Instrument: CTD Sea-Bird 25

Dataset: 
CTD_fv
Instrument: 
CTD Sea-Bird 25
Instrument Short Name: CTD SBE 25
Community Standard Description
(http://vocab.nerc.ac.uk/collection/L22/current/TOOL0040/)
Instrument Description:

The Sea-Bird SBE 25 SEALOGGER CTD is battery powered and is typically used to record data in memory, eliminating the need for a large vessel, electrical sea cable, and on-board computer. All SBE 25s can also operate in real-time, transmitting data via an opto-isolated RS-232 serial port. Temperature and conductivity are measured by the SBE 3F Temperature sensor and SBE 4 Conductivity sensor (same as those used on the premium SBE 9plus CTD). The SBE 25 also includes the SBE 5P (plastic) or 5T (titanium) Submersible Pump and TC Duct. The pump-controlled, TC-ducted flow configuration significantly reduces salinity spiking caused by ship heave, and in calm waters allows slower descent rates for improved resolution of water column features. Pressure is measured by the modular SBE 29 Temperature Compensated Strain-Gauge Pressure sensor (available in eight depth ranges to suit the operating depth requirement). The SBE 25's modular design makes it easy to configure in the field for a wide range of auxiliary sensors, including optional dissolved oxygen (SBE 43), pH (SBE 18 or SBE 27), fluorescence, transmissivity, PAR, and optical backscatter sensors. More information from Sea-Bird Electronics: http:www.seabird.com.

PI supplied instrument name: CTD Seabird 25
Dataset-specific description

The UNH SeaBird SBE-25 SeaLogger measures - Temperature (degrees C) with a SeaBird SBE-3F. Conductivity (Siemens/m) with a SeaBird SBE-4C. Pressure (decibars) with a SBE 29 strain gage sensor. Percent light transmission with a Wet Labs CST-126R transmissometer across a 25 cm distance at the red light wavelength 660 nm. Data are presented as a percentage relative to pure water. Chlorophyll concentration in micrograms/liter with a Wet Labs WETStar Fluorometer model 9607003. PAR (photosynthetically active radiation) with a Biospherical QPS-200PD which observes an upper hemispherical total irradiance in quanta/sq-cm/sec. Dissolved oxygen with a SBE-23Y (Yellow Springs Instrument) in milliliters/liter.During a cast, sensors are flushed with a SBE-5T pump at approximately 25 ml/s. The system samples and stores all data at 8 Hz (8 samples/ second). Profiling rates should be 20 meters/minute for an average of 24 samples/1 m pressure level. Normally only the downcasts are analyzed (unless a problem is noted). Sensors are factory calibrated annually.