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March 24, 1994
The new criteria requires reading the CTD salinity from the 2db files and calculating the local salinity gradient (G = dS/dp) at the mark pressure (p0) applying a least square fit to two levels above and two below p0 (8-db interval). The absolute value of the CTD-bottle salinity difference divided by |G| gives a pressure (Dp) that is used as an additional parameter to check the bottle quality.
The new criteria includes the comparison of CTD-bottle (DS) against 3 or 4 times the cutoff standard deviation (STD) that varies with pressure (old criteria), and the comparison of Dp against a constant cutoff value (Dp_cutoff, new additional criteria). The new flagging method is as follows:
Flag the bottle bad if |DS| > 4*STD and |Dp| > Dp_cutoff
Flag the bottle suspect if |DS| > 4*STD and |Dp| < Dp_cutoff or
if |DS| > 3*STD and |Dp| > Dp_cutoff
Flag the bottle good if |DS| > 3*STD and |Dp| < Dp_cutoff or
if |DS| < 3*STD After running some tests we decided on a value of Dp_cutoff = 7 dbar, which seems to serve the purposes of this new flagging method. We chose this cutoff value by considering that a measurement with a CTD-bottle salinity difference of DS would have traveled 7 dbars in the vertical as a result of ship roll between the time of the mark and the closing of the bottle. A greater difference would imply vertical movement of more than 7 dbars, which seems implausible. We looked at several plots showing the bottle and CTD casts and this cutoff value seems appropriate to change the quality to suspect or good for bottles in high gradient regions.
HOT 13-32 salinity flags changed to good (2) or suspect (3) after applying the new flagging procedure.
Station-Cast-Bottle
HOT-13
2-4-7 quality sal 3 => 2
2-17-11 quality sal 3 => 2
2-17-8 quality sal 3 => 2
2-2-14 quality sal 3 => 2
HOT-14
2-12-18 quality sal 3 => 2
1-1-10 quality sal 3 => 2
HOT-15
2-1-11 quality sal 3 => 2
2-5-3 quality sal 3 => 2
2-5-2 quality sal 3 => 2
2-6-11 quality sal 3 => 2
2-9-1 quality sal 4 => 3
2-17-1 quality sal 4 => 3
HOT-16
2-10-4 quality sal 3 => 2
2-10-3 quality sal 3 => 2
HOT-17
2-11-1 quality sal 4 => 2
2-5-18 quality sal 4 => 3
HOT-18
2-4-9 quality sal 3 => 2
2-11-13 quality sal 3 => 2
2-2-14 quality sal 3 => 2
2-9-12 quality sal 4 => 3
HOT-19
2-14-7 quality sal 3 => 2
2-3-5 quality sal 3 => 2
2-6-7 quality sal 3 => 2
2-1-7 quality sal 3 => 2
2-1-6 quality sal 3 => 2
2-1-5 quality sal 3 => 2
2-1-4 quality sal 3 => 2
2-1-2 quality sal 3 => 2
1-1-1 quality sal 4 => 3
HOT-22
1-1-12 quality sal 3 => 2
2-2-12 quality sal 3 => 2
2-10-5 quality sal 3 => 2
2-4-1 quality sal 4 => 2
HOT-23 2-8-7 quality sal 3 => 2
HOT-24
2-3-10 quality sal 3 => 2
2-3-19 quality sal 4 => 3
2-7-16 quality sal 4 => 3
2-1-3 quality sal 4 => 3
2-7-1 quality sal 4 => 3
HOT-25
2-6-3 quality sal 3 => 2
1-2-20 quality sal 4 => 3
2-2-23 quality sal 4 => 3
2-9-21 quality sal 4 => 3
2-8-3 quality sal 4 => 3
HOT-26
2-8-12 quality sal 3 => 2
2-11-13 quality sal 3 => 2
2-11-7 quality sal 3 => 2
1-1-1 quality sal 3 => 2
1-1-4 quality sal 4 => 3
2-4-17 quality sal 4 => 3
2-5-13 quality sal 4 => 3
2-7-21 quality sal 4 => 3
HOT-27
2-3-13 quality sal 3 => 2
2-3-1 quality sal 4 => 2
HOT-28
1-1-7 quality sal 4 => 2
HOT-29
2-4-1 quality sal 3 => 2
2-9-2 quality sal 4 => 2
2-9-1 quality sal 3 => 2
2-3-13 quality sal 4 => 3
2-11-6 quality sal 4 => 3
HOT-30
2-9-1 quality sal 3 => 2
HOT-31
2-6-15 quality sal 3 => 2
2-4-6 quality sal 3 => 2
2-14-1 quality sal 3 => 2
2-5-13 quality sal 4 => 3
2-6-18 quality sal 4 => 3
2-8-4 quality sal 4 => 3
HOT-32
2-1-22 quality sal 4 => 3
2-6-4 quality sal 4 => 3
2-15-14 quality sal 4 => 3