Knapp George P.

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Knapp
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George P.
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  • Technical Report
    Hydrographic station data of five surveys of the beta-triangle in the eastern North Atlantic, 1978-1981
    (Woods Hole Oceanographic Institution, 1983-07) Behringer, David W. ; Knapp, George P. ; Stanley, Robert J. ; Stommel, Henry M.
    This is a data report, giving temperature, salinity and dissolved oxygen data obtained during five surveys of the beta-triangle area of the eastern North Atlantic in the years 1979-81. The report is divided into two parts. Part I consists of a listing of station data obtained on all stations occupied -- on the periphery of the triangle, inside it, and some nearby stations outside it. Part II is a set of profiles of this data drawn on the three sides of the triangle, for easy reference and visual comparison. Detailed scientific study of the data is published elsewhere.
  • Technical Report
    A trans-Indian Ocean hydrographic section at latitude 32°South : data report of RRS Charles Darwin cruise #29
    (Woods Hole Oceanographic Institution, 1992-01) Cook, Margaret F. ; Toole, John M. ; Knapp, George P. ; Fine, Rana A. ; Top, Zafer ; Jennings, Joe C.
    A trans-Indian Ocean hydrographic section employing CTD/O2 profilers was conducted between Africa and Australia during austral spring 1987. The cruise track ranged between 29°S and 34°S; the average latitude of the crossing was 32°S. The purpose of the cruise was to explore various aspects of the South Indian Ocean including the characteristics of the core water masses of this ocean, the strength of the subtropical gyre, the structure and transport of deep western-boundary currents, and the net meridional heat flux. A total of 109 CTD/O2 profiles with associated rosette water sample measurements and 347 XBT profiles were collected, supplemented by underway upper ocean velocity, bathymetric and sea surface temperature and salinity data. This report detals the data collection, calibration, and reduction methods, and summarizes the hydrographic observations.
  • Technical Report
    Automated oxygen titration and salinity determination
    (Woods Hole Oceanographic Institution, 1990-08) Knapp, George P. ; Stalcup, Marvel C. ; Stanley, Robert J.
    This report describes a newly developed automated Winkler titration system for dissolved oxygen in seawater which is presently in use at the Woods Hole Oceanographic Institution. This amperometric, calculated, endpoint system was compared with two different automated and one manual Winkler method during a recent cruise. The four different methods agreed to within about 0.04 ml/l. The system described here measures the titrant needed to reach the endpoint with a resolution better than 0.001 ml. The standard deviation of replicate samples is 0.005 ml/l and the accuracy is about 0.02 ml/l. A technique to automatically acquire conductivity ration measurements and calculate salinity using a Guildline Autosal Salinometer is also described.
  • Technical Report
    Automated oxygen titration and salinity determination
    (Woods Hole Oceanographic Institution, 1990-08) Knapp, George P. ; Stalcup, Marvel C. ; Stanley, Robert J.
    This report describes a newly developed automated Winkler titration system for dissolved oxygen in seawater which is presently in use at the Woods Hole Oceanographic Institution. This amperometric, calculated endpoint system was compared with two different automated and one manual Winkler method during a recent cruise. The four different methods agreed to within about 0.04 ml/l. The system described here measures the titrant needed to reach the endpoint with a resolution better than 0.001 ml. The standard deviation of replicate samples is 0.005 ml/l and the accuracy is about 0.02 ml/l. A technique to automatically acquire conductivity ratio measurements and calculate salinity using a Guildline Autosal Salinometer is also describe.
  • Technical Report
    Hydrographic data from R.V. Oceanus cruise 133, leg VII
    (Woods Hole Oceanographic Institution, 1985-12) Knapp, George P. ; Stommel, Henry M.
    Hydrographic data collected during R.V. Oceanus cruise 133, leg VII are presented. These data include temperature, salinity and dissolved oxygen observed at standard levels by a Neil Brown Instrument Systems' CTD-02 profiler and salinity, dissolved oxygen, silicate, phosphate and nitrate values at the observed depths of the collected water samples. Ninety-four stations were occupied on a meridional section at (nominally) 52°West from Brazil to Greenland. Also presented are a series of sectional profiles of the six observed parameters as a function of depth.
  • Technical Report
    Dissolved oxygen measurments in sea water at the Woods Hole Oceanographic Institution
    (Woods Hole Oceanographic Institution, 1989-07) Knapp, George P. ; Stalcup, Marvel C. ; Stanley, Robert J.
    This report describes a modified Winkler titration technique that has been used for the past 25 years at the Woods Hole Oceanographic Institution (WHOI). During this time most of the dissolved oxygen measurements made at sea by WHOI personnel have been analyzed with this technique and only relatively minor, evolutionary changes in the procedures and equipment have occurred. These changes, however, have improved the precision and accuracy of deep-sea dissolved oxygen measurements to 0.005 ml/l and 0.02 ml/l respectively.
  • Technical Report
    Hydrographic data from R. V. Endeavor cruise 129
    (Woods Hole Oceanographic Institution, 1988-09) Knapp, George P.
    Hydrographic and CTD data collected during R.V. Endeavor cruise 129 are presented. These data include temperature, salinity and dissolved oxygen observed at standard levels by a Neil Brown Instrument Systems' CTD-02 profiler and salinity, dissolved oxygen, silica, phosphate and nitrate values at the observed depths of the collected water samples. Ninety- two stations were occupied on two short sections within the Caribbean and one long meridional section at (nominally) 64° West from the British Virgin Islands to the 200 m depth contour south of Newfoundland. Also presented are a series of sectional profiles of the six observed parameters as a function of depth.
  • Technical Report
    Progress in the measurement of salinity and oxygen at the Woods Hole Oceanographic Institution
    (Woods Hole Oceanographic Institution, 1987-01) Knapp, George P. ; Stalcup, Marvel C.
    Improvements in the measurement of salinity and dissolved oxygen during the past few years at WHOI have increased the accuracy of salinity observations to +/- 0.001 ppt and that of dissolved oxygen determinations to +/- 0.04 ml/1. These improvements are attributable to the careful maintenance of the sample collection and analysis equipment, the construction of portable, sea going laboratories in which the temperature is constant to +/- 1 degree C and the skillful use of an Autosal 8400-A salinometer and a Metrohm Titroprocessor by well trained technicians. An automated data logging system eliminates transcription errors and facilitates the timely calibration of the CTD sensors.
  • Working Paper
    A comparison of methods for the determination of dissolved oxygen in seawater
    (WOCE Hydrographic Programme Office, Woods Hole Oceanographic Institution, 1991-08) Culberson, Charles H. ; Knapp, George P. ; Stalcup, Marvel C. ; Williams, Robert T. ; Zemlyak, Frank
    An intercalibration of dissolved oxygen methods was conducted at 2 stations in the Sargasso Sea between April 28 and May 3, 1990. The experiment compared three techniques using automated endpoint detection with the manual Winkler method using a starch endpoint. Institutions participating in the intercomparison were the Bedford Institute of Oceanography (automated photometric titration), the University of Delaware (automated amperometric titration), the Scripps Institution of Oceanography (manual titration), and the Woods Hole Oceanographic Institution (automated amperometric titration). Differences in measured oxygen concentrations between institutions were encouragingly small. However, small, systematic differences in dissolved oxygen between institutions did exist. The range between the highest and lowest oxygen values reported by the 4 institutions never exceeded 0.6% over the entire concentration range studied (3.4 to 6.2 mlj1). The good agreement is probably due to the use of the essentials of Carpenter's (1965) modification of the Winkler method by all institutions. The intercalibration revealed several aspects of dissolved oxygen measurements that require further research: (1) the intercalibration should be extended to very low oxygen concentrations; (2) procedures for measur ing and applying corrections for the seawater blank need to be formalized; (3) a simple procedure to measure the temperature of seawater at the time of sampling needs to be developed; and (4) the solubility of atmospheric oxygen in the Winkler reagents must be measured as a function of temperature. The intercalibration also revealed that analytical techniques required for precise and accurate volumetric measurements were often not applied, even by experienced analysts. It was found that uncalibrated pipets were used to dispense standards, that the volumes of oxygen flasks were not corrected for buoyancy, and that corrections for the thermal expansion of aqueous solutions were often not applied.