Temperature, salinity, pressure, depth, oxygen, fluorescence, and irradiance data are collected at a higher temporal frequency than latitude and longitude observations that come from the ship’s NEMA system. Latitude and longitude values have been linearly interpolated between observations using time.
In 2014, latitude and longitude data from the NEMA system were not automatically logged with the physical data during ISIIS tows. To address this, temperature, salinity, pressure, depth, oxygen, fluorescence, and irradiance data were binned to the nearest second (mean for each second bin) in order to merge them with the ship’s GPS data.
Seawater density (kg per cubic meter) was calculated from pressure, temperature, and salinity using the UNESCO equation of state from the ‘R’ Library ‘OCE’ package.
Temperature, salinity, oxygen, fluorescence, irradiance values less than zero were excluded as they are erroneous
Density values less than 1000 kg per cubic meter were excluded as they are erroneous
Oxygen (2015 only) was corrected for post-calibration sensor drift using the equation:
Final oxygen (ml L-1) = Initial oxygen (ml L-1)*1.0649702 – 0.0029434
Fluorescence (volts) data from the Wet Labs Eco Fluorometer was converted to chlorophyll (ug/L) using the following equation:
chlorophyll (µg L-1) = scale factor*(volts – dark counts)
2014: Scale factor = 25; Dark counts = 0.028. 2015: Scale factor = 24; Dark counts = 0.026.
Large camera parameters used in volume imaged calculations:
2014:
Image width: 2048 pixels
Scan rate: 35,000 lines s-1
Depth of field: 50 cm
Field of view: 11.2 cm
2015:
Image width: 2048 pixels
Scan rate: 35,000 lines s-1
Depth of field: 50 cm
Field of view: 11 cm
Small camera parameters used in volume imaged calculations:
2014:
Image width: 1024 pixels
Scan rate: 62,000 lines s-1
Depth of field: 10 cm
Field of view: 6 cm
2015:
Image width: 1024 pixels
Scan rate: 55,000 lines s-1
Depth of field: 10 cm
Field of view: 4.6 cm
Derived camera data calculated using equations below:
lg.hz.line = horizontal.velocity (cm s-1) / lg.scan.rate
lg.eff.image.length (cm) = lg.image.width *lg.hz.line
lg.vol.image (cm3) = lg.dof*lg.fov*lg.eff.image.length
lg.image.sec (images s-1) = horizontal.velocity (cm s-1)/lg.eff.image.length
lg.vol.rate (m3 s-1) = (lg.image.sec*lg.vol.image)*1E-06
sm.hz.line = horizontal.velocity (cm s-1) / sm.scan.rate
sm.eff.image.length (cm) = sm.image.width *sm.hz.line
sm.vol.image (cm3) = sm.dof*sm.fov*sm.eff.image.length
sm.image.sec (images s-1) = horizontal.velocity (cm s-1)/sm.eff.image.length
sm.vol.rate (m3 s-1) = (sm.image.sec*sm.vol.image)*1E-06