
Title:  METADATA FOR  CTD PROFILE DATA SETS 
	COLUMBIA RIVER LMER PROJECT

Contact: David Jay
	Center for Coastal and Land Margin Research
	Oregon Graduate Institute of Science & Technology
	PO Box 91000 
	Portland, OR  97291-1000
	USA
	email: djay@lternet.edu

Principle Investigators (Institution) and research area: 
	Antonio Baptista (Oregon Graduate Inst. of Science & Technology)		hydrodynamics;
	David Jay (Oregon Graduate Inst. of Science & Technology)			geophysics;

Data Description: General hydrographic profiles indicate the nature of physical, biological, and particle 
stratification in the water column.  From these data, PIs determined depths to sample during pump casts.  In 
addition, profiles of hydrographic and biophysical parameters may be used to explore potential links betwen 
or among these parameters and to verify instrument accuracy.  Location and vertical extent of water column 
phenomena (e.g. ETMs) can be determined on a scale of 0.2 m.

Spatial and Temporal Resolution:  Pump cast sampling, and associated CTD casts took place from a fixed 
vessel during one 28-35 day cruise per year in 1990, 1991, 1992, 1995, and 1996.   During 1997 and early 1998, 
there were 2 week "seasonal" cruises in May, July, and October (1997) and February to March (1998).  During 1999, 
sampling was conducted for two weeks in June on the Columbia River and for two weeks in July on the Fraser River 
in British Columbia, Canada.

Methodology:   Measurements were conducted from an anchored vessel.  A Seabird (1990-1992) SBE 9/11 
or Ocean Sensors (1995-1996) model OS-200 CTD equipped with a CT cell, OBS sensor, and a WetLabs 
AC-3 chlorophyll absorption-attenuation sensor were deployed for vertical profiles approximately every 30 minutes.  
More frequent casts were conducted during "high intensity" sampling (e.g E or F series, see below).  Data were averaged 
into 0.2 m bins and referenced from the surface (i.e. not de-tided).

Data files are listed by series designation, i.e. each series file contains profiles from all casts during that 
series.

Variables:
	Code			cast-specific code number (see below)
	Date			Date in MM/DD/YY format
	Time			Time of day (Pacific Standard Time)
	Salinity		salinity
	Temp			temperature in degrees Celcius
	Depth			depth in meters
	Density			density (sigma-T)
	OBS			optical backscattering (see below)
	Fluor			chlorophyll a (mg/m^3) determined by AC-3 (1992 only)
	AC3chla			chlorophyll a (mg/m^3) determined by AC-3 (see below) 
	Atten			beam attenuation (1/m)
	Transmiss		transmissivity (% pure water)


Explanation of Code:
	Format of code is:  YYBSENN
		
		YY	first two digits indicate year
		B	letter(s) indicates boundary location or tidal series as follows: U=upstream 
(beyond salt wedge), D=downstream (below estuarine turbidity maximum), N=neap tide, S=spring tide, 
SN=spring-neap transition, E= ebb, F=flood, L=long time series, YB=Young's Bay, CB=Cathlamet Bay, P=Pitt 
River (Fraser only), T=Transect (Fraser only)
		S	number of sample series at that location/tidal stage
		E	event number (sequence) within that series (an 'E' or 'F' may follow this number 
indicating and ebb or flood tide sampling
		NN	two (or three) digits indicate CTD cast number that corresponds to the pump cast
		*	an asterisk after the code indicates CTD data taken from the downcast 
immediately prior to the pump cast

Other data notes:
	*** OBS units are linearly related to suspended particulate material as measured in mg/L.

	***  The AC-3 unit was used beginning in 1995; data sets since then will have a column for  this 
variable. The voltage reading from the AC-3 is transformed into a chlorophyll a value using the factory 
calibration coefficients.  The voltage signal is proportional to chlorophyll absorption after light passage 
through a series of filters contained within the AC-3 unit.

	*** In 1995 and 1996, there was a malfunction in the AC-3 unit on the CTD.  This resulted in no 
chlorophyll or transmissometer readings.  Furthermore, temperature readings were affected at low salinities 
(< 1.0) and may be inaccurate by as much as +/- 0.2 degrees C.  It is unknown if/when these data can be 
reconstructed.  No chlorophyll sensor was employed in 1990 and 1991.

*** In 1999, up to a 50cm offset may exist in the depth data.  The CTD's pressure offset varies slightly from 
cruise to cruise, and is typically less than 50cm.  Superimposed on this relatively constant offset, the effect 
of ordinary atmospheric pressure fluctuations is small, and varies from -10cm to 10cm (except perhaps in very strong 
low pressure systems.)  The pressure offset was not accounted for in the 1999 cruise data.


File format: tab-delineated ASCII with header line;
	maximum number of records = 5351;
	number of data columns = 11


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