White Caps
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Whitecaps are the bright, wind-driven products of breaking waves and they've been largely ignored by climate models. Until now.

Hi, I'm Bryan Yeaton and this is The Weather Notebook.

Whitecaps, it turns out, have a cooling effect on global warming by reflecting sunlight, or solar radiation, from the ocean's surface. That's according to a new study by researchers from the Scripps Institute of Oceanography in California and the Laboratoire d'Optique Atmospherique in France.

Using satellite data and other measurements, these scientists were able to calculate how much solar radiation the whitecaps can reflect away from the surface. They found that it depends on the region of the oceans and more specifically, how much wind there is and whether the skies are clear or cloudy.

In some parts of the Indian Ocean, for example, whitecaps reflect the radiation at double the average global rate. This is also true in the Arabian Sea. The reasons, according to the scientists? A greater abundance of cloudless skies and greater wind speed in those regions.

The authors say that when compared to the impact of carbon dioxide, one of the greenhouse gases, whitecaps have a relatively small influence. But with other greenhouse gases, such as nitrous oxide, whitecaps have a comparable effect.

The scientists note that their findings are part of the larger, tangled equation of changes stemming from global warming. For example, greenhouse gases may alter wind speed, which means that the amount of whitecaps may be altered, changing how much radiation the whitecaps reflect, and therefore affecting the temperatures.

The study states that the impact of whitecaps on climate change is not huge, but emphasizes that it should be included in future climate models.

Thanks today to writer David Appell of Gilford, New Hampshire. The Weather Notebook is a production of the Mount Washington Observatory, and is supported by Subaru of America. For more on weather, visit us at www.mountwashington.org