15

1.06

88

13251

0.01

0.88

0.08

0.97

0.08

0.69

Table 4.9b: CTD-Bottle dissolved oxygen at HALE ALOHA and AC-2 (µmol kg-1)

 

 

0-1500 dbars

Cruise

Sensor #

Mean

SD

HA-1A

13251

0.01

0.68

80

13341

0.07

1.14

81

13341

0.00

1.03

82

13341

0.07

1.63

83

13341

      -0.02

0.55

HA-2A

13251

0.00

0.16

84

13251

0.00

0.56

85

13251

0.00

0.10

86

13251

0.00

0.42

87

13251

0.00

0.02

88

13251

0.00

0.08

AC-2

13251

0.01

1.46

     Figure 4.10 shows the CTD oxygen data quality for every 2-dbar bin in each cast at Station ALOHA for cruises 79 through 88.

Figure 4.10. CTD oxygen data quality per cast (vertical bars) and per 2-dbar bin at Station ALOHA during HOT cruises 79 through 88. The tick marks along the x-axis separate different casts. Casts from the same cruise are separated by vertical black lines.

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