Instruments for Gulf Stream Observations

Observations made with a wide variety of instruments have been critical to our understanding of the Gulf Stream. In situ data from instruments deployed from ships first provided information about water temperature, current speed and direction, and the location of the Stream boundaries. Later, as oceanographers developed more sophisticated techniques, moored and drifting instruments were deployed in the Stream for longer duration observations and more extensive ship surveys were undertaken. More recently, aircraft and satellites have been used to obtain synoptic views of the spatial and temporal variations of the Stream, as well as the generation and trajectories of rings and eddies.

Early Instruments

Reversing Bottle - The reversing bottle is a metal bottle with a valve at each end. When the bottle reaches the desired depth, it is tripped by a messenger weight. The bottle then turns over. As it turns, the valves close, capturing 1 liter of water. Usually, reversing bottles were lowered in series. The salinity of the sampled water could then be found by chemical titration.

Reversing Bottles of the Type used on the Challenger Expedition

Reversing Thermometer - The reversing thermometer was usually mounted on a water sampling bottle. When the thermometer turns, the mercury column breaks, measuring the in-situ temperature. The reversing bottle and the reversing thermometer were used when a ship was hovering above the sampling region, moving slowly against a current, or into the wind. These two instruments were necessary for early geostrophic current calculations.

Examples of Early Reversing Thermometers