Petermann Glacier

The Petermann Glacier grinds and slides toward the sea along the northwestern coast of Greenland, terminating in a giant floating ice tongue. Like other glaciers that end in the ocean, Petermann periodically calves icebergs. A massive iceberg, or ice island, broke off of the Petermann Glacier in 2010. Now, nearly two years later, another chunk of ice has broken free.

The Moderate Resolution Imaging Spectroradiometer, or MODIS, on NASA’s Aqua satellite observed the new iceberg calving and drifting downstream on July 16–17, 2012. Because Aqua is a polar-orbiting satellite, it makes multiple passes over the polar regions each day.

Image Credit: NASA

Pine Island Glacier

In mid-October 2011, NASA scientists working in Antarctica discovered a massive crack across the Pine Island Glacier, a major ice stream that drains the West Antarctic Ice Sheet. Extending for 19 miles (30 kilometers), the crack was 260 feet (80 meters) wide and 195 feet (60 meters) deep. Eventually, the crack will extend all the way across the glacier, and calve a giant iceberg that will cover about 350 square miles (900 square kilometers). This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NAS's Terra spacecraft was acquired Nov. 13, 2011, and covers an area of 27 by 32 miles (44 by 52 kilometers), and is located near 74.9 degrees south latitude, 101.1 degrees west longitude.
 
Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

NASA's Terra Spacecraft Sees Thailand Flooding

Since July 2011, heavy monsoon rains in southeast Asia have resulted in catastrophic flooding. In Thailand, about one third of all provinces are affected. On Oct. 23, 2011, when this image from ASTER, the Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument on NASA's Terra spacecraft was acquired, flood waters were approaching the capital city of Bangkok as the Ayutthaya River overflowed its banks. In this image, vegetation is displayed in red, and flooded areas are black and dark blue. Brighter blue shows sediment-laden water, and gray areas are houses, buildings and roads. The image covers an area of 35.2 by 66.3 miles (56.7 by 106.9 kilometers) and is located at 14.5 degrees north latitude, 100.5 degrees east longitude.
 
With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products. The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change.
 
Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team

NASA Releases Visual Tour Of Earth's Fires

Steve Cole
Headquarters, Washington

WASHINGTON -- NASA has released a series of new satellite data visualizations that show tens of millions of fires detected worldwide from space since 2002. The visualizations show fire observations made by the MODerate Resolution Imaging Spectroradiometer, or MODIS, instruments onboard NASA's Terra and Aqua satellites.

NASA maintains a comprehensive research program using satellites, aircraft and ground resources to observe and analyze fires around the world. The research helps scientists understand how fire affects our environment on local, regional and global scales.

"What you see here is a very good representation of the satellite data scientists use to understand the global distribution of fires and to determine where and how fire distribution is responding to climate change and population growth," said Chris Justice of the University of Maryland, College Park, a scientist who leads NASA's effort to use MODIS data to study the world's fires.

One of the new visualizations takes viewers on a narrated global tour of fires detected between July 2002 and July 2011. The fire data is combined with satellite views of vegetation and snow cover to show how fires relate to seasonal changes. The Terra and Aqua satellites were launched in 1999 and 2002, respectively.

The tour begins by showing extensive grassland fires spreading across interior Australia and the eucalyptus forests in the northwestern and eastern part of the continent. The tour then shifts to Asia where large numbers of agricultural fires are visible first in China in June 2004, then across a huge swath of Europe and western Russia in August. It then moves across India and Southeast Asia, through the early part of 2005. The tour continues across Africa, South America, and concludes in North America.

The global fire data show that Africa has more abundant burning than any other continent. MODIS observations have shown that some 70 percent of the world's fires occur in Africa. During a fairly average burning season from July through September 2006, the visualizations show a huge outbreak of savanna fires in Central Africa driven mainly by agricultural activities, but also driven by lightning strikes.

Fires are comparatively rare in North America, making up just 2 percent of the world's burned area each year. The fires that receive the most attention in the United States -- the uncontrolled forest fires in the West -- are less visible than the wave of agricultural fires prominent in the Southeast and along the Mississippi River Valley. Some of the large wildfires that ravaged Texas this year are visible in the animation.

NASA maintains multiple satellite instruments capable of detecting fires and supports a wide range of fire-related research. Such efforts have yielded the most widely used data records of global fire activity and burned area in the world. NASA-supported scientists use the data to advance understanding about Earth's climate system, ecosystem health, and the global carbon cycle.

NASA's Applied Sciences Program seeks out innovative and practical benefits that result from studying fires. For example, the program has found ways to integrate space-based wildfire observations into air quality models used by the U.S. Environmental Protection Agency that help protect public health.

NASA will extend the United States' capability to monitor and study global fires from space with the launch this month of the National Polar-orbiting Operational Environmental Satellite System Preparatory Project, known as NPP. The satellite is the first mission designed to collect data to increase our understanding of long-term climate change and improve weather forecasts.

One of NPP's new, state-of-the-art science instruments will provide scientists with data to extend the long-term global fires data record. The satellite is targeted to launch from Vandenberg Air Force Base in California on Oct. 28. The mission is managed by NASA's Goddard Space Flight Center in Greenbelt, Md., for the Earth Science Division of the Science Mission Directorate at NASA Headquarters in Washington.

MODIS data are processed by the MODIS Advanced Processing System at Goddard. The algorithm and product validation is done by scientists at the University of Maryland. The visualizations were created at Goddard's Scientific Visualization Studio. The fire, vegetation and snow data all come from the MODIS instruments on Terra and Aqua.

To watch the global tour of the world's fires, visit http://www.nasa.gov/mission_pages/fires/main/modis-10-overview.html.

For regular updates on fires and their effects worldwide, visit http://www.nasa.gov/fires.

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Hurricane Season 2011: Tropical Depression 10 (Atlantic Ocean)

Hurricane Irene is a major hurricane, and NASA satellite data shows its diameter is now about one-third the length of the U.S. Atlantic coastline. Meanwhile, far in the eastern Atlantic Ocean a tenth tropical depression formed. One satellite image captured both storms and shows the tremendous difference in their size.

NOAA's GOES-13 satellite saw Hurricane Irene moving through the Bahamas on August 25, 2011 at 10:02 a.m. EDT and far to the east off the African coast was newly born Tropical Depression 10. The GOES-13 image shows Irene to be almost one third of the size of the U.S. east coast. The distance from Augusta, Maine to Miami, Florida is 1662.55 miles. Hurricane Irene's tropical storm-force winds extend 255 miles from the center making Irene 510 miles in diameter, almost one-third the size of the U.S. Hurricane-force winds extend 70 miles from the center, or 140 miles in diameter.

GOES-13 images and animations are created at NASA's GOES Project at the NASA Goddard Space Flight Center, Greenbelt, Md.

NASA satellites are providing valuable data to forecasters to assist them in the forecasts for Irene's track and power. As of this morning, a Hurricane Watch is now in effect for the coastal U.S.

On Thursday morning, August 24, a hurricane warning is in effect for the central and northwestern Bahamas. The National Hurricane Center (NHC) has also issued the first watch for the U.S. east coast. A hurricane watch is in effect for north of Surf City, North Carolina to the North Carolina-Virginia border including the Pamlico, Albemarle, and Currituck Sounds. A tropical storm watch is in effect for north of Edisto Beach, South Carolina to Surf City North Carolina.

NASA satellites are flying above Hurricane Irene, providing forecasters at NHC with temperature, pressure, wind, and cloud and sea surface temperature data. All of those things are critical in helping forecasters determine how Irene will behave and track.

The Moderate Resolution Imaging Spectroradiometer (MODIS) Instrument aboard NASA's Terra satellite captured a visible image of Hurricane Irene's eye directly over Crooked Island in the southern Bahamas on August 24, 2011 at 18:15 UTC (2:15 p.m. EDT).

By 11 a.m. EDT on August 25, Irene had moved north and was 75 miles (105 km) east-northeast of Nassau near 25.9 North latitude and 76.8 West longitude. Irene's winds dropped slightly from 120 mph (195 kmh) to 115 mph (kmh) and it was moving to the north-northwest near 13 mph (20 kmh). The NHC, however, noted that some further strengthening is possible today and tonight.

Irene's minimum central pressure has fallen from 954 to 951 millibars since the day before, indicating the storm is still intensifying despite the slight temporary drop in maximum sustained winds.

Hurricane-force wind gusts were already reaching Nassau at 8 a.m. EDT. Hurricane force winds are spreading over the northwestern Bahamas this morning and the central Bahamas are still being battered by hurricane or tropical storm force winds, which will diminish later today as Irene moves away.

Residents in South Florida are also under warnings for dangerous rip currents and high surf along the eastern shores through Friday, August 26. A tropical storm warning in effect for the offshore marine waters of Palm Beach County, Florida beyond 20 nautical miles, and at 5:30 a.m. EDT this morning, rainbands spreading west over the adjacent Atlantic waters. Numerous showers and thunderstorms are expected along the south Florida coast today and tonight.

Far in the eastern Atlantic, Tropical Depression 10 formed about 435 miles (700 km) west-southwest of the southernmost Cape Verde Islands. It was centered near 12.4 North and 30.4 West, and moving to the west-northwest near 13 mph (20 kmh). Tropical Depression 10 (TD10) has maximum sustained winds near 35 mph (55 kmh) and may become a tropical storm in the next day or two. It is not expected to be a threat to the U.S. and is expected to remain at sea.

In the meantime, evacuation plans are already under way in North Carolina for the massive Hurricane Irene.

Updates on Irene's strength and forecast track can be found at the National Hurricane Center's website: www.nhc.noaa.gov. Follow NASA's Hurricane coverage on Facebook and Twitter and at the NASA Hurricane Web page: www.nasa.gov/hurricane.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.

New NASA Map Reveals Patterns Of Tropical Forest Carbon Storage

Steve Cole

Headquarters, Washington

 

Alan Buis

Jet Propulsion Laboratory, Pasadena, Calif.

WASHINGTON -- A NASA-led research team has used a variety of NASA satellite data to create the most precise map ever produced depicting the amount and location of carbon stored in Earth's tropical forests. The data are expected to provide a baseline for ongoing carbon monitoring and research and serve as a useful resource for managing the greenhouse gas carbon dioxide.

The new map, created from ground- and space-based data, shows for the first time the distribution of carbon stored in forests across more than 75 tropical countries. Most of that carbon is stored in the extensive forests of Latin America.

"This is a benchmark map that can be used as a basis for comparison in the future when the forest cover and its carbon stock change," said Sassan Saatchi of NASA's Jet Propulsion Laboratory in Pasadena, Calif., who led the research. "The map shows not only the amount of carbon stored in the forest, but also the accuracy of the estimate." The study was published May 30 in the Proceedings of the National Academy of Sciences.

Deforestation and forest degradation contribute 15 to 20 percent of global carbon emissions, and most of that contribution comes from tropical regions. Tropical forests store large amounts of carbon in the wood and roots of their trees. When the trees are cut and decompose or are burned, the carbon is released to the atmosphere.

Previous studies have estimated the carbon stored in forests on local and large scales within a single continent, but there existed no systematic way of looking at all tropical forests. To measure the size of the trees, scientists typically use a ground-based technique, which gives a good estimate of how much carbon they contain. But this technique is limited because the structure of the forest is extremely variable and the number of ground sites is very limited.

To arrive at a carbon map that spans three continents, the team used data from the Geoscience Laser Altimeter System lidar on NASA's ICESat satellite. The researchers looked at information on the height of treetops from more than 3 million measurements. With the help of corresponding ground data, they calculated the amount of above-ground biomass and thus the amount of carbon it contained.

The team then extrapolated these data over the varying landscape to produce a seamless map, using NASA imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra spacecraft, the QuikScat scatterometer satellite and the Shuttle Radar Topography Mission.

The map reveals that in the early 2000s, forests in the 75 tropical countries studied contained 247 billion tons of carbon. For perspective, about 10 billion tons of carbon is released annually to the atmosphere from combined fossil fuel burning and land use changes.

The researchers found that forests in Latin America hold 49 percent of the carbon in the world's tropical forests. For example, Brazil's carbon stock alone, at 61 billion tons, almost equals all of the carbon stock in sub-Saharan Africa, at 62 billion tons.

"These patterns of carbon storage, which we really didn't know before, depend on climate, soil, topography and the history of human or natural disturbance of the forests," Saatchi said. "Areas often impacted by disturbance, human or natural, have lower carbon storage."

The carbon numbers, along with information about the uncertainty of the measurements, are important for countries planning to participate in the Reducing Emissions from Deforestation and Degradation (REDD+) program. REDD+ is an international effort to create a financial value for the carbon stored in forests. It offers incentives for countries to preserve their forestland in the interest of reducing carbon emissions and investing in low-carbon paths of development.

The map also provides a better indication of the health and longevity of forests and how they contribute to the global carbon cycle and overall functioning of the Earth system. The next step in Saatchi's research is to compare the carbon map with satellite observations of deforestation to identify source locations of carbon dioxide released to the atmosphere.

For information about NASA and agency programs, visit http://www.nasa.gov.

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Iceland’s Grimsvotn Volcano

On May 21, 2011, Iceland’s Grimsvotn Volcano erupted, sending an ash plume 12 miles (20 kilometers) high and closing Keflavik Airport, Iceland’s largest. Ash fell on much of Iceland, with some areas pitch black at midday on the 22nd. This eruption is not expected to disrupt air travel as much as taht of Eyjafjallajokull in 2010 because the Grimsvotn ash particles are larger and settling out of the atmosphere more quickly.

This natural-color satellite image, acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite, shows the towering ash plume at 1:00 p.m. local time. Beneath the ash plume, clouds cover much of the scene. Lingering snow is visible beneath the clouds to the northeast (upper left). Brown ash covers a portion of the Vatnajokull Glacier near the Atlantic coast (lower right).

Grimsvotn is Iceland’s most active volcano, but it hasn’t erupted so forcefully since 1902. The lava is basaltic, which typically erupts in non-explosive, Hawaiian-style eruptions. Grimsvotn is located beneath a glacier, however, and the interaction of melting ice with the lava can create an explosive eruption, at least in the initial stages.

Image Credit: NASA, GSFC, MODIS Rapid Response Team

Tornado Challenges Satellite Damage Track Detection Techniques

The Short-term Prediction Research and Transition, or SPoRT, team has used satellite data from the North Alabama region to identify tornado damage from the April 27th super storm outbreak.

NASA's Terra satellite, part of the Earth Observing System of satellites, captured images of the damage path. An instrument aboard Terra called the Advanced Spaceborne Thermal Emission and Reflection Radiometer, or ASTER, was used to discern vegetation contrasts over the region.

"This is the first time ASTER data has been applied to such a massive outbreak of storms," said Gary Jedlovec, atmospheric scientist at Marshall Space Flight Center. "The usefulness of satellite information in providing improved accuracy along with damage assessment in severe weather events continues to evolve."

The tornado track signature observed by ASTER is seen as a disruption in the vegetation or other reflective surfaces over a region caused by tornado winds. Uprooted trees quickly stop the process of photosynthesis and change color -- this is easily detected by satellite.

However, detecting damage in areas outside of heavy forestland is challenging.

In Madison and Limestone counties much of the area scarred by the tornadoes are agricultural in nature. Fields are either pasture land or row crops -- therefore the effect of tornado winds is minimal and the mark on satellite imagery is suppressed.

While this indicates a limitation to the use of this particular image analysis for tornado track detection over primarily agricultural land use, the SPoRT team is exploring the use of temperature channels from ASTER to better identify damage marks on Earth's surface. Terra/ASTER is a joint activity between NASA's Science Mission Directorate Earth Science Division and Japan's Ministry of Economy, Trade and Industry. Terra is one of 14 NASA satellites that look at the Earth to study and understand changes in the Earth system and provide societal benefits.

The NASA image created by the Short-term Prediction and Research Transition or SPoRT project at the Marshall Space Flight Center in Huntsville, using data provided courtesy of NASA Goddard Space Flight Center, the Land Processes Distributed Active Archive Center, Japan’s Earth Remote Sensing Data Analysis Center, the Ministry of Economy, Trade and Industry, along with the Japan Research Observation System Organization.

Flooding From Mississippi River Levee Breach

The U.S. Army Corps of Engineers detonated explosives at the Birds Point levee near Wyatt, Missouri, at 10:02 p.m. on May 2, 2011. Water from the intentional breach flooded a 130,000-acre stretch of land. Two more breaches were detonated on May 3 and 5. This image from the Advanced Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft shows the resultant flooding of farmland west of the Mississippi 20 miles (32 kilometers) south of the levee breach. On the image, vegetation is displayed in red, bare fields in gray and water in blue. The image covers an area of 30.7 by 39 miles (49.5 by 63 kilometers), and is located near 36.5 degrees north latitude, 89.4 degrees west longitude.

With its 14 spectral bands from the visible to the thermal infrared wavelength region and its high spatial resolution of about 50 to 300 feet, or about 15 to 90 meters, ASTER images Earth to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched Dec. 18, 1999, on Terra. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and data products.

The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping and monitoring of dynamic conditions and temporal change. Example applications are monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and, measuring surface heat balance.

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

The Water Planet

Viewed from space, the most striking feature of our planet is the water. In both liquid and frozen form, it covers 75% of the Earth’s surface. It fills the sky with clouds. Water is practically everywhere on Earth, from inside the planet's rocky crust to inside the cells of the human body.

This detailed, photo-like view of Earth is based largely on observations from MODIS, the Moderate Resolution Imaging Spectroradiometer, on NASA's Terra satellite. It is one of many images of our watery world featured in a new story examining water in all of its forms and functions.

Image Credit: NASA

Alaska’s Susitna Glacier

Like rivers of liquid water, glaciers flow downhill, with tributaries joining to form larger rivers. But where water rushes, ice crawls. As a result, glaciers gather dust and dirt, and bear long-lasting evidence of past movements.

Alaska's Susitna Glacier revealed some of its long, grinding journey when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite passed overhead on Aug. 27, 2009. This satellite image combines infrared, red and green wavelengths to form a false-color image. Vegetation is red and the glacier's surface is marbled with dirt-free blue ice and dirt-coated brown ice. Infusions of relatively clean ice push in from tributaries in the north. The glacier surface appears especially complex near the center of the image, where a tributary has pushed the ice in the main glacier slightly southward.

Susitna flows over a seismically active area. In fact, a 7.9-magnitude quake struck the region in November 2002, along a previously unknown fault. Geologists surmised that earthquakes had created the steep cliffs and slopes in the glacier surface, but in fact most of the jumble is the result of surges in tributary glaciers.

Glacier surges--typically short-lived events where a glacier moves many times its normal rate--can occur when melt water accumulates at the base and lubricates the flow. This water may be supplied by meltwater lakes that accumulate on top of the glacier; some are visible in the lower left corner of this image. The underlying bedrock can also contribute to glacier surges, with soft, easily deformed rock leading to more frequent surges.

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

NASA Satellites Detect Extensive Drought Impact On Amazon Forests

Steve Cole

Headquarters, Washington                              

 

Ruth Dasso Marlaire

Ames Research Center, Moffett Field, Calif.

 

WASHINGTON -- A new NASA-funded study has revealed widespread reductions in the greenness of Amazon forests caused by last year's record-breaking drought.

"The greenness levels of Amazonian vegetation -- a measure of its health -- decreased dramatically over an area more than three and one-half times the size of Texas," said Liang Xu, the study's lead author from Boston University. "It did not recover to normal levels, even after the drought ended in late October 2010."

The drought sensitivity of Amazon rainforests is a subject of intense study. Computer models predict a changing climate with warmer temperatures and altered rainfall patterns could cause moisture stress leading to rainforests being replaced by grasslands or woody savannas. This would release the carbon stored in rotting wood into the atmosphere, which could accelerate global warming. The United Nations' Intergovernmental Panel on Climate Change has warned similar droughts could be more frequent in the Amazon region in the future.

The comprehensive study was prepared by an international team of scientists using more than a decade's worth of satellite data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measuring Mission (TRMM). Analysis of these data produced detailed maps of vegetation greenness declines from the 2010 drought. The study has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The authors first developed maps of drought-affected areas using thresholds of below-average rainfall as a guide. Next, they identified affected vegetation using two different greenness indexes as surrogates for green leaf area and physiological functioning.

The maps show the 2010 drought reduced the greenness of approximately 965,000 square miles of vegetation in the Amazon -- more than four times the area affected by the last severe drought in 2005.

"The MODIS vegetation greenness data suggest a more widespread, severe and long-lasting impact to Amazonian vegetation than what can be inferred based solely on rainfall data," said Arindam Samanta, a co-lead author from Atmospheric and Environmental Research Inc. in Lexington, Mass.

The severity of the 2010 drought also was seen in records of water levels in rivers across the Amazon basin, including the Rio Negro which represents rainfall levels over the entire western Amazon. Water levels started to fall in August 2010, reaching record low levels in late October. Water levels only began to rise with the arrival of rains later that winter.

"Last year was the driest year on record based on 109 years of Rio Negro water level data at the Manaus harbor," said Marcos Costa, co-author from the Federal University in Vicosa, Brazil. "For comparison, the lowest level during the so-called once-in-a-century drought in 2005 was only eighth lowest."

As anecdotal reports of a severe drought began to appear in the news media last summer, the authors started near-real time processing of massive amounts of satellite data. They used a new capability, the NASA Earth Exchange (NEX), built for the NASA Advanced Supercomputer facility at the agency's Ames Research Center in Moffett Field, Calif. NEX is a collaborative supercomputing environment that brings together data, models and computing resources.

With NEX, the study's authors quickly obtained a large-scale view of the impact of the drought on the Amazon forests and were able to complete the analysis by January 2011. Similar reports about the impact of the 2005 drought were published about two years after the fact.

"Timely monitoring of our planet's vegetation with satellites is critical, and with NEX it can be done efficiently to deliver near-real time information, as this study demonstrates," said study co-author Ramakrishna Nemani, a research scientist at Ames. An article about the NEX project appears in this week's issue of Eos, the weekly newspaper of the American Geophysical Union.

For more information about this study and the NEX project, visit https://c3.ndc.nasa.gov/nex/projects/1209/.

For more information about the MODIS sensor and data products, visit http://modis.gsfc.nasa.gov.

For information about the Tropical Rainfall Measuring Mission, visit http://trmm.gsfc.nasa.gov.

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NASA Satellites Detect Extensive Drought Impact on Amazon Forests

A new NASA-funded study has revealed widespread reductions in the greenness of the forests in the vast Amazon basin in South America caused by the record-breaking drought of 2010.

"The greenness levels of Amazonian vegetation -- a measure of its health -- decreased dramatically over an area more than three and one-half times the size of Texas and did not recover to normal levels, even after the drought ended in late October 2010," said Liang Xu, the study's lead author from Boston University.

The drought sensitivity of Amazon rainforests is a subject of intense study. Scientists are concerned because computer models predict that in a changing climate with warmer temperatures and altered rainfall patterns the ensuing moisture stress could cause some of the rainforests to be replaced by grasslands or woody savannas. This would cause the carbon stored in the rotting wood to be released into the atmosphere, which could accelerate global warming. The United Nations' Intergovernmental Panel on Climate Change (IPCC) has warned that similar droughts could be more frequent in the Amazon region in the future.

The comprehensive study was prepared by an international team of scientists using more than a decade's worth of satellite data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and Tropical Rainfall Measuring Mission (TRMM).

Analysis of these data produced detailed maps showing vegetation greenness declines from the 2010 drought. The study has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The authors first developed maps of drought-affected areas using thresholds of below-average rainfall as a guide. Next they identified affected vegetation using two different greenness indices as surrogates for green leaf area and physiological functioning. The maps show the 2010 drought reduced the greenness of approximately 965,000 square miles of vegetation in the Amazon -- more than four times the area affected by the last severe drought in 2005.

"The MODIS vegetation greenness data suggest a more widespread, severe and long-lasting impact to Amazonian vegetation than what can be inferred based solely on rainfall data," said Arindam Samanta, a co-lead author from Atmospheric and Environmental Research Inc. in Lexington, Mass.

The severity of the 2010 drought was also seen in records of water levels in rivers across the Amazon basin. Water levels started to fall in August 2010, reaching record low levels in late October. Water levels only began to rise with the arrival of rains later that winter.

"Last year was the driest year on record based on 109 years of Rio Negro water level data at the Manaus harbor. For comparison, the lowest level during the so-called once-in-a-century drought in 2005, was only eighth lowest," said Marcos Costa, coauthor from the Federal University in Vicosa, Brazil.

As anecdotal reports of a severe drought began to appear in the news media during the summer of 2010, the authors started near real-time processing of massive amounts of satellite data. They used a new capability, the NASA Earth Exchange (NEX), built for the NASA Advanced Supercomputer facility at the agency's Ames Research Center in Moffett Field, Calif. NEX is a collaborative supercomputing environment that brings together data, models and computing resources.

With NEX, the study's authors quickly obtained a large-scale view of the impact of the drought on the Amazon forests and were able to complete the analysis by January 2011. Similar reports about the impact of the 2005 drought were published about two years after the fact.

"Timely monitoring of our planet's vegetation with satellites is critical, and with NEX it can be done efficiently to deliver near-real time information, as this study demonstrates," said study coauthor Ramakrishna Nemani, a research scientist at Ames. An article about the NEX project appears in this week's issue of Eos, the weekly newspaper of the American Geophysical Union.

For more information about this study and the NEX project, visit https://c3.ndc.nasa.gov/nex/projects/1209/.

For more information about the MODIS sensor and data products, visit http://modis.gsfc.nasa.gov.

For information about the Tropical Rainfall Measuring Mission, visit http://trmm.gsfc.nasa.gov.

Ruth Dasso Marlaire

Ames Research Center, Moffett Field, Calif.

Flooding from Tsunami near Sendai, Japan

NASA’s Terra satellite's first view of northeastern Japan in the wake of a devastating earthquake and tsunami reveal extensive flooding along the coast. The Moderate Resolution Imaging Spectroradiometer (MODIS) acquired the right image of the Sendai region on March 12, 2011, at 10:30 a.m. The left image, taken by Terra MODIS on February 26, 2011, is provided as a point of reference.

Water is black or dark blue in these images. It is difficult to see the coastline in the March 12 image, but a thin green line outlines the shore. This green line is higher-elevation land that is above water, presumably preventing the flood of water from returning to the sea. The flood indicator on the left image illustrates how far inland the flood extends.

Credit: NASA