Scientists participating in the United Nation's International Polar Year effort recently spent two weeks flying head-on into hurricane-force winds that lash the frigid land mass known as Greenland to study how some of the strongest -- and most mysterious -- winds on the plant affect weather patterns, climate and global ocean circulation.

Weather experts have only really known about these so-called tip jets for less than a decade, and most of what they discovered came from satellite data.

Tip jets form at Greenland when cyclones, large rotating weather systems, meet with the island's hulking mass on their northward journey across the Atlantic Ocean, causing air flow to be distorted and winds to speed up.

"The air is forced to move around the obstacle, [which] causes these accelerations of the wind," said study team member Kent Moore of the University of Toronto.

These accelerations are created in the same way as a plane gains lift. The plane's wing diverts the air into two directions: air traveling over the top of the wing flows over a flat surface, while air flowing under the bottom travels over a curved surface; because the curved surface creates a longer path for the air to travel, the air must speed up to meet up with the wind flowing over the top.

"The air parcels that are forced to go around Greenland have a longer path than [parcels] that go over it, for instance. And because they have to all meet up at the end, the ones that go around have to accelerate," Moore explained. "Cape Farewell is this really odd place where you get really strong winds of both directions, and that's very rare. There's very few places in the world where the winds blow very strong from two different directions.".

Moore said the divergent winds add turbulence and the 100-mph winds that result could be one of the drivers of the ocean's main circulation."

On the global conveyor belt's path, warm water from the tropics flows northward to the pole, where it becomes denser and sinks to the ocean floor, and then returns to the tropics. The water's density increases as it becomes colder and saltier -- winds blowing over the water can transfer heat and moisture away from the surface waters, which is what Moore suspected the tip jets were doing.

"This experiment was to test the hypothesis that we could actually get enough heat and moisture transfer between the ocean and the atmosphere in these tip jet events to actually trigger convection in the ocean," Moore said.

Turbulence in the air near the ocean's surface are the mechanism for the heat transfer, just as bubbles transfer heat in a pot of boiling water.

Though Moore's results are not yet final, it appears as if enough heat is transferred to cause the ocean water to overturn, he said.

Moore hopes that by clarifying the role the tip jets play in driving ocean circulation and how the cyclones that create them affect Greenland's climate, a better picture of just how climate change is affecting the island will come into focus.

Source:Xinhua/Agencies