Hawaii Ocean Time-series (HOT)
in the School of Ocean and Earth Science and Technology at the University of Hawai'i
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Vertical profiles of upwelling radiance and downwelling irradiance were made using a Biospherical PRR-600 Profiling Reflectance Radiometer. Surface irradiance was collected using a sister instrument (PRR-610). These instruments measures downwelling irradiance (Ed) and upwelling radiance (Lu) as well as surface irradiance (Es) from a deck unit on 7 wavelength channels (Table below). The radiance channels comply with the SeaWIFS satellite optical parameters. The instrument is lowered by hand and depending on the subsurface currents, is deployed to a depth between 125 and 175 meters.
Figure 58 shows a time-series of the 1% light level and KPAR during the 18 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 106.0 m while the average KPAR between 100 & 150m is 0.0437 m-1. Downwelling irradiance measured during the Primary Production incubation period is shown in Table xxx. The results compare favorably with the integrals obtained using the LICOR LI-1000 which also measures PAR.
This study is a collaborative effort between the College of Oceanic and Atmospheric Sciences of Oregon State University and the Laboratory for Microbial Oceanography of the University of Hawai'i at Manoa.