Arctic science
Circulation of ocean water

Water in the oceans circulates around the globe in a conveyor-belt-like process. What drives the circulation is the interaction of bodies of water that have different densities because of their salinity (the amount of salt dissolved in the water) and temperature. Scientists call this conveyor-belt the thermohaline circulation. "Thermo" refers to the temperature differences, while "haline" refers to salinity.

Water in the far north is cold and salty, which makes it dense. It sinks to the ocean bottom and travels south, where it encounters the Antarctic Circumpolar Current. This current carries the dense bottom water east. The flow branches into two currents: one carries bottom water to the Indioan Ocean, the other to the Pacific Ocean. As it warms in these tropical areas, the bottom water becomes less dense and rises toward the surface. This surface current then travels all the way back to the North Atlantic, where it mixes with colder, saltier water and sinks to the sea floor, to begin its journey again.

Explore the ocean's thermohaline with this map, which you can print and color. You'll need Adobe's Acrobat Reader software to view and print the file.

Arctic watersheds
A watershed is the land area over which all water on or beneath the surface goes into the same place. This chart outlines the watersheds of the six largest arctic rivers: Ob, Yenisey, Lena, Kolyma, Yukon, and Mackenzie. Together, these rivers contribute more than half of the freshwater from rivers entering the Arctic Ocean.

Live from the North Pole

The U.S. National Oceanographic and Atmospheric Administration (NOAA) began placing solar-powered web cams at the North Pole in 2002. The cameras operate during the Arctic summer (April to October). The live images help scientists track snow cover and weather conditions. Click here to visit NOAA's North Pole Web Cam site.