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Page 1 | Page 2 | Page 3 | Page 4 FIRST DISPATCHESOceanographers usually need decades worth of data to follow cycles that last that long. However, Argo data, viewable by anyone with an Internet connection, has already been cited in more than 100 research papers. In several key areas, it is already yielding new perspectives: Ocean heat content What people call "global warming" typically refers to air temperatures, but knowledge of ocean temperatures is just as important to climate researchers because the oceans store far more heat energy than the atmosphere. For this reason, the top of the ocean acts as a "thermostat" in controlling air temperature. Though the ocean's temperature has been taken by naval, commercial, and oceangoing ships of all kinds for centuries, the effort has been piecemeal compared to what Argo offers. A recent research paper by Roemmich reported the discovery that the strongest warming in the oceans is taking place between 40 and 50 degrees south latitude in a region of the Southern Ocean. Such findings will enable scientists to identify cause-and-effect relationships between ocean heat and climate phenomena experienced on land. Sea level rise The height of the ocean surface is rising for two reasons. First, ocean warming causes the water to expand. Second, mountain glaciers and polar ice are melting and adding new water to the oceans. Argo observes the first of these effects directly by measuring ocean temperature. A study by former Scripps student Josh Willis using Argo data found that the expansion of ocean water caused by rising temperatures has been responsible for half of the sea level rise recorded in the last 14 years. Argo observes the second effect indirectly by measuring salinity. As land-bound ice melts and runs into the sea, it makes seawater fresher by a small amount. Argo data have shown that present-day salinities are fresher than a few decades ago. New ways of seeing the oceans Sea surface height maps show one
view (top) calculated from Argo data
alone and one (bottom) that is the
difference of present-day sea
surface height from Argo from
decades-old sea surface height
readings gathered by traditional
methods. The lower map, showing
height increases due to ocean
warming, has helped scientists
quantify the degree to which
modern-day oceans are warmer than in
decades past, especially in the
Southern Ocean.   This view of stored heat in the oceans as it varies with latitude over the course of a year confirmed oceanographers' suspicions that cooling in Southern Hemisphere oceans is a stronger force governing climate than heating in Northern Hemisphere oceans.   Two views of the temperature of the top 2,000 meters (6,560 feet) of the oceans. The left-hand side shows a recreation of temperatures over a 40-year period has a margin of error as high as 100 percent in some portions. By contrast, three thin years of global Argo coverage show a more nuanced view of temperature. The error rate of the Argo data is virtually nil on this scale. Over 50 years, the surface layer of the ocean has warmed by a half degree Celsius (0.9 degrees F) while the average temperature of the upper 2,000 meters (6,560 feet) has increased by only .07 degrees Celsius (0.1 degrees F).   Global hydrological cycles Rain and snow originate in the oceans, the reservoir of precipitation. Rain and snowfall patterns are easy to observe over land but until Argo have been difficult to trace in the oceans. The geographic patterns of salinity readings of Argo floats reveal how fresh water passes back and forth between oceans and the atmosphere and let scientists test the hypothesis that global warming will cause the hydrological cycle to intensify. Extreme weather events The durable floats have beamed data through hurricanes and typhoons to show what happens below the surface during such events, providing data that would be too hazardous to try collecting with ship-based instruments. Not only has this led to a better understanding of cyclone dynamics but the frequently updated data helps meteorological agencies around the world create better extreme weather forecasts. Knowledge of current conditions in remote ocean stretches has also been useful to cargo shippers, fishing fleets, and oil exploration firms. |
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