Cruise Report (See PDF report for Tables. Figs not yet available) A. CRUISE NARRATIVE A.1. HIGHLIGHTS a. WOCE designation: SR04 b. Expedition designation: 06AQANTX_7 c. Chief scientist: EBERHARD FAHRBACH Alfred-Wegener Institut für Polar und Meeresforschung Columbusstrasse Postfach 1201061 D-27515 Bremerhaven Germany Telephone: +49-471-4831-501 Telefax: +49-471-4831-149 or -425 Telex: 238695 POLAR D Internet: efahrbach@awi-bremerhaven.de d. Ship: Polarstern e. Ports of call: Cape Town, South Africa to Ushuaia, Argentina f. Cruise dates: December 3, 1992 to January 22, 1993 A.2. CRUISE SUMMARY INFORMATION a. GEOGRAPHIC boundaries: The first part of the cruise involved a transit from Cape Town south-southwest to Neumayer Station. ADCP, XBTs, and some mooring work were done during that transit. The repeat section, SR04, was begun near 70°31´S 9°9´W and proceeded northwest through the Weddell Sea to finish near 61°S 58°25´W. Another CTD transect was completed to the east of the Larsen Ice Shelf in the area between 61°S and 69°S, 45°W to 60°42´W. The cruise finished with a transit from the South Shetland Islands across Drake Passage, during which ADCP and XBTs were done, to finish in Ushuaia near Cape Horn. b. Stations occupied: 57 CTD-profiles (Conductivity, Temperature, Depth) and discrete samples for temperature, salinity, oxygen, nutrients and trace substances were done along SR04. A second transect with 20 stations was made from the edge of the Larsen Shelf Ice at 69°S 60°42´W towards the northeast. c. Floats and drifters deployed: No floats or drifters were deployed on this cruise. d. Moorings deployed or recovered: On the main section from Kapp Norvegia to Joinville Island 18 of 21 moorings were recovered (Fig. 7.2.3, Table 1) and 9 of them were exchanged (Table 2). The moorings to recover were equipped with 55 Aanderaa current meters (RCM4, RCM5 RCM7, RCM8) as well as six Aanderaa thermistor cables and two Aanderaa water level recorders. In the near bottom layer nine EG&G acoustic current meters were used (ACM-2). On six moorings, upward-looking sonars (ULS) built by the Christian Michelsen Institute, were installed to measure the ice thickness. One mooring carried an acoustic Doppler current profiler (ADCP) from RD Instruments. The locations of the instruments in the moorings are shown in Fig. 7.2.6. The recovery of the moorings was hampered by the malfunction of the acoustic releases. In water depths greater than 1500 m no reply signal could be received from the moored releases neither after interrogating nor after releasing, even when the instruments were returned to the surface and floating in sight of the ship in a distance of a few hundred meters. The missing communication link made it impossible to use the available ranging and bearing systems. Only due to the favorable ice conditions, serious losses did not occur. Normally some floats reached the surface in open water between the ice floes and could be located visually. Only one mooring was completely hidden under the ice after its release and was found only after some hours of searching. Five times a mooring did not appear at the sea surface after being acoustically released, and dredging had to be tried. In three cases dredging was at least partially successful. The dredged moorings could not be recovered completely, from one only the ground weight and the release was obtained. One mooring was lost due to the rupture of the Kevlar dredging cable, which was used in order to increase the cable length to pick up the mooring with the release. The successful dredging indicates that unreliable acoustic releases are the most likely reason for the failure. The mooring KN4 and two moorings of the University of Southern California which were acoustically released on earlier cruises were dredged unsuccessfully. Mooring 215 in a water depth of 448 m was most likely lost by contact with icebergs. It could neither be dredged nor acoustically ranged or released in spite of the shallow depth. Three other moorings had obviously been touched by icebergs, but only mooring 206-2 was seriously affected by the loss of the uppermost floats. Because the risk of damage by icebergs had to be accepted in order to obtain ice thickness and upper layer current measurements, moorings and instruments were designed to reduce the resistance to an iceberg in case of contact. The ULS in 150 m depth were protected by a conical floatation collar and the main buoyancy of the mooring was only in 250 m depth to allow the upper part of the mooring to be depressed by icebergs. The recovery rate of five out of six ULS proved that the taken precautions were efficient. As a consequence of three complete and two partial losses of moorings, we lost 15 current meters, one ULS and one water level recorder. From 59 recovered instruments, three were deployed only for one year and worked reliably, but only 18 of the ones deployed for two years recorded longer than 600 days, whereas 30 stopped after approximately one year due to the mismatch of power consumption and battery power, and eight instruments failed completely due to loss of memory or water intrusion. The five recovered ULS had to be returned to the Christian Michelsen Institute to read out the data due to a malfunction of the communication link. Moorings recovered on the way from Cape Town to the Neumayer Station are shown in Table 3. Moorings deployed on the way from Cape Town to the same station are listed in Table 4. A.3. List of Principal Investigators TABLE 5: Principal investigators Parameter Investigator Institution ------------ --------------- ----------- CTD E. Fahrbach AWI Salinity E. Fahrbach AWI Oxygen E. Fahrbach AWI Nutrients K.-U. Richter AWI Carbon dioxide Moorings ADCP XBTs Thermosalinograph Meteorology Biological measurements Bathymetry A.4. SCIENTIFIC PROGRAMME AND METHODS ITINERARY AND SUMMARY (E. Fahrbach/AWI) On 3 December 1992 the R.V. Polarstern left Cape Town to cross the Southern Ocean towards the Weddell Sea (Fig. 7.1.1). Oceanographic measurements from the moving ship started immediately on the continental shelf with XBT (Expendable Bathythermograph) and ADCP (Acoustic Doppler Current Profiler) profiles. Additionally, the COMED-system to measure mixed layer temperature, salinity and the concentration of chlorophyll-a and humic substances as well as Raman- and Mie-backscattering was activated. The measurements showed a warm Agulhas ring and the Subtropical, Subantarctic and Polar Fronts during the transect across the Antarctic Circumpolar Current. The first iceberg was sighted at 44°45´S, 10°23´E on 6 December and the Polar Front was crossed on 7 December at 48°20´S, 07°20´E. Two moorings with sediment traps were recovered and redeployed in the area of the Antarctic Polar Frontal Zone. At the mooring positions the first profiles with the CTD sonde (conductivity, temperature, depth) were measured. The ice edge was reached at 58°24´S, 02°15´E. The transition zone from the Antarctic Circumpolar Current to the Weddell Gyre was marked by a belt of frequent icebergs between 56° and 59°S. A third mooring was recovered in the northern Weddell Gyre boundary. On the way further south, towards Atka Bight we searched for some meteorological buoys and recovered one of them. At 65°00´S, 08°48´W, the first biological station was carried out with a multinet. The CTD- profile obtained at that station revealed a surprisingly high temperature of 0.9°C in the temperature maximum of the Warm Deep Water. Even if the ice belt extended extremely far to the north when we left Cape Town, it decayed dramatically during our way to the south with the consequence that we could proceed rather undisturbed by the ice and reached the wide coastal polynya on 16 December. At the Neumayer-Station overwintering personnel and building crews disembarked to finish the new station and to dismantle the old one. Additional groups, which carried out drilling programs on the shelf ice with a hot water and an electrically heated system and the testing of an instrument to measure ice thickness by radar, I stayed at the station. Supply goods and equipment for the next overwintering period were deposited. During the night to 19 December we left the Atka Bight and followed the coastal polynya to the southwest. The basic scientific program in the Weddell Sea, on a transect from Kapp Norvegia to Joinville Island (Fig. 7.1.1), consisted of the measurement of vertical profiles of temperature, salinity and natural trace substances at 57 hydrographic stations. On that transect 18 moorings with 79 instruments, current meters, thermistor chains, water level recorders and sediment traps were recovered and nine moorings were redeployed. Six upward-looking sonars are presently installed to measure ice thickness and five were recovered. The recovery was hampered by the malfunction of acoustic releases. The ones deeper than 1500 m meters and moored for two years did not respond with enough power to be acoustically ranged. Three of them did not release at all. Due to the favorable ice conditions and various dredging operations all but three moorings were recovered with a total loss of 16 instruments. The measurements aim to determine the circulation and the water mass distribution in the Weddell Gyre with the transports of mass, heat and salt. The data allow to estimate the rate of bottom water formation in the Weddell Sea which controls to a large extent the vertical exchange and consequently the ability of the ocean to store heat and dissolved substances. Bottom water formation determines the contribution of the Weddell Sea to the effect of the world ocean on climate variations. The investigations are part of the Weddell Gyre Study which began in 1989 in the framework of the World Ocean Circulation Experiment (WOCE). The preliminary data show that the mass transport of the cyclonic gyre of 30 106 m3s-1 is mainly determined by the 500 km wide boundary currents. In the interior an anticyclonic gyre transports about 3 m3s­1. In most part of the gyre the current direction reverses with depth. The outflow cycle. Longer period changes are especially visible in the temperature field. The most obvious variation was measured in the maximum temperature of the Warm Deep Water which increased significantly from 1990 to 1992. The knowledge of the physical conditions provides the basis for chemical, biological and biogeochemical investigations. The biogeochemical programs referred to cycles of different inorganic and organic compounds in sea water and the exchange of carbon dioxide between ocean and atmosphere. The biological work focused on phyto- and zooplankton ecology. For this purpose 21 biological stations with multi- and bongo-net catches were carried out. Distribution of microbial biomass and respiratory activity was studied. Dissolved organic carbon and humic substances as well as dissolved and particulate sterns were measured. Altogether these programs contribute to a better understanding of the global carbon cycle and are to be viewed in the context of the Joint Global Ocean Flux Study (JGOFS). Special emphasis was given to the investigation of the effect of increasing UV-B radiation on Antarctic marine organisms. With moderate winds, air temperatures at the freezing point and overcast sky we reached on 7 January the western ice edge at 64°34´S,44°25´W where the ice cover decreased from 90 to 10% within a short distance. The ice cover was split in two large bands which were separated by a rather open area in the center of the gyre and surrounded by the wide eastern and western polynyas. This structure was reflected in the hydrographic conditions and the status of the biological systems. Whereas in the area of the ice belt winter conditions still prevailed, the open areas, where light was available and the water column was stabilized by warming and melt water input, rich blooms had developed. In the eastern coastal polynya an advanced bloom of diatoms and Phaeocystis was observed. The one in the center was much less intense and obviously affected by grazing. In the west, where spring conditions prevailed since several weeks, the maximum of the diatom bloom was passed due to intensive grazing and a strong Phaeocystis bloom dominated the system. The station work on the main transect stopped east of Joinville Island. Due to the favorable ice conditions time was still available to take advantage at the unique conditions and to proceed to 69°S along the Larsen Ice Shelf (Fig. 7.1.1), 50 nautical miles further south than C. A. Larsen when he explored this ice shelf in 1893. On the way we passed the Argentine Station "Marambio" on Seymour Island, where we could cultivate the international relations by a reception on board of "Polarstern". The shelf was cut by a series of depressions to a depth of 600 m which seemed to steer the cross shelf circulation. Sea surface temperatures of up to 2°C were observed in the polynya. From 64°34´S,44°25´W we directed a transect with 20 CTD and four biological stations towards the northeast (Fig. 7.1.1). On the shelf three hauls with the Agassiz Trawl were carried out. The location of the transect was determined according to SSM/I (Special Sensor Microwave/lmager) satellite data of the ice cover as obtained from the Ice Centre of the Atmospheric Environment Service, Canada. It was in accordance with the satellite data, that we met heavy ice conditions only around 66°25´S,47°55´W where we were forced to turn northwest and to finish the transect at 64°48´S,47°35´W at about 40 nautical miles from our main transect. The hydrographic conditions on that transect indicate by low saline water overlying a thin near bottom higher saline layer, the admixture of Larsen Shelf water to the northward flowing Weddell Sea Bottom Water. From the end of the transect Polarstern proceeded through the Antarctic Sound to King George Island where we deposited material at the Argentine "Jubany" Station which is now used jointly with German scientists. In the Maxwell Bight we met the Spanish R.V. "Hesperides" which was working in the Bransfield Strait and we transferred one of our CTDs. On our way to the Drake Passage we passed by Deception Island where we continued the oceanographic work from the moving ship across the Antarctic Circumpolar Current with XBT, ADCP and COMED measurements. On 22 January 1993 "Polarstern" arrived at the port in Ushuaia. SR04 ‹ PHYSICAL OCEANOGRAPHY Water masses and circulation in the Weddell Sea (T. Boehme, J. Corleis v. d. Voet, E. Fahrbach, H. Fischer, R. Hamann, L. Kolb, A. Latten, G. Rohardt, E. Schutt, G. Seiss, V. Strass, H. Witte, F. Zwein/AWI) OBJECTIVES The physical oceanography work was aimed at investigating the water mass distribution and circulation in the Weddell Sea in order to understand the influence of ocean, ice and atmosphere on the formation of water masses which leave the Weddell Gyre and affect the characteristics of the bottom water of the world oceans. The activities during ANT X/7 are part of a multiyear program, the Weddell Gyre Study, which contributes to the World Ocean Circulation Experiment (WOCE). During this programme, a hydrographic section between the northern tip of the Antarctic Peninsula and Kapp Norvegia (Fig. 7.1.1) was repeated four times. The repetition of the same section during different seasons and years allows to measure longer term mean conditions of water mass characteristics and to assess the seasonal as well as the interannual variability. The programme was initiated in 1989 with a hydrographic survey in late winter during which a set of seven current meter moorings was deployed. A second survey in early spring followed in 1990 during which the first set of moorings was recovered and a new set of 21 moorings was deployed. Early winter conditions were observed in 1992. However, due to the severe ice conditions during that cruise the section could not be covered completely. The present cruise was aimed to recover the 21 moorings, to deploy a new set of 9 moorings and to obtain a summer survey. The data from the moored current meters are used to describe the large scale current patterns of the Weddell Gyre and to estimate its volume transport. This can only be done with measurements from moored current meters, because of the contribution of the barotropic current field, which, for the time being, can only be derived from direct measurements as there is no indication on an appropriate reference level. Furthermore, intensive current fluctuations require long time series to determine statistically significant averages representative for those circulation patterns which are relevant to water mass formation. From the mass transport measured with the moored current meters and the water mass characteristics obtained during the hydrographic surveys, we can estimate heat and salt transports across the transect. The differences in volume between the water masses which are advected into the southwestern Weddell Sea and the ones which leave the area to the north reflect the formation of water masses south of the transect. WORK AT SEA The distribution of water mass characteristics along the hydrographic section from Kapp Norvegia to Joinville Island at the northern tip of the Antarctic Peninsula (Fig. 7.2.1) was measured with 57 CTD-profiles (Conductivity, Temperature, Depth) and discrete samples for temperature, salinity, oxygen, nutrients and trace substances. A second transect with 20 stations was made from the edge of the Larsen Shelf Ice at 69°S60°42´W towards the northeast (Fig. 7.2.1). In order to measure during the available time the characteristics of the Weddell Sea Bottom Water as far south from the main section as possible, the location of the section was chosen to avoid areas with heavy pack ice. PRELIMINARY RESULTS The sections of potential temperature, salinity and oxygen between Kapp Norvegia and Joinville Island (Fig. 7.2.9, 7.2.10, 7.2.13) show the typical water masses of the central Weddell Sea. The near surface layer is characterized during the summer by temperatures significantly above the freezing point, relatively low salinity and high oxygen concentrations. The Winter Water layer below it is obvious at a temperature minimum. In the section plots small scale structures and extreme values do not appear in the near surface and near bottom layers due to the applied smoothing procedures. The Winter Water is separated from the Warm Deep Water by a shallow thermo- and halocline. Its depth increases to several hundred meters from the open water towards the coast, above the upper continental slope in the east and the west. Due to its origin from the Antarctic Circumpolar Current the Warm Deep Water causes a temperature and salinity maximum as well as an oxygen minimum. The Warm Deep Water is most pronounced near the eastern and western boundaries. The deeper parts of the water column are filled by Antarctic and Weddell Sea Bottom Waters, separated by the potential temperature of ­0.8°C. The newly formed Weddell Sea Bottom Water is most prominent at the western continental slope where the deepest temperatures and highest oxygen concentrations are found. On the continental slope off the Larsen Ice Shelf, between 1500 and 2500 m, a colder and saltier layer of only a few meters thickness is found under the lens of cold and fresh Weddell Sea Bottom Water (Fig. 7.2.11, 7.2.12). If the saline near bottom layer represents flow from the area of the Larsen Ice Shelf or water from the outflow of the Filchner Depression will be investigated in the course of the future analysis by use of all available parameters, in particular the stable isotope 180. On the shelf, in front of the Larsen Ice Shelf, depressions of up 600 m depth (Fig. 7.2.15) could guide the flow to the deep sea. Significant variability of sea surface temperature and salinity are indicative of cross shelf flow, however, no supercooled water can be detected in the XBT records (Fig. 7.2.16). Comparison of the near surface water mass characteristics observed during the present cruise, with the ones measured during ANT IX/2 from 17 November to 31 December 1990 and ANT VIII/2 from 6 September to 30 October 1989, reveals the seasonal progress by the development of the summer surface water layer with increasing temperatures and decreasing salinities (Fig. 7.2.17) from late winter through spring to summer. However, as the present cruise occurred only two to four weeks later than ANT IX/2, not only seasonal change contributes to the differences, but interannual variability has also to be taken into account. It is obvious from the ice conditions that the present observations are subject to significant interannual variations. This is supported by the conditions in the Winter Water and Warm Deep Water layers (Fig. 7.2.18) which are significantly warmer during the present survey than in 1990. The measurements from the moored current meters reveal the large scale circulation pattern of the Weddell Gyre. The record long average flow across the transect from Kapp Norvegia to Joinville Island is shown in Fig. 7.2.19. The structure of the cyclonic gyre is determined by the western and eastern boundary currents with annual mean speeds of up to 16 cm/s in the east and 11 cm/s in the west. The volume transport of the boundary currents which are approximately 500 km wide amounts to 25 x 106 m3/s. The interior of the Weddell Sea circulation consists of an anticyclonic circulation cell of about 1000 km diameter. There, the current has an important component in the direction of the transect. Therefore, the annual mean speeds amount to 1 cm/s, whereas the flow across the transect is smaller than 0.5 cm/s. The transport of the interior anticyclonic gyre amounts to 3 x 106 m3/s. The vertical distribution of the current indicates a significant baroclinic component. Almost in the whole basin the flow reverses in the near bottom layers. This flow pattern suggests that the newly formed Weddell Sea Bottom Water leaves the southern part of the basin in the west. Partly, it recirculates in the interior supporting a secondary outflow in the east. The average current system is subject to intensive fluctuations. Whereas the seasonal cycle dominates the variability of the eastern boundary current, it is barely visible in the west (Fig. 7.2.20). However, the temperature of the outflowing Weddell Sea Bottom water is subject to a clear seasonal cycle. In the interior only higher frequency fluctuations are present. The currents do not show a significant longer term trend, while the records of the thermistor cables (Fig. 7.2.20) indicate an increase of the maximum temperature in the Warm Deep Water layer during the two years of the observation period. This is consistent with the CTD measurements. Simultaneously, the temperatures of the outflowing Weddell Sea Bottom Water decrease (Fig. 7.2.20). The correlation of the observed seasonal and interannual variability of the oceanic circulation and temperatures with the fluctuations of the atmospheric driving forces and ice conditions will be investigated when the complete data sets will be available. STRUCTURE OF THE ANTARCTIC CIRCUMPOLAR CURRENT (T. Boehme, J. Corleis v. d. Voet, M. Damm, E. Fahrbach, H. Fischer, R. Hamann, L. Kolb, A. Latten, G. Seiss, V. Strass, M. Tibcken, H. Witte, F. Zwein/AWI) OBJECTIVES The Antarctic Circumpolar Current is the connection between three ocean basins. Its major transport occurs in oceanic fronts, the Subtropical, the Subantarctic and the Polar Front. In the area of our observations the boundary between the Antarctic Circumpolar Current and the Weddell Gyre is of special interest. In spite of the dominant zonal component of the mean current, significant meridional transports occur which are to a large extent caused by mesoscale fluctuations. These fluctuations are of interest also to the dynamics of the current, because they are transferring the momentum from the surface to the deep water. Measurements in the Antarctic Circumpolar Current, made repeatedly underway and by moored current meters, aim at obtaining better statistics of the fluctuations and the fronts. WORK AT SEA On the way to and from the major working area 166 XBTs (Table 10 and Table 11) were launched and current profiles were measured with a vessel mounted acoustic Doppler sonar current meter (VM-ADCP) to gather information on the variability of the Antarctic Circumpolar Current. In the area of the Antarctic Polar Frontal Zone and the northern boundary of the Weddell Gyre three current meter moorings were recovered and two were deployed (Table 3 and Table 4). The COMED system was recording temperature, salinity, Raman- and Mie-backscattering, fluorescence and chlorophyll in the ice free parts of the transects. PRELIMINARY RESULTS The data from the XBTs show the typical structure of the Circumpolar Current with the associated fronts on the southbound transect from Cape Town to Antarctica (Fig. 7.2. 21) and in Drake Passage (Fig. 7.2.22). A statistical analysis is only possible in connection with the data from previous and further cruises. A.5. MAJOR PROBLEMS AND GOALS NOT ACHIEVED On the transect across the Drake Passage, the VM-ADCP measurements are degraded due to the failure of the ship´s pitch and roll platforms. A.6. OTHER INCIDENTS OF NOTE None noted. A.7. LIST OF CRUISE PARTICIPANTS Cruise participants are listed in Table 6. The participating institutions and their addresses and the abbreviations used in this report are given in Table 7. TABLE 6: Cruise participants Name RESPONSIBILITY Institution ------------------ -------------------------------------- ----------- Ahlers, Petra AWI Balen van, Antonius NIOZ Baumann, Marcus AWI Boehme, Tobias AWI/FPB Brandini, Frederico CBM Büchner, Jurgen HSW Corleis v. d. Voet, Janja AWI Döhler, Gunter BIF Fahl, Kirstin AWI Fahrbach, Eberhard CHIEF SCIENTIST, CTD, SALINITY, OXYGEN AWI Fischer, Haika AWI/FPB Goeyens, Leo AWI/VUB Gorny, Mathias AWI Günther, Sven AWI Hamann, Rudolph AWI/FPB Hanke, Georg AWI Hillebrandt, Marc-Oliver HSW Hoppema, Mario AWI/NIOZ Jesse, Sandra AWI Klatt, Olaf AWI/FPB Kolb, Leif AWI/FPB Kurbjeweit, Frank AWI Latten, Andrees AWI/FPB Lundström,Volker HSW Nachtigäller, Jutta DUI Richter, Klaus-Uwe NUTRIENTS AWI Riegger, Lieselotte AWI Rohardt, Gerd AWI Röttgers, Rudiger AWI Schreiber, Detlef HSW Schröder, Sabine AWI Schütt, Ekkehard AWI Schweimler, Imgrun AWI/FPB Seifert, Wolfgang DWD Seiss, Guntram AWI/FPB Skoog, Annelie AMK Sonnabend, Hartmut DWD Strass, Volker AWI Tibcken, Michael AWI Vosjan, Jan H. NIOZ Wedborg, Margareta AMK Witte, Hannelore AWI Zwein, Frank AWI/FPB TO NEUMAYER-STATION Ahammer, Heinz PM Behnsen, Uwe AWi Behrens, Detlev KRA Damm, Michael AWI Eckstaller, Alfons AWI El Naggar, Saad El D. AWI Etspüler, Wolfgang AWI Gruhne, Mario AWI Heinrich, Andreas TRE Hofmann, Jorg AWI Koenig, Roland TRE Mertens, Rolf KRA Muhle, Heiko AWI Nixdorf, Uwe AWI Nolting, Michael AWI Reder, Giselher CN Reiter, Alois AWI Rosenberger, Andreas AWI Schneider, Hans AWI Strecke, Volker AWI Terzenbach, Uwe AWI Trendelkamp,Joseph TRE Tüg, Helmut AWI Wlcht, Manfred AWI Wissing Manfred TRE Witt, Raif AWI Wunder, Hans CN Zmmermann, Frerich CN TABLE 7: Participating Institutions GERMANY AWI Alfred-Wegener-lnstitute fur Polar- und Meeresforschung Columbusstrasse 275 68 Bremerhaven Aussenstelle Potsdam Telegraphenberg A43 144 73 Potsdam BIF Johann Wolfgang Goethe-Universitat Botanisches Institut Siesmayerstr. 70 W-6000 Frankfurt am Main 11 DUI Deutsches Obersee-lnstitut Neuer Jungfernstieg 21 W-2000 Hamburg 36 DWD Deutscher Wetterdienst, Seewetteramt Bernhard-Nocht-Str. 76 2000 Hamburg 4 FBB Universitat Bremen Meeresbotanik, FB2 Postfach 33 04 40 2800 Bremen 33 FGB Universitat Bremen Fachbereich Geowissenschaften FB5 Postfach 33 04 40 2800 Bremen 33 HSW Helicopter Service, Wasserthal GmbH Katnerweg 43 2000 Hamburg 65 IFM Institut fur Meereskunde Abt. Planktologie Dusternbrooker Weg 20 2300 Kiel 1 SFB Universitat Kiel SFB 313 Olshausenstr. 40-60 2300 Kiel 1 UOL Universitat Oldenburg Fachbereich Physik 8 Carl-von-Ossietzky-Str. 9-11 2900 Oldenburg UNU Universitat Ulm Abt. Analyt. Chemie & Umweltchemie Albert-Einstein-Allee 11 7900 Ulm BELGIUM VUB Vrije Universiteit Brussel-Anch Pleinlaan 2 B-1050 Brussel, BELGIUM Groupe de Microbiologie des Milieux Aquatiques ULB Universite Libre de Bruxelles ULB Campus de la Plaine, CP 221 B-1050 Brussels, BELGIUM BRASIL CBM Centro de Biologia Marinha/UFPr Av. Beira Mar s/n, Pontal do Sul Paranagua 83200, PR, Brasil DENMARK MBL K0benhavns Universitet Marine Biological Laboratory Strandpromenaden 5 DK-3000 Helsing0r, Denmark ESTONIA IEMR Institute of Ecology and Marine Research Paldiski Road 1 200031 Tallinn, Estonia France IEM Universite de Bretagne Occidentale Institut d'Etudes Marines Laboratoire de Chimie des Ecosystemes Marins Avenue V. Le Gorgeu F-29287 Brest Cedex, France NETHERLANDS NIOZ Nederlands Instituut voor Onderzoek der Zee NIOZ Postbox 59 NL-1790 AB Den Burg, The Netherlands IBN Institute for Forestry & Nature Research (IBN-DLO) Postbox 167 NL-1790 AD Den Burg, The Netherlands SWEDEN AMK University of Goteborg and Chalmers University of Technology Analytical and Marine Chemistry S-412 96 Goteborg, Sweden UNITED STATES OF AMERICA OSU Oregon State University College of Oceanography Oceanography Admin. Bld. 104 Corvaliis, Oregon 97331-5503, U.S.A. TO NEUMAYER STATION CN Fa. Christiani & Nielsen Basedowstr. W-2000 Hamburg 26 KRA Fa. J.H. Kramer Labradorstr. W-2850 Bremerhaven TRE Fa. Trendelkamp Stahl und Maschinenbau Westring 18 W-4418 Nordwalde PM POLARMAR GmbH Burger W-2850 Bremerhaven B. UNDERWAY MEASUREMENTS B.1. NAVIGATION AND BATHYMETRY B.2. ACOUSTIC DOPPLER CURRENT PROFILER (ADCP) B.3. THERMOSALINOGRAPH AND UNDERWAY DISSOLVED GASSES B.4. EXPENDABLE BATHYTHERMOGRAPH AND SALINITY MEASUREMENTS XBT sections were carried out during the crossing of the western ice edge (Table 8) and off the Larsen Ice Shelf (Table 9). Because the XBTs had a high failure rate, most likely due to the low water temperatures, the sections have large gaps. The deployment locations of XBTs launched during the transit of the Antarctic Circumpolar Current from Cape Town to Atka Bight are given in Table 10. The launch locations of XBTs deployed during the transit across the Drake Passage are given in Table 11. B.5. METEOROLOGICAL OBSERVATIONS (W. Seifert, H. Sonnabend/DWD) During the first week of December the South Atlantic high-pressure-centre was situated relatively far north, near 25°S. Therefore a strong westerly flow formed an intensive frontal zone with a well developed gale centre southwest of Bouvet Island. It forced warm wave depressions from subtropical latitudes and secondary lows moving form the Drake Passage eastward in its steering circulation system which maintained the baroclinic structure. "Polarstern" passed the rear of the gale centre with southwesterly gales and wave heights up to 5 m. Reaching the sea-ice-belt the sea state weakened in spite of crossing cold fronts with snow showers and gusty conditions. By mid-December the circulation pattern changed. The development of an intensive gale centre at the Antarctic Peninsula and the southeastern Weddell Sea generated a high pressure ridge over the eastern Weddell Sea with a descending air flow and rapidly decreasing cloud cover giving rise to sunny sky with light to moderate southerly winds during the stay at the Neumayer-Station. During the following week the high pressure ridge moved northward while secondary lows formed at the western flank of the low east of Bouvet Island near 20°E. Wave depressions embedded in the southwesterly flow produced gusty flurries. The weak anticyclonic southwesterly flow, locally interrupted by small embedded mesoscale waves persisted until 10. January 1993. The development of such waves is frequently observed in the Weddell Sea. It is caused by the vertical transport of mass and water vapor over regions with no or weak ice cover and water temperatures higher than ­1°C. The typical range of the mesoscale waves is 200 to 500 km. They form a vortex with frontal structures and the associated wind and weather conditions. Towards mid-January, the high pressure system weakened and one of the mesoscale lows moved from the Filchner Shelf west-northwestwards under the influence of an upper secondary trough as part of the northeastern Antarctic low pressure system. It developed to a gale centre and became stationary two days later northeast of the Antarctic Sound with a core pressure below 975 hPa. At its rear the southerly winds increased to gale force Beaufort 8 to 9 with gusty snow showers and sea heights in open waters up to 3 m. The southerly winds were forced as barrier winds by the Antarctic Peninsula from southwest to northeast. By 15 January the low filled slowly up, while a high was moving from the southern Pacific across the Antarctic Peninsula to the western Weddell Sea inducing a weak pressure gradient with light southeasterly winds. During the last five days of the cruise an intensive storm centre formed far northwest of the Drake Passage with eastward moving secondary lows developing at the occlusion point off the Drake Passage. With strong northerly winds and gusty snow showers "Polarstern" crossed the Antarctic Sound and reached the "Jubany" station under a following high pressure ridge. Another intensive gale centre west of the Drake Passage produced a stormy secondary low moving quickly east with northeasterly gales, force Beaufort 8, and waves up to 3.5 m. In a following ridge the wind decreased to force 4 Beaufort but the visibility became rather poor. The meteorological conditions were favorable to achieve the objectives of the cruise. The wind statistics show that 70% of all observations were below force 6 Beaufort (22 knots). The predominant wind directions were southerly to southwesterly in contrast to other years as 1990 when during ANTIX/2 easterly directions were frequently observed (Fig. 7.5.1). The zonal wind component averaged along the main transect was approximately 5 knots, while the longtime mean value for December and January averaged along 65°S over the same longitudes is ­2 knots,**** How can wind velocity, here expressed as magnitude, be negative?**** representing easterly wind components. The circulation seemed to differ from the typical pattern with a dominant low over the western Weddell Sea which would produce easterly winds south of 65°S due to the frequent formation a high pressure ridge over the Weddell Sea (Fig. 7.5.2). From the time series of surface air temperature, surface pressure and wind direction it appears that the wave depressions were triggered convective processes and not by advection. B.6. ICE CONDITIONS (T. Boehme, E. Fahrbach, H. Fischer, R. Hamann, L. Kolb, A. Latten, G. Seiss, F. Zwein/AWI) On 10 December 1992 hourly routine ice observations began with a more detailed observation every three hours. The first iceberg had been sighted at 44°45´S, 10°23´E on 6 December. The ice edge was reached at 58°24´S, 02°15´E. The transition zone from the Antarctic Circumpolar Current to the Weddell Gyre was marked by a belt of frequent icebergs between 56° and 59°S. Even if the ice belt extended extremely far to the north when we left Cape Town, it decayed dramatically during our way to the south with the consequence that we could proceed rather undisturbed by the ice and reached the wide coastal polynya on 16 December. The ice concentration on a transect from Kapp Norvegia to Joinville Island was split in two large scale bands which were separated by a rather open area in the center of the gyre and surrounded by the wide eastern and western polynyas (Fig. 7.6.1, 7.6.2). The western ice edge, where the ice cover decreased from 90 to 10% within a short distance was reached on 7 January at 64°34´S, 44°25´W. From 64°34´S, 44°25´W, we directed a transect towards the northeast according to the satellite data on the ice cover which we obtained from the Canadian Ice Center of the Atmospheric Environment Service. We met heavy ice conditions only at 66°25´S, 47°55´W which forced us to turn northwest and to finish the transect at 64°48´S, 47°35´W at about 40 nautical miles from our main transect. The ice observation record is available on diskette. C. HYDROGRAPHIC MEASUREMENTS C.1. CTD The CTD-measurements were carried out with a NB Mark IIIB sonde connected to a General Oceanics rosette water sampler with 24 12-liter bottles. The quality of the CTD-data relies on the laboratory calibrations of the temperature and pressure sensors made before the cruise at the Scripps Institution of Oceanography. The performance of the instrument during the cruise was controlled by use of SIS digital thermometers and pressure meters as well as Gohla mercury reversing thermometers. The pre-cruise temperature and pressure calibration values were applied to the measurements on board. ***Need these calibration values and how the measurements were fit to the calibrations **** The conductivity readings of the CTD were corrected by means of salinity measurements from the rosette water samples. The means and the standard deviations of the salinity differences between bottle samples and CTD readings for each profile are shown together with the number of samples for each profile in Fig. 7.2.2. Due to the stratification of the water column the scatter of the differences is higher in the upper levels. Therefore only differences in levels deeper than 500 m are used and displayed in Fig. 7.2.2 to get an impression of the quality of the instruments and processing. The preliminary data presented in this report are corrected by a constant offset of 0.0588. The accuracy of the preliminary data was estimated to 4 m°C in temperature, 4 dbar in pressure and 0.005 PSU in salinity. The final data will be available after the post cruise laboratory calibration. The salinity correction will take into account the slight time drift which was observed. C.2. WATER SAMPLE SALINITIES The salinity of the water samples was determined with a Guildline Autosal 8400 A salinometer in reference to IAPSO Standard Seawater (**** Need batch number****). The salinities are given in PSU and calculated by use of the UNESCO Practical Salinity Scale (PSS78). C.3. WATER SAMPLE OXYGEN MEASUREMENTS During the cruise the concentration of dissolved oxygen was measured by means of a computer controlled SIS Winkler-titrator from 1923 water samples taken at 81 stations. The precision of the measurements was estimated by means of three calibration stations where all water bottles were closed in the same depth and 24 samples were taken. The standard error of each station ranged between 0.04 and 0.09 pM with a standard deviation from 0.19 to 0.44 mM corresponding to a precision of 0.1 to 0.2%. For the continuous control of precision, 238 double samples were taken from the same bottle during the cruise. C.4. DISTRIBUTION OF NUTRIENTS IN THE WEDDELL SEA (P. Ahlers, K.-U. Richter, S. Schroder/AWI) OBJECTIVES The near surface layers, in particular the Winter Water, of the Weddell Gyre are supplied with nutrients by entrainment and upwelling of Warm Deep Water. Therefore, macronutrients are generally not considered as limiting factors for phytoplankton production in the Weddell Sea. Our objective was to measure the distribution of the nutrients on a transect through the Weddell Gyre from Kapp Norvegia to the Antarctic Peninsula and on a second transect from the Larsen Ice Shelf to the northeast. WORK AT SEA Water samples were collected with the oceanographic rosette sampler and analyzed on a Technicon Autoanalyzer II system. Nitrate was determined as nitrite after reduction with cadmium and reaction with sulfanilamide and N-(1naphtyl)- ethylendiamin dihydrochloid as red colored azodye at l=520 nm. Ammonium was measured as blue colored indophenole at l=630 nm after the reaction with phenolate and hypochlorite under alkaline conditions (Berthelot reaction). For the determination of silicate and phosphate the compounds react with ammonium molybdate by forming a blue molybdate-complex that was measured at l=660 nm respectively at l=880 nm. PRELIMINARY RESULTS As an example for the distribution of nutrients in the different water masses of the Weddell Sea the concentration of silicate is shown on the transect from Kapp Norvegia to Joinville Island (Fig. 7.3.1). The near surface layers are characterized by a strong vertical gradient due to nutrient consumption by phytoplankton in the euphotic zone. In the deeper layers of the Warm Deep Water and the Antarctic Bottom Water the concentration values between 120 and 130 mM vary only slightly with two exceptions. Silicate values higher then 130 mM indicate the inflow of silicate enriched Antarctic Bottom Water from the Enderby Basin near the eastern continental slope below 4000 m depth. At the western continental slope a distinct silicate minimum below 1500 m depth is related to the Weddell Sea Bottom Water. It is most pronounced with values of less than 95 mM between 2000 and 3000 meters depth. The low silicate concentrations near the bottom extent almost over the total Weddell Basin and indicate the spreading of the Weddell Sea Bottom Water. The nitrate values show comparable structures with a strong gradient in the near surface layers and the influence of the Weddell Sea Bottom Water (Fig. 7.3.2). A nutrient maximum is related to the Warm Deep Water which is more pronounced in the western part of the gyre (Sta. 44 - 61) with maximum nitrate concentrations higher then 35 mM between 300 and 1000 m. In the Weddell Sea Bottom Water the concentration decrease to values below 33 mM. The surface values of nitrate, silicate and phosphate reflect the biological conditions (Fig. 7.3.3). Due to the extensive bloom of large phytoplankton stocks in the coastal polynya off Kapp Norvegia (Sta. 13 to 23) and off the Antarctic Peninsula (Sta. 61 to 64), nutrients were remarkably depleted. The silicate concentration reached values of less than 58 mM in the eastern bloom and 62 mM in the western one. Similar minima are found in the nitrate and phosphate concentrations for both bloom areas with nitrate values of 19.8 mM in the east and 16.7 mM in the west and with phosphate values of 1.43 mM and 1.12 mM respectively. A slight depletion at approximately 700 km from the western boundary, at the Sta. 47 to 49, can be related to a third bloom area. In contrast to the bloom areas, the nutrient concentrations are high elsewhere (Sta. 24 to 44). The concentrations range from 70 mM to 77 mM for silicate, from 26.2 mM to 30.0 mM for nitrate and from 1.77 mM to 1.99 mM for phosphate. C.5. CARBON DIOXIDE CHEMISTRY IN THE WEDDELL SEA (J.M.J. Hoppema, I. Schweimler/AWI) OBJECTIVES Carbon dioxide is a widely known greenhouse gas, whose concentration in the atmosphere has increased because of anthropogenic causes. The oceans are the most important sink of anthropogenic CO2 and among those the polar oceans are thought to be pivotal. For the Southern Ocean the details of the possible uptake of CO2 are still unclear. Particular attention will be given to the following points: 1. Partial pressures of CO2 in sea water and atmosphere. The difference between those two is the driving force for the exchange of CO2 between both reservoirs, which will be used to estimate the sink (or source) function of the Weddell Sea. 2. Factors governing the CO2-system. For this purpose the total-CO2 and alkalinity will be correlated with other properties such as salinity, oxygen, nutrients etc. 3. Total-CO2 and alkalinity are unique properties of water masses. Their potential as a tracer will be investigated. 4. Differences between the present measurements and those in winter, which were performed during June and July 1992 in the Weddell Sea, will be analyzed. WORK AT SEA CO2 dissolved in sea water is actually part of a system of chemical equilibria, where the main component is the bicarbonate ion. Because of this it is not trivial to measure CO2, but rather one has to determine the CO2-system. Knowing two measurable quantities of the system enables calculation of all other system parameters. During this cruise, measurements were done of three parameters, notably, total-CO2 (TCO2), which is all inorganic carbon, total alkalinity and the partial pressure of CO2 (pCO2). In addition, the pCO2 of air was measured. On almost all stations, where water was collected with the CTD-Rosette sampler TCO2 was determined with a standard coulometric method. Thus complete depth profiles were obtained for TCO2. Alkalinity was measured by means of a rapid potentiometric titration with open vessel. The alkalinity will be calculated from the titration data using the Gran method. As for TCO2, samples were analyzed for alkalinity at almost all CTD-stations, but at about half of the stations only the surface layer until 200 m was sampled. In between stations semi-continuous measurements for pCO2 were done. The water was taken in from about 9 m below the surface and continuously sprayed into an equilibrator where it was brought to equilibrium with air. Via a chemical dryer this air was pumped through a non-dispersive infrared Analyzer (Li-cor) where the absorption caused by CO2 was recorded. In the same way the CO2 concentration of marine air from approximately 20 m above sea level was obtained. PRELIMINARY RESULTS Fig. 7.3.4 shows a depth profile of TCO2 of a station in the centre of the Weddell Gyre. It has to be kept in mind that data are indeed preliminary and further processing has to be done. This can change the figure slightly, but will not significantly affect the shape of the profile. The profile shows a CO2 depletion in the surface layer compared to the deep and bottom waters, which is mainly biologically mediated. At about 500 m there is a TCO2 maximum, indicating the depth where the Warm Deep Water exerts its largest influence. The depth of the TCO2 maximum in the Weddell Sea is not constant. In the surface layers a large variation of the TCO2 content was observed, with generally high values in the centre of the Weddell Gyre and values up to 100 mmol/l lower in the western Weddell Sea. The TCO2 values in the central Weddell Sea were comparable to values measured in the winter. The continuous pCO2 measurements confirmed this trend in the TCO2 data. In the central Weddell Sea the pCO2Of the sea water was always close to atmospheric values, whereas in the western Weddell Sea there was always undersaturation of CO2 with respect to the atmosphere, with values decreasing to approximately 150 ppm. C.6. ORGANIC CARBON AND HUMIC SUBSTANCES IN THE WEDDELL SEA (A. Skoog, M. Wedborg/AMK) OBJECTIVES Dissolved organic matter (DOM) in the ocean is the largest organic carbon reservoir in the global carbon cycle. It may be of importance as a sink of atmospheric carbon dioxide. Substantial quantities of DOM, mainly in the form of humic substances (HS), are added to the ocean by the rivers. The fate of this DOM, which is often referred to as biologically refractory, is uncertain. In the literature it has been reported that structural units, typical of terrestrial vascular plants are present in HS from the deep ocean, and that the marine HS can be quite old, between 5,000 and 10,000 years. This suggests that terrestrial DOM may be of significance as a part of the marine HS. The objective of this project was to increase the scarce information on total/dissolved organic carbon (TOC/DOC) and HS in the open ocean. The Weddell Sea is of special interest because the direct influence from the Antarctic continent is assumed to be negligible, while the biological productivity in the water column can be high. WORK AT SEA Water samples for determination of TOC/DOC and HS were taken at all but ten CTD stations. TOC/DOC was determined by the high temperature catalytic oxidation method, and HS by fluorescence spectrophotometry, excitation 350 nm, emission 450 nm. The samples were normally processed within a few hours after sampling. HS were isolated on Amberlite XAD-2 columns, mainly for the purpose of estimating the fraction of TOC/DOC that is present as HS. PRELIMINARY RESULTS The concentrations of TOC/DOC and HS found in the Weddell Sea were slightly lower than those from the Atlantic water in the deep Skagerrak, approximately 40 to 50 mM of TOC/DOC and 0.2 to 0.7 mg/l (as quinine sulphate equivalents, QS) of HS. For TOC/DOC, the concentration normally increased towards the surface, whereas for HS the lowest concentrations were in most cases found at the surface, and a maximum at approximately 500 to 1000 m. At a few stations, some of which had a high biological productivity (e.g. Sta. 14 and 62, 72 to 76), the HS profile showed an increase at the surface but the TOC profiles for the stations with a high biological productivity were not notably different from those of the other stations (Fig. 7.3.5). For stations 79 to 85 the HS profiles resembled that of Sta. 62, with a marked decrease near the bottom, but without the increase at the surface (Fig. 7.3.5). The concentrations of TOC and HS in brown ice were found to be two to ten times as high as in the water column. D. ACKNOWLEDGEMENTS When we left "Polarstern" in Ushuaia, we all felt that we had an extremely successful cruise which was obviously to a large extent due to the most favorable ice and weather conditions and due the outstanding technical facilities of "Polarstern". However, it was obvious to us all, that only the continuous efforts of Master Jonas, his officers and his crew gave us the possibility to use this outstanding instrument. It was not only the active support which helped us to overcome difficult situations, but it was the hearty mood on board which made this cruise not only to a scientific success, but a cheerful adventure. E. REFERENCES APPENDIX I: CTD Measurements during AQANTX/7 Instrument : Neil Brown CTD, Mark IIIB, Sn: 1069, BJ: 1984 CTD temperature sensor : Rosemount Platinum Thermometer resolution : 0.0005 deg C accuracy : +/- 0.005 deg C CTD pressure sensor : Paine Model resolution : 0.1 dbar accuracy : +/- 6.5 dbar CTD conductivity sensor : EG&G NBIS resolution : 0.001 mmho accuracy : +/- 0.005 mmho Software : EG&G Oceansoft MkIII/SCTD Aquisition Version 2.01 CTD postprocessing Version 1.12 Time lag : 0.05 s Pressure pre-cruise calibration coefficients a1 = -1.022974E+01 a2 = 6.503845E-03 a3 = -1.175345E-05 a4 = 7.631715E-09 a5 = -2.169818E-12 a6 = 2.851089E-16 a7 = -1.427193E-20 dp = a1 +a2*p +a3*p**2 +a4*p**3 +a5*p**4 +a6*p**5 +a7*p**6 p = p + dp no post-cruise calibration for the calibration data are the same Temperature pre-cruise calibration coefficients a1 = -2.992423E+00 a2 = -6.467617E-04 a3 = -1.247109E-05 a4 = 1.406644E-06 a5 = -1.906594E-08 dt = a1 +a2*t +a3*t**2 +a4*t**3 +a5*t**4 t = t + dt no post-cruise calibration for the calibration data are the same ----------------------------------------------------- correction of the CTD-conductivity data with the bottle-samples ( conductivity of the salinometer data) evaluation of the coefficients with the mean of 14 stations CD = ( CONDUCTIVITY SALINOMETER - CONDUCTIVITY CTD ) * 1000 CD = A0 + A1*PRES + A2*PRES**2 + A3*PRES**3 ---------------------------------------------------------------------------- STATION A0 A1 A2 A3 ---------------------------------------------------------------------------- 00301 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 00501 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 00801 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01003 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01101 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01202 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01301 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01401 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01501 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01702 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 01901 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 02001 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 02101 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 02201 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 02301 0.40097E+02 0.13961E-02 -0.62035E-06 0.78273E-10 correction of the CTD-conductivity data with the bottle-samples evaluation of the coefficients with the running mean of 7 stations 02401 0.44965E+02 -0.86689E-03 0.42263E-06 -0.47595E-10 02505 0.44965E+02 -0.86689E-03 0.42263E-06 -0.47595E-10 02601 0.44965E+02 -0.86689E-03 0.42263E-06 -0.47595E-10 02702 0.44965E+02 -0.86689E-03 0.42263E-06 -0.47595E-10 02802 0.43822E+02 0.48446E-03 -0.25160E-06 0.42966E-10 02901 0.43835E+02 0.32420E-03 -0.14951E-06 0.28644E-10 03001 0.43919E+02 0.18689E-03 -0.10745E-06 0.23665E-10 03102 0.44038E+02 0.21539E-04 -0.73212E-07 0.21681E-10 03201 0.44107E+02 0.58768E-04 -0.83728E-07 0.20917E-10 03301 0.44296E+02 -0.26691E-03 0.46702E-07 0.29663E-11 03401 0.44689E+02 -0.51701E-03 0.15368E-06 -0.10712E-10 03501 0.45097E+02 -0.10554E-02 0.44458E-06 -0.52303E-10 03606 0.45559E+02 -0.14528E-02 0.55199E-06 -0.61322E-10 03701 0.45726E+02 -0.18585E-02 0.80565E-06 -0.98044E-10 03804 0.45772E+02 -0.20032E-02 0.84883E-06 -0.10243E-09 03901 0.45779E+02 -0.20912E-02 0.87895E-06 -0.10570E-09 04002 0.45903E+02 -0.21774E-02 0.91354E-06 -0.10854E-09 04105 0.45454E+02 -0.98999E-03 0.38891E-06 -0.44703E-10 04201 0.45211E+02 -0.14068E-03 -0.65040E-08 0.59972E-11 04301 0.44979E+02 0.48931E-03 -0.26277E-06 0.34550E-10 04405 0.45075E+02 0.90788E-03 -0.52558E-06 0.76034E-10 04501 0.45334E+02 0.82027E-03 -0.48796E-06 0.75557E-10 04601 0.45851E+02 0.46172E-03 -0.34841E-06 0.59039E-10 04709 0.45734E+02 0.38609E-03 -0.33138E-06 0.59671E-10 04802 0.45946E+02 0.21605E-03 -0.41581E-06 0.83885E-10 04901 0.46239E+02 -0.68338E-03 -0.13293E-07 0.35283E-10 05001 0.46660E+02 -0.15578E-02 0.48073E-06 -0.32647E-10 05107 0.47010E+02 -0.21735E-02 0.70932E-06 -0.55246E-10 05201 0.47566E+02 -0.31364E-02 0.11145E-05 -0.10517E-09 05301 0.47907E+02 -0.36161E-02 0.13570E-05 -0.13784E-09 05409 0.48284E+02 -0.23454E-02 0.69915E-06 -0.51260E-10 05501 0.48173E+02 -0.21436E-02 0.90543E-06 -0.99688E-10 05601 0.48565E+02 -0.22444E-02 0.96576E-06 -0.10912E-09 05704 0.48100E+02 -0.16081E-02 0.55235E-06 -0.44177E-10 05801 0.48070E+02 -0.17760E-02 0.67554E-06 -0.68829E-10 05904 0.47483E+02 -0.72877E-03 0.18102E-06 -0.60924E-11 06001 0.47238E+02 -0.37313E-03 0.27003E-07 0.11686E-10 06101 0.47019E+02 -0.63778E-03 0.20635E-06 -0.17690E-10 06204 0.47084E+02 -0.47038E-03 -0.53129E-09 0.21141E-10 06303 0.47289E+02 -0.99113E-03 0.26980E-06 -0.21588E-10 06401 0.47328E+02 -0.14829E-02 0.59135E-06 -0.72485E-10 06501 0.47322E+02 -0.17544E-02 0.85824E-06 -0.12835E-09 06804 0.47449E+02 -0.18297E-02 0.76997E-06 -0.93999E-10 06904 0.47992E+02 -0.35443E-02 0.20304E-05 -0.36930E-09 07002 0.48227E+02 -0.48164E-02 0.34287E-05 -0.78486E-09 07104 0.49396E+02 -0.11713E-01 0.12510E-04 -0.39442E-08 07201 0.49853E+02 -0.14506E-01 0.18912E-04 -0.85326E-08 07304 0.50611E+02 -0.26918E-01 0.76237E-04 -0.75660E-07 07402 0.49996E+02 -0.10873E-01 -0.11264E-04 0.64430E-07 07501 0.50713E+02 -0.30963E-01 0.98277E-04 -0.86457E-07 07603 0.49564E+02 -0.13137E-01 0.30550E-04 -0.21597E-07 07701 0.49193E+02 -0.75210E-02 0.11256E-04 -0.53980E-08 07801 0.47759E+02 0.62618E-03 -0.56092E-06 0.27427E-11 07901 0.47730E+02 0.13132E-02 -0.13962E-05 0.26690E-09 08004 0.47470E+02 0.28071E-02 -0.30814E-05 0.82316E-09 08101 0.47496E+02 0.13994E-02 -0.10899E-05 0.20585E-09 08201 0.47560E+02 0.97582E-03 -0.70183E-06 0.11414E-09 08301 0.47733E+02 0.85061E-03 -0.77909E-06 0.15358E-09 08404 0.47811E+02 0.25509E-02 -0.22105E-05 0.45056E-09 08501 0.47768E+02 0.29178E-02 -0.22634E-05 0.44073E-09 08601 0.47543E+02 0.27148E-02 -0.16473E-05 0.27629E-09 08701 0.47875E+02 0.18920E-02 -0.13298E-05 0.24001E-09 08801 0.47627E+02 0.20224E-02 -0.11203E-05 0.17250E-09 08901 0.47627E+02 0.20224E-02 -0.11203E-05 0.17250E-09 09001 0.47627E+02 0.20224E-02 -0.11203E-05 0.17250E-09 09101 0.47627E+02 0.20224E-02 -0.11203E-05 0.17250E-09 The CTD-temperature is IPTS-68 CTD-Files column 5 : transmissiometer ( TRANSM ) raw data , range between 0 - 5 volt input voltage 5 volt maximum level output voltage 4.81 volt zero level 0.026 volt station 15 to 91: the transmissiometer don't work The *.SEA file: The variable in column 15 : TCARBN is Total-CO2