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Information in this document has been derived from documentation files on NSIDC's CD-ROM titled Eastern Arctic Ice, Ocean and Atmosphere Data, Volume 1: CEAREX-1, version 1.0, 8/91.
The meteorology data consist of hourly averaged observations of wind speed, wind direction, air temperature, relative humidity and sea level pressure made from the CEAREX biophysical stations. All optics profile data are in units per meter. The variable 'k' for all fields is the diffuse attenuation coefficient for the designated wavelength. All bioluminescence data values are in photons (*E10) per cubic meter. Values in the zooplankton data file are the mean densities for replicate tows. The phytoplankton and particulate matter variables from the biological analyses include:
The design was based on the NORDA HIDEX. A 220 volt stainless steel well (Crown) pump was used to pump 100 gallons per minute through a detection chamber. Bioluminescence was stimulated by the shear created as the flow of seawater passed through a 1-cm x 1-cm grid at the intake to the detection chamber. The walls of the detection chamber were lined with optical fibers that collect light from the entire detection chamber and direct it to the photomultiplier tube (PMT) in the MER-2050 profiling bioluminescence photometer (BP) (Biospherical Instruments, Inc.). This instrument samples voltages at the photomultiplier tube at a sampling interval of 1 microsecond. Through a shipboard computer, the instrument is directed to sample the PMT a specified number of times, and then to sample any other sensors. In this case, the only other parameters sampled were voltage to the PMT and depth. Typically, these parameters were sampled at 1-second intervals. The MER-2050 allows for the high voltage to the PMT to be set at four levels: off (0 volts), low (500 volts), medium (700 volts) and high (900 volts), with higher voltages resulting in increased sensitivity. The BP was usually operated at its highest sensitivity, except in highly bioluminescent waters where bioluminescence was too bright to be accurately measured at the highest sensitivity.
One bioluminescence data file contains data averaged at 5 m intervals. Data from the top 5 meters were discarded. Values are in photons (*E10) per cubic meter. Another data file contains data from four stations (66, 69, 71 and 73) at which the BP was stopped at 10 m intervals and the pump was run for five minutes at each depth. The variables in these files are defined in the CD-ROM documentation file.
Particulate carbon and nitrogen: Particulate matter concentrations were determined by pyrolysis of filtered samples in a Perkin Elmer Model 240B elemental analyzer. Samples (approximately 0.3-1.1 l) were filtered through precombusted (450 C for four hours) GF/F filters, rinsed with a few ml of weak (0.01 N) HCl, placed in precombusted glass vials and covered with aluminum foil, and dried at 60 C. Blanks were filters placed under another filter and processed as above (Nelson et al. 1989).
Primary productivity: Rates of primary productivity were determined using simulated in situ 14C-incorporation experiments (Smith and Nelson 1990). Samples were collected from depths which corresponded to known percentages of surface irradiance and placed in bottles covered with neutral density screens. The samples were inoculated with approximately 20 uCi of HCO3 and incubated on deck for approximately 24 hours. Incubations were terminated by filtering the samples through GF/F filters, which were rinsed with 5 ml 0.1N HCl just prior to the completion of the filtration (Goldman and Dennett 1985). All samples were counted on a liquid scintillation counter, and counting efficiencies determined by the external standard method. Total added isotope was determined by counting 0.5 ml of unfiltered sample directly.
Integration was from the surface to the depth at which 0.1 percent of surface irradiance penetrated. This depth varies for each station.
Please refer to the CD-ROM documentation file for discussions of the continuous vertical nutrient profiles obtained, ammonium method problems encountered, and nutrient data errors detected.
Marine particulate absorption and fluorescence excitation spectra were determined according to the methods of Mitchell and Kiefer (1984) and Mitchell (1990). Briefly, from 0.5 to 2.0 liters of seawater collected in rosette Niskin bottles were filtered through Whatman GF/F filters. The particles concentrated on the filters were then analyzed in a spectrophotometer and spectrofluorometer. An analysis using the spectrophotometer provided the raw absorbance, which was then corrected according to Mitchell (1990) to determine the absorption coefficient of the particles in the sea water suspension. The method is considered to have an accuracy of +/- 15 percent. Absorption coefficients at selected wavelengths corresponding to the channels of the optical profiler are included in the data files. The spectral fluorescence data are not included in the data base.
For the biophysical data files, ONLY CTD DATA FOR THE DEPTHS OF THE WATER SAMPLES ARE INCLUDED. The final CTD data set for the bio-physical cruise is included in the hydrography data files.
The quality control file used on the final data file is available in the CD-ROM documentation file. The file compares the trip log information obtained as each bottle was tripped and reported and bottle salinities with the final processed CTD/fluorescence profiles. The contents of the physical oceanography data files are also discussed in CD-ROM documentation file. For a discussion of the errors associated with the physical oceanography data, please refer to the data processing section of the CD-ROM documentation file.
Only bio-physical station data from the POLARBJORN Cruise were extracted and are included. A PC diskette containing the CEAREX hourly meteorological data is available from NSIDC User Services. The complete CEAREX ten minute meteorological data are contained on the CEAREX CD-ROM.
Tables describing the data files are provided in the CD-ROM documentation file. Each table includes variable names, formats, and a brief variable descriptions.
In the larger bioluminescence data file, the first three header records have the FORTRAN format 21(A7,1X). The FORTRAN format for the fourth header record is A7,161X. The data record FORTRAN format is 21(F6.1,1X). "1X" indicates one blank between each field in the headers and data records. For the smaller bioluminescence data file, the format of the first three header records is 4(A7,1X), the format of the fourth header record is A7,25X, and the data record format is 4(F6.1,1X).
Heading titles in the zooplankton data file correspond to categories in a table in the documentation files on the CEAREX CD-ROM that shows all values in floating point format. The FORTRAN format of the header record is 29(A10,1X). The format of the data records is 29(F10.2,1X). Values are number of observations of zooplankton groups per cubic meter.
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Goldman, J. C., and M. R. Dennett. 1985. Susceptibility of some marine phytoplankton species to cell breakage during filtration and post-filtration rinsing. J. Exp. Mar. Biol. Ecol. 86:47-58.
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Lackmann, G. M., P. S. Guest, K. L. Davidson, R. J. Lind and J. Gonzales. 1989. CEAREX/POLARBJOERN Meteorology Atlas. Naval Postgraduate School, NPS-63-89-005. 545 p.
MGD77 Task Group. 1989. Key to Geophysical Records Documentation no. 10 (revised): Marine Geophysical Data Exchange Format - 'MGD77' (Bathymetry, Magnetics, and Gravity). NOAA, National Geophysical Data Center. 16 p.
Mitchell, B. G. 1990. Algorithms for determining the absorption coefficient of aquatic particulates using the quantitative filter technique (QFT). In Ocean Optics X, ed. R. Spinrad. Bellingham, WA: Society of Photo-optical Instrumentation Engineers.
Mitchell, B. G. 1992. Predictive bio-optical relationships for polar oceans and marginal ice zones. Journal of Marine Systems 3(1-2):91-105.
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Mitchell, B. G., and D. A. Kiefer. 1988. Chlorophyll a specific absorption and fluorescence excitation spectra for light limited phytoplankton. Deep-Sea Research 35:639-663.
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Nelson, D. M., W. O. Smith, Jr., R. Muench, L. I. Gordon, D. Husby and C. W. Sullivan. 1989. Particulate matter and nutrient distributions in the ice-edge zone of the Weddell Sea: Relationship to hydrography during late summer. Deep-Sea Research 36:191-209.
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Smith, W. O., Jr., and D. M. Nelson. 1990. Phytoplankton growth and new production in the Weddell Sea marginal ice zone in the austral spring and autumn. Limnol. Oceanogr. 35:809-821.
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