Continuous, underwater profiles of ultraviolet (UV), PAR irradiance, and temperature observations with surface reference measurements collected from R/V LAURENTIAN and other small boats in the Lakes Michigan and Huron in the Great Lakes region from 2012-09-27 to 2021-09-16 (NCEI Accession 0276075)

NOAA Great Lakes Environmental Research Laboratory (GLERL) samples and studies the ecosystem of the lower food web of the Laurentian Great Lakes. This collection contains continuous, underwater ultraviolet (UV), PAR and temperature profiles at 26 stations during the open water seasons in Lakes Michigan and Huron from 2012 to 2021. The measurements were collected using a Biospherical Instruments Inc. PUV-2500 submersible, multichannel, profiling, ultraviolet radiometer and PUV2510 reference radiometer attached to the ship during profile collection. UV measurements are in units of microwatts per square centimeter at wavelength (µW/(cm²nm)), PAR measurements are in the units of microEinsteins per square centimeters per second (µE/(cm²sec)) and temperature are in the units of degrees Celsius. Chlorophyll measurements were collected with the instrument, but not included in this data package because the instrument was not calibrated for these locations. The instrument was calibrated for dark offsets as described in the instrument manual on each day the instrument was deployed.

Two summary tables are included in this accession summarizing the attenuation coefficients (Kd) and the 1% attenuation depth. The attenuation coefficients (Kd) were calculated as the slope of the linear regression of the natural logarithm of the ratio_uv versus depth, as described by Kirk (1994). The 1% attenuation depth was calculated using the Kd and intercept from the linear regression of the natural logarithm of the ratio_uv versus depth as: (ln(0.01)-Intercept)/Kd. Only data above 1% of the ambient irradiance were used in these calculations.

Blank cells indicate no data. In the table, “noaa-glerl-uv-TB82-20210927.csv” there are no ambient UV values due to a surface sensor not working, but it does include ratio values. The ratio values were calculated using the first UV measurement at depth (z) as the assumed ambient UV through the entire profile.

The data table column headings and units are described in detail in the data dictionary file named “noaa-glerl-uv-data-dictionary-2012-2021.csv”. File formats included in this data package are .csv and jpg.