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Posted on by Tassia Owen Posted in News and Events

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a 15-channel imaging instrument operating on NASA’s Terra satellite. A joint project between the U.S. National Aeronautics and Space Administration and Japan’s Ministry of Economy, Trade, and Industry, ASTER has been acquiring data for 15 years, since March 2000. The archive now contains over 2.8 million scenes; for the majority of them, a stereo pair was collected using nadir and backward telescopes imaging in the NIR wavelength.The majority of users require only a few to a few dozen scenes for their work. Studies have ranged over numerous scientific disciplines, and many practical applications have benefited from ASTER’s unique data. A few researchers have been able to mine the entire ASTER archive, that is now global in extent due to the long duration of the mission. Six examples of global products are described in this contribution:the ASTER Global Digital Elevation Model (GDEM), the most complete, highest resolution DEM available to all users; the ASTER Emissivity Database (ASTER GED), a global 5-band emissivity map of the land surface; the ASTER Global Urban Area Map (AGURAM), a 15-m resolution database of over 3500 cities;the ASTER Volcano Archive (AVA), an archive of over 1500 active volcanoes; ASTER Geoscience products of the continent of Australia; and the Global Ice Monitoring from Space (GLIMS) project.

Access the complete article on International Journal of Applied Earth Observation and Geoinformation

Posted on by Tassia Owen Posted in News and Events

Hagupit_tmo_2014338

The twenty-second tropical weather system (and eleventh typhoon) of the year in the Western Pacific Ocean had the potential to be one of the most damaging of 2014. In early December, Hagupit approached The Philippines as a major and slow-moving typhoon that threatened to hit the islands with torrential rain and a large storm surge. Hundreds of thousands of people were evacuated in the lead-up to the storm on December 5.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this image at 11:20 a.m. Palau time (0210 Universal Time) on December 4, 2014. At the time, Hagupit was a category 5 super typhoon with sustained winds of 155 knots (180 miles or 290 kilometers per hour). It was the fourth category 5 typhoon of the year in the Western Pacific.

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Posted on by Tassia Owen Posted in News and Events

ASTER GED with Death Valley

 

ASTER GED Death Valley Color Bar

Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

Like the sun, Earth emits energy, yet this energy cannot be seen. Instead, it can be felt as heat because it is emitted in the thermal infrared wavelength range of the electromagnetic spectrum. While some energy in the electromagnetic spectrum can be seen in the form of light, other energy can only be felt as heat. For example, if you stand next to an oven or hover your hand over a hot burner you can feel the heat being emitted without directly touching either appliance. The strength of the energy emitted depends on both the temperature of the surface and how efficiently it can emit radiation, known as its emissivity.

The emissivity of most natural Earth surfaces is a unitless quantity and ranges between approximately 0.6 and 1.0, but surfaces with emissivities less than 0.85 are typically restricted to deserts and semi-arid areas. Vegetation, water and ice have high emissivities, above 0.95 in the thermal infrared wavelength range.

Instruments sensitive to thermal infrared radiation on-board NASA’s Earth Observing Satellites are designed to calculate Earth’s emissivity. The Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on-board Terra is one of these instruments. It calculates emissivity at 90 m spatial resolution for five different wavelengths in the thermal infrared spectrum. Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California produced the most detailed global map of emissivity by compositing millions of clear-sky images from ASTER, collected since its launch in 2000. This global map is the ASTER Global Emissivity Database (ASTER GED). ASTER GED is approximately 100 times more detailed than any other previous emissivity map produced by NASA.

Emissivity, unlike surface temperature, is an intrinsic property of the surface and does not depend on the angle of the sun in relationship to Earth or on local weather conditions. Instead emissivity variations occur due to land cover and use changes, as well as, the mineral composition of the land’s surface.

In the image, red areas (>0.95) have high emissivity and are covered with large amounts of vegetation, water, or ice. Blue areas (<0.8) have low emissivity and are indicative of quartz sands, which are found in arid regions such as the Sahara Desert in northern Africa. Transition areas from desert regions to more heavily vegetated regions, such as in the Sahel in Africa, appear green and yellow.

ASTER GED is a global, 90m spatial resolution emissivity map of the Earth’s non-frozen land surfaces at five different wavelengths in the thermal infrared spectrum. ASTER along with the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board both Terra and Aqua and the Atmospheric Infrared Sounder (AIRS) on-board Aqua measure thermal infrared radiation. Therefore, the high resolution ASTER GED can be used to calibrate and validate these instruments coarser resolution estimates of emissivity at the kilometer-scale. ASTER GED is also being used for improving estimates of Earth’s surface temperature, atmospheric water vapor, and the accuracy of climate models, which currently have large uncertainties in their use of emissivity information.

Resources:

Jet Propulsion Laboratory Photojournal. (2014, October 20). NASA Spacecraft Maps Earth’s Global Emissivity. accessed October 23, 2014.

Land Processes Distributed Active Archive Center. (2014, April 2). ASTER Global Emissivity Database (GED) Product Release. Accessed October 7, 2014.

Joint Emissivity Database Initative (JEDI) Accessed October 7, 2014

ASTER-GED. Accessed October 23, 2014

Posted on by Tassia Owen Posted in News and Events
albedo_change

NASA Earth Observatory images by Robert Simmon based on data from CERES. Caption by Mike Carlowicz.

Sunlight is the primary driver of Earth’s climate and weather. Averaged over the entire planet, roughly 340 watts per square meter of energy from the Sun reach Earth. About one-third of that energy is reflected back into space, and the remaining 240 watts per square meter is absorbed by land, ocean, and atmosphere. Exactly how much sunlight is absorbed depends on the reflectivity of the atmosphere and the surface.

As scientists work to understand why global temperatures are rising and how carbon dioxide and other greenhouse gases are changing the climate system, they have been auditing Earth’s energy budget. Is more energy being absorbed by Earth than is being lost to space? If so, what happens to the excess energy?

For seventeen years, scientists have been examining this balance sheet with a series of space-based sensors known as Clouds and the Earth’s Radiant Energy System, or CERES. The instruments use scanning radiometers to measure both the shortwave solar energy reflected by the planet (albedo) and the longwave thermal energy emitted by it. Read more

Posted on by Tassia Owen Posted in News and Events
australia_tmo_2014280

NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC. Caption by Adam Voiland, with information from Daniel Lindsey (NOAA) and Rick McRae (Australian Capital Territory Emergency Services Agency).

The intense bushfires that strike southern Australia in the summer usually attract the most headlines, but the country’s largest and most frequent blazes actually occur in northern Australia in the spring. In fact, in terms of sheer area burned, satellite observations show that over 98 percent of large fires in Australia occur well outside of densely populated southeastern and southwestern parts of the country.

A fire that began burning in Northern Territory on September 10, 2014, offers a prime example of just how expansive fires from this part of the continent can become. After racing through grasslands for just a few weeks, the fire had charred an area about the size of Massachusetts by October 8, 2014.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this sequence of images showing the progression of the fire.  Read more