Dataset: CTD

Name: Depth profiles of temperature, conductivity, dissolved oxygen, pH, chlorophyll fluorescence, etc., collected with a SeaBird SBE 25plus CTD in Lake Michigan during 2017, 2018, and 2019
Published: 2022-11-01
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.737534.3

Spatial Extent: N:43.09932 E:-87.7187 S:43.06992 W:-87.86447

Temporal Extent: 2017-05-11 - 2019-10-01

Project:

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

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)

Version:

Version Date:

2022-11-01

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Depth profiles of temperature, conductivity, dissolved oxygen, pH, chlorophyll fluorescence, etc., collected with a SeaBird SBE 25plus CTD in Lake Michigan during 2017, 2018, and 2019

Abstract:

This dataset provides conductivity-temperature-depth (CTD) data from Lake Michigan collected over several cruises conducted during 2017, 2018, and 2019. Data were obtained using a SeaBird SBE 25plus CTD. Water chemistry and CTD profiles were measured at several stations in Lake Michigan, ranging in depth from 10 to 55 m, in a region northeast of Milwaukee Harbor. Measurements included soluble reactive phosphorus, total dissolved phosphorus, particulate phosphorus, chlorophyll a, the concentrations and stable isotope ratios of particulate carbon and particulate nitrogen, dissolved carbon dioxide, dissolved total inorganic carbon, and dissolved organic carbon. In addition, continuous lake surface and atmospheric CO2 data collected in 2019 and 2021 on a Lake Michigan transect between Milwaukee, WI and Muskegon MI. The chemistry and CO2 data are provided in separate datasets. These data have several applications, including: 1) Constructing an annual carbon and nutrient budget for the water column, which is used along with direct measurements of quagga mussel nutrient recycling to assess the role of invasive quagga mussels in the lake's carbon and nutrient cycles; 2) When combined with separate measurements of the vertical structure of water density and currents, to quantify vertical fluxes of dissolved nutrients and inorganic carbon, to determine how carbon and nutrient recycling by profundal quagga mussels may affect plankton production in the euphotic zone; 3) The calibration and validation of physical / biogeochemical models used to better understand how invasive quagga mussel have altered energy flow and nutrient dynamics in the Great Lakes, and guide management decisions with regard to nutrients and fish stocking.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2022-11-01	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.737534.3	2024-02-12
2019-05-22	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.737534.2	2021-04-26
2018-05-25	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.1575/1912/bco-dmo.737534.1	2019-03-15

Description

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

Methods & Sampling

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

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.

BCO-DMO Processing

Version 1 and 2:
- converted date/time field to ISO 8601 format;
- modified parameter names to conform with BCO-DMO naming conventions;
- replaced blanks (missing data), -9.99E-29, 9.99E-29, and #VALUE! with "nd" (no data);
- updated to version 2 on 2019-05-22.

Version 3:
- converted date/time field to ISO 8601 format;
- modified parameter names to conform with BCO-DMO naming conventions;
- rounded latitude and longitude values to 5 decimal places;
- removed 'nd' as the missing data identifier (missing data are empty/blank in the final CSV file);
- updated to version 3 on 2022-11-01.

Data Files

File
737534_v3_lake_michigan_ctd.csv (Comma Separated Values (.csv), 1.70 MB) MD5:3e3132412d957caa613a93c4e2001235 Primary data file for dataset ID 737534, version 3

More Information about this dataset

Funding Sources

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

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
Neeskay_Cruises_2017-2020	Station AT55	2017-05-11	R/V Neeskay	Harvey Bootsma (Chief Scientist)	data info
Osprey_Lake_Michigan_2017-2020		2017-05-11	R/V Osprey	Harvey Bootsma (Chief Scientist)	data info

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

Date and time formats are described in python strftime() syntax.

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

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Dataset: CTD