* Astronomy

North Pacific Circulation Was Radically Changed by Past Post-Glacial Warming

A study in the July 9, 2010, issue of Science identifies changes in oceanic circulation that followed past glacial retreat. The article, titled, "Deep Water Formation in the North Pacific during the Last Glacial Termination" is by Axel Timmermann of the University of Hawaii, Honolulu, and his colleagues.
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NASA Study Finds Atlantic 'Conveyor Belt' Not Slowing

New NASA measurements of the Atlantic Meridional Overturning Circulation, part of the global ocean conveyor belt that helps regulate climate around the North Atlantic, show no significant slowing over the past 15 years. The data suggest the circulation may have even sped up slightly in the recent past.
The findings are the result of a new monitoring technique, developed by oceanographer Josh Willis of NASA's Jet Propulsion Laboratory in Pasadena, California, using measurements from ocean-observing satellites and profiling floats. The findings are reported in the March 25 issue of Geophysical Research Letters.
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Ocean Floor Geysers Warm Flowing Sea Water
With about 71 percent of the Earth's surface being ocean, much remains unknown about what is under the sea, its geology, and the life it supports. A new finding reported by American, Canadian and German earth scientists suggests a rather unremarkable area off the Costa Rican Pacific coast holds clues to better understand sea floor ecosystems.

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 A team of NASA and university scientists has detected an ongoing reversal in Arctic Ocean circulation triggered by atmospheric circulation changes that vary on decade-long time scales. The results suggest not all the large changes seen in Arctic climate in recent years are a result of long-term trends associated with global warming.
The team, led by James Morison of the University of Washington's Polar Science Centre Applied Physics Laboratory, Seattle, used data from an Earth-observing satellite and from deep-sea pressure gauges to monitor Arctic Ocean circulation from 2002 to 2006. They measured changes in the weight of columns of Arctic Ocean water, from the surface to the ocean bottom. That weight is influenced by factors such as the height of the ocean's surface, and its salinity. A saltier ocean is heavier and circulates differently than one with less salt.
The very precise deep-sea gauges were developed with help from the National Oceanic and Atmospheric Administration; the satellite is NASA's Gravity Recovery and Climate Experiment (Grace). The team of scientists found a 10-millibar decrease in water pressure at the bottom of the ocean at the North Pole between 2002 and 2006, equal to removing the weight of 10 centimetres  of water from the ocean. The distribution and size of the decrease suggest that Arctic Ocean circulation changed from the counterclockwise pattern it exhibited in the 1990s to the clockwise pattern that was dominant prior to 1990.
Reporting in Geophysical Research Letters, the authors attribute the reversal to a weakened Arctic Oscillation, a major atmospheric circulation pattern in the northern hemisphere. The weakening reduced the salinity of the upper ocean near the North Pole, decreasing its weight and changing its circulation.

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