The questions what causes polar ice to melt, variation in temperature at same latitudes, climate change and others have led meteorologist, ocean scientist and other researchers to investigate currents. According to the oxforddictionaries.com, a current is a body of water or air moving in a definite direction, especially through a surrounding body of water or air in which there is less movement. Currents can be generated both on the ocean surface flowing horizontally and sub surface flowing vertically. However these currents are generated by different factors. Horizontal currents are generated by the wind blowing across the ocean surface while vertical currents are generated by the density differences in water masses caused by temperature and salinity variation. To understand the significance of these currents researchers used a number of oceanographic tools which incorporates different techniques to measure them. The Lagrangian measurement incorporates all drifter measurements, which was named after the mathematician Joseph Louis Lagrange while the Eulerian measurement incorporates measuring currents of a fluid at only a given point and was named after Swiss mathematician Leonhard Euler (oceanservice.noaa.gov). Ocean currents are typically measured in Knots. According to NOAA ocean service education, Knot is defined as one nautical mile per hour and is used to measure speed (oceanservice.noaa.gov).
Oceanographic Tools to Measure Currents
Incorporating both the Lagrangian and Eulerian measurements allowed researchers to measure both surface and sub surface currents. The floating devices, which scientist call a ‘drifter’, to take the measure surface current as well as devices which scientist call a ‘profiling floats’ , that submerge to specific depth in the ocean to take the measure of deep water currents were both employed. Scientist also employed the use of Acoustic Doppler Current Profile or ADCP and Shore-based current meter to measure currents.
One of the simplest method oceanographers used in the past to measure wind driven surface currents velocity was the use of drifters. A person would stand on an anchored ship with a timer in the ocean and would release a floating device, usually a piece of wood in the water. That person would allow the device to float alongside the ship to reach a specific distance while measuring the amount of time elapse from the time of release to the point where he or she wants the floating device to reach. He or she would then take a note of the direction and would measure the distance the device have floated. After which that person would calculate the speed of the current by dividing the distance the floating device traveled by the time it took the floating device to travel that distance (oceanservice.noaa.gov). Finally that person would combine the speed of the current with the direction in which it moved to determine the current’s velocity. Modern technology has improved and allows the use of...