WHP Ref. No.: P1 EXPOCODE: 31TTTPS47/1 Chief Scientist: Lynne Talley (SIO) Cruise Dates: 4 August - 7 September 1985 The following paragraphs are condensed from Scripps Technical Report SIO-88-9 entitled: Transpacific Section in the Subpolar Gyre (TPS47) Physical, Chemical, and CTD Data Report 4 August 1985 - 7 September 1985 RV Thomas Thompson TT 190 1. INTRODUCTION A nearly zonal CTD/hydrographic section across the subpolar North Pacific was occupied from August 4, 1985 to September 7, 1985 on cruise TT 190 of the RIV Thomas Thompson. The cruise track was primarily along 47¡N except at the western boundary. The section consisted of 115 high quality, full water-column CTD/hydrographic stations. Additional components of the physical oceanographic program were: continuous acoustic doppler current profiling (T. Joyce, WHOI), towed salt-bridge GEK (P. Spain and T. Sanford, Univ Wash ), and XBTs (P. Spain and T. Joyce). Each station consisted of a CTD lowering with a rosette carrying 36 10-liter Niskin bottles. Water samples were collected on the upcast. Salinity, oxygen, and nutrient analyses were performed at sea by the Oceanographic Data Facility at SIO. Initial CTD processing was accompished at sea by ODE. In addition to this standard suite of measurements, water samples from the same casts were made available for analyses by other investigators. Chlorotluorocarbons (freons) F-11 and F-12 were analyzed at sea by R. Weiss' group from SIO with the assistance of K Kelly-Hansen (NOAA/PMEL); their results are included in this data report and are also available in a separate data report. Samples for tritium and alkalinity analyses were collected for processing by the tritium laboratory of the University of Miami (G. Osltund and R. Fine) and by R. Feely at NOAA/PMEL, respectively. A separate, complete tritium data report is available (Ostlund, 1987) Chlorophyll-a and phaeopigment measurements were made by E. Venrick's group at SIO. High-performance liquid chromatography pigment measurements were made by R. Bidigare's group at Texas A&M University; results are available in a separate data report (Bidigare, et al., 1987). Samples were collected for helium-3, carbon-14 (AMS), manganese, plutonium, and rare earth elements for analyses by other investigators. In addition to the basic CTD/hydrographic stations included in this report, approximately one shallow bottle cast was made per day for primary productivity measurements by E Venrick's group at SIO. 2. DISCRETE DATA - METHODS 2.1. Temperature and Salinity Pressure and temperature for the discrete hydrographic tabulations was taken from the calibrated CTD data; calibrations are discussed in the following section. Reversing thermometers were mounted on 4 to 5 Niskin bottles on each cast to be used to resolve shifts in the CTD temperature calibration. As there was at most a 001 deg. C shift in temperature calibration from the beginning to the end of the cruise and as the reversing thermometers had not been calibrated in some time, the reversing thermometer information was not required. Depths were calculated from CTD pressures (Saunders,1981). Salinity samples were analyzed at sea using one of two Guildline Autosal inductive salinometers. All salinities were calculated from conductivity using the 1978 practical salinity scale (UNESCO, 1981) and are tabulated to three decimal places. Wormley standard seawater batch P96 was used for calibration at the beginning and and of each station's analyses; hydrographic and CTD salinities are reported herein relative to P96 and have not been adjusted further. Mantyla (1987) reported differences between various other batches of standard seawater and P96. Deep salinities from TPS47 relative to P96 have been compared with deep salinities on a prior cruise in 1984 at 152 W on which standard seawater batch P92 was used. The average difference in deep salinities between the cruises using stations from the intersecting region was about 0.003 ppt with P92 salinities lower than P96; this is in agreement with Mantyla's finding. Precision of the bottle salinities is +/- 0.002 ppt. Bottle salinities were compared with CTD salinities to identify leaking bottles or salinometer malfunctions. Calibrated CTD salinities replace bottle salinities in the event of problems and are indicated by the letter "D" in this data report. CTD values were used on 27 stations, almost exclusively at one level only. Exceptions are stations 25 and 83 where three CTD values were required due to faulty sample drawing, and at stations 104, 105, 106, l l0, and l l l, where 3 to 5 samples drawn for detailed vertical profiling of helium-3 and manganese were not analyzed for salinity, oxygen, or nutrients. The spread in deep bottle salinities is approximately +/-0.001 ppt. 2.2. Oxygen and Nutrients Dissolved oxygen content was determined by the Winkler method as modified by Carpenter (1965), using the equipment and procedures outlined by Anderson (1971). Oxygen measurements are given in ml STP per liter of water at 1 atmosphere and at the potential temperature of the sample. A small number of oxygen outliers was discarded. The precision of the oxygen measurements within a single cast is 0.01 ml/I and the accuracy is 1%. Silicate, phosphate, nitrate, and nitrite were analyzed using a Technicon autoanalyzer. The procedures are similar to those described in Atlas et al. (1971). Nutrient measurements are reported here in micromoles/liter at 1 atmosphere and 25 deg. C, which is assumed to be the laboratory temperature. A failure of the nitrate channel power supply at station 91 resulted in loss of measurements below 800 m. The precision of nutrient measurements (within a single cast) is better than 0.5% and the station-to-station, cruise-to-cruise accuracy is 2% to 3%. 2.3. Chlorofluorocarbons Concentrations of the dissolved atmospheric chlorofluorocarbons F-l l (trichlorofluoromethane) and F-12 (dichlorodifluoromethane) were measured by shipboard electron-capture gas chromatography, according to the methods described by Bullister and Weiss (1988). The results have been corrected for sampling and analysis blanks, the statistical variations of which are responsible for occasional negative values near the detection limit. It is important to emphasize that the data have been edited to remove serious "flyers" and contaminated samples, and to correct gross numerical errors. However, the data have not yet been subjected to the level of scrutiny associated with careful interpretive work. Readers are therefore requested to contact R. Weiss' group at SIO for any revisions in the data which may post-date this report, and to draw to their attention any suspected inconsistencies. The results are reported on the SIO 1986 calibration scale. The precision (+/- one s.d.) of the measurements is about 1% or about 0.005 pmol/kg, whichever is greater, for both chlorofluorocarbons, except during the first 29 stations, where the low-level F-12 measurements had a larger error of about 0.01 pmol/kg caused by large sampling contamination blanks. The estimated accuracy of the calibrations is about 1.3% for F-l l and 0.5% for F-12. 2.4. Tritium Tritium was measured by electrolytic enrichment and low level gas counting, according to Ostlund and Dorsey (1977) The listed TU81N values are the tritium ratios (T/H x E-18) in the "new NBS scale" based on the NBS standard #4926 as on 1961/09/03, with the new half-life of 12.43 years, i e., a decay rate of 5.576% per year. All values are age corrected back to the reference date of 1981/01/01. All TU81N data are directly comparable without further age correction. Negative TU values are reported as such for the benefit of allowing the user unbiased statistical treatment of sets of the data. For other applications, 0 TU should be used. The errors are 3.5% or 0.05, whichever is larger. 2.5 Alkalinity Water samples for alkalinity measurements were transferred from the 10-L Niskin bottles into 1-L glass-stoppered bottles containing 1.0 mL of a saturated solution of Hg2Cl2 to decrease bacterial oxidation of organic matter. The samples were stored in a dark, cold storage room at 4 deg. C. The samples were analyzed by the potentiometric method using a Brinkman E636 titroprocessor linked to a Hewlett-Packard 85 computer. The data from the titroprocessor were automatically fed into the computer and processed using the nonlinear, least squares fitting program of Dickson (1981) with the modifications suggested by Johansson and Wedborg (1982). Alkalinity contributions from boric, silicic, and phosphoric acid were computed from equations similar to those presented by Takahashi, at al. (1982) in the GEOSECS Pacific Expedition report. Total borate concentration was computed using the relation given by Culkin (1965). The dissociation constants of carbonic acid and boric acid are from the work by Almgren, el al. (1977). Potassium chloride was used to adjust the ionic strength of the sodium carbonate standards to 0.7. At each station a blank was determined by titrating aliquots of a KCI solution containing no sodium carbonate. The average blank was 4 ueq/L The results have been corrected for sampling and analysis blanks. The data have been edited to remove "flyers" resulting from bottle contamination. The precision of the measurements is about 0.1 % (+/- one S. D ). 3. CTD DATA 3.1. Processing Summary 116 CTD casts were completed using a 36-bottle rosette sampling system. ODF CTD #l (a modified NBIS Mark 3) was employed exclusively for all CTD casts. The CTD data were initially processed into a filtered, I-second average time-series during-data acquisition. The pressure and PRT temperature channels were corrected using laboratory calibrations. The conductivity channel was calibrated to salinity check samples acquired on each cast. The CTD time-series data were then pressure-sequenced into two decibar pressure intervals. 3.2. CTD Laboratory Calibrations 3.2.1. Pressure Transducer Calibration The CTD pressure transducer was calibrated in a tomperature-controlled bath to the ODF Ashcroft to (pre-cruise) and Ruska (post-cruise) deadweight-testcr pressure standards. Thermal responsc-time, thermal hysteresis and mechanical hysteresis were measured. The mechanical hysteresis loading curves were measured at 0/1 deg. C and 24/22 deg. C (pre-/post-cruise) and at maximum loadings of 1530 and 8830 PSI. The transducer thermal response-time was derived from the pressure response to a thermal step-change from 23 to 0 C. 3.2.2. PRT Temperature Calibration The CTD PRT temperature transducer was calibrated in a temperature-controllcd bath to a Leeds and Northrup standard PRT (pre-cruise) and to a Rosemont standard PRT (post-cruise). Seven calibration temperatures, spaced across the range of 0 to 27 C, were measured both pro and post-cruise. 3.3. CTD DATA PROCESSING 3.3.1. CTD Data Acquisition Seven channels (pressure, temperature, conductivity, dissolved oxygen, elapsed time, altimeter and voltage) were acquired at a data rate of 31.25 FPS. The FSK CTD signal was demodulated by an ODF-designed deck unit and output to an IEEE-488 bus interface. An IBM CS-9000 served as the real-time data acquisition processor. Data acquisition consisted of storing all raw binary data on hard disk (and later on nine-track magnetic tape) and generating a corrected and filtcred one-second average time-series. Data calculated from this time series were reported and plotted during the cast. A ten-second average of the time-series data was calculated for each water sample collected during the data acquisition. Generating the one-second time-series involved applying single-frame absolute value and gradient filters, then performing a two-pass standard-deviation test to all channels, rejecting points exceeding 4 standard deviations from the mean on the first pass, then repeating the rejection using 2 standard deviations as the criterion. The pre-cruise laboratory calibration data were applied to pressure and temperature. Pressure and conductivity were lagged to match the thermal response of the PRT temperature transducer. The conductivity channel was corrected for thermal and pressure effects. 3 3.2. CTD Dissolved Oxygen Data The dissolved oxygen channel was not processed beyond averaging the raw oxygen current Raw CTD oxygen data were continuously examined for signal quality. There is moderate noise in much of the oxygen data, with occasional large spikes. Stations 6 through 8 had severe spiking problems, and stations 91 through 93 had spiking/drifting problems which remained to a smaller extent until the end of the cruise. Small- scale oxygen noise was evident in the data beginning at station 78, and re-appeared intermittently until the end of the cruise. The oxygen transducer was replaced several times during the cruise because of cracked sensor holders. 3.3.3. Pressure, Temperature, and Conductivity Corrections A maximum of 36 salinity check samples and 4 to 5 thermometric pressure and temperature measurements were collected on each cast. A ten-second average of the CTD time-series was calculated for each water sample. Differences between bottle and CTD data were then used to verify the pro- and post-cruise pressure and temperature calibrations and to derive CTD conductivity calibrations 3.3.3.1. CTD Pressure Corrections The pre- and post-cruise pressure calibrations were compared. The post-cruise calibration was applied to the CTD data because newer, more accurate pressure standard equipment and techniques were used to collect the data, and because its calibration date was three months closer to the time of the cruise. The shipboard processing pressures differ from the revised pressures by up to 3 dbar due to the new calibration data was well as improvements to the pressure correction model. No significant drift was apparent in comparisons between CTD and thermometric pressures. 3.3.3.2. CTD Temperature Corrections A comparison of the pre- and post-cruise laboratory PRT temperature transducer calibration curves indicated a difference of 1 millidegree at 1 C up to 3 millidegrees at 25 C. The pre-cruise data is very scattered at each calibration temperature due to bath instability and the cumbersome manual method used to collect the information. The post-cruise calibration was able to take advantage of a new, very stable temperature bath and a new resistance-measuring system which can collect data more rapidly and accurately. Since there was no apparent drift or shift in the CTD and thermometric temperature differences over the time scale of the cruise, and because of less scatter in the data and its close proximitiy to the cruise, the post-cruise calibration was applied to the temperature data. 3.3.3.3. CTD Conductivity Corrections Check sample conductivities were calculated from the sample salinities and from corrected CTD pressures and temperatures The differences between sample and CTD conductivities were fit to CTD conductivity using a linear least-squares fit. Values greater then two standard deviations from the fit were rejected. The resulting conductivity correction slopes for each east were fit to station number, giving a continuous smoothed conductivity slope correction as a function of station number. Conductivity correction slopes were then derived from this smoothed fit. Conductivity differences were calculated for each cast after applying the conductivity slope correction. These differences were fit to station number at various pressure ranges. Conductivity correction offsets were then generated individually for each east, weighted more toward deep and/or mixed-layer differences. Some offsets were manually fine-tuned to compensate for discontinuous shifts in the conductivity transducer response and for bottle salinity problems, as well as to insure a consistent deep T-S relationship from station to station. Less than 10% of the casts were manually adjusted from 0.001 to 0.0025 psu. Conductivity offset corrections for shallow casts were checked against adjacent deep casts for consistency. 3.3.4. Additional Processing A filter was used on 12 percent of the stations to remove conductivity spikes larger than 0.1 above 1000 dbar and 0.01 below 1000 dbar Less then 0.1% of the time-series data in those stations were affected. Temperature and pressure did not required filtering. The down cast portion of each time-senes was then pressure- sequenced into two decibar pressure intervals. A ship-roll filter was applied to disallow pressure reversals. 3.4. General Comments/Problems There were 119 CTD rosette casts. Three were aborted and were neither processed nor included on the tape. One pressure-sequenced CTD data set exists for each CTD station, with an extra shallow cast included for station 98. All data was simultaneously recorded on audio cassette tape. Due to deck-unit malfunction, station 97 was redigitized from the audio tape following the cruise, with no degradation of quality. Up-cast thermocline data were typically noisier than the corresponding downcast data, possibly due to the positioning of the CTD near the bottom of the large rosette package. Nine up-casts were used as final data instead of down-casts because of conductivity offsets or other instrument-related problems on the down- casts. The up-casts are: 1-1, 8-1, 9-1, 16-1, 18-1, 28-2, 31-1, 77-2, and 84-1. Because ship-roll effects cause more severe thermocline density inversions on the up-casts, some down-casts were included despite deep ca. 0.002 psu salinity offsets, apparently caused by an intermittent CTD malfunction. The following casts are affected: 19-1, 25-1, 26-1, 42-1, 62-1, 76-1, 78-1, 81-1, 82-1, 83-1, and 87-1. Salinity offsets at stations 25, 26, 36, 42, 47, and 76 were removed individually. On several casts, the CTD was held at one pressure or cycled up and down in mid-cast ("yoyo"). The effect after pressure-sequencing is a discontinuity in the pressure-series data. Yoyos larger than 10 dbar occurred on stations 8, 18, 32 and 58. Intermittent single-level gaps in the data are due to the removal of ship-roll effects and filtering. Two groups of stations had a significantly larger percentage of single-level data gaps than the rest of the stations (up to two percent versus less than 0.2 percent gaps) The weather log for stations 28 through 36 and stations 104 until near the end of the cruise indicates that the majority of these casts occurred in 20+ knot winds and/or 8 to 12 foot waves, both much larger than recorded for the other casts. Multi-level data gaps where data were not recorded occurred at stations 8, 12 and 97. The deep T-S relationship was examined for calibration problems and consistency Instrument problems have been corrected where possible and otherwise documented. Remaining density inversions in high-gradient regions cannot be accounted for by a mismatch of pressure, temperature, and conductivity sensor response. Detailed examination of the raw data shows significant mixing occurring as a consequence of ship roll. The ship-roll filter, applied to most casts to disallow pressure reversals, resulted in a reduction in the amount and/or size of density inversions in the upper 500 dbar of the water column. 4. ACKNOWLEDGEMENTS The acquisition and publication of this data set was funded by the National Science Foundation, Ocean Sciences Division, under Grants OCE84-16211, OCE8740379 (hydrographic and CTD work), OCE 83 16602 (chlorofluorocarbons), and OCE85-10842 (tritium), and by a grant from the Pacific Marine Environmental Laboratory of NOAA (alkalinity) 5. REFERENCES Almgren, T., D Dyrssen, and M Stranberg, 1977. Computerized high precision titrations of some major constituents of sea water onboard the R/V/Dmitry Mendeleev. Deep Sea Res., 24, 325-364 Anderson, G.C., compiler, 1971 "Oxygen Analysis " Marine Technician's Handbook SIO Ref. No 71-8, Sea Grant Pub. No. 9 Atlas, E.L., 1.C. Callaway, R.D Tomlinson, L l. Gordon, L. Barstow, and P.K. Park, 1971 A Practical Manual for Use of the Technicon Autoanalyzer Nutrient Analysis; Revised Oregon State University Technical Report 215, Reference No 71 -22 Bidigare, R. R. M. Ondrusek, S. Sweet and J.M Brooks, 1987 Transpacific data report Geochemical and Environmental Research Group, Depanment of Oceanography, Texas A&M University Bullister, I.L and R. F. Weiss, 1988 Determination of CC13P and CC12F2 in seawater and air Deep. Sea. Res., 35, in press Carpenter, 1 H. 1965 The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method Limnol. Oceanogr., 10: 141-143 Culkin, F., 1965 The major constituents of seawater, in Chemical Oceanography, vol. 1, edited by J P. Riley and G. Skirrow, pp 121-158, Academic, Orlando, FL Dickson, A.G, 1981. An exact definition of total alkalinity and a procedure for the estimation of alkalinity and total inorganic carbon from titration data Deep Sea Res., 38A, 609-623 Johansson, D., and M Wedborg, 1982 On the evaluation of potentiometric titrations of sea water with hydrochloric acid. Oceanol. Acta., 5(2),209-218 Mantyla, A W., 1987. Standard seawater comparisons updated. J. Phys. Oceanogr., 17, 543-548. Ostlund, H. G. 1987, Tritium Laboratory Data Release #87-33: TPS47-Transpacific Cruise 1985, Tritium Results RSMAS Tritium Laboratory, University Of Miami Ostlund, H. G., and H. G Dorsey, 1977 Rapid electrolytic enrichment and hydrogen gas proportional counting of tritium In Low-Radioactivity Measurements and Applications, Proceedings of the International Conference on Low-Radioaclivity Measurements and Applications, 6-10 October 1975 The High Tatras, Czechoslovakia, Slovenske Pedagogicke Nakladatel'stvo, Bratislava Saunders, P. M, 1981. Practical conversion of pressure to depth J Phys. Oceanogr., It, 573-574 Takahashi, T. R.T. Williams, and D.L Bos, 1982. Carbonate chemistry in GEOSECS Pacific Expedition, vol. 3, Hydrographic Data, edited by W.S Broecker, D W Spencer, and H. Craig, pp 78-82, National Science Foundation, Washington, D C Talley, L., M. Martin, P.Salameh, 1988. Transpacific section in the subpolar gyre (TPS47), Physical, chemical and CTD data, R/V Thomas Thompson TT190, 4 August 1985 - 7 September 1985. Scripps Institution of Oceanography, SIO Reference 88-9. UNESCO, 1981 Background papers and supporting data on the International Equation of Slate 1980 UNESCO Tech Pap in Mar. Sci., No 38 6. PERSONNEL Ships' Captain: C. W. Clampitt - R/V THOMAS THOMPSON Personnel participating in collection of data at sea: Talley, Lynne Chief Scientist, Assistant Professor, SIO Joyce, Terrence Co-Chief Scientist, Associate Scientist,WHOI Beaupre, Marie Staff Research Associate, SIO Costello, James Staff Research Associate, SIO Cummings, Sherrie Staff Research Associate, SIO Delahoyde, Frank Principal Programmer, SIO Dunworth, Jane Research Assistant, WHOI Field, Timothy Marine Technician, SIO Hamann, Ilse Graduate Student, Univ of Washington Kelly-Hansen, Kim Oceanographer, NOAA/PMEL Martin, Margie Staff Research Associate, SIO Mattson, Carl Electronics Technician, SIO Pierce, Stephen Graduate Student, WHO/MIT Schnitzer, Michelle Research Associate, Texas A & M Univ. Spain, Peter Graduate Student, Univ. of Washington Sweet, Paul Staff Research Associate, SIO Vanwoy, Rick Staff Research Associate, SIO Warner, Mark Graduate Student, SIO Wells, James Marine Technician, SIO Additional personnel participating in analysis of CTD/hydrographic data: Bos, David Staff Research Associate,SIO Johnson, Mary Staff Research Associate, SIO Muus, David Staff Research Associate, SIO Patrick, Ronald Staff Research Associate, SIO