Dataset: Biofloat_48 CSTAR transmissometer Profiles
Deployment: Biofloat_48

Raw and derived parameters from WET Labs C-Star Beam Transmissometer

Principal Investigator:

Eric D'Asaro (University of Washington, UW APL)

Contact:

Eric Rehm (University of Washington, UW APL)

BCO-DMO Data Manager:

Theresa McKee (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

North Atlantic Bloom Experiment 2008 (NAB 2008)

Current State:

Preliminary and in progress

Version:

08 March 2011

Deployment Synonyms:

B4-2008_Lagrangian_Float 48

Coordinated Deployments:

KN193-03, B4-2008, B10-2008, B9-2008, SG140, SG141, SG142, SG143

Version Date:

2011-03-08

Data URL:

https://www.bco-dmo.org/dataset-deployment/454420/data

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Description

Profiles of raw transmittance, particulate attenuation coefficient, and particulate organic carbon.

Methods & Sampling

Dataset acquisition description

Data Processing Description

Dataset Processing Description

Particulate attenuation coefficient cp (parameter name beam_cp): Beam transmissometers from Floats 48 (CST-1063), the R/V Knorr cruise 193 (CST-284 and CST-1090), and the two cruises on the R/V Bjarni Saemundsson (CST-284, CST-1090) were compared and rectified to yield a consistent measurement of transmittance (%) and particulate attenuation coefficient due to particles cp at 652 nm. This analysis allowed the application of a single correlation between cp and particulate organic carbon based on linear regression of cruise CTD measurements and bottle measurements of POC. For more details, see C-Star_Calibration-NAB08.pdf.

Deployment-specific processing description

Particulate attenuation coefficient, cp at 652 nm, was intercalibrated with Knorr 193-03 transmissometer.
Particulate organic carbon (POC) derived from cp (parameter name POC_cp):  A relationship between Ship-based cp (R/V Knorr 193-03) and bottle POC data was used to produce a regression for application to CTD downcast cp.  The ship and float WET Labs C-Star beam transmissometers were intercalibrated (see above).  Therefore, the same cp-POC regression as used for the R/V Knorr 193-03 cruise can applied to float 48 cp data (parameter name cstar.beamc): 
POC (mg C m-3) = cp (m-1) * 408 (mg C m-2) – 10 (mg C m-3); r2 = 0.80, 
This relationship is empirical and it should not be applied to the other cruises without independent verification. For more details, see the datasets associated with KN193-03 and POC_cp_bbp_Calibration-NAB08.pdf.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-0628107	NSF Division of Ocean Sciences
OCE-0628379	NSF Division of Ocean Sciences

Instruments

Lagrangian Float

Supplied Description:

The 2008 North Atlantic Bloom Experiment (NAB08) employed a “Lagrangian float”, custom built at the University of Washington Applied Physics Laboratory. (D’Asaro, 2003, Performance of Lagrangian Floats, Journal of Atmospheric and Oceanic Technology, Vol. 20, 896-911).

Instrument Type

Generic Name: Lagrangian Float

Generic Description:

Built at the University of Washington Applied Physics Laboratory, the Lagrangian Float is not an ARGO float. It is primarily designed to accurately follow the three-dimensional motion of water parcels within the mixed layer, through a combination of neutral buoyancy and high drag provided by a one meter diameter black drogue. Typical buoyancies of a few grams result in vertical velocities relative to the water of a few mm/s, small compared to the cm/s turbulent velocities in the mixed layer. The float’s motion within the mixed layer thus closely imitates that of a planktonic organism. The float can also profile vertically. It sends data and receives commands using the Iridium satellite system. The float is designed to accommodate a wide variety of sensors.

Wet Labs CSTAR Transmissometer

Supplied Description:

Instrument Type

Generic Name: Wet Labs CSTAR Transmissometer

Acronym: WL CSTAR Trans

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0160/

Generic Description:

A highly integrated opto-electronic design to provide a low cost, compact solution for underwater measurements of beam transmittance. The instrument is capable of either free space measurements, or through the use of an optical flow tube, flow-through sampling with a pump. It can be used in profiling, moored, or underway applications. more information from Wet Labs

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise_ID	Cruise identifier	dimensionless	cruise_id
julian_day_yr0	time when sample was taken in decimal days since Jan-0-0000 (Matlab)	dimensionless	julian_day_yr0
latitude	latitude	decimal degrees	lat
longitude	longitude	decimal degrees	lon
start_date	date sampling begins	YYYYMMDD	date_begin
start_time	time sampling begins	HHMM	time_begin
end_date	date sampling ends	YYYYMMDD	date_end
end_time	time sampling ends	HHMM	time_end
press	water pressure at measurement	decibars	press
depth	depth at which sample was taken	meters	depth
temp	Temperature	degrees Celsius	temp
potemp	Potential Temperature	degrees Celsius	potemp
sal	Salinity	dimensionless	sal
sigma_0	water potential density minus 1000	kilograms/meter^3	sigma_0
xmiss_raw	Raw 12-bit transmittance	counts	trans_raw
beam_cp	Particulate attenuation coefficient, cp at 652 nm, intercalibrated with Knorr 193-03 transmissometer.	reciprocal meters	beam_cp
POC_cp	Particulate organic carbon (POC) estimated from cp, using relationship determined from Knorr 193-03 cruise.	milligrams per meter cubed	POC_cp
yrday	Yearday 2008. Yearday 1 is 2008-01-01:00:00:00Z	dimensionless	yrday
mode	0 = down profile 1 = settle 2 = up profile 3 = drift_iso 5 = drift_ml	dimensionless	float_operational_mode
float_cycle	one float cycle	dimensionless	float_cycle

Database

Contribute Data

Dataset: Biofloat_48 CSTAR transmissometer Profiles
Deployment: Biofloat_48

Dataset acquisition description

Dataset Processing Description

Deployment-specific processing description

Database

Contribute Data

Dataset: Biofloat_48 CSTAR transmissometer ProfilesDeployment: Biofloat_48

Dataset acquisition description

Dataset Processing Description

Deployment-specific processing description

Dataset: Biofloat_48 CSTAR transmissometer Profiles
Deployment: Biofloat_48