
NODC DOCUMENTATION FOR CTD DATASETS

#documentation_file_name:            *     
#nodc_accession_number:              *
#nodc_reference_number:              * 
#nodc_documentation_date:            *
#nodc_documentor: 		     *                    
#distribution_restriction:           none
#date_received:                      *
#submission_medium: ftp tar file	
#submittor_name:  Robert O'Malley
#submittor_institution: College of Oceanic and Atmosperic Sciences,
			Oregon State University
#submitter_street_address: 104 Ocean Admin Bldg
#submitter_city: Corvallis 
#submitter_state: Oregon
#submitter_country: USA
#submitter_zip_code:  97331-5503
#sumitter_telephone_no: 541-737-2180
#submitter_internet: 
#submitter_email: omalley@coas.oregonstate.edu
#collection_information (i.e cruise dates, ports, cast numbers, 
 time of cast, longitude and latitude of casts):
	R/V Oceanus cruise OC340 (referred to here as O9903)
	28 March to 13 April, 1999
	Woods Hole to Woods Hole, Massachusetts
	Seasoar sampling in 11 tows during O9903 as follows:

Tow no. Start date,time       End date,time          Parameters measured
          (1999) (UT)           (1999) (UT)
  1       30 Mar 1351           30 Mar 1504     P, T1, C1, T2, C2, FL, TRANS
  2       30 Mar 1622           31 Mar 1831     P, T1, C1, T2, C2, FL, TRANS
  3       01 Apr 0856           01 Apr 2110     P, T1, C1, T2, C2, FL, TRANS
  4       02 Apr 1911           03 Apr 1923     P, T1, C1, T2, C2, FL, TRANS
  5       04 Apr 0302           06 Apr 0417     P, T1, C1, T2, C2, FL, TRANS
  6       06 Apr 1418           07 Apr 1721     P, T1, C1, T2, C2, FL, TRANS
  7       07 Apr 2043           08 Apr 0908     P, T1, C1, T2, C2, FL, TRANS
  8       08 Apr 1332           08 Apr 1657     P, T1, C1, T2, C2, FL, TRANS
  9       08 Apr 1702           09 Apr 0425     P, T1, C1, T2, C2, FL, TRANS
 10       09 Apr 1213           10 Apr 0132     P, T1, C1, T2, C2, FL, TRANS
 11       10 Apr 0440           11 Apr 1208     P, T1, C1, T2, C2, FL, TRANS

 All observations were between 42.5 and 41.9 degrees N. latitude, and 
 between 66.8 degrees and 66.2 degrees W. longitude. Maximum sampling 
 depth approximately 120 m for all tows.

#principal_investigator_name: John A. Barth (also D. Hebert from URI)
#pi_institution:College of Oceanic and Atmospheric Sciences, 
    	       	Oregon State University 
#pi_street-address:  104 Ocean Admin Bldg
#pi_city: Corvallis
#pi_state: Oregon
#pi_country: USA
#pi_zip_code: 97331-5503
#pi_telephone_no: 541-737-1607
#pi_internet: 
#pi_email:  barth@coas.oregonstate.edu
#project: GLOBEC Georges Bank
#funding agency: NSF
#grant/contract-no: OCE-9813641
#platform_type: research vessel
#platform_name: Oceanus
#collection_methods:  
 (i.e. how were the data obtained) 
 SeaBird 9/11 plus CTD inside Seasoar vehicle; with dual ducted SBE-3 and SBE-4
 temperature and conductivity sensors inside seasoar vehicle; flow through 
 sensor duct pumped by SBE-5 pumps; intake and outlet for each sensor pair was 
 directed forward through center of lower nose with intake and outlet 
 separated by about 2 cm, the T1-C1 pair were starboard of the centerline,
 and the T2-C2 pair were port of the centerline; final data were from
 the T1-C1 pair for tows 5,8-11; the T2-C2 pair were used for
 tows 1-4,6,7; final data were from the following pairs of sensors: 

	Tows   1-4,6,7:  SN 2127 and 1737 for T and C

	Tows    5,8-11:  SN 2128 and 1738 for T and C

 The CTD subunit was replaced between tows 3 and 4, resulting in the
 use of the following pressure sensors:

	Tows   1-3:  SN 50506 for P (CTD #258)
	Tows  4-11:  SN 63505 for P (CTD from Oceanus)

#analysis_methods:
 (i.e. how were the data processed, calibrated etc)
  - used SBE (SeaBird Electronic, Inc.) calibrations for temperature,
    conductivity and pressure sensors;
 
    dates of SBE CTD #258 calibrations as follows:

		P:(SN 50506) 23 April 1992 
                T1:(SN 2128) 20 February 1999
		T2:(SN 2127) 20 February 1999
                C1:(SN 1738) 23 February 1999
		C2:(SN 1737) 23 February 1999

    and date of alternate CTD SBE calibration:

		P:(SN 63505) 10 Novemer 1996 


 Data Processing:

	We compute lagged correlations between temperature and 
	conductivity for each sensor pair, and separately for each  
	ascending and descending profile, provided the segment contains  
	at least 180 scans, and were obtained between depths of 1 and 
	150 m. The fractional value of the lag at maximum correlation 
	was determined by fitting a parabola to the cross-correlation 
	values.  The lags were then repeatedly cleaned using a three-
	sigma test on a centered, moving, 100-pt window until all values 
	were within three sigma of the mean, the nulled outliers were 
	then replaced with the mean value at that point.  This time series 
	of lags was then examined to be certain the automated cleaning 
	was appropriate, and corrections were made when necessary.  The 
	final values of the alignment offset were then applied sequentially 
	in reprocessing the 24-Hz T/C data.  To reprocess data from depths 
	shallower than 1 m, we used the value determined from the associated 
	(ascending or descending) shallowest layer.

	To correct the 24-Hz conductivity data for the thermal mass of the
	conductivity cell, we used variable values for both the thermal
	amplitude and the thermal anomaly time constant depending on the 
	alignment offset (values shown are for all tows):

	T1-C1:
		alpha = 1.06533E-02 + 2.72118E-03(lag)
		tau   = 7.15038     + 1.33821 (lag**0.5)
			  
	T2-C2:
		alpha = 0.0000   + 1.22128E-02(lag)
		tau   = 7.14939  + 1.33904 (lag**0.5)
			  
			  
	These variable alpha and tau values represent the optimal
	thermal mass correction based on minimizing the area in
	T-S space of selected test hours for the survey.
			  
	The corrected and realigned 24-Hz temperature and conductivity data are
	used to calculate 24-Hz salinity, and these are averaged to yield one-
	second averages stored in hourly files.

	Successive hourly files of the reprocessed one-second average data
	were joined to yield a single data file for each tow of the survey.

	
#instruments: 
	tow 1-3:   SBE 9/11 plus CTD SN 0258 with
	           SBE pressure sensor SN 50506
	           SBE temperature  sensors SN 2127 and SN 2128
	           SBE conductivity sensors SN 1737 and SN 1738
	           WetLABS WETStar Fluorometer 
	           Seatech Transmissometer SN 15

	tow 4-11:  SBE 9/11 plus CTD from Oceanus with
	           SBE pressure sensor SN 63505
	           SBE temperature  sensors SN 2127 and SN 2128
	           SBE conductivity sensors SN 1737 and SN 1738
	           WetLABS WETStar Fluorometer 
	           Seatech Transmissometer SN 15

#publications: 
#associated_datasets:  
#associated_versions:		     *
#data_set_information:               *
#data_set_name:			     * 
#data_set_volume: 67,769 kbytes  (752,707 records)
#source_computer:  Sun Sparc 20
#source_computer_operating_system: Sun OS 5.6
#source_language: Fortran, C
#computer_code: ASCII
#originator_dataset_identifier: O9903
#data_dates: 30 March - 11 April 1999 
#left_geographic_upper_bound:       67W  43N
#right_geographic_lower_bound:	    66W  41N
#geographic_region: 		     
 Northwest Atlantic
#data_type: SEASOAR  data 
#sphere:                             * 
#parameters: latitude (decimal degrees), longitude (decimal degrees), pressure
 (dbars), temperature (C), salinity (psu), Sigma-t (kg/cubic meter), time 
 (decimal year-day of 1999), date and time (integral year, month, day, hour, 
 minute, second), flag, fluorescence (0-5 volts), light transmission (0-5
 volts).
.
#format_description:
 (e.g. description of the header, data, record layouts. Include
 units, scales, resolution, accuracy)

 no header; each line contains:
  unfiltered GPS latitude
  unfiltered GPS longitude
  pressure (dbars), accurate to better than plus/minus 2 db
  temperature (C), accurate to plus/minus 0.01 C
  salinity (psu), accurate to plus/minus 0.01 psu
  sigma-t (kg/cubic meter),
  decimal year-day (of 1999),
  integral year, month, day, hour, minute, second 
  flag word (see format comments below for interpretation)
  fluorescence (volts), accurate to 0.001 volts
  light transmission (volts), accurate to 0.001 volts

 The FORTRAN format for each record is:
 format (f10.5,f11.5,f6.1,3f8.4,f10.5,1x,6i2.2,1x,a4, 2f6.3)
#format_publication: 
(a reference for any document which defines/describes the data format(s))
#format_comments: 
 (any information about the format that will be useful, but is not
 elsewhere on this form)
 
 The variable at the end of each line (the flag word) indicates
 different items:

	the ones place:  

		0 indicates use of sensor pair 1 (T1, C1)
		1 indicates use of sensor pair 2 (T2, C2)

	the tens place:
  
		0 indicates gps fix for location
		1 indicates linear interpolation between gps fixes

	the hundreds place:  

		2 indicates top or bottom of seasoar cycle
		0 indicates otherwise

	the thousands place:  

		1 indicates collection of water sample from the 
		  5-m intake
		0 indicates otherwise
 
 The files all have the extension of ".dat" and are divided into
 the eleven tows (tow1.dat, etc).
#misc_documentation:                *
#submittor_documentation:
 any textual information about the data, provided by the submitter,
 or investigator, (not NODC folks)  For example, in most cases this
 has been an ASCII text file accompanying the data on a DAT , diskette,
 or CDROM.  It may contain information which is redundant with other
 parts of this form.



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