Dataset: CTD
Deployment: Neeskay_Cruises_2017-2020

CTD

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/737534

Principal Investigator:

Harvey Bootsma (University of Wisconsin, UW-Milwaukee)

Co-Principal Investigator:

Qian Liao (University of Wisconsin, UW-Milwaukee)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Collaborative Research: Regulation of plankton and nutrient dynamics by hydrodynamics and profundal filter feeders (Filter Feeders Physics and Phosphorus)

Current State:

Final with updates expected

Deployment Synonyms:

Station AT55

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Description

CTD data were collected from Lake Michigan during 2017, 2018, and 2019.

Methods & Sampling

Dataset acquisition description

Research cruises were conducted on R/V Neeskay and R/V Osprey. CTD profile data were collected by lowering a Sea-Bird SBEplus 25 CTD at a rate of 0.5 meters per second. Variables measured included depth, temperature, conductivity, photosynthetically active radiation (PAR), pH, dissolved oxygen, pH, and chlorophyll a fluorescence.

The CTD was returned to Sea-Bird annually for servicing and calibration of all sensors.

Data Processing Description

Dataset Processing Description

Data Processing:
All nutrient data are stored in a common database Following analyses, nutrient standard curves are examined to ensure that calibration coefficients are within the range of variability of a long-term (5-year) dataset (±3%). Fluorometer measurements are entered into a spreadsheet containing the fluorometer calibration coefficients, which are used to calculate chlorophyll a and phaeophytin concentrations. The fluorometer is calibrated annually against extracted chlorophyll astandards. CO2 and DIC gas chromatograph measurements are entered into a spreadsheet program that calculates all inorganic carbon species concentrations, as well as pH and carbonate alkalinity. Concentrations are then corrected for any temperature difference between in situ and time of analysis. Stable isotope measurements are stored in a stable isotope database, while DOC measurement data are stored along with nutrient, chlorophyll and inorganic carbon measurements in a chemistry database.

CTD data are processed using the "SBE Data Processing" software package provided by Sea-Bird Scientific. The processing modules used were configured as follows:

Data Conversion. Potential temperature anomaly set to 0. Tau correction is applied to dissolved oxygen measurements, with a 2-second window.

Filter. Low pass filter A time constant = 0.1 seconds. Low pass filter B time constant = 0.5 seconds.

Align CTD. An advance value of 0.1 seconds was applied to conductance measurements, and an advance value of 5 seconds was applied to dissolved oxygen measurements.

Loop Edit. Minimum CTD velocity set to 0.1 meters per second. Scans marked bad are excluded.

Bin Average. Bin type = Depth. Bin size = 0.25 meters. Both the upcast and the downcast were processed.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1658390	NSF Division of Ocean Sciences

Instruments

Sea-Bird SBE 25 Sealogger CTD

Supplied Name: SeaBird SBEplus 25 CTD

Supplied Description:

Instrument Type

Generic Name: Sea-Bird SBE 25 Sealogger CTD

Acronym: CTD SBE 25

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0040/

Generic Description:

The Sea-Bird SBE 25 SEALOGGER CTD is battery powered and is typically used to record data in memory, eliminating the need for a large vessel, electrical sea cable, and on-board computer. All SBE 25s can also operate in real-time, transmitting data via an opto-isolated RS-232 serial port. Temperature and conductivity are measured by the SBE 3F Temperature sensor and SBE 4 Conductivity sensor (same as those used on the premium SBE 9plus CTD). The SBE 25 also includes the SBE 5P (plastic) or 5T (titanium) Submersible Pump and TC Duct. The pump-controlled, TC-ducted flow configuration significantly reduces salinity spiking caused by ship heave, and in calm waters allows slower descent rates for improved resolution of water column features. Pressure is measured by the modular SBE 29 Temperature Compensated Strain-Gauge Pressure sensor (available in eight depth ranges to suit the operating depth requirement). The SBE 25's modular design makes it easy to configure in the field for a wide range of auxiliary sensors, including optional dissolved oxygen (SBE 43), pH (SBE 18 or SBE 27), fluorescence, transmissivity, PAR, and optical backscatter sensors. More information from Sea-Bird Electronics: http:www.seabird.com.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Year	4-digit year	unitless	year
Lat	Latitude. Locations south of equator are negative.	Decimal degrees	lat
Long	Longitude. Locations west of prime meridian are negative.	Decimal degrees	lon
ISO_DateTime_UTC	UTC Date and time. Local time + 5 hours between March 12, 2:00 a.m. and November 5, 2:00 a.m. Local time + 6 hours between November 5, 2:00 a.m. and March 12, 2:00 a.m. Formatted to ISO 8601 standard (YYYY-MM-DDThh:mmZ).	unitless	ISO_DateTime_UTC
Depth	Depth below lake surface; resolution = 0.01; accuracy = 0.15	meters (m)	depth
Temp	Water Temperature; resoultion = 0.0003; accuracy = 0.001	Degrees celsius (°C)	temp
Cond	Water conductance; resoultion = 0.4 uS/cm; accuracy = 3 uS/cm	microsiemens per cm (uS/cm)	cond
SpCond	Water Specific Conductance (conductance normalized to a temperature of 25 degrees celcius). Resolution = 0.4 uS/cm; accuracy = 3 uS/cm.	microsiemens per cm (uS/cm)	specc
flECO_AFL	Chlorophyll a fluorescence.	Fluorescence units that are calibrated to approximate chlorophyll concentration in units of microgram per liter (ug/L)	chl_a_fluor
PAR	Photosyntheticall active radiation (within the range of approximately 400 to 700 nm wavelength). Accuracy = 3%	micromoles of photons per square meter per second	PAR
pH	pH is a measure of the concentration of free hydrogen ions. Resolution = 0.01; accuracy = 0.1	pH = -log10 [H+], where [H+] = moles per liter of the hydrogen ion.	pH
DO	Dissolved oxygen concentration; resolution = 0.01; accuracy = 2%.	milligrams per liter (mg/L)	O2
prdM	Pressure; resolution = 0.01; accuracy = 0.15	decibars (dbar)	press
DOSat_pcnt	Dissolved oxygen concentration as % saturation at in situ temperature and a pressure of 1.0 atmospheres. Calculated as: DOSat% = DO(mg/L)100/(-0.00007T^3+0.0075T^2-0.3976T+14.602. T = water temperature (oC). Resolution = 0.1; accuracy = 2%	percent (%) saturation	O2sat
BeamAtt	Beam attenuation over 25 cm path length; accuracy = 0.02%	inverse meters (m-1)	beam_cp
Beam_pcnt	Beam % transmission over 25 cm path length; accuracy = 0.02%	percent (%)	trans

Database

Contribute Data

Dataset: CTD
Deployment: Neeskay_Cruises_2017-2020

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: CTDDeployment: Neeskay_Cruises_2017-2020

Dataset acquisition description

Dataset Processing Description

Dataset: CTD
Deployment: Neeskay_Cruises_2017-2020