Gradients4-TN397-Optics-LISST-ACS-ECO_2022-04-07

Cruise Name: Gradients 4 , TN397

Vessel: R/V Thompson

Funding: Simons Collaboration on Ocean Processes and Ecology (SCOPE)

Dataset description:

This dataset was collected on the R/V Thompson during the Gradients IV cruise which departed from San Diego, CA and ended in Honolulu, HI. A transect was performed on the 140 degree longitude line from roughly 19 degrees N to 2.5 degrees S before heading to Honolulu. Three biooptical instruments were plumbed to the underway uncontaminated seawater (intake depth 8m). Data for each instrument were averaged to the minute and matched to a timestamp on the minute.  LISST:  Filtered values (<0.2 um) removed from all data. The summed volume concentration of particles (in uL/L), the standard LISST output, is presented for 3 size ranges: 1.25-2 µm, 2-20 µm, and 20-100 µm. Particle volume concentration can be converted to particle concentration by assuming spherical particles. Larger size classes are excluded due to low detection limits and scattering at density gradients. Note that data have not been processed to remove outliers. AC-S: Filtered values (<0.2 um) removed from all data (see White et al., 2017, GRL); data corrected for residual temperature and scattering; AC-S chl a concentrations obtained from a Gaussian fit over absorbance spectra in the red portion of the spectrum, assuming in vivo chl-a specific absorption of 0.0203 m2/mg at 674 nm. ECO: filtered values (<0.2 um) removed from chl and volume scattering data; chl fluorescence converted to mg/m3 using factory calibrations, and corrected to HPLC chlorophyll values.  CDOM not included due to faulty channel.