Weekly Report for the Week of January 28, 2008
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GSFC Laboratory for Atmospheres, Code 613
In the last two decades, it has become clear that the release of particles in the atmosphere due to human activity (such as smoke stacks) influence clouds and as a result can impact weather and climate. In a paper in press in the Journal of Geophysical Research, Santiago Gassó (613.2, GEST/UMBC) reports observations made over the volcanoes of the South Sandwich Islands in the South Atlantic and in the Aleutian Arc in the North Pacific. This study involved the use of two NASA instruments – the Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer (AMSRE), both on board the Aqua satellite. It demonstrated the impact of volcanic emissions on clouds and demonstrated that high concentrations of naturally occurring aerosols can change clouds properties in a way similar to that produced by anthropogenic aerosols. The effect of volcanic activity on the environment is usually studied in the context of violent volcanic eruptions that release large amounts of gases and particulates reaching high altitudes in the atmosphere. The eruptions of Krakatoa, or more recently Pinatubo, and their resulting global climatic impact are good examples. On the other hand weak eruptions or quiescent degassing volcanoes are phenomena of much smaller scale but still release a sizeable amount of sulfur dioxide (SO2), a major precursor for the formation of aerosol particles and cloud droplets in the natural environment. These observations prove the existence of a naturally occurring phenomenon that produces an observable small-scale impact on clouds similar to that produced by anthropogenic sources. In addition, it demonstrates that all levels of volcanic activity (violent eruptions and low levels of emission usually ignored in most monitoring networks) can have a significant impact on cloud properties.
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