Dataset: Biofloat_48 Satlantic ISUS Nitrate profiles
Deployment: Biofloat_48

Nitrate and Raw spectral profiles from Satlantic Nitrate Sensor

Principal Investigator:

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

Contact:

Eric Rehm (University of Washington Applied Physics Laboratory, UW APL)

BCO-DMO Data Manager:

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

Project:

North Atlantic Bloom Experiment 2008 (NAB 2008)

Version:

15 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:

2011-03-15

Data URL:

https://www.bco-dmo.org/dataset-deployment/454438/data

Expand/Collapse All

Description

Methods & Sampling

Dataset acquisition description

Data Processing Description

Dataset Processing Description

Nitrate (parameter names nitrate): The Satlantic in situ ultraviolet spectrophometer ISUS V3 sensor was deployed on Float 48. Post calibration of the ISUS instrument and subsequent processing of the spectrophotometric data acquired by the ISUS incorporating in situ temperature and salinity measurements to correct for the temperature-dependent, ultraviolet absorbance by the bromide ion results in a precision of duplicate nitrate measurements of 0.1μM. These nitrate concentrations were then calibrated against bottle measurements collected during the R/V Knorr process cruise (April 17 through May16) and subsequently analyzed for nitrate plus nitrite (NO3-+ NO2-) concentration. A simple linear regression was sufficient to make the ISUS nitrate concentrations (NO3ISUS) fit the bottle for nitrate plus nitrite measurements with a standard deviation of 0.6μM:
nitrate = 1.1536 x NO3ISUS + 2.6227 (r2 = 0.927, n = 53)
Comparisons with water samples taken on the R/V Bjarni Saemundsson deployment cruise are inconclusive due to high spatial variability. No obvious drift of the ISUS response with time or depth was apparent. For more details, see ISUS_Nitrate_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

ISUS Nitrate sensor

Supplied Description:

Instrument Type

Generic Name: ISUS Nitrate sensor

Acronym: ISUS Nitrate

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0135/

Generic Description:

The Satlantic ISUS nitrate sensor is an in-situ UV absorption sensor which calculates nitrate concentration from the seawater spectrum. The ISUS V2 has a 1cm path length, a 200-400 nm wavelength range., and is depth rated to 1000 m. Satlantic's ISUS V3 nitrate sensor uses advanced UV absorption technology to measure nitrate concentration in real-time.

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.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise_ID	Cruise identifier	dimensionless	cruise_id
float_cycle	index counting float cycles	dimensionless	float_cycle
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
yrday	Yearday 2008. Yearday 1 is 2008-01-01:00:00:00Z	dimensionless	yrday
wavelength	Calibrated wavelength (256 channels), with measurements valid from 320-950 nm. Wavelengths outside this range contain dark pixel data for measuring dark current. Spectral resolution is ~3.3 nanometers (instrument: TriOS ACC)	nanometers	wavelength
spectrum_light	Raw UV absorbance spectrum (light samples only, 256 channels.)	counts	spectrum_light
spectrum_dark	Raw UV absorbance spectrum (dark samples only, 256 channels.)	counts	spectrum_dark
spectrum_ref	Reference spectrum: post-cruise measurement of raw UV absorbance spectrum in de-ionized water - reverse osmosis (17.5 megohm-centimeter resistivity) at ambient atmospheric pressure.	counts	spectrum_ref
NO3_NO2	Nitrate concentration, calibrated against bottle nutrient samples that were analyzed for nitrate plus nitrite (NO3+ NO2).	micromol/liter	NO3_NO2
mode	0 = down profile 1 = settle 2 = up profile 3 = drift_iso 5 = drift_ml	dimensionless	float_operational_mode

Database

Contribute Data

Dataset: Biofloat_48 Satlantic ISUS Nitrate profiles
Deployment: Biofloat_48

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Biofloat_48 Satlantic ISUS Nitrate profilesDeployment: Biofloat_48

Dataset acquisition description

Dataset Processing Description

Dataset: Biofloat_48 Satlantic ISUS Nitrate profiles
Deployment: Biofloat_48