<P> Direct estimates of the strength of the thermohaline circulation have been made at 26.5 ° N in the North Atlantic since 2004 by the UK - US RAPID programme . By combining direct estimates of ocean transport using current meters and subsea cable measurements with estimates of the geostrophic current from temperature and salinity measurements, the RAPID programme provides continuous, full - depth, basinwide estimates of the thermohaline circulation or, more accurately, the meridional overturning circulation . </P> <P> The deep water masses that participate in the MOC have chemical, temperature and isotopic ratio signatures and can be traced, their flow rate calculated, and their age determined . These include Pa / Th ratios . </P> <P> The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean . The process of western intensification causes the Gulf Stream to be a northward accelerating current off the east coast of North America . At about 40 ° 0 ′ N 30 ° 0 ′ W ﻿ / ﻿ 40.000 ° N 30.000 ° W ﻿ / 40.000; - 30.000, it splits in two, with the northern stream crossing to northern Europe and the southern stream recirculating off West Africa . The Gulf Stream influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe . Although there has been recent debate, there is consensus that the climate of Western Europe and Northern Europe is warmer than it would otherwise be due to the North Atlantic drift, one of the branches from the tail of the Gulf Stream . It is part of the North Atlantic Gyre . Its presence has led to the development of strong cyclones of all types, both within the atmosphere and within the ocean . The Gulf Stream is also a significant potential source of renewable power generation . </P> <P> All these dense water masses sinking into the ocean basins displace the older deep water masses that were made less dense by ocean mixing . To maintain a balance, water must be rising elsewhere . However, because this thermohaline upwelling is so widespread and diffuse, its speeds are very slow even compared to the movement of the bottom water masses . It is therefore difficult to measure where upwelling occurs using current speeds, given all the other wind - driven processes going on in the surface ocean . Deep waters have their own chemical signature, formed from the breakdown of particulate matter falling into them over the course of their long journey at depth . A number of scientists have tried to use these tracers to infer where the upwelling occurs . </P>

Thermohaline circulation patterns are caused by variations in