ac-9

The ac-9 is an optical instrument that measures water absorption and attenuation at 9 wavelengths.  The instrument is attached to a cage in a horizontal position and lowered over the side of the ship.  Data are collected during the upcasts and downcasts as water flows through the ac-9.

The ac-9 instrument used in this study has sensors at wavebands with the following center wavelengths:

412, 440, 488, 510, 532, 555, 650, 676 and 715 nm.

Each of these wavebands have bandpasses of approximately 10 nm.  The sampling frequency is approximately 6 Hz.

Casts with and without a 0.2 m cartridge filter are made so the the absorption of both the particulate and dissolved particles can be studied.

Further information regarding this instrument can be found at the home page for WET Labs, the instrument manufacturer. 

CTD

Deployed in the same cage is an SBE 25 SEALOGGER CTD instrument from Sea-Bird Electronics, Inc.  This instrument measures temperature, conductivity and pressure at a frequency of approximately 6 Hz.

Webpage by Jasmine S. Nahorniak, Oregon State University.