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Ocean Currents Slow, Causing Warmer Ocean And Less Co2 Input To Atmosphere
Washington - Feb 10, 2002 An ocean circulation system that brings cool water from ocean depths to the surface has been slowing down since the mid-1970s, causing an increase in sea surface temperatures along the Equator in the Pacific Ocean and a decrease of carbon dioxide (CO2) released into the atmosphere, say NOAA scientists. "Looking back at records for the past 50 years, we found that the ocean currents flowing in the north-south direction have been slowing down in the tropical Pacific Ocean since the mid-1970s," said Michael McPhaden, a senior research scientist at NOAA's Pacific Marine Environmental Laboratory in Seattle. His findings, which were co-authored by Dongxiao Zhang from NOAA's Joint Institute for the Study of Atmosphere and Ocean at the University of Washington, will be published in the Feb. 7 issue of the science journal Nature. "Cool water hundreds of feet below the surface typically flows from the mid-latitudes to the tropics, and these waters are eventually upwelled -- or brought up -- to the surface along the equator," McPhaden explained. "When the circulation slows down, the supply of cool water for equatorial upwelling decreases. In our study we found a reduction of 25 percent, causing the sea surface temperatures in a band about 600 miles on either side of the Equator to rise about 1.4 degrees Fahrenheit since the mid-1970s." Not only does the temperature rise, but the amount of carbon dioxide released by the equatorial Pacific Ocean decreases. At present, the equatorial Pacific is the largest oceanic source of carbon dioxide to the atmosphere. These circulation changes are linked to the shifts in the climate of western North America, and can affect Pacific fisheries. They may be part of the naturally occurring ocean and atmosphere phenomenon called the Pacific Decadal Oscillation, which has a roughly 50-year cycle. But they also could be influenced by greenhouse gases. McPhaden and Zhang studied historical ocean data sets and wind records going back a half century, when sufficiently large numbers of reliable observations began. They focused their attention on this region as an outgrowth of their interest in the El Nino/La Nina cycle, which, over the past 25 years, has favored stronger El Ninos, and more frequent El Ninos than La Ninas. McPhaden notes that the system is driven by the trade winds, which have weakened since the 1970s. The trade winds in turn have weakened because the sea surface temperatures have risen. "It's the same chicken-and-egg riddle we encounter with El Nino," he said. Community Email This Article Comment On This Article Related Links NOAA's Pacific Marine Environmental Laboratory NOAA's Global Carbon Cycle Program El Nino/Southern Oscillation (ENSO) Diagnostic Discussion Most Recent 2 Months Sea Surface Temperature Anomaly Animation SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express Dirt, rocks and all the stuff we stand on firmly
Magnetic Reconnection Region Larger Than 2.5 Million Km Found In The Solar Wind
Paris (ESA) Jan 12, 2006Using the ESA Cluster spacecraft and the NASA Wind and ACE satellites, a team of American and European scientists have discovered the largest jets of particles created between the Earth and the Sun by magnetic reconnection. This result makes the cover of this week's issue of Nature. |
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