Charlene McGilles, age 15, of Peterborough, Ontario, Canada, for her question:

Is there really an Antarctic Ocean?

The boundaries of the earth's land masses meet the sea and hence it is easy to define them. But all the oceans link together and form one world wide ocean. Parts of the watery realm are almost surrounded by continents and it is simple to see them as separate oceans. The Atlantic, for example, is bordered by the Americas, Europe and Africa. The equator forms a convenient marker to divide the world ocean into two hemispheres    for example, the North and South Atlantic. But there are no such hints to help us define the ocean waters around Antarctica.

In the past, many geographers regarded the Antarctic waters as southern extensions of the Atlantic, Pacific and Indian Oceans. The Antarctic land mass covers the South Pole and occupies most of the Antarctic Circle. Beyond its borders, the world ocean reaches northward to the tip of South America, Africa's Cape of Good Hope, New Zealand and the Southern shores of Australia. It is true that this watery expanse merges and mingles with the Pacific, Atlantic and Indian Oceans. But even though there are no hints to suggest a boundary, the Antarctic waters have special features that qualify them as a different ocean.

Since the International Geophysical Year of the late 1950s, most scientists have recognized the vast Antarctic Ocean as a qualified unit of the global ocean. Its distinctive feature is the fact that it sweeps around the globe in a wide, unbroken circle. The other oceans are interrupted by large land masses. The unbroken sweep of the Antarctic Ocean creates some unique features. The surface is at the mercy of prevailing winds that circle. the globe. Here, uninterrupted by bumpy land masses, they drive sweeping currents around in endless circles.

Offshore, the prevailing easterlies drive the east wind drift current around and around the frozen land masses. Farther north, the Antarctic waters are within the belt of. the prevailing westerlies. Here the waves are driven in the continuously circling west wind drift current. The turbulent boundary, where these opposite currents brush, is called the Antarctic divergence. Much farther north, the swirling Antarctic currents brush with the warmer waters of the Atlantic, Pacific and Indian Oceans. This turbulent region is the Antarctic convergence    where warm and cold air and water mingle and mix up a special brew of stormy weather.

Near the shores, the Antarctic Ocean is jammed with ice flows and icebergs, often 1,000 feet thick and sometimes almost half the size of Ontario. The icebergs drift northward before they begin to melt because the Antarctic water is as cold as 29 degrees Fahrenheit. This cold water teems with microscopic algae and diatoms. Whales, seals and thriving fish populations come there to feed in the rich plankton meadows. Cold as it is, the Antarctic Ocean teems with enormous populations of assorted animal life.