An Oceanographic Bottle System for CTD Calibration

An oceanographic bottle has been developed to sample seawater for the calibration of the conductivity cell on a rapidly descending CTD probe. The bottle is streamlined with a small horizontal cross-section, has low weight in wa ter, and avoids sample contamination through leakage by maintaining equal sample and ambient pressures. Three bottles have been clustered within a diameter of 25cm. and interfaced to a Guildline 8706 probe to enable electronic triggering by the operator, and logging of bottle closures on the CTD data record. Samples can be acquired while the probe is descending at 1.6ms^-1, which is the fall speed for optimal sensor function for this probe. The bottle is made from plastic to minimize the problem of sample freezing which is common during surveys at low air temperature in polar regions. The plastic used is essentially non-absorptive and non-reactive, and samples can be stored within the sampling bottle for up to 24 hours without degradation.