Atmosphere LandOcean and Global Biogeochemical Transports

Emissions from both anthropogenic and natural sources on land and the oceans are transported to substantial altitudes in the atmosphere and many circumnavigate the globe with the air currents. During this process, various gases, aerosols, and particulates undergo chemical transformations. Some interact with cloud systems, and by changing the concentrations of cloud condensation nuclei, they affect precipitation process. They also affect the radiation budgets of the atmosphere and the surface. Aerosols can have either a heating or cooling effect depending on composition and particle size. Natural and man-made fires produce large clouds of pollution, as does industrial output. Dust from the great deserts of the world, and terpine aerosols from vegetation that produce near-surface haze, are also injected into the atmospheric circulation. Along with these aerosols and particles, also observed are the cross-oceanic transport of microbial matter that survives the journey across the oceans as encrusted spores. Moreover, the atmospheric transport of land sources of minerals also provides a pathway for nutrient resources at distant locations. As an example, it is

Figure 8 The Black Sea more closely resembled mixed paint on an artist's palette than the normally black surface of deep water when the moderate resolution imaging spectroradiometer (MODIS) on NASA's Aqua satellite captured this image on 20 June 2006. Swirls of color ranging from deep olive green to bright turquoise were created by a massive phytoplankton bloom that covered the entire surface of the sea. The sea was able to support such a large bloom largely because of its unique structure. The web site provides a more detailed explanation http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=13675. Courtesy Jeff Schmaltz, MODIS Land Rapid Response Team at NASAGSFC.

Figure 8 The Black Sea more closely resembled mixed paint on an artist's palette than the normally black surface of deep water when the moderate resolution imaging spectroradiometer (MODIS) on NASA's Aqua satellite captured this image on 20 June 2006. Swirls of color ranging from deep olive green to bright turquoise were created by a massive phytoplankton bloom that covered the entire surface of the sea. The sea was able to support such a large bloom largely because of its unique structure. The web site provides a more detailed explanation http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=13675. Courtesy Jeff Schmaltz, MODIS Land Rapid Response Team at NASAGSFC.

2 December 2004 4 February 2005

Figure 9 In places such as North Reef Island, shown in this pair of images from the advanced spaceborne thermal emission and reflection radiometer (ASTER) on NASA's Terra satellite, the quake lifted the reefs permanently out of the water. The images use VIS and IR light detected by ASTER to make different land surfaces stand out clearly from one another: water is blue, vegetation is red, coral or bare sand appears white. In the 'before' image, from 2 December 2004, the submerged reef creates a bright blue glow around the island. In the 'after' image, from 4 February 2005, the white coral stands completely up out of the water. It is even tinged with red, which suggests the exposed coral had died, and algae had colonized it. Credit: NASA images created by Jesse Allen, Earth Observatory, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and US/Japan ASTER Science Team (http://asterweb.jpl.nasa.gov). From http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17412.

2 December 2004 4 February 2005

Figure 9 In places such as North Reef Island, shown in this pair of images from the advanced spaceborne thermal emission and reflection radiometer (ASTER) on NASA's Terra satellite, the quake lifted the reefs permanently out of the water. The images use VIS and IR light detected by ASTER to make different land surfaces stand out clearly from one another: water is blue, vegetation is red, coral or bare sand appears white. In the 'before' image, from 2 December 2004, the submerged reef creates a bright blue glow around the island. In the 'after' image, from 4 February 2005, the white coral stands completely up out of the water. It is even tinged with red, which suggests the exposed coral had died, and algae had colonized it. Credit: NASA images created by Jesse Allen, Earth Observatory, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and US/Japan ASTER Science Team (http://asterweb.jpl.nasa.gov). From http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17412.

estimated that somewhere around 250 Tg of Saharan dust is transported across the Atlantic Ocean. The dust deposited to the surface provides nutrients that feed the aquatic ecosystems of the Atlantic Ocean and the terrestrial ecosystems of South America, the Caribbean, and North America. The long-range transport of dust is, however, also a source of pollutant particulate matter. On much longer timescales, paleoclimatic and proxy records appear to suggest a 500 000 year cycle in the mineralization and fertilization of the Amazon tropical forests by desert dust from the Sahara. These cycles have been linked to solar variability and orbital forcing on the planet with resulting global climate change. Curiously, it is hypothesized that the Amazon would expire if not for the import of mineral-laden dust and aerosols from the Sahara desert. Such an event could conceivably occur if there were to be a strong intensification of the African monsoon systems and vegetation cover over the vast expanses of the African desert regions. Other examples include the fertilization of land vegetation by the transport and deposition of nitrous oxides, and the fertilization of the oceans by mineral iron.

Currently, satellites provide the only viable means by which the global transport of pollutants, nutrients, and minerals can be monitored. Examples include data from NASA's Terra, Aqua satellites (e.g., MODIS and multi-angle imaging spectroradiometer (MISR)), and the European Space Agency's ENVISAT satellite. Of course, in order to calibrate and validate the satellite data as also to develop the necessary algorithms for the retrieval of satellite-derived products, a large number of extensive field campaigns and experiments are typically conducted. They include instrumented balloon flights, research aircraft, research ships, and other in situ observing platforms and ground-based networks. An example of such a field campaign is the Intercontinental Chemical Transport Experiment-North America (INTEX-NA) to track the path of polluting gases and aerosols traveling from North America to Europe. The experiment aims at quantifying the North American import and export of ozone and associated pollutant gases, aerosols, and long-lived greenhouse gases. The INTEX-NA mission is coordinated under the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT). The UK, Germany, Canada, and France will also conduct concurrent airborne campaigns (see http://www.nasa.gov/ centers/goddard/earthandsun/0621_intex.html).

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