NBP09-01 Cruise Report - British Oceanographic Data Centre

In order to estimate the accuracy of the comparisons between RosSalts and CTDsalts two linear fits ofDeltaS0 and DeltaS1 vs Sta# were performed. Fit1 allowed identifying and flagging outliers that were twostandard deviations away from the fit. Fit2 was applied to the calculate residuals and gave a final overallaccuracy of the preliminary errors. The fitting coefficients and the residual standard deviation for bothsensors are presented in Table 4. This table also shows the number of RosSal values that felt over 2 standarddeviations from the fits, considered not good for calibration.Sensor Fit Res St Dev # points discarded % usedPri DeltaS0 = 7.78E-006 * Sta# + 0.00164 0.0032 420 89 78.8Sec Y = 2.137E-005 * X + 0.00193 0.0031 411 86 79.1Table 4: Fitting of DeltaS values as a function of Sta#, standard deviations of residuals are presented forprimary and secondary sensor. Also the percentage of point used for the fittings.The accuracy in these preliminary error estimations are reflected in the standard deviations of the residuals,being 0.0032 for primary and 0.0031 for secondary sensors respectively. The residual histograms are presentedin fig. 12. These standard deviations should be lessreduce if an adjustment of the error is previouslyperformed as function of Pressure.Errors reported here on salinity have been estimated with the only objective being the evaluation of thebehavior of the Conductivity sensors throughout the cruise. Most points marked here as outliers can probablybe related to niskin leakage and/or contamination, and unstable layers not suitable for calibration.Associated Bottle Data Files A Microsoft Excel spreadsheet file was generated with bottle informationcoming from the rosette niskin measurements performed onboard (Salinity and Oxygen) and from CTDinstruments at the corresponding niskin firing levels. CTD instrument values are extracted by the SBEsoftware modules “datcnv” and “rossum”, which average over 2 seconds or 48 scans around the tripping ofthe niskin. An Excel file, named ’Bottle NBP0901.xls’ (spread sheet ’nbp0901001.btl’) contains the integratedbottle information. All rosette salinities (SaRos) and corresponding error calculations have been included inthe bottle files (columns Y to AM). Values with a residual larger than 2 standard deviations from the fitsare labeled ’outliers’. Other associated bottle files are:• NBP0901001.bl thru NBP0901160.bl are output bottle files from SBE data processing.• NBP0901A thru NBP0901K.dat are ACI 2000 software output files from Autosal runs (Autosal folder)• NBP0901A thru NBP0901K.xls are excel files used to average salt readings (Bottle folder)• Salbottles.xls is an excel file that compiles all the final salts by run.Note: CTD salinity entries for primary sensor on station 2 were punched in from the CTD log sheet. Datawas not archived on this station (see CTD report) but salinity bottles were taken and measured.3 Autosub III OperationsAdrian Jenkins (BAS), Pierre Dutrieux (BAS), Steve McPhail (NOCS), James Perrett (NOCS), Andy Webb(NOCS), Dave White (NOCS)3.1 IntroductionThe UK component of NBP0901 was funded by the Natural Environment Research Council (NERC) andwas undertaken by personnel from the British Antarctic Survey (BAS) and the National OceanographyNBP09-01 Cruise Report (p. 17 of 83) Revised February 27, 2009