WHP Cruise Summary Information WOCE section designation A05 Expedition designation (EXPOCODE) 29HE06_1-3 Chief Scientist(s) and their affiliation Gregorio Parrilla, IEO Dates 1992.07.14 - 1992.08.15 Ship B.I.O. HESPÉRIDES Ports of call Cádiz to Sta. Cruz de Tenerife to Las Palmas de G.C. to Miami Number of stations 118 Geographic boundaries of the stations 26°04.19''N 80°03.95''W 15°58.08''W 24°28.40''N Floats and drifters deployed none Moorings deployed or recovered none Contributing Authors (In order of appearance) R. Millard M.J. Garcia A. Cruzado R. Molina J. Escánez W. Smethie F. Millero A.F. Ríos G. Rosón M. Garcia E. Alvárez Z.R. Velásquez J. García-Braun M.D. Gelado J.J. Hernández WHP Ref. No.: A5 Last updated: 2 May 1994 REPORT OF THE CRUISE HE06 1.1 CRUISE NARRATIVE 1.1.1 HIGHLIGHTS Expedition Designation: HESPÉRIDES A-5 CRUISE 06 (HE06) Chief Scientist: Gregorio Parrilla, IEO Ship: B.I.O. Hespérides Ports of Call: Leg 1 Cádiz - Sta. Cruz de Tenerife. Leg 2 Sta. Cruz de Tfe. - Las Palmas de G.C. Leg 3 Las Palmas de G.C. - Miami Cruise Dates: Leg 1 July 14 to July 17, 1992 Leg 2 July 17 to July 18, 1992 Leg 3 July 19 to August 15, 1992 1.1.2 CRUISE SUMMARY Cruise track is shown in fig. 1. Situation and date of stations are given in table I. Sampling: Water sampling included measurements of salinity both by CTD and bottle samples, CTD and bottle sample Oxygen determination, CTD temperature, nutrients (silicate, nitrate, nitrite and phosphate), CFC, pH, alkalinity, CO2, particulate matter, chlorophyll pigments, C14. Al. ACDP. Type and Number of stations: During the cruise 118 CTD/rosette stations were occupied using a 24 bottle rosette equipped with 10 or 12 liter in GO water sampling bottles; 6 test stations were made between Cadiz and Las Palmas de G.C., 101 on the A-5 section and 11 on the Strait of Florida Section. For navigation and placement of stations, GPS and dynamic positioning were used. 1.1.3 LIST OF PRINCIPAL INVESTIGATORS NAME RESPONSIBILITY AFFILIATION G. Parilla CTD IEO H. Bryden CTD JRC R. Molina S IEO J. Escánez O2 IEO A. Cruzado Nutrients CEAB W. Smethie CFC LDGO A. Ríos ph, Alk, CO2 IIM F. Millero ph, Alk, CO2 RSMAS G. Rosón Calcium IIM J. Garcia Braun Chlorophyll IEO Z. Velásquez Chlorophyll CEAB J. Hernández Al FCMLP W. Broecker C14 LDEO M. García ADCP UPC 1.1.4 PRELIMINARY RESULTS The ship departed from Cádiz on July 14, 1992 and 4 stations were made to test CTD and Rosette before arriving to Sta. Cruz de Tenerife on the 17th. After the ship left Tenerife on the 18th and before arriving to L. Palmas the same day two more test stations were performed and the ACDP was checked. During these stations several tests of a Falmouth Scientific Inst. CTD were also carried out. The ship departed from L. Palmas in the early hours of the 20th to arrive to the first station of the section A-5 the same day. This section was finished, after 101 stations were made, at the Bahamas on August 14th. During the next day the Strait of Florida Section was completed and the cruise accomplished. We carried 3CTDs, 2 belonging to IEO and 1 to WHOI. They are EG&G NBIS MARK III instruments equipped with Sensor Medics dissolved oxygen sensors and titanium pressure sensor (Millard et al 1991). All were calibrated at the WHOI facilities before the cruise. Because the delays inflicted by the hurricane Andrew on the equipment shipment from Miami to Woods Hole the post-cruise calibration were not performed on the CTDs until December. The conductivity and oxygen sensors were also calibrated at sea using the analysis of the water samples collected at each station. The depths of the sampling were based on the classical standard ones although they were varied on a station by station basis according to participants need to sample a particular layer provided there was no impairment of the in situ calibration activities. Table I STATION LATITUDE LONGITUDE DEPTH DATE TIME 1 24 29.97N 15 58.08W 51 07 20 92 17 23 2 24 29.96N 16 24.27W 120 07 20 92 20 07 3 24 29.95N 16 29.95W 570 07 20 92 21 31 4 24 30.18N 16 55.87W 1505 07 21 92 00 32 5 24 29.98N 17 04.93W 1895 07 21 92 05 47 6 24 29.72N 17 30.81W 2402 07 21 92 11 52 7 24 30.02N 18 00.04W 2555 07 21 92 16 02 8 24 29.43N 18 20.29W 2734 07 21 92 21 41 9 24 30.04N 18 45.04W 2944 07 22 92 02 22 10 24 30.08N 19 09.82W 3034 07 22 92 07 08 11 24 30.26N 19 35.04W 3378 07 22 92 22 25 12 24 30.20N 20 00.02W 3739 07 23 92 04 41 13 24 30.09N 20 40.01W 4162 07 23 92 11 12 14 24 30.00N 21 20.13W 4350 07 03 92 17 46 15 24 30.09N 21 59.07W 4673 07 04 92 01 00 16 24 29.85N 22 40.00W 4700 07 24 92 08 17 17 24 30.14N 23 20.32W 4991 07 04 92 15 22 18 24 30.04N 23 59.95W 5101 07 24 92 21 55 19 24 29.91N 24 40.21W 5197 07 05 92 04 23 20 24 29.90N 25 20.13W 5285 07 25 92 11 11 21 24 30.17N 25 59.92W 5347 07 25 92 17 40 22 24 30.17N 26 40.06W 4854 07 26 92 00 20 23 24 30.28N 27 19.65W 5536 07 26 92 06 51 24 24 30.00N 27 59.83W 5601 07 26 92 13 40 25 24 30.20N 28 39.39W 5655 07 26 92 20 15 26 24 30.16N 29 20.01W 5648 07 27 92 03 20 27 24 30.01N 29 59.90W 5408 07 27 92 09 57 28 24 30.01N 30 38.90W 5678 07 27 92 16 03 29 24 30.06N 31 20.27W 6080 07 27 92 22 45 30 24 30.17N 31 59.72W 5830 07 28 92 05 10 31 24 30.19N 32 39.57W 6320 07 28 92 12 05 32 24 29.95N 33 20.06W 6195 07 28 92 18 25 33 24 30.22N 33 59.85W 5650 07 29 92 01 24 34 24 30.27N 34 40.03W 5950 07 29 92 07 44 35 24 30.02N 35 19.85W 5035 07 29 92 14 22 36 24 30.10N 36 00.13W 5600 07 29 92 20 20 37 24 30.07N 36 39.91W 5020 07 30 92 02 55 38 24 30.06N 37 19.98W 5835 07 30 92 08 44 39 24 30.13N 38 00.05W 5567 07 30 92 15 38 40 24 30.14N 38 39.67W 4501 07 30 92 22 02 41 24 30.03N 39 19.93W 4370 07 31 92 03 39 42 24 30.15N 40 00.04W 5100 07 31 92 09 22 43 24 30.15N 40 34.85W 4572 07 31 92 14 45 44 24 29.95N 41 10.08W 5200 07 31 92 19 57 45 24 30.17N 41 44.97W 4789 08 01 92 01 37 46 24 30.00N 42 19.82W 4000 08 01 92 06 53 47 24 30.08N 42 54.88W 3574 08 01 92 12 15 48 24 30.02N 43 29.73W 3797 08 01 92 16 35 49 24 30.02N 44 04.85W 4177 08 01 92 21 39 50 24 30.21N 44 40.07W 3000 08 02 92 02 37 51 24 30.01N 45 15.08W 3640 08 02 92 07 00 52 24 29.93N 45 49.79W 2778 08 02 92 11 34 53 24 29.95N 46 24.91W 3511 08 02 92 14 58 54 24 29.95N 47 00.00W 3707 08 02 92 20 40 55 24 30.08N 47 34.98W 3980 08 03 92 01 25 56 24 29.84N 48 09.84W 3894 08 03 92 06 24 57 24 29.99N 48 44.97W 4379 08 03 92 11 27 58 24 30.03N 49 19.94W 5135 08 03 92 16 53 59 24 30.07N 49 54.77W 4796 08 03 92 22 29 60 24 29.90N 50 29.74W 4994 08 04 92 03 51 61 24 30.00N 51 04.95W 5076 08 04 92 09 25 62 24 30.08N 51 39.87W 4810 08 04 92 15 32 63 24 30.02N 52 14.99W 4728 08 04 92 22 03 64 24 29.99N 52 50.00W 5100 08 05 92 03 27 65 24 30.06N 53 24.93W 5637 08 05 92 09 04 66 24 29.92N 53 59.61W 6140 08 05 92 15 18 67 24 29.96N 54 40.00W 6209 08 05 92 21 34 68 24 29.94N 55 19.80W 5540 08 06 92 03 46 69 24 29.95N 56 00.01W 6444 08 06 92 09 57 70 24 30.03N 56 40.03W 6180 08 06 92 16 42 71 24 29.88N 57 19.79W 6116 08 06 92 23 51 72 24 29.91N 58 00.05W 6123 08 07 92 06 30 73 24 29.94N 58 39.96W 6071 08 07 92 13 09 74 24 30.08N 59 19.49W 5827 08 07 92 19 48 75 24 30.06N 60 00.12W 5937 08 08 92 02 04 76 24 30.00N 60 39.92W 5794 08 08 92 08 29 77 24 30.17N 61 19.40W 08 08 92 14 56 78 24 29.93N 61 59.88W 5891 08 08 92 21 37 79 24 30.07N 62 39.90W 5909 08 09 92 03 51 80 24 29.95N 63 20.12W 5850 08 09 92 10 33 81 24 29.95N 63 59.90W 5771 08 09 92 16 43 82 24 29.93N 64 39.94W 5762 08 09 92 23 12 83 24 30.37N 65 20.39W 5642 08 10 92 10 25 84 24 29.96N 65 59.98W 5764 08 10 92 17 05 85 24 30.04N 66 39.93W 5647 08 10 92 22 58 86 24 29.98N 67 19.99W 5658 08 11 92 05 14 87 24 30.01N 68 00.04W 5739 08 11 92 11 34 88 24 29.95N 68 39.93W 5712 08 11 92 17 32 89 24 29.92N 69 19.93W 5620 08 11 92 23 27 90 24 29.97N 70 00.00W 5561 08 12 92 05 20 91 24 29.87N 70 40.00W 5541 08 12 92 11 10 92 24 29.88N 71 19.92W 5519 08 12 92 16 50 93 24 30.00N 71 59.97W 5510 08 12 92 22 35 94 24 45.05N 72 35.94W 5497 08 13 92 04 10 95 24 59.80N 73 10.00W 5344 08 13 92 09 56 96 24 59.97N 73 49.95W 5242 08 13 92 15 38 97 25 00.00N 74 20.04W 4948 08 13 92 20 23 98 25 06.11N 74 49.77W 4702 08 14 92 01 47 99 24 32.77N 75 27.70W 3347 08 14 92 08 22 100 24 37.41N 75 19.12W 4800 08 14 92 11 45 101 24 30.00N 75 31.00W 930 08 14 92 16 03 Water samples were collected from 10 or 12 liters PVC Niskin GO bottles mounted on a GO Rosette Sampler. All the water sample conductivity and oxygen measurements were made in a constant temperature laboratory soon after each cast was completed. Descriptions of analytical techniques, precision and accuracy are given later in this report. Additional samples were also collected for the analysis of the other parameters listed above, description of which are presented in other sections of this report. According to the WOCE Implementation Plan this line was located at 24šN. As two oceanographic sections had been made previously in 1957 and 1981) around 24.5šN (Roemmich and Wunsch, 1985) we asked the WOCEIPO to move the WOCE section A5 to this latitude, which was agreed to. With respect to the station separations and because we were constrained by ship time, we decided to use the following judgment: the first 6 stations were located at the 50, 100, 150, 1500, 2000 and 2500 isobaths (about 18nm separation). From there to the 4000m depth (stl2) the separation was about 23nm. From station 12 to the eastern limits of the Mid Atlantic Ridge we separated the stations by 36nm. Across the Ridge the separation was 32nm. From its western limits to the 5000 isobath near the Bahamas, stations were separated again 36nm. Stations close to the Bahamas were separated by less than 30nm. The stations across the Straits of Florida were occupied every 5nm. Near to Bahamas we deviated the heading of the section slightly from the original plan in order to cross the continental slope perpendicular to the direction of the isobaths and to obtain a clear crossing of the Deep Western Boundary Current. The ADCP and a thermosalinograph recorded continuous during the whole cruise. Wind information was recorded every hour. At the end of the cruise the ship was checked for Tritium and C14 contamination by the Tritium laboratory of the University of Miami. Vertical profiles for T, S and O2 together with a listing of this data for standard depths for each station are given in the Annex. 1.1.5 INCIDENCES During the test stations, there were problems with the rosette: several of the bottles were not triggered. The trouble had to do, probably, with too much friction on the bolts since this rosette had never been used before. After some lubrication the problem disappeared. There were some problems, during the test stations and some of the first stations of the A-5 section, with the portside winch. The oil of the hydraulic circuit became too hot causing the winch to lose power. After station 11 we switched to the other winch that worked from the stern. On station 62, CTD # 1 stop sending conductivity data and it was replaced by CTD # 2 until station 74 when CTD# 1 was brought back, only for 7 stations since we started getting pressure spiking. From station 81 to 88 we used CTD #2 and from there on we used CTD# 1 after it was repaired on board. On station 83 the wire was reterminated after cutting off 10 m of wire because of a faulty electrical contact. It was also reterminated after station 110 (in the Florida Strait) because of two-blocking the CTD on recovery at this station. On station 61 the CTD hit the bottom because of a failure of the depth recorder. The portable hydrophone-recording system for use with the pinger failed from the beginning and we were not able to repair it. We tried to use the EA500 SIMRAD echo-sounder of the ship, but there was not the necessary documentation on board so we could not effectively use the pinger at all. We decided to keep the CTD package between 50 or 100 m above the bottom when the floor was too rough and less that 50 m when it was flat. The proposed Tritium and Helium survey by Dr. Z. Top could not be made since the equipment was lost during shipment from Miami and it never arrived to the ship. 1.1.6 LIST OF PARTICIPANTS NAME RESPONSIBILITY AFFILIATION G. Parrilla Chief Scientist IEO H. Bryden Co-Chief Scientist WHOI J. Alonso CTD Watch IEO E. Alvarez CTD Watch/Thermosalingraph PCM B. Amengual S, O2 IEO G. Bond CTD Watch/CTD Electronics WHOI J. Garcia-Braun O2, Chlorophyll IEO J. Hernández Al FCMLP A. Cantos CTD Watch/ADCP Ainco I A. Cruzado Nutrients CEAB J. Escánez O2 IEO S. Fiol CO2 U. La Coruña M.J. García CTD Watch/Data Processing IEO D. Gelado Al FCMLP E. Gorman CFC LDGO A. Lavín CTD Watch/Data Processing IEO R. Millard CTD Watch/CTD Programming WHOI R. Molina CTD Watch/S IEO J. Molinero Electronics IEO A. Osiroff CTD Watch/ Data Processing SHMA A.F. Ríos CO2/M.O.P. IIM G. Rosón Calcium IIM P. Sánchez CTD Watch/Data Processing IEO W. Smethie CFC LDGO Z. Velasquez Chlorophyll CEAB A. Fougere Falmouth SI CTD WHOI C. Heuer Tritium/Helium RSMAS G. Mathieu CFC LDGO 1.1.7 ACRONYMS IEO Instituto Espanol de Oceanografia IIM Instituto de Investigaciones Marinas CEAB Centro de Estudios Avanzados Blanes FCMLP Facultad de C. del Mar PCM Programa Clima Maritimo RSMAS Rosenstiel School of Marine and Atmospheric Sciences WHOI Woods Hole Oceanographic Institution LDGO Lamont Doherty Geological Observatory SHMA Servicio de Hidrografía Naval UPC Unversidad Politecnica de Cataluna JRC James Rennell Centre 2 MEASUREMENT TECHNIQUE AND CALIBRATIONS 2.1 CTD MEASUREMENTS (R. Millard and M.J. Garcia) 2.1.1 INSTRUMENTATION, CALIBRATIONS AND STANDARDS Two EG&G/NBIS Mark IIIb CTD underwater units each equipped with pressure, temperature, conductivity and polographic oxygen sensors were used throughout the cruise. The CTD instrument numbers are 1100 and 2326 and they belong to the Instituto Espanol de Oceanografia (IEO). Each CTD is configured identically with the same data scan length, variables, and scanning rate of 31.25 Hz. (A detailed description of the Mark IIIb CTD can be found in Brown and Morrison, 1978.) Both instruments were modified at Woods Hole Oceanographic Institution (WHOI) to add a titanium pressure sensor with a separately digitized resistive temperature device (RTD). A third EG&G/NBIS Mark IIIb CTD was provided by WHOI (WHOI instrument No. 8) but was not used during this expedition. A General Oceanics (GO) rosette fitted with 24 10 liters Niskin bottles was used with the CTD for collecting water samples. The GO rosette bottles are mounted approximately 0.5 m above the CTD sensors. Titanium pressure sensors were manufactured by Paine Instrument and were installed with a separate pressure-temperature sensor in both CTDs prior to the cruise. The pressure data has a resolution of 0.1 decibars and an overall accuracy of + 2.0 decibars for CTD# 1100 and + 5.0 decibars for CTD # 2326. The pre-cruise pressure calibration was used for CTD # 1100 while a combination of pre and post cruise pressure calibration was used to process CTD # 2326. The Titanium pressure transducer processing methods follow Millard, et. al (1993). Pressure is calibrated across the pressure sensor's range in the laboratory before and after the cruise. These calibrations are carried out at both room temperature and at the ice point. The temperature sensor is Rosemount platinum # 171. The fast response temperature thermistor normally employed in the Mark IIIb has been removed. The temperature resolution is 0.0005šC and the accuracy is better than ± 0.0015šC (Millard & Yang (1993)) over the range 0 to 30.0šC. Temperature was calibrated in the laboratory before and after the cruise with the CTD instrument fully immersed as described by Millard & Yang (1993). A large (0.01 to 0.015šC) shift of temperature in the same direction was observed to occur with both CTD's 1100 and 2326. This shift was traced to a faulty pre-cruise laboratory temperature standardization. The conductivity sensor is a 3 centimeter alumina cell manufactured by EG&G/NBIS. The resolution of conductivity is 0.001 Ms/cm and the accuracy is directly tied to the water sample salinity accuracy discussed elsewhere in this report. The overall accuracy of the CTD conductivity calibrated to the rosette water bottle salinities is believed to be better than ± 0.0025 psu. The CTD oxygen is measured with a polographic sensor manufactured by Sensormedics. The CTD oxygens are calibrated to shipboard Winkler oxygens. 2.1.2 CTD DATA COLLECTION AND PROCESSING The CTD data logging and processing was accomplished on two MSDOS PCs. The data logging was handled on an IBM compatible 80386 system with an 80387 math co- processor. The EG&G data logging program CTDACQ was used to record down and up profiles, separately on disk together with a rosette bottle file. The CTD data was edited to flag spurious data using the EG&G program CTDPOST. The remainder of the CTD post-processing was performed using the WHOI PC-based CTD processing system as described by Millard and Yang (1993). The post-processing was performed on an IBM compatible 80486 system with a 600 Mbyte optical disk (Sony SMO-C501) used for data archiving. 2.1.3 CTD CALIBRATION CONSTANTS The standard Alumina conductivity cell materials expansion factors: Alpha = -6.5 E-6, Beta = 1.5 E-8 were applied to CTD #1100 and CTD #2326. When the pre- cruise pressure calibration was applied to CTD 2326 data, a Beta = -1.5 E-8 was required to produce a salinity without a depth dependence; but a combination of pre/post-cruise pressure calibration allowed the use of the standard Beta value. The combined pressure calibration was used to process all CTD #2326 data because it produced CTD salinities free of depth dependence and yielded the pressure bias observed at sea. 2.1.3.1 PRE AND POST-CRUISE LABORATORY CALIBRATIONS POLYNOMIAL COEFFICIENTS Eng = E+Dr+Cr2 (where r is the measured raw CTD data value and Eng is the standard engineering unit of the variable). The coefficients for each sensor are: a) Pressure: (Loading/unloading) CTD #1100 E= -1.075; D= .108604; C= 0.593893 E-9 pre-cruise CTD #2326 E= 0.15; D= .104831; C= -0.799383 E-9 (pre-cruise) E= -12.5; D= .105437; C= -0.752607 E-9 (post-cruise) E= -6.3; D= .105127; C= -0.752607 E-9 (pre/post cruise combined) b) Temperature: (post-cruise) CTD #1100 (2nd order fit, stand. dev. = 0.00035) E= -0.4055; D= 0.499576 E-3;C= 0.13946 E-11: Lag= 0.225 s CTD #2326 (1st order fit, stand. dev. = 0.0006) E= 0.0026; D= 0.499889 E-3; Lag= 0.250 s c) Conductivity: For CTD #2326 and CTD #1100 conductivity calibrations the post-cruise temperatures were used. For CTD #2326 the data was pressure averaged again after the cruise using the combined pre/post-cruise pressure calibrations while CTD 1100 used the pre-cruise pressure calibration. The conductivity (salinity) calibration was examined closely at the change of instruments during the cruise (i.e. instrument swap outs at stations 62 - 63, 73 - 74, 80 - 81, 88 - 89) and no shifts were found that were not arguably due to oceanic variability. CTD #1100 This CTD required some fine-tuning of conductivity slope calibrations. Bias, E= -0.0116 for all the stations STATIONS SLOPE D= 1 - 62 0.1000 453 E-2 74 (fit to itself) 0.1000 565 E-2 75 0.1000 512 E-2 76 0.1000 510 E-2 77 0.1000 508 E-2 78 0.1000 506 E-2 79 0.1000 505 E-2 80 0.1000 503 E-2 89 - 91 0.1000 500 E-2 92 - 101 0.1000 483 E-2 (fit to sta. 93 - 95) Stations 96, 97 and 98 salinities are low compared to the water samples, but we believe that water sample salinities are suspect for these stations. CTD #2326 For this CTD, there is significant down-up hysteresis in one of the salinity sensors (P, T, or C: mostly likely Conductivity). The up-profile salinity is .005 - .007 fresher than the corresponding down-profile at a given potential temperature. Of course, at the bottom of the profile the salinity agrees but by 2.5šC (3500 dbars) on the 6000 dbar profiles a .005 psu discrepancy exists. A program was written to extract and create down-profile conductivity calibration data and we have to refit CTD #2326 conductivities below 2500 dbars. Stations 63 - 73, bias; E= 0.0083 STATION SLOPE, D= 63 0.1000 2693 E-2 (Fit to down profile conductivity) 64 0.1000 1727 E-2 65 0.1000 1699 E-2 66 0.1000 1671 E-2 67 0.1000 1642 E-2 68 0.1000 1614 E-2 69 0.1000 1585 E-2 70 0.1000 1557 E-2 71 0.1000 1529 E-2 72 0.1000 1500 E-2 73 0.1000 1472 E-2 81 - 88 Bias, E= 0.0121 0.999936 E-3 (01-27-93 calibration) Final CTD data edit: Two mean profiles were created. One for the West African Basin and a second for the North American Basin, by averaging all deep BIO Hésperides stations on pressure surfaces. These mean profiles have been used to screen the individual casts of each basin for question able temperature, salinity and oxygen data, comparing individual profiles to respective mean profile. Two edit criteria were used to flag questionable data: 1) Temperature, Salinity and Oxygen variations whose difference from the mean profile exceeding 5.5 standard deviations; 2) Stability parameter exceeding -1.0E-5 per meter. A list of stations with bad or questionable data at the surface is given below: 1 2 W African B. 17, 26, 32, 35, 39, 2, 5, 10, 18, 19, 41, 44, 47 20, 22, 23, 27, 28, 29, 31, 33, 34, 36, 37, 38, 42, 43, 45, 46, 48, 50, 51, 52, 53 N American B. 57, 74, 76, 81 55, 56, 58, 59, 60, 61, 62, 68, 69, 70, 72, 77, 78, 79, 80, 82, 85, 86, 87 1. Stations with bad or too low surface salinities. 2. Stations with questionable surface salinities. d) Oxygen The oxygen parameters were adjusted as shown on tables II and III. The header abbreviations denote the following: - STA= First and last station numbers of the group used for calibration. - BIAS, SLOPE, PCOR, TCOR, WT, LAG and Edit factor are parameters of the fit as described by Millard and Yang (1993). - STD DEV= Standard deviation of the fit after some outlying water sample observations are discarded. - OBS= Number of water sample observations used for the calibration. Table II COEFFICIENTS FOR OXYGEN CALIBRATIONS STN BIAS SLOPE PCOR TCOR WT LAG 1-11 .029 .1104e-02 .1664e-03 -.2783e-1 .7510e+00 .7560e+01 12-14 .049 .1139e-02 .1461e-03 -.2990e-1 .7500e+00 .7500e+01 15-19 .031 .1504e-03 -.2939e-1 .8219e+00 .4167e+01 15 " .1129e-02 " " " " 16 " .1156e-02 " " " " 17 " .1158e-02 " " " " 18 " .1170e-02 " " " " 19 " .1182e-02 " " " " 20-22 .024 .1197e-02 .1517e-03 -.3090e-1 .7408e+00 .7299e+01 23-31 .032 .1205e-02 .1491e-03 -.3033e-1 .7934e+00 .3211e+01 32-40 .024 .1228e-02 .1501e-03 -.2926e-1 .9210e+00 .7833e+01 41-43 .015 .1233e-02 .1553e-03 -.2998e-1 .7740e+00 .7000e+01 44-46 .006 .1229e-02 .1616e-03 -.3065e-1 .6702e+00 .1623e+02 47-50 .000 .1235e-02 .1673e-03 -.3092e-1 .5287e+00 .2187e+02 51-55 .012 .1226e-02 .1590e-03 -.2953e-1 .8080e+00 .7340e+01 56-62 .032 .1216e-02 .1499e-03 -.2906e-1 .8221e+00 .1549e+02 63-71 -.036 .1256e-02 .1683e-03 -.3041e-1 .7448e+00 .4612e+01 70 " .1269e-02 " " " " 72-73 -.047 .1338e-02 .1686e-03 -.3241e-1 .6362e+00 .2927e+01 74-80 .027 .1201e-02 .1515e-03 -.2865e-1 .8869e+00 .1027e+02 81-83 -.053 .1276e-02 .1788e-03 -.3177e-1 .6312e+00 .3351e+01 84-87 -.030 .1284e-02 .1645e-03 -.3047e-1 .8147e+00 .1998e+00 88 " .1320e-02 " " " " 89-101 .039 .1200e-02 .1459e-03 -.2779e-1 .9109e+00 .1390e+02 Table III STATISTICS OF ADJUSTMENTS FOR OXYGEN CALIBRATIONS STN STD DEV OBS STN STD DEV OBS 1-11 .7188e-01 59 of 59 47-50 .5274e-01 84 of 91 12-14 .4233e-01 46 of 60 51-55 .5526e-01 83 of 100 15-19 56-62 .3870e-01 116 of 131 15 .6791e-01 19 of 21 16 .1566e+00 18 of 20 63-71 .5401e-01 176 of 189 17 .5021e-01 19 of 21 70 .7953e-01 22 of 23 18 .3341e+00 21 of 21 19 .5171e-01 21 of 22 72-73 .8711e-01 45 of 45 20-22 .56355e-01 62 of 67 74-80 .6576e-01 159 of 161 23-31 .6148e-01 189 of 203 81-83 .6388e-01 64 of 66 32-40 .5958e-01 150 of 170 84-87 .7946e-01 72 of 72 88 .8969e-01 24 of 24 41-43 .7023e-01 68 of 69 89-101 .5241e-01 213 of 229 44-46 .4442e-01 68 of 69 Notes to these tables - Parameters obtained from stations 7 to 9 apply to stations 1 - 11. - Stations 15 to 19 were fit fixing parameters of 15 - 21 except slope. - Stations 32 to 39 calibrations applied to stations 32 to 40. - Station 70 calibrated as group 63 - 71 except slope - Station 88 calibrated as 84 - 87 except slope - Station 89 to 101. Sta. 96 and 98 are excluded in setting calibration parameters. When they were included WT was negative. Figure 2 shows the histograms for salinity and oxygen differences between CTD and bottle samples deeper than 2500 db. The mean and standard error for the first one are 1.9 E-4 and 1.3 E-4 respectively. For oxygen, they are 1.1 E-4 and 2 E-3. 2.2 SALINITY (R. Molina) For the salinity measurements the recommendations given in the training Course Notes (Ocean Scientific Int., Funchal, July 1991) were followed. The water sample salinities were measured with a Guildline Autosal Model 8400A salinometer. The manufacturer claims a precision of 0.0002 and an accuracy of 0.003 when the instrument is operated at a temperature between +4š and -2šC of ambient temperature. All the salinity measurements were made in a temperature controlled laboratory about 1š to 3šC below that of the salinometer water bath. Two different batches of standard water were used: batch P120 (April 6, 1992) with 50 ampoules and 20 ampoules from batch P117 (July 10, 1991). After the salinometer was standardized with water from the first batch, 8 samples from an ampoule of the second batch were measured, and the labelled value of 34.994 was obtained within 2x10-5. On the average, the salinometer was standardized every 31 samples. Water samples were collected from the Niskin bottles in Ocean Scientific International glass bottles and the measurements were made within the 24 hours after the station was finished. In total 2294 samples were measured. In determining the conductivity ratio, three measurements were made from every sample providing the differences were smaller than 2x10-5. If not, more measurements were made until three consecutive values exhibited differences smaller than 2x10-5. In 3 stations, samples were replicated with the following results: STA. DEPTH BOTTLE NO. NO. OF SAMPLES STANDARD DEV. 50 2500 02,3,4,5,6,7 6 ± 3.6x10-4 64 2532 6 8 ± 1.3x10-4 72 249 16 8 ± 2.1x10-4 During one day when the air conditioning of the laboratory broke down, salinity measurements for stations 2 to 3 were made with the laboratory temperature 0.3šC above the salinometer bath temperature. 2.3 OXYGEN (J. Escánez) Oxygen determinations were carried out following the Winkler method and using the reagents prepared according to Carpenter (1965). We used the modified Carpenter's equation as given by Culberson et al (1991). The endpoint of titration was determined visually using starch as indicator. Reagents were dispensed with all glass and teflon dispensers "Dispensette" from Brand GMBH and Co. (0-2 ml capacity) with certified accuracy of ± 0.6% and a coefficient of cariation of ± 0.1%. The tips of the dispensers were lengthened up to 6 cm with thin plastic tubing to avoid the precipitation of manganese hydroxide in the neck of sample flasks. Titration was done with a Metrohm Dosimat E.412 automatic burette using Potassium Iodate "pro.anlaysi" Merck (Lot Nº 150 BZ 252853. Assay 99.95 - 100.05%) at a concentration of 0.0100 N. Standards and blanks were dispensed with class "A" calibrated hand pipets with certified accuracy of ± 0.02 ml for 10 ml pipets and ± 0,006 ml for 1 ml pipets. In total, 2338 samples were taken (Table IV). In order to assess good quality results, calibration sets were run through 7 stations. Inter-sample calibrations were run on 3 stations by taking 1 sample from 6 Niskin bottles triggered at the same depth, while on 4 stations intra-samples calibrations were performed taking 6 samples of 2 Niskin bottles triggered at the maximum and minimum O2 layers respectively. Values are shown in Tables V and VI. Table IV DISTRIBUTION OF CASTS/ANALYSTS ANALYSTS STATION CASTS STATIONS ANALYZED NO. OF SAMPLES ANALYZED J.G. Braun 36 11 234 B. Amengual 38 20 446 J. Escánez 38 81 1658 Table V CALIBRATIONS BETWEEN CASTS STN DEPTH BOTTLE NO. O2 (ML/L) MEAN O2 (ML/L) STD. DEV. 1 40 m 12,13,14,15,17 X= 5.711 sd= ± 0.009 1 40 m 1,2,3,4,5,6 X= 4.661 sd= ± 0.031 50 2500 m 2,3,4,5,6,7 X= 5.655 sd= ± 0.005 107 378 m 3,4,5,6,7,8 X= 2.998 sd= ± 0.005 Table VI CALIBRATIONS WITHIN CASTS (MAXIMUM AND MINIMUM) STN BOTTLE MAX/MIN O2 (ml/l) O2 (ml/l) NO. O2 MEAN STD. DEV. 14 1 Max X= 5.601 sd= ± 0.015 14 10 Min X= 2.575 sd= ± 0.003 32 8 Max X= 5.622 sd= ± 0.002 32 12 Min X= 3.294 sd= ± 0.014 67 6 Max X= 5.907 sd= ± 0.009 67 12 Min X= 3.513 sd= ± 0.002 89 5 Max X= 6.193 sd= ± 0.003 89 11 Min X= 3.469 sd= ± 0.005 2.4 NUTRIENTS (A. Cruzado) Analyses were performed on board with a four channel SKALAR segmented flow autoanalyzer. Samples were collected in 150 ml acid-rinsed polythene flasks directly from the Niskin bottles, following the protocol established by the WOCE Hydrographic Programme. Analyses were carried out immediately without any treatment of the samples. When necessary, samples were kept in the cold room (unfrozen and never for more than 10 hours) without additives. The analytical techniques followed were those described by Whitledge et al. (1981) with minor modifications to adapt them to the particular conditions of the instrument used and concentration ranges observed. Primary standards were prepared at the beginning and in the middle of the cruise prepared every two days and preserved with some drops of chloroform in the fridge. Running standards were interleaved with unknown samples in order to provide a measure of analytical stability. Whenever changes in sensitivity (particularly in the case of nitrate) were noticed, these standards allowed for a correction to be applied. All concentrations were referred to double distilled water prepared by reverse osmosis through milliRo, dionization through Milli-Q and distillation. No sea water sample has ever given a concentration negative with respect to this double distilled water. Phosphate analysis corrected for the change in absorbance due to the salinity effect. Surface seawater was used as carrier and, except for silicate, it always showed the minimum concentrations in the water column. Silicate concentrations below the surface were often found to be lower than the surface values and very close to the values given by double distilled water. Replicate samples were analysed at various depths both from the same and from different Niskin bottles. A comparison of all the primary and secondary standards used during the cruise is underway and may introduce some small corrections to the results. A statistical assessment of such analyses is being prepared. Some nutrient diagrams are shown in figure 3. ADDENDUM TO THE REPORT ON CRUISE HE06 (A-5, WOCE 1992). NUTRIENTS (A. Cruzado) During the HE06 cruise (July/August 1992) along the WOCE line A-5, dissolved inorganic nutrients (orthophosphate, nitrate+nitrite, nitrite, and orthosilicate) were collected and analyzed on board the R/V Hesperides using a continuous flow analyzer by Antonio Cruzado (Centro de Estudios Avanzados de Blanes, Spain) following methods adapted from Withledge et al. (1981). These methods were used in the fifth 1989/1990 ICES international inter-comparison exercise for nutrients in seawater (Aminot and Kirkwood, 1995). Three different quality control procedures were applied to the A5 nutrient data. First, spurious chemical data were flagged according to WOCE quality control codes. These are data values shown to be analytically incorrect ("Bad"). Second, the A5 chemical data were compared to the August 1992, Trident cruise on the RV Baldrige between Abaco Island, the Bermuda Rise and the Mid-Atlantic Ridge (Garcia, 1996). This provided a mean to compare the two cruises in the western basin only. Third, the A5 data were compared to historical oceanographic data collected since the GEOSECS program (Table 1). The long-term precision of the A5 chemical data was estimated following the method of Saunders (1986). Potential temperature (Fofonoff and Millard, 1983) was fitted to the nutrient data from the HE06 and AT109 cruises by linear least-squares for water with temperatures less than or equal to 1.8ºC and 2.1ºC in the western (45-75 W) and eastern (20-44 W) Atlantic basins, respectively (Garcia, 1996). The standard deviation of the measured values for each chemical variable from the expected values calculated from the coefficients of the regression lines for stations in the western and eastern basins are shown in Table 2. Chemical data points which deviated significantly (more than 5 SD from the mean) were flagged as questionable. No quality control was applied to the nitrite data. Table 1 HISTORICAL DATA (1972-92) USED IN THIS WORK CRUISE/LEG SHIP CRUISE DATES INSTITUTION AT109-II Atlantis II August-September,1981 WHOI AT109-I Atlantis II June-July,1981 WHOI Trident Baldridge August,1992 LDEO EN129 Endeavor April,1985 WHOI GEOSECS Knorr July,1972-April,1973 SIO TTO-NAS Knorr April-October,1981 SIO TTO-TAS Knorr December-February,1983 SIO KN104 Knorr July-August,1983 WHOI OC133-II Oceanus January,1983 WHOI OC202 Oceanus July-September,1988 SIO Table 2 ESTIMATES OF PRECISION (1 SD) OF THE AT109-II AND HE06 CHEMICAL DATA. NUMBERS IN PARENTHESIS INDICATES THE NUMBER OF DATA POINTS IN THE CALCULATION DESCRIBED IN THE TEXT ABOVE (GARCIA, 1996). CRUISE PHOSPHATE N+N SILICATE OXYGEN WESTERN ATLANTIC (75-45 W) AT109-II 0.04 (81) 0.5 (83) 1.8 (83) 2.2 (86) HE06 0.08 (58) 0.3 (79) 1.9 (82) 1.4 (83) EASTERN ATLANTIC (20-44 W) AT109-II 0.03 (65) 0.2 (64) 0.6 (64) 1.9 (74) HE06 0.08 (62) 0.2 (88) 0.9 (94) 1.6 (99) 2.5 CFC-11 AND CFC-12 (W. Smethie) The objective of the CFC measurement program on this cruise was to measure the distribution of CFC-11 and CFC-12 in the thermocline along 24šN in the Atlantic and in recently ventilated components of North Atlantic Deep Water, including the Deep Western Boundary Current, spreading southward in the western North Atlantic. The CFC measurements were made on board with a CFC analysis system interfaced to a gas chromatograph with an electron capture detector. This method is described in Smethie et al. (1988) and is similar to the Bullister and Weiss (1988) technique. One difference for this cruise was the use of a Porasil B precolumn and a SP21000 main column instead of Porasil B for both columns. This combination allowed CFC-113 and carbon tetrachloride to be detected as well as CFC-11 and CFC-12. However carbon tetrachloride and CFC-113 were not measured on every station because of the longer analysis time required. The purpose of these measurements was to obtain preliminary information on the distribution of these substances in the ocean and they are not of the same quality as the CFC-11 and CFC-12 measurements. Some problems were encountered. A set of new syringes had a low level CFC-11 contamination (0.02 - 0.04 pmol/kg). Blanks for these syringes were determined and monitored by analyzing zero CFC water from the deep eastern basin or by comparison to duplicate samples collected in old syringes which were not contaminated. These blanks decreased during the cruise. There was a high (20- 30% of surface water concentration) and variable CFC-113 system blank and the Niskin bottles became severely contaminated with CFC-113 at station 75, probably due to a fire control exercise by ship's personnel, and remained contaminated for the remainder of the cruise. The general sampling strategy was to sample every other station which resulted in approximately 60 nm spacing. Every station was sampled near the western boundary. Generally 10 or 11 samples were taken between the surface and 1000 m along the entire section. In the eastern basin the deep water contained no CFCs, but samples were collected to determine Niskin bottle/sampling blanks and syringe blanks. In the western basin, CFCs were detected throughout the water column. Vertical spacing varied between 150 and 400 m with more closely spaced samples at about 1500 m and 3500-4000m to resolve CFC maxima at these levels. A section was also taken across Florida Strait with approximately 5 nm horizontal resolution and 50-100 m vertical resolution. A total of about 1100 water samples, not including duplicates, were analyzed. In the figure 4, shown are vertical profiles of preliminary shipboard values of F-11. 2.6 pH, ALKALINITY, CO2 These measurements were carried on board by two independent groups. 2.6.1 CO2 (F. Millero) The total alkalinity, TA, total carbonate, TCO2 and pH were determined from titrations of seawater collected at 31 stations. The titrators were calibrated with Dickson standard before and during the cruise. The results agree to ±7 µmol Kg-1. The pH was determined from the initial emf reading relative to TRIS buffers. The results for Dickson samples agree with laboratory spectroscopic measurements to ±0.005m ptl. The values of the partial pressure of carbon dioxide, pCO2, were calculated from the TA and TCO2 are higher than the atmospheric values. In figure 5 some preliminary results are shown. 2.6.2 pH AND CO2 (A.F. Ríos) Direct pH measurements were made on the NBS scale for all stations (1 to 112 inclusive and at all levels, about 2400 samples total). The samples, kept in a 50 ml plastic bottles and perfectly closed, were introduced into a combined glass electrode associated to a thermocompensater. Measurements were referred to 15šC according to the variation of pH with temperature (Pérez and Fraga, 1987a). The accuracy of measurement is 0.1% of the total inorganic carbon (Zirino, 1985), i.e. ±0.004 units, but in samples taken in very homogenous water columns it is possible to detect differences less than this value. Alkalinity measurements were made by titration of about 250 ml of a seawater sample with HCl O, 13N, with potentiometric detection of the endpoint (Pérez and Fraga, 1987b). Stations 1 to 101 were sampled at all levels (about 2300 samples). Reproducibility was tested by sampling a 25 l storage bottle and was found to be less than 0.1%. Total inorganic carbon and carbon dioxide pressure was determined indirectly from the pH and alkalinity according to methods described by Pérez and Fraga (1987b). Some preliminary results are shown in figure 6. 2.7 PARTICULATE ORGANIC MATTER (A.F. Ríos) Two liters of seawater at levels (10, 15, 50, 100, 200 and 400 m) on 25 stations were filtered through a glass fiber filter (Whatman GF/F of 25 mm diameter) in order to determine the particulate carbon and nitrogen using a 2400 Perkin Elmer Elemental Analyzer. To determine particulate phosphorous, samples of one liter of seawater retained I filters (Millipore AAWPO2500) were taken at the same stations and levels as before. These samples will be oxydized with percloric-sulphuric acid (Ríos and Fraga, 1987) and later determination of phosphate will be carried out by the method described by Grasshoff et al. (1983). Carbohydrates will be determined by the technique of Antron reagent (Rios, 1992) from samples of one liter of seawater retained in filters (Millipore AAWP02500) taken at these same stations and levels. 2.8 CALCIUM (G. Rosón) The 450 samples analyzed for this parameter were taken on 20 stations at all levels. The method used for determining calcium is a volumetric titration of about 130 g of seawater with potentiometric detection of end point by calcium selective electrode, using EGTA (ethyleneglycol-bis) (B-aminoethyleter), N, N, N1, N1, tetraacetic acid) as titrant (0.18 M) and 25 ml of borax (0.1 M) as buffer (Rosón and Pérez, 1990; Rosón, 1992). The reproducibility of the method, made on a 25 l storage bottle, was 0.07% for 70 samples. 2.9 CARBON-14 (W. Smethie for W. Broecker) Carbon-14 samples were collected in the thermocline at a few select stations. These samples will be analyzed by accelerator mass spectrometry. This is part of a larger program to collect samples over the entire North Atlantic from ships of opportunity during the next few years. The objective is to determine the distribution of bomb carbon-14 in the thermocline and compare this distribution to the distributions measured in 1981 on the TTO program and 1972 on the GEOSECS program. The evolving bomb carbon-14 distribution will be used to investigate circulation and mixing in the thermocline and uptake of carbon dioxide by the ocean. Samples were collected at stations 13, 24, 35, 53, 66, 81, and 92. In general 8 samples were collected at each station, one in the surface mixed layer and seven at the following sigma-theta surfaces: 26.2, 26.4, 26.6, 26.8, 27.0, 27.2, and 27.4. Samples were also collected at stations 103 (one in the oxygen maximum) and 107 (six throughout the water column) in the Straits of Florida and at test station (ten samples) just west of the Strait of Gibraltar. A total of 71 samples were collected. 2.10 ADCP (M. Garcia) The ADCP model used was a RD-VMO 150. The selected sampling intervals were 180 s, 40 depth bins of 8 m length. The profiler was recording continuously during the whole cruise and the data was recorded on diskettes. 2.11 THERMOSALINOGRAPH (E. Alvárez) During W.O.C.E. A-5 section, temperature and salinity were measured across the Atlantic Ocean surface using a Seabird thermosalinometer (serial number 626a). Data acquisition began on station number one and finished close to Miami harbor. The time step between each acquisition was three minutes. The obtained data were stored in groups of files, each group corresponding to one navigation day. Water conductivity was recorded from the third navigation day on. Two electricity failures (during the second and fourth days) and at least one water flux stoppage (during the fourth day) interrupted the continuous time series. 2.12 CHLOROPHYLL PIGMENTS AND PRIMARY PRODUCTION Two kinds of analysis have been undertaken for pigment studies. One was based on spectrophotometric equations with readings of absorbances at 664, 645, 630 and 750 nm. In the other smaller volumes of seawater were used for analysis of chlorophyll and phaeopigments based on fluorescence readings before and after acidification of the sample. 2.12.1 CHLOROPHYLL PIGMENTS (Z.R. Velásquez) Water samples were taken at several depths (0-250m) on all stations of the WOCE A-5 section from NW Africa to the Bahamas. The phytoplanktonic pigments were determined on board immediately after sampling by the spectrophotometric technique described by Jeffrey and Humphrey (1975). About 3.3 liters of seawater were filtered under vacuum through 4.7 cm Whatman GF/F filters. After extraction during a minimum of 24 hours with 5 ml (90%) acetone in the dark at 0šC, the resulting suspension was centrifuged at 3000 rpm for 30 minutes. The absorbances at 664, 645 and 630 nm, required for the computation of the concentrations of Chlorophyll A, B and C, were determined in the supernatant (5 ml), allowance being made for the eventual presence of turbidity by measuring also the absorbance at 750 nm. All absorbance measurements were done with a LBK spectrophotometer linked to a computer. The following formula was used for the computation of the pigment concentration in the supernatant in µg/l. (Chlorophyll (µg/l) =OD* Vac/Vsw OD (a) = 11.85*(D664-D750)-1.54* (D645-D750)-0.08*(D630-D750) OD (b) = 21.03*(D645-D750)-5.43* (D664-D750)-2.26*(D630-D750) OD (c) = 24.52*(D645-D750)-1.67* (D664-D750)-7.66*(D645-D750) where Vac = volume of acetone (in ml); Vsw = volume of seawater (in l); Dxxx = optical density at wavelength xxx and 1 cm optical path Pheopigments were determined by acidifying the extracts with two drops of 10% HCl and reading at the same wavelengths. Samples of water at the same level were preserved with Lugol (Potassium Iodate/Iodine solution buffered with sodium acetate) for further phytoplankton analysis with an Olympus inverted microscope to which a computer/video digitizing system has been adapted. In the figure 7 vertical profiles of total chlorophyll for stations 1 through 60 are shown. 2.12.2 CHLOROPHYLL PIGMENTS AND PRIMARY PRODUCTION (J. García-Braun) Water samples were taken for pigment analysis at several depths (mainly, 0 - 200 m) on 90 stations for a total of 1152 analyses for chlorophyll and phaeophytin. With respect to the pigment distribution in the water column, ours main objectives were: to obtain the vertical distribution of chlorophyll a, based on fluorescence readings, calibrated against spectrophotometer following SCOR- UNESCO (1966) and the vertical distribution of chlorophyll and phaeophytin, based on fluorescence readings, before and after acidification, according to equations by Lorenzen (1966); and to estimate the pigments biomass including size classes, evaluating picoplankton less than 2 microns and populations bigger than 2 microns. Two samples of 1 liter sea water for each depth were filtered through Whatman GF/F filters. Pigments were extracted in 10 ml of 90% acetone during about 12 hours in the dark at 0šC. The fluorescence measurements (before and after acidification with two drops of 10% ClH) were used to calculate the pigments according with the following equations: Chlorophyll a = 11.64 e663 - 2. 16 e645 + 10 e630 where e663, e645 and e630 are the absorbances at 663, 645 and 630 nm after substration of the absorbance at 750 nm, using 1 cm spectrophotometer cell. If the obtained value is multiplied by the extract volume in ml and divided by the volume of seawater filtered in liters, the amount of chlorophyll a in mg/m3 is obtained. The equation proposed by SCOR-UNESCO (1966) was used to calibrate the Fluorometer Turner Design in which all the readings of Fluorescence were made during the cruise. Concentrations of chlorophyll a and phaeophytin a were also calculated following the equations given by Lorenzen (1966). Vertical profiles of chlorophyll and phaeophytin for several stations are shown in figure 8. 2.12.2.1 PRIMARY PRODUCTION (J. García-Braun) Water samples for primary production experiments were taken at several depths in the photic zone, representing approximately 100%, 25%, 10% and 1% of surface light. The standard C14 method proposed by Steeman Nielsen (1952) was used with some modifications. The incubations were done in incubators under artificial light during 2-3 hours. The selected stations (11 stations and 99 samples) were chosen in order to make the incubations in early hours during the morning. For each depth, samples of 100 cc of seawater were inoculated with 4 µ Ci of C14 bicarbonate. After incubation one sample was passed through Nucleopore filter (2 micron pore size) and the other sample through Whatman GF/F filters. A separate sample was incubated in the dark in order to substract the incorporated radioactivity with respect to the light bottles. The filters were preserved in the deep freeze for future readings of counts per minute in a Liquid Scintillation Counter. 2.13 ALUMINUM (M.D. Gelado and J.J. Hernández) A voltametric method was used for aluminum determination during WOCE-AS Cruise. The procedure is based on complexation of aluminum with 1,2- dihydroxyanthraquinone-3-suplhonic acid (DASA) and measurement of reduction current of this complex using high speed cathodic stripping voltametry (HSCSV). Reduced Al-DASA complex produces an intensity of faradaic current proportional to dissolved Al concentration. The free DASA ligand has a cathodic peak at - 0.63 V while Al-DASA peak is more negative at -1.1 V (Ag/ClAg). Optimal experimental parameters include an accumulation potential of -0.95 V during 45 s, DASA concentration 2x10-6 M and staircase scan mode to 30 V/s speed. Samples are buffered at 7.1 pH using N, N1bis(2-hydroxyethyl)-2- aminoethane suphonic acid(BES). The method (Gelado-Caballero, 1992) is specially adapted for on board determinations. The electrochemical system has been designed to measure the instantaneous currents at short times with a low noise level (Hernandez-Brito et al., 1990). Thus, the analytical time required for each sample is substantially reduced, allowing an increase of the number of measurements in situ. A PAR303A electrochemical cell with hanging mercury drop electrode (HMDE) was connected to a specially made computer-controlled potentiostat. The detection limit was 1.75 nM for 30 s adsorption time. The deviation was less than 3% for a 19 nM Al concentration based on repetitions for 7 seawater samples. In total 1000 samples were taken in 52 stations. In most of the stations, except in those close to the African coast, maximum was detected at the surface layers. Below a minimum at intermediate depths the dissolved Al concentrations increased with depth. ACKNOWLEDGEMENTS This project was supported by IEO (Proy.1308), CICYT (Acc. Esp. AMB92-1114-E). Participation on this cruise by H. Bryden, R. Millard and G. Bond and subsequent processing and analysis of the measurements by H. Bryden and R. Millard were supported by NSF and NOAA. We are grateful to Junta de Gestión del B.I.O. Hespérides for its support and collaboration, as well as to those colleagues of the IEO who encouraged us and lent us their help. We also wish to acknowledge the seamanship, ability and friendship displayed by the captain and crew of the B.I.O. Hespérides who contributed specially to the completion of the cruise. 3 REFERENCES Aminot, A. and D. Kirkwood. 1995. Report on the results of the fifth ICES intercomparison exercise for nutrients in sea water. International Council for the Exploration of the Sea. ICES Cooperative Res. Rep. No. 213. 79 pp. Bullister, J.L. and R.F. Weiss. 1988. Determination of CC3F and CCl2F2 in seawater and air. Deep-Sea Research. No. 35. pp. 839-853. Carpenter, J.H. 1965. The Chesapeake Bay Institute technique for the Winkler dissolved oxygen titration. Limnology and Oceanography. No. 10. pp. 141- 143. Cruzado, A., Z.R. Velásquez. 1991b. Expert System for the Management of a Plankton Taxonomy and Environment Data and Video Image Base. (in press). Culberson, C.H., G. Knapp, M.C. Stalcup, R.T. Williams and F. Zemlyak. 1991. A comparison of methods for the determination of dissolved oxygen in seawater. WHPO publication 91-2. WOCE Rep. No. 73/91. 77 pp. Fofonoff, N. P., and R. C. Millard. 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. Mar. Sci. No. 44. 53 pp. Garcia, H. E. 1996. On the large-scale characteristics, fluxes and variability of the North Atlantic deep water and its deep western boundary current deduced from nutrient and oxygen data. Ph.D. thesis, College of Oceanic and Atmospheric Sciences. 184 pp. Gelado-Caballero, Ma.D. 1992. Determinación electroquímica del Aluminio en Agua de Mar. Una Aproximación al Ciclo Biogeoquímico. Tesis Doctoral, Universidad de Las Palmas de Gran Canaria. Grasshoff, K., M. Ehrhardt and Kremling. 1983. Methods of Seawater Analysis. Verlag Chemie, Weinheim, New York, 419 pp. Hernandez Brito, J.J., P. Cardona-Castellano, J. Perez-Pena and Ma.D. Gelado- Caballero. 1990. Development of a Computerized Electrochemical System for Stripping Voltametry. Electroanal., No. 2. pp. 401-408. Jeffrey, S.W., G.F. Humphrey. 1975. New spectrophotometric equations for determination of chlorophyll a, b, c and C2 in higher plants, algae and natural phytoplankton. Biochemie und Physiologie des Pflanzen. No. 167. pp. 191- 194 Lorenzen, C.J. 1966. A method for the continuous measurements of "in vivo" chlorophyll concentration. Deep-Sea Research. No. 13. pp. 223-227. Millard, R., G. Bond and J. Toole. 1993. Implementation of a Titanium strain gange pressure transducer for CTD applications. WHOI Contr. No. 7865. Millard, R. and K. Yang. 1993. CTD calibration and processing methods used by Woods Hole Oceanography Institution. WHOI Techn. Rep. 93-44. 95 pp. Pérez, F.F. and F. Fraga. 1987a. The pH measurements in seawater on the NBS escale. Mar. Chem. No. 21. pp. 315-327. Pérez, F.F. and F. Fraga. 1987b. A precise and rapid analytical procedure for alkalinity determination. Mar. Chem. No. 21. pp. 169-182. Ríos, A.F. and F. Fraga. 1987. Composición química elemental del plancton marino. Inv. Pesq. No. 51. pp. 619-632. Ríos, Aida F. 1992. El fitoplancton en la Ria de Vigo y sus condiciones ambientales. Tesis doctoral, Universidad de Santiago. 416 pp. Roemmich, D. and C. Wunsch. 1985. Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean. Deep-Sea Research. No. 32 (6). pp. 619-664. Rosón, G. and Fix F. Pérez. 1990. Determinación potenciométrica de calcio en agua de mar. Sem. Qui. Mar. No. 5. pp. 121-128. Universidad de Cádiz. Rosón, Gabriel. 1992. Flujos y ciclo del carbonato cálcico en la Ría de Arosa. Tesis doctoral, Universidad de Santiago. 485 pp. SCOR-UNESCO. 1966. Determination of phosynthetic pigments in seawater. In. Monographs on oceanographic methodology. 69 pp. Smethie, W., D.W. Chipman, J.H. Swift and K.P. Koltermann. 1988. Chlorofluoromethanes in the Arctic Mediterranean Seas: Evidence for formation of bottom water in the Eurasian Basin and Deep Water through Fram Strait. Deep-Sea Research. No. 35. pp. 347-369. Steeman Nielsen, E. 1952. The use of radioactive carbon (C14) for measuring organic production in the sea. J. Cons. Int. Explor. Mer. No. 18. pp. 117- 140. Whitledge, T. E., S. C. Malloy, C. J. Patton and C. D. Wirick. 1981. Automated nutrient analysis in seawater. Brookhaven National Laboratory, U.S. Dept. of Energy and Environment, Upton, NY. 216 pp. Zirino, A. (Editor). 1985. Mapping Strategies in Chemical Oceanography. American Chemical Society, Washington D.C. 470 pp. --------------------------------------------------------------------------------- DQE OF CTD DATA FOR THE 6TH CRUISE OF THE R/V "HESPERIDES", WOCE SECTION A5 ACROSS THE NORTH MID-LATITUDE ATLANTIC. Eugene Morozov Data quality of 2-db CTD temperature, salinity and oxygen profiles and reference rosette samples were examined. Vertical distributions and theta-salinity curves were compared for individual stations using the data of up and down CTD casts and rosette probes. Data of several neighboring stations were compared. Questionable data in *.hy2 file were marked in QUALT2 word. The calibration of upcast CTDSAL and CTDOXY data seem to be worse than downcast data. There were two data sets for WCT files. One for the eastern part of the section the (station numbers 49 and less) and the western part (stations 50-112). The data sets came different sources so I analyzed them separately. Listing of results from the comparison of salinity and oxygen data. Only those stations are listed which have data remarks. Eastern part STATION PRESSURE REMARKS 9 585 db OXYGEN is low (2.61) compared with upcast CTDOXY (3.94) and downcast CTDOXY (3.06). Downcast CTDOXY seems reasonable. I flag both OXYGEN and upcast CTDOXY 4 -Bad. Upcast CTDTEMP is wrong (3.943) 11 3045 db OXYGEN (5.59) is high compared with upcast CTDOXY (5.45) and downcast CTDOXY (5.44), flag 4. 3372 db SALNTY is 0.02 PSU higher that CTD upcast and downcast, the flag is 4 - SALNTY - Bad 12 A strange sequence of samples is given in .hy2 file. It is not in accordance with pressure. It causes difficulties to work with such a file. Some of samples correspond to negative pressure, they should be removed from the file. Enormous differences (over 2.3 PSU) are found between SALNTY and CTDSAL at several levels. Some of them are flagged 4 - Bad, some not. I flag bad SALNTY at: 343 db 367 db 401 db. 454 db SALNTY (35.750) and upcast CTDSAL (35.846) both are Bad. They do not match with downcast CTDSAL (35.720). Similar problems with oxygen at the same levels: I flag OXYGEN 4 - Bad at levels: 343 db 367 db 401 db 454 db I flag upcast CTDOXY 4 - Bad at levels: 78 db 343 db 367 db 401 db 13 2025 db SALNTY (35.050) is high compared with 35.039 upcast and 35.041 downcast CTDSAL, flag 4. 2533 db SALNTY (34.989) is high compared with 34.982 upcast and 34.979 downcast CTDSAL, flag 4. 3053 db SALNTY (34.946) is high compared with 34.940 upcast and 34.941 downcast CTDSAL, flag 3. 4078 db SALNTY (34.894) is low compared with 34.896 upcast and 34.896 downcast CTDSAL, flag 3, these are very deep waters. 14 SALNTYes are lower than upcast CTDSAL by at least 0.01 for the whole station, better for downcast CTDSAL. The flag is 3 for the whole station SALNTYes 403 db SALNTY (35.789)is high compared with 35.742 upcast and 35.734 downcast CTDSAL, flag 4. 4070 db SALNTY (34.884) is low compared with 34.898 upcast and 34.899 downcast CTDSAL, flag 4. 4377 db SALNTY (34.881) is low compared with 34.894 upcast and 34.894 downcast CTDSAL, flag 4. 15 65 db There is a strange 20 m thick layer of low salinity water. It is temperature compensated and even the oxygen is slightly less. It seems true because it is supported by bottle measurements although there are differences between CTDSAL and SALNTY. They can be explained by high salinity gradient. There is no such a layer on neighboring stations. I cannot make out where this freshened water could appear from in the middle of the Canary Basin. 1515 db There are differences between SALNTY (35.170) and downcast CTDSAL (35.157). Upcast CTDSAL matches well with SALNTY (35.172). I don't flag anything questionable and attribute these differences to tidal internal waves which are extremely large here. 4646 db SALNTY (34.901) is high compared with upcast 34.892 and downcast CTDSAL 34.892 flag 4. 16 762 db SALNTY (35.223) is high compared with upcast CTDSAL 35.212 and downcast CTDSAL 35.198, flag 4. 4734 db SALNTY (34.905) is high compared with upcast CTDSAL 34.890 and downcast CTDSAL 34.890 , flag 4. CTDOXY downcast calibration is wrong below 1500 db. The values are higher that OXYGEN and measurements on neighboring stations. 4734 db OXYGEN (5.59) is low compared with upcast CTDOXY 5.79 and downcast CTDOXY 5.78, flag 4. 18 1316 db SALNTY (35.158) is very low compared with upcast CTDSAL 35.220 and downcast CTDSAL 35.216, flag 4. 19 3553 db OXYGEN (5.68) is high compared with upcast CTDOXY 5.61 and downcast CTDOXY 5.60, flag 3. 4066 db SALNTY (34.896) is low compared with upcast CTDSAL 34.899 and downcast CTDSAL 34.900, flag 4. 21 204 db SALNTY (36.663) does not match with upcast CTDSAL (36.645) I flag them both 3 - Qble. There is a large salinity gradient at this pressure, but nevertheless the discrepancy is very large and they both differ from downcast CTDSAL (36.507). 22 4069 db SALNTY (34.891) is low compared with upcast CTDSAL 34.901 and downcast CTDSAL 34.902, flag 4. 24 You have a wonderful Meddy around 1200 db and CTDSAL is questioned by originators. It is absolutely true. 1517 db SALNTY (35.120) is high compared with upcast CTDSAL 35.118 and downcast CTDSAL 35.117, I don't flag these differences as questionable they must be accounted for internal waves. 5663 db OXYGEN (5.61) is low compared with upcast CTDOXY (5.68) and downcast CTDOXY (5.68), flag 4. 25 3107 db OXYGEN (5.70) is high compared with upcast CTDOXY (5.65) and downcast CTDOXY (5.65), flag 3. 27 5472 db SALNTY (34.890) is high compared with upcast CTDSAL (34.887) and downcast CTDSAL (34.888), I flag SALNTY 3. 28 2526 db SALNTY (35.056) is high compared with upcast CTDSAL (34.985) and downcast CTDSAL (34.991). Originators flag upcast CTDSAL Qble, I flag SALNTY 4. 4067 db SALNTY (34.908) is high compared with upcast CTDSAL (34.900) and downcast CTDSAL (34.902), I flag SALNTY 4. 4581 db SALNTY (34.894) is high compared with upcast CTDSAL (34.891) and downcast CTDSAL (34.892), I flag SALNTY 3. 5092 db SALNTY (34.890) is high compared with upcast CTDSAL (34.886) and downcast CTDSAL (34.888), I flag SALNTY 3. 28 5718 db SALNTY (34.888) is high compared with upcast CTDSAL (34.886) and downcast CTDSAL (34.886), I flag SALNTY 3. 29 1213 db OXYGEN (4.36) is high compared with upcast CTDOXY (4.15) and downcast CTDOXY (4.12), flag 4. 2430 db OXYGEN (5.48) is low compared with upcast CTDOXY (5.58) and downcast CTDOXY (5.58), flag 4. 30 5613 db SALNTY (34.887) is high compared with upcast CTDSAL (34.884) and downcast CTDSAL (34.885), I flag SALNTY 3. 5924 db SALNTY (34.886) is high compared with upcast CTDSAL (34.884) and downcast CTDSAL (34.884), I flag SALNTY 3. 31 1517 db SALNTY (35.165) is high compared with upcast CTDSAL. (35.163) and downcast CTDSAL (35.154), I do not flag these data questionable as I think that the differences are caused by internal waves Stations 30, 31, 32. Calibration of downcast CTDOXY is wrong in the interval 2000-5500. CTDOXY is lower than bottle measurements 33 809 db OXYGEN (3.65) is high compared with upcast CTDOXY(3.42) and downcast CTDOXY (3.35), flag - 4. 34 3556 db OXYGEN (5.73) is high compared with upcast CTDOXY (5.62) and downcast CTDOXY (5.61), flag 4. 4066 db OXYGEN (5.72) is high compared with upcast CTDOXY (5.66) and downcast CTDOXY (5.65), flag 4. 4572 db SALNTY (34.898) is high compared with upcast CTDSAL (34.891) and downcast CTDSAL (34.892), I flag SALNTY 4. 5091 db SALNTY (34.879) is low compared with upcast CTDSAL (34.884) and downcast CTDSAL (34.885), I flag SALNTY 4. 35 3555 db SALNTY (34.912) is low compared with upcast CTDSAL (34.914) and downcast CTDSAL (34.916), I flag SALNTY 3. 4068 db SALNTY (34.895) is low compared with upcast CTDSAL (34.899) and downcast CTDSAL (34.899), I flag SALNTY 4. 4581 db SALNTY (34.888) is low compared with upcast CTDSAL (34.892) and downcast CTDSAL (34.893), I flag SALNTY 4. Stations 35, 36. Calibration of downcast CTDOXY is wrong in the interval 2500-4500. CTDOXY is lower than bottle measurements and measurements on neighboring stations. 37 4068 db SALNTY (34.902) is low compared with upcast CTDSAL (34.903) and downcast CTDSAL (34.905), I flag SALNTY 3. 38 3001 db SALNTY (34.973) is high compared with upcast CTDSAL (34.945) and downcast CTDSAL (34.945), I flag SALNTY 4. Stations 37, 38. Calibration of downcast CTDOXY is wrong in the interval below 1500 db. CTDOXY is higher than bottle measurements and measurements on neighboring stations. Station 40. Calibration of downcast CTDOXY is wrong in the interval 1800-2800. CTDOXY is higher than bottle measurements and measurements on neighboring stations. 44 4998 db SALNTY (34.887) is low compared with upcast CTDSAL (34.889) and downcast CTDSAL (34.890), I flag SALNTY 3. 46 4434 db SALNTY (34.903) is high compared with upcast CTDSAL (34.900) and downcast CTDSAL (34.900), I flag SALNTY 3. WESTERN PART Salinity and oxygen are examined separately because there were many problems with CTDOXY calibration. SALINITY STATION PRESSURE REMARKS 58 2535 db SALNTY (34.980) is high compared with upcast CTDSAL (34.960) and downcast CTDSAL (34.962), I flag SALNTY 4. 64 Some bad CTDSAL measurements are flagged 3 -Qble. They are really bad. 67 5012 db SALNTY (34.846) is low compared with upcast CTDSAL (34.855) and downcast CTDSAL (34.855), I flag SALNTY 4. 75 4579 db SALNTY (34.886) is low compared with upcast CTDSAL (34.889) and downcast CTDSAL (34.890), I flag SALNTY 3. 5609 db SALNTY (34.842) is low compared with upcast CTDSAL (34.844) and downcast CTDSAL (34.845), I flag SALNTY 3. 83 1703 db SALNTY (35.000) is low compared with upcast CTDSAL (35.030) and downcast CTDSAL (35.030), I flag SALNTY 4. 89 There is great difference between SALNTY and upcast and downcast CTDSAL in the upper 80 db layer. Bottle samples taken at 11; 28; 53; 77 dbars OXYGEN There are problems with calibration of CTD oxygen sensor for many of the stations. Some CTD casts contain data that are definitely bad and they are not flagged bad at all. STATION PRESSURE REMARKS 52 2002 db OXYGEN (5.65) is high compared with upcast CTDOXY (5.60) and downcast CTDOXY (5.57), flag - 4. 53 1518 db OXYGEN (5.27) is high compared with upcast CTDOXY (5.14)and downcast CTDOXY (5.14), flag - 4. 55 3973 db OXYGEN (5.84) is low compared with upcast CTDOXY (5.87) and downcast CTDOXY (5.88), flag - 4. 58 5157 db OXYGEN (5.75) is low compared with upcast CTDOXY (5.80) and downcast CTDOXY (5.82), flag - 4. 63 4306 db OXYGEN (5.85) is high compared with upcast CTDOXY (5.79) and downcast CTDOXY (5.80), flag - 4. 68 3564 db OXYGEN (5.96) is high compared with upcast CTDOXY (5.87) and downcast CTDOXY (5.87), flag - 4. CTDOXY calibration is wrong below 2500 db. CTD measurements are less than bottle. 69 CTDOXY calibration is wrong below 5000 db. CTD measurements are less than bottle OXYGEN approximately by 0.02ml/l. 70 2505 db OXYGEN (5.72) is low compared with upcast CTDOXY (5.80) and downcast CTDOXY (5.80), flag - 4. Almost all CTDOXY measurements to the west of station 70 are noisy. Many of them have wrong CTDOXY calibration mostly in deep waters. 73 CTDOXY calibration is wrong below 1500 db. CTD measurements are less than bottle OXYGEN approximately by 0.02ml/l. 74 CTDOXY calibration is wrong below 5000 db. CTD measurements are greater than bottle OXYGEN approximately by 0.02ml/l. 84 CTDOXY calibration is wrong below 1500 db. CTD measurements are less than bottle OXYGEN approximately by 0.02ml/l. 85 CTDOXY calibration is wrong in the interval 2500-4000 db. CTD measurements are lower than bottle OXYGEN approximately by 0.02ml/l. 86 CTDOXY calibration is wrong below 1500 db. CTD measurements are lower than bottle OXYGEN approximately by 0.02ml/l. 87 CTDOXY calibration is wrong below 1500 db. CTD measurements are lower than bottle OXYGEN approximately by 0.02ml/l. 88 CTDOXY calibration is wrong below 1500 db. CTD measurements are lower than bottle OXYGEN approximately by 0.02ml/l. 89 4003 db OXYGEN (6.06) is high compared with upcast CTDOXY (6.17) and downcast CTDOXY (6.15), flag - 4. The calibration is better but problems below 5000 db. CTDOXY is higher than norm. 95 5408 db OXYGEN (6.03) is high compared with upcast CTDOXY (5.97) and downcast CTDOXY (5.94), flag - 4. 97 1904 db OXYGEN (5.80) is low compared with upcast CTDOXY (6.01) and downcast CTDOXY (5.99), flag - 4. 99 CTDOXY calibration is wrong below 2500 db. CTD measurements are lower than bottle OXYGEN approximately by 0.02ml/l. 107 618 db sample 15 OXYGEN is bad, flag - 4. 622 db sample 14 OXYGEN is bad, flag - 4. 109-111 The stations are not deep. CTDOXY calibration is bad in the entire depth. FIGURES Fig. 1 Positions of the stations. Fig. 2 The histograms for a) salinity and b) oxygen differences between CTD and bottle samples deeper than 2500 db Fig. 3 Nutrients diagrams. Fig. 4 Vertical profiles of preliminary shipboard values of F-11 for minor and major depths of a)1000m and b) respectively. Fig. 5a Total carbonate according to the depth for all the stations in which it was measured. Fig. 5b Calculated pressure of CO2 throughout the passage of the cruise. Fig. 6a Vertical distribution of pH and O2 dissolved for station 47. Fig. 6b Vertical distribution of the alkalinity and total carbon for station 47. Fig. 7 Vertical distribution of the chlorophyll for stations 1 to the 60. Fig. 8 Vertical profiles of chlorophyll and phaeophytin for stations 1, 11, 50 and 95.