Transcript ppt
Gulf stream, recirculation, and other western boundary layer currents • 1. the Gulf Stream • 2. the coriolis force ant the gyre • 3.the western boundary current layer The Gulf Stream • powerful, warm, and • swift Atlantic ocean current originates in the Gulf of Mexico, follows the eastern coastlines of the United States, and exits through the Strait of Florida. The Gulf Stream • Modifying influence of the climate of • • the east cost of north America. extension toward Europe,(North Atlantic drift): Western Europe warmer. For example, in January, the temperature difference between coastal Norway and northern parts of continental Canada is approximately 30 °C on average, even if they are the same latitude. The Gulf Stream • Finally, the Gulf Stream is one of the strongest • • • ocean currents known: transporting 1.4 petawatts of power. moves at a rate of 30 million cubic meters per second. The volume of the Gulf Stream dwarfs all rivers that empty into the Atlantic combined, which barely total 1 million cubic meters per second. The Coriolis force and the Gyre Historically • Some early writers thought the mighty Mississippi • • River empties in the Gulf of Mexico, and from there become the Gulf Stream Later, Benjamin Franklin understood that winds were the supreme current-producing power in the sea. In the middle of the 19th century, Commander M.F Maury understood, that the currents do not invariably follow the winds, but run at right angles, or even against the wind The Coriolis Force • Every moving object • • responds to the "Coriolis force." In the northern hemisphere the Coriolis force always deflects objects to the right. In the southern hemisphere the Coriolis force deflect objects to the left. The Gyre • Trade winds set up a large-scale gyre motion of surface waters in each ocean basin, centered roughly on the tropics of Cancer and of Capricorn. • Because of the Coriolis force, surface water is deflected toward the interior of the gyres • if the wind should cease, the water will attempt to run downhill from the center of the gyre, and be deflected by the Coriolis force • The gyre keeps turning, while balancing the forces of gravity with those of the Coriolis force Western boundary current layer • The Gulf Stream is just a portion of the circle of the North Atlantic Current • Why is it so strong compared to its symmetric towards Europe costs?. The asymmetry • Coriolis: f=2*W*sin(theta) • Define Beta: • 3 attemps to explain: limit condition in PDEs Sverdrup Stommel Munk Sverdrup’s theory of the Oceanic Circulation Stommel theory of Western boundary currents • He adds a botom stress proportional to velocity • Coriolis depending or not on latitude explains Gulf Stream Munk’s solution • He adds lateral friction Thanks, may I help you?