An ocean current is a continuous, directed movement of seawater generated by forces acting upon this mean flow, such as breaking waves, wind, the Coriolis effect, cabbeling, temperature and salinity differences, while tides are caused by the gravitational pull of the Sun and Moon.
RDDs - Radar Detector Detectors, All Acronyms, viewed April 15, 2017, <https://www.allacronyms.com/RDDS/Radar_Detector_Detectors>.
RTDs - Resistance Temperature Detectors. Resistance temperature detectors (RTD) accurately sense temperature with an excellent degree of repeatability and interchangeability of elements. The RTD is composed of certain metallic elements whose change in resistance is a function of temperature.