R/V Knorr Athena metadata file
Wed 12/May/2004 05:37:59
Current time zone: GMT Standard Time
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12kHz depth  ( Depth12)
  Format:  Depth  (meters)
  Depth in meters obtained from the 12 kHz channel of the Knudsen bathymetry
  system.  5 meter depth of transducer has been applied.
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3.5kHz depth  ( Depth35)
  Format:  Depth  (meters)
  Depth in meters obtained from the Knudsen 3.5 kHz channel.   5 meter 
  transducer depth correction has been applied.
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EDO  speed  ( EDO_knt)
  Edo speedlog, converted to knots
  millivolts * .004 = knots
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EDO Speedlog  ( EDO)
  Ship speed from Edo Speedlog - millivolts
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Edo Depth String  ( EDO_VDstr)
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Sea Surface Conductivity (SSCND)
  Falmouth Scientific TSG (OCM-S-212) sea surface conductivity (mmho/cm)
  Format:   Conductivity  -- fixed data input time interval: 15 seconds
  OCM sensor is mounted in the bow chamber on the suction side of the 
  clean sea water distribution pump, approximately 5 feet from the forward
  facing inlet at 15 feet depth.

  Calibration - Jan 2004
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Sea Surface Temperature (SSTMP)
  Falmouth Scientific TSG (OTM-S-212) sea surface conductivity (degrees C)
  Format:    Sea surface temperature -- fixed data input time interval: 15 
  seconds OTM sensor is mounted in the bow chamber on the suction side of the
  clean sea water distribution pump approximately 5 feet from the forward facing
  inlet, at 15 feet depth.

  Calibration - Jan 2004
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GPS course over ground (GPS_COG)
  Course over ground (true) obtained from NMEA GPS_VTG data sentence.
  Format:  Course
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Latitude (GPS_Lat)
  Latitude from GPS NMEA GGA data sentence formatted for display.
  Format:  dd mm.mmm, N/S
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Longitude (GPS_Lon)
  Longitude from GPS NMEA GGA data sentence formatted for display.
  Format:  ddd mm.mmm, E/W
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GPS Navigation data (GPS)
  Complete NMEA data output from the primary GPS receiver.
  The datum used by both the P-Code and Northstar GPS receivers is WGS84.

  The single digit following the position information in the GPGGA data 
  string indicates the type of GPS fix as follows:
      0=No valid fix; 1=Standard; 2=Differential; 3=P-Code

  NMEA GPGGA data sentence:  Header , UTC of position, Latitude, N/S,
  Longitude, E/W, Quality indicator, Number of satellites in use, Horizontal 
  dilution, Altitude, M (meters),  Geoidal seperation, M (meters), Age of 
  differential data (secs), Differential reference station I.D. * checksum.
  (Lat & Lon values are "degrees minutes.decimal_minutes") 

  NMEA GPVTG data sentence:  Header, Course, T (degrees true),
  Course, M (magnetic), Speed, N (knots), Speed, K (km/hr) * checksum.

  NMEA GPRMC data sentence - not always available:
  Header, UTC of position fix, Status (A=valid, V=warning), Latitude, N/S, Longitude,
  E/W, Speed over ground (knots), Course over ground (True), Date (ddmmyy), Magnetic
  variation (degrees), E/W (Easterly variation subtracts from True course)
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GPS speed over ground (GPS_SOG)
  Speed over ground (knots) obtained from NMEA GPS_VTG data sentence.
  Format:  Speed
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GPS type (GPS_TYPE)
  GPS position type (Std, Diff, P-Code)
  GPS position type indicator is obtained from the "quality indicator" included
  as part of the GPS NMEA GGA data sentence.
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Gyro heading (Gyro)
  Ship's heading (degrees true) obtained from the Gyro NMEA HEHDT data
  sentence.
  Format:   Heading  (degrees true)
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IMET Wind (IMET_WND)
  Format: X, Y, Total, Max, Min, LastVane, LastCompass, C1, C2

	Wind X (m/sec), Positive for a stbd to port wind
	Wind Y (m/sec), Positive for a bow to stern wind
	Wind Total (m/sec), Averaged over previous minute
	Wind Max (m/sec, 15 sec interval),
	Wind Min (m/sec, 15 sec interval),
	Last Vane Reading (deg),
	Last Compass Reading (deg),
	Counter1 ("0"), Counter2 ("4")
	
	Note - Wind direction is not provided as a
	  single quantity.  Direction values are ship relative.
	  The wind sensor does not have a compass installed
	  (value should always be 0.0).

  Calibration - Jan 2003
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IMET Air Temperature (Air_Temp)
  Format: Temp (C)
  Data is obtained from IMET_HRH primary sensor.
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IMET Barometric Pressure (IMET_BPR)
  Format:  Barometric pressure (milli-bars)

  Calibration - Jan 2003
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IMET longwave radiation  ( IMET_LWR)
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IMET Precipation (IMET_PRC)
  Format:  Precipitation (millimeters)
  Last minute (mm/min), Last hour (mm/hr), Present Level (mm)

  Calibration - Jan 2003
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IMET relative humidity (HRH)
  Format:   Humidity (%RH)
  Data is obtained from IMET_HRH primary sensor.
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IMET Shortwave Radiation (IMET_SWR)
  Format:  Radiation (watts/square meter)

  Calibration - Jan 2003
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IMET Humidity (IMET_HRH)
  Format:  Humidity (%RH), Temperature (C)
  Note - IMET humidity and air temperature data are both obtained from this
  instrument.

  Calibration - Jan 2003
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Knudsen bathymetry  ( PKEL99)
  Depth data obtained from the Knudsen bathymetry system.  Values have
  been corrected for transducer depth (5 meters). 
  Format:  Header ($PKEL99), time (hhmmss), 12 kHz depth (meters),  
  3.5 kHz depth (meters), Speed of sound (m/s),  Lat (dd mm.mmm N/S),  
  Lon (ddd mm.mmm E/W)

  Speed of sound is the value used by the Knudsen.  It is entered manually
  and therefore is not necessarily correct.
  The time listed after the header should be nearly identical to the data item's
  time stamp - if it isn't, it means the Knudsen control computer is not synchronized
  to the ship's master clock.
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MetraByte #1  ( MByte1)
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NMEA Gyro (HEHDT)
  Ship's heading obtained from the Sperry Gyro.
  NMEA format:  Header ($HEHDT), Heading (degrees), T (true),
  Heading (degrees), M (magnetic) * checksum.

  Version 2.20 (1/1/97) of the NMEA 0183 standard does not show magnetic
   heading in this data sentence and the validity of this item is questionable.
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Position from GPS receiver (Lat_Lon)
  Latitude & Longitude in decimal degrees.
  Format:  +/-dd.dddddd  +/-ddd.dddddd
  (N & E are "+")
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Salinity (Salinity)
  Format:  Salinity
  Salinity calculated from sea surface temperature and conductivity data values
  in accordance with UNESCO 44.
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Sea surface fluorometer  ( Fluorometer)
  WetLabs Wet-Star fluorometer located in the clean seawater system.  
  Value reported in millivolts.  Calibration must be done by interested
  science parties.

  Purchased & installed Jan 2003
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Sound velocity  ( SSV)
  Format:  Sound_Velocity  (meters/sec)
  Surface sound velocity calculated from sea surface temperature and
  conductivity data values.  Intermediate salinity values are calculated in
  accordance with UNESCO 44.
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True wind direction (Wnd_Dir)
  Format:  Wnd_dir  (degrees)
  Wind direction obtained from the IMET wind sensor and corrected for ship
  heading (gyro) plus ship course and speed (GPS SOG & COG).
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True wind speed (Wnd_Spd)
  Format:  Wnd_spd  (meters/sec)
  Wind speed obtained from the IMET wind sensor and corrected for ship heading
  (gyro) plus ship course and speed (GPS SOG & COG).

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True wind speed & direction (TWind)
  Format:   Speed, Direction  (meters/sec, degrees)
  Wind direction is given in meteorological terms; a 0 degree wind comes from
  the north.  Ship speed and direction of travel are obtaned from GPS data
  (GGA SOG & COG).  Sensor mounting orientation is corrected using the
  direction the ship is pointing obtained from the gyro (the ship is not 
  necessarily moving in the direction its pointing).
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Turner fluorometer data (TF10_data)
  Fluorometer data from Turner Designs Model 10.  Full scale = 1 volt (1000.00
  from MetraByte A/D module).  Exact value is not in agreement with instrument
  front panel meter due to the characteristics of the calibration resistor.  
  Science party is responsible for recording comparative readings during the 
  cruise if needed.
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Turner fluorometer range (TF10_Range)
  Fluorometer range setting from Turner Designs Model 10 (full scale = 1 volt).
  Actual values reported by the MetraByte A/D module (1000.00=1 volt) are
  not in agreement with the value indicated in the Turner manual due to the 
  accuracy of the calibration  resistor.  Actual readings are per the following 
  table (science party should check these values at some point during the 
  cruise):

	Range		Expected	Actual	 
	X0		0.0v		000.10
	X3.16		0.4v		488.60
	X10		0.7v		831.00
	X31.6		1.0v		9999.99
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Wyse (data)  ( Wyse_data)
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Defined constants:
 
WindSensorOffset = 0.0
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Auxiliary information:
 
Time stamp formats:
Individual items in Athena ".dat" data files are time stamped with two different formats.  The first time stamp
value is in the format used by Microsoft Visual Basic: the number of days since December 31, 1899 (Dec. 31 is
day 1, not day 0).  Its primary purpose is to provide a continuously increasing date and time indicator for use
in data graphing applications. The VB format facilitates this for some applications but converting the number
to the normal human readable form can be painful.  The second time stamp value (hh:mm:ss format) in
combination with the file header's date information may eliminate the need for this conversion.  If not,
the following may be helpful:
00.00 is 00:00:00 on Dec. 30, 1899.
00.50 is 12:00:00 (noon) on the same day.
35390.58333 is 14:00:00 May 15, 1998.