The amount of vegetation in a city is an important factor in the urban heat island, where temperatures in urban areas rise an average of 1 to 3°C due to the absorption of heat by asphalt, concrete, stone, steel, and other impervious surfaces. Vegetation helps cool these areas and a new study by NASA, shows how essential plant cover is. Researchers modeled urban areas and their surroundings, using data from multiple satellites including MODIS on-board both Terra and Aqua and Landsat 7’s Enhanced Thematic Mapper Plus (EMT+), finding that areas covered partly by impervious surfaces had an average summer temperature 1.9°C higher than surrounding rural areas. In winter, the temperature difference was 1.5 °C higher. Lahouri Bounoua, a researcher at Goddard Space Flight Center and lead author, along with his colleagues used the model environment to simulate what the temperature would be for a city if all the impervious surfaces were replaced with vegetation.
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Image courtesy NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Adam Voiland.
In most American states, the Turtle Mountains—which rise 600 to 800 feet (180 to 240 meters) above the surrounding plain—would be called hills. But in North Dakota, one of the flattest states, people have a habit of calling even relatively modest rises mountains. (In the past, the U.S. Board of Geographic Names argued that mountains should have at least 1,000 feet (300 meters) of local relief to earn the designation, but the group abandoned the argument for linguistic consistency in the 1970s.)
Whether hills or mountains, the hummocky highlands that straddle the border between North Dakota and southern Manitoba have enough elevation that they receive significantly more precipitation than the surrounding plains. As shown by this image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite, enough moisture collects on the hills to support forests. The surrounding lowlands are a patchwork of grasslands and farms. In the lower image, a detailed view of a largely undeveloped part of Turtle Mountain Provincial Park, hundreds of ponds and lakes pockmark the landscape. A few roads and oil wells also appear. Read more
NASA Earth Observatory map by Joshua Stevens and Jesse Allen, using data from the Global Fire Assimilation System (GFAS) and the State of the Climate in 2014 report. Caption by Adam Voiland.
On Earth, there is always something burning. On a typical day in August, the Moderate Resolution Imaging Spectroradiometers (MODIS) on NASA’s Aqua and Terra satellites detect approximately 10,000 active fires, as well as huge swaths of freshly charred land in ecosystems ranging from boreal forests to savanna to tropical forests.
In order to determine how much carbon dioxide and other pollutants all these fires contribute to the atmosphere in a given year, scientists have developed computer models that combine satellite observations of burned area and active fires together with information about vegetation, fuel loads, and other details. Data produced by two computer modeling efforts—the Global Fire Assimilation System (GFAS) and the Global Fire Emissions Database (GFED)—were highlighted in NOAA’s 2014 State of the Climate report, published in the Bulletin of the American Meteorological Society. Read more
NASA Earth Observatory image by Jesse Allen, using data from NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Caption by Kathryn Hansen.
Crete is the largest and most populous Greek island, spanning 8,300 square kilometers (3,200 square miles) and supporting a population of 620,000. A short distance northwest of Crete is a lesser-known Greek island, Antikythera. The island is comparatively tiny, spanning just 20 square kilometers (8 square miles) and supporting a human population that hovers around 50.
This view of Antikythera was acquired on September 23, 2013, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. The landscape is typical of a small Mediterranean island, consisting primarily of open countryside and low shrubs. Steep, limestone cliffs line most of the island; flatter expanses of beach are more common on Kythira, a larger Greek island to the north. Read more
NASA Earth Observatory image by Jesse Allen, using data provided by John Yorks and Matthew McGill of the Cloud-Aerosol Transport System (CATS) team. Caption by Kathryn Hansen.
Cirrus—the wispy, icy clouds that form high in the atmosphere—are known to have a net warming effect on the climate. But how much? The question is hard to answer because even among cirrus clouds, there is wide variety and complexity in their structure.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a natural-color view of clouds over the South Pacific on April 2, 2015. Cirrus are the thinner clouds appearing to spread out from points across the center of the image.
The red line on the MODIS image shows the area scanned just hours before by the Cloud-Aerosol Transport System (CATS) onboard the International Space Station. “The space station orbit provides comprehensive coverage of the tropical and mid-latitude regions, where cirrus clouds are most prevalent,” said John Yorks, science lead of the CATS team at NASA’s Goddard Space Flight Center. Read more