Free-falling Optical Profiler (AKA, the HyperPro)
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To assist in the interpretation of the data, it can be displayed using the Hawaii Ocean Time-series Data Organization & Graphical System (HOT-DOGS©).

Sampling Procedure

The Satlantic HyperPro is an in-situ free-fall profiling unit designed to measure the apparent optical properties of the ocean with concurrent measurements of temperature, salinity, chlorophyll and dissolved matter fluorescence, and optical backscattering (a proxy for total particle load). The unit is equipped with one up-looking and one down-looking hyperspectral (350-800nm) radiometer with 10 ± 0.3 nm resolution, a WET Labs ECO-Puck Triplet, and temperature, pressure, and conductivity sensors. It also incorporates a ship-mounted surface (air) hyperspectral radiometer. The applications for this sensor include bio-optical algorithm development, satellite calibration and validation, and environmental monitoring. The data products include water leaving radiance, remote sensing reflectance, energy fluxes, and PAR.

Results

Profiles of photosynthetically available radiation (PAR) and PAR attenuation coefficient (K_PAR) measured using the HyperPro are shown in the bottom panels of the figures below. Due to the tendency for the instrument to tilt back-and-forth when brought up through the water column, only the downcast profiles are included.

• HOT-335 : Mar 22
  
• HOT-336 : May 22
  
• HOT-337 : Jul 22
  
• HOT-338 : Aug 22
  
• HOT-339 : Sep 22
  

Figure 58 shows a time-series of the 1% light level and K_PAR during the 25 years we've been collecting in-situ PAR data. Both vary seasonally. Data for HOT cruises 90-214 were collected using a Biospherical PRR-600, while cruises 215 (Sep 09) onward used a Satlantic HyperPro. The average 1% light-level at Station ALOHA is 105.6 m while the average K_PAR between 100 & 150m is 0.0439 m^-1.