August 21st, 2014
Courtesy of Yale’s Environment360, a look at several initiatives that use Earth observation satellites to measure and monitor global climate change:
1. NASA’s Orbiting Carbon Observatory (OCO-2) is one of five Earth-observing missions launched in 2014 — the most in a single year in more than a decade. OCO-2, which joins a set of five observation satellites already orbiting the Earth, will monitor the global carbon cycle by measuring how atmospheric carbon dioxide absorbs individual bands, or wavelengths, of sunlight. The satellite will collect roughly one million measurements per day, although only about a tenth of those are expected to be cloud-free enough to provide useable data. The two-year mission will allow scientists to track sources of CO2 emissions and the “sinks” where it is absorbed from the atmosphere.
2. Launched in 2010 as part of the European Space Agency’s Earth Explorer program, CryoSat-2 is the first mission specifically targeted at measuring changes in polar sea ice thickness, one indicator of warming seas. The satellite orbits 700 kilometers above the Earth at latitudes 88° North and South. It uses a Synthetic Aperture Interferometric Radar Altimeter (SIRAL) to measure changes in land ice elevation and sea ice thickness relative to ocean surface levels, giving researchers a better understanding of changes in the volume of polar sea ice. CryoSat-2’s altimeter also measures sea level, including localized ocean phenomena such as eddies, storm surges, and the ocean floor with unprecedented accuracy. This image shows Arctic sea ice as measured by CryoSat-2 in April 2013.
3. Comprising 3.5 percent of the ocean, salt plays a major role in both regulating ocean currents and moderating Earth’s climate. The Aquarius Mission, a partnership between NASA and Argentina’s space program (the Comisión Nacional de Actividades Espaciales), helps scientists better understand how surface salinity levels affect heat and water exchange between the ocean and the atmosphere. Because salinity levels are affected by precipitation, evaporation, freshwater inputs, and melting ice, scientists can use Aquarius to trace changes in the global water cycle. This image depicts sea surface salinity as measured in June 2014. Reds show higher salinity (40 grams per kilogram), and purples show relatively low salinity (30 grams per kilogram).
4. Originally created in 1978 by the United States and the French space agency to monitor meteorological and oceanographic conditions, the Argos system is now used for a variety of observations, including tracking terrestrial, avian, and aquatic wildlife migrations. Biologists attach small tags, called platforms, to wildlife, and the platforms continuously transmit signals to orbiting satellites, enabling scientists to determine wildlife locations. With 21,000 animals tagged worldwide, scientists use Argos to monitor how migratory species such as manta rays, Alaska’s porcupine caribou herd, and albatrosses adapt to global change. This image is an example of an Argos map showing platform locations.
5. Farmers are facing increasing uncertainty due to climate change. Programs such as the European Space Agency’s Sentinel-2, part of the Copernicus Land Monitoring Service, monitor soil moisture conditions and forecast crop yields so that farmers can apply water and chemicals more accurately and efficiently. In addition to site-specific crop and plant health, Copernicus satellites detect variables such as measures of global vegetation, water cycling, and heat emitted from the Earth’s surface. These technologies promote what is called “precision farming” and help farmers maintain high crop yields amid changing climatic conditions. This image, captured near Garden City, Kansas, reveals circular crop plots in infrared.
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