bathythermographs

A bathythermograph, often abbreviated as BT, is an instrument used to measure temperature and depth in the ocean. It is a thermometric device that records the temperature of seawater at various depths as it is lowered and raised through the water column. Early bathythermographs were mechanical devices that recorded temperature and depth on a smoked glass slide. As the instrument descended, a stylus etched a line representing temperature against depth. Modern electronic bathythermographs, also known as expendable bathythermographs (XBTs), are typically launched from ships and transmit data via a thin wire back to the ship as they sink.

The data collected by bathythermographs is crucial for understanding oceanographic conditions. It helps scientists study ocean currents, thermal layers, and the distribution of heat in the ocean. This information is vital for a variety of applications, including weather forecasting, climate research, fisheries management, and naval operations. The temperature-depth profiles generated by BTs provide insights into the thermocline, a boundary layer where temperature changes rapidly with depth, which significantly influences marine ecosystems and acoustic propagation. The widespread use of bathythermographs has contributed immensely to our knowledge of the ocean's thermal structure.