Conductivity Temperature Depth (CTD) sensor profile data binned by depth from PAL LTER annual cruises, 1991 - 2017 (ongoing).

Since 1991 (and ongoing), the PAL LTER program has deployed a SeaBird 911+ CTD mounted on a 24-bottle rosette during annual (Austral Summer) cruises plus a few supplemental cruises at other times of the year. An equal area grid oriented parallel to the average coast provides the basis for sampling, as well as specific process studies and on-the-fly scientific needs. The CTD-rosette is lowered into the ocean (usually to just above the sea-floor) using the ship's conductive-wire winch. Data is collected and displayed real-time to ensure quality and make decisions about where to collect seawater with the bottles. Bottle data is typically collected extensively in the seasaonal mixed layer and pycnocline, plus at Tmin, in the permament pycnolcine and at Tmax and Smax, as well as near the bottom. Bottle data allows measurement adn calculation of additional variables and helps ensure quality data collected via sensors. Sensors include: Pressure, Conductivity (for Salinity), Temperature, Oxygen, Transmissometer, Flourometer, Photosynthetically Available Radiation (PAR/Irrandiance). Additional Bottle Data Variables include: Phosphate, Silicate, Nitrite, Nitrate, Ammonium. After each cruise, Temperature, Conductivity and Oxygen sensors are calbrated and post-crusie processing is applied, making use of pre- and post- cruise calibrations as well as SeaBird software and algorithms for getting the best quality data. Each profile is then inspected for any issues and if needed, suitable corrections are made such as using secondary sensors (temperature, conductivity and oxygen all currently measured in duplicate), using the upcast, or flagging the data as bad.