California Cooperative Oceanic Fisheries Investigations

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Home Field Work CTD Profiling
CTD Profiling
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CalCOFI collects vertical profile data through Seasave V7 using a Seabird 911plusV2 CTD. Our SBE 911plus CTD system includes: 9plus Underwater Unit and a 11plus V2 Deck Unit. Current sensor complement includes:
• Dual Temperature - SBE 3plus
• Dual Conductivity - SBE 4
• Dual Oxygen - SBE 43
• Fluorometer - Seapoint Fluorometer
• Nitrate Sensor - Satlantic ISUS V2 		• pH Sensor - SBE 18
• Transmissometer - WetLabs 25cm 650nm
• Underwater PAR - Biospherical QSP-2300
• Surface PAR - Biospherical QSP-240
• Carousel Water Sampler - SBE 32


CTD System

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A Sea-Bird Electronics 911plus V2 CTD collects vertical profile data at every CalCOFI station. In addition to being a dual TCO (temperature, conductivity, and oxygen) system, the CTD also interfaces with a transmissometer, fluorometer, PAR/SPAR meters, altimeter, nitrate, and pH sensor. Connected to a shipboard data-acquisition computer through an electronically-conductive winch wire, sensor data are collected and displayed real-time using Seasave V7. The CTD is normally lowered to terminal depth of 515 m, bottom-depth permitting, but is routinely deployed within meters from the seafloor at nearshore SCCOOS and basin stations. To ensure high resolution sampling in areas with significant hydrological and biological gradients a speed of ~30 m/min is used for the first 100 m then ~60 m/min to depth without stopping. During retrieval, the CTD is paused for at least 20 seconds at target bottle depths to adequately flush each 10 liter sample bottle prior to closure. Seawater samples are analyzed onboard (e.g., salinity, oxygen, nutrients, chl) and are used to correct measured CTD values.

Last Updated on Wednesday, 26 September 2012 13:57 Read more...