Earth Science Studies
- New maps of burn areas from two California megafires are so detailed, they can show individual trees.
- The maps are being used in rehabilitating the burn areas and protecting wildlife.
April 30, 2015
NASA Administrator Statement on House Authorization Bill
“Moving out on Landsat 9 is a high priority for NASA and USGS as part of a sustainable land imaging program that will serve the nation into the future as the current Landsat program has done for decades,” said John Grunsfeld, associate administrator for science at NASA Headquarters, Washington. “Continuing the critical observations made by the Landsat satellites is important now and their value will only grow in the future, given the long term environmental changes we are seeing on planet Earth.”
With decades of observations, scientists can tease out subtle changes in ecosystems, the effects of climate change on permafrost, changes in farming technologies, and many other activities that alter the landscape.
NASA has joined forces with the U.S. Environmental Protection Agency, National Oceanic and Atmospheric Administration, and U.S. Geological Survey to transform satellite data designed to probe ocean biology into information that will help protect the American public from harmful freshwater algal blooms.
Algal blooms are a worldwide environmental problem causing human and animal health risks, fish kills, and taste and odor in drinking water. In the United States, the cost of freshwater degraded by harmful algal blooms is estimated at $64 million annually. In August 2014, officials in Toledo, Ohio, banned the use of drinking water supplied to more than 400,000 residents after it was contaminated by an algal bloom in Lake Erie.
The new $3.6 million, multi-agency effort will use ocean color satellite data to develop an early warning indicator for toxic and nuisance algal blooms in freshwater systems and an information distribution system to aid expedient public health advisories.
Ocean color satellite data from NASA’s Aqua, the USGS-NASA Landsat, and the European Space Agency’s Sentinel-2 and -3 are currently available to scientists, but are not routinely processed and produced in formats that help state and local environmental and water quality managers. Through this project, satellite data on harmful algal blooms developed by the partner agencies will be converted to a format that stakeholders can use through mobile devices and web portals.
NOAA and NASA pioneered the use of satellite data to monitor and forecast harmful algal blooms. Satellites allow for more frequent observations over broader areas than water sampling. The satellite data support NOAA’s existing forecasting systems in the Gulf of Mexico and Great Lakes.
The new network builds on previous NASA ocean satellite sensor technologies created to study the global ocean’s microscopic algal communities, which play a major role in ocean ecology, the movement of carbon dioxide between the atmosphere and ocean, and climate change. These sensors detect the color of the sunlit upper layer of the ocean and are used to create indicators that can help identify harmful algal blooms.
Under certain environmental conditions, algae naturally present in marine and fresh waters rapidly multiply to create a bloom. Some species of algae called cyanobacteria produce toxins that can kill wildlife and domestic animals and cause illness in humans through exposure to contaminated freshwater and the consumption of contaminated drinking water, fish or shellfish. Cyanobacteria blooms are a particular concern because of their dense biomass, toxins, taste and odor.
The project also includes a research component to improve understanding of the environmental causes and health impacts of cyanobacteria and phytoplankton blooms across the United States. Blooms in lakes and estuaries are produced when aquatic plants receive excess nutrients under suitable environmental conditions. Various land uses, such as urbanization and agricultural practices, change the amount of nutrients and sediment delivered in watersheds, which can influence cyanobacterial growth.
Researchers will compare the new freshwater algal blooms data with satellite records of land cover changes over time to identify specific land-use activities that may have caused environmental changes linked to the frequency and intensity of blooms. The results will help to develop better forecasts of bloom events.
NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term satellite data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.
For more information on NASA’s Earth science activities, visit: http://www.nasa.gov/earth
› Groundwater pollution is a worldwide threat to water availability.
› A new technique uses satellite observations of land use changes to assess a region’s risk of groundwater pollution.
The next time you’re digging for buried treasure, stop when you hit water. That underground resource is more valuable than all legendary hoards combined. Ninety percent of Earth’s available fresh water is beneath the surface at any particular time. We drink it, we grow our food with it, and we power industries with it.
We also pollute it. When pollutants get into groundwater, they can stay there for decades. Cleanup efforts are difficult, expensive and not always successful. It would be better to protect groundwater from contamination in the first place, but risks to groundwater are moving targets. Although unchanging factors such as porous soil or shallow aquifer depth play a role, the greatest risk comes from the source of the pollutants: people. And people are always moving. A growing city, in particular, usually means a growing threat to groundwater quality. To lock on to the moving target of groundwater risk, planners worldwide need up-to-date information on how people are changing the land surface.
Son Nghiem, a research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, has devised a new technique to use satellite observations of changes in land use to assess the threat of groundwater pollution by a common group of polluting compounds called nitrates. “To test the method, we successfully conducted the Po Plain Experiment [POPLEX] in northern Italy,” said POPLEX leader Marco Masetti, a professor at the University of Milan, Italy. Combining data from the experiment with satellite data and two other data sets on population and land use, they discovered that in this region, groundwater is more vulnerable in urban than in agricultural areas. The satellite data produced a more accurate map of groundwater risks than either of the other data sets.
Nghiem’s new technique uses data from NASA’s QuikScat scatterometer, a satellite managed by JPL. The method improves the “focus” of the QuikScat image from a pixel size of about 15 miles (25 kilometers) per side to 0.6 mile (1 kilometer) per side, capturing far more detail on how the landscape has changed. Nghiem explained his technique takes advantage of the fact that human-made structures bounce back more of the radar signal than does soil or vegetation. Since large buildings with steel frames are concentrated in cities, the strength of the return signals is a good measure of urbanization.
Lombardy, the region of Italy where the POPLEX experiment took place, “is both one of the most urbanized and one of the most agricultural regions in Italy,” said Stefania Stevenazzi, a doctoral candidate at the University of Milan and lead author of a paperon the research, which appears in the March 19 Hydrogeology Journal. The city of Milan is in the north, and the southern part of the region is mainly farmland. Lombardy’s farmers have usually been blamed for nitrate pollution in the region’s aquifers because nitrates are used as fertilizers, but the compounds also have urban sources, including leaks from sewage systems.
The research team produced three groundwater vulnerability maps based on observed changes from 2000 to 2009. Each map used the same hydrological and geological data, but a different data set representing human factors: census results, a high-resolution aerial photographic survey and the QuikScat observations processed by Nghiem’s method. Statistical techniques were applied to rank the vulnerability of every part of the plain. Water samples from about 200 wells were used to verify the results.
The three maps agreed that in Lombardy, urban sources of nitrate were more important than the rural in polluting groundwater. The QuikScat map, however, proved to match the water samples most accurately. For example, the map using census data indicated that several areas in greater Milan were not at much risk, whereas the satellite data caught the reality that these areas are highly vulnerable. That is because censuses place people at their home addresses, but most of the people in Milan’s labor force are commuters who spend many waking — and polluting — hours at work.
Stevenazzi added, “Our analysis shows how much changes in land use were related to increasing or decreasing contamination in the 2000s. These results are also useful to evaluate how future land-use plans can be developed appropriately to safeguard groundwater quality and human health.”
For more information on the Po Plain Experiment, see:
For more on QuikScat, please visit:
JPL is managed for NASA by the California Institute of Technology in Pasadena.
Those who feel as though they’ve been living in the never-ending winter of the movie “Frozen” this year may be glad to hear that the spring thaw is now typically arriving up to two weeks earlier in the Northern Hemisphere than it did 20 to 30 years ago. But the changing date of the spring thaw has consequences far beyond reducing the number of mornings when you have to scrape off your windshield.
One ecosystem where scientists would most like to understand the effects of changing freeze/thaw cycles is boreal forests, the great ring of green covering the land nearest the North Pole. The forests of Alaska, Canada, Scandinavia and Siberia cover almost 15 percent of Earth’s land surface. The Arctic is warming more quickly than lower latitudes, and the way these forests respond to this rapid change could provide valuable clues about our planet’s warmer future.
But we know very little about how the boreal forests are changing. Millions of square miles have no roads or even villages. “What we have now are very sparse, seasonal measurements from the ground,” said John Kimball, a professor of systems ecology at the University of Montana, Missoula, and a member of the science team for NASA’s Soil Moisture Active Passive (SMAP) mission, launched Jan. 31. “We do have long-term, global satellite data sets that are sensitive to freeze-thaw, but they tend to be very coarse.” That means each measurement averages the status of a large area. Like a mosaic made of large tiles, these data cannot show much detail.
That’s about to change. By the end of April, SMAP will begin monitoring the frozen or thawed state of the landscape north of 45 degrees north latitude (about the latitude of Minneapolis) every two days. The primary mission of SMAP is to measure the amount of moisture in the top few inches of soil globally, but it also detects whether that moisture is frozen or in liquid form. SMAP’s radar measurements, with “tiles” only half a mile to a mile and a half (1 to 3 kilometers) across, will reveal far more detail than scientists now have about the freeze/thaw status of the land surface.
Why is greater detail needed? In the Arctic, the timing of the spring thaw can vary considerably within a small area. Because the returning sun is low on the horizon, the shadowed north side of a hill may remain icy many days after plants have started growing again on the sunlit south side. Those early spring weeks are critical in the short Arctic growing season. “Once the vegetation thaws, boom! Photosynthesis takes off,” Kimball explained. “You can get your highest rates of photosynthesis within a few weeks after the thaw, and a later thaw can mean much lower vegetation growth for the season. We need observations at what I call the landscape level to more precisely monitor those patterns and changes.”
During photosynthesis, plants absorb carbon dioxide from the air. The carbon stays in their wood, roots and leaves, and when they die, most of it remains in the soil. That makes undisturbed forests what scientists call carbon sinks — places that remove carbon from the atmosphere. Longer unfrozen seasons in the Arctic give forests more time to grow and spread, increasing the extent of the carbon sink.
On the other hand, climate warming has increased the occurrence of droughts and wildfires in the Arctic. A burning forest spews enormous amounts of carbon into the atmosphere; in scientific terms, it is a carbon source. Thus, global climate change is causing the northern forests both to absorb and to release more carbon.
With so little Arctic data to crunch, models of Arctic land processes do not agree on which of these trends is prevailing, much less what the future could hold. Lack of consensus does not indicate fundamental disagreements on the physical processes involved, according to JPL scientist Josh Fisher, a member of the SMAP algorithm team. The problem is that, at present, if you put the Arctic’s emitted carbon on one side of a scale and absorbed carbon on the other, the scales would almost balance. “The source/sink balance is usually close to zero, and it’s very easy to get on the wrong side of the zero,” he said. Yet the wrong answer on this fundamental question can cascade into a chain of wrong answers in the course of a model simulation. SMAP’s fine-scale observations have the potential to improve modelers’ understanding of both today’s situation and how it may change in the future.
This spring, SMAP will spin up in time to track the spring thaw in the boreal forest with the detail scientists need — as Princess Anna in “Frozen” says, “For the first time in forever.”
For more about SMAP, visit:
JPL is managed for NASA by the California Institute of Technology in Pasadena.
Researchers at the University of Texas at Austin, NASA and other research organizations have discovered two seafloor troughs that could allow warm ocean water to reach the base of Totten Glacier, East Antarctica’s largest and most rapidly thinning glacier. The discovery likely explains the glacier’s extreme thinning and raises concern about its impact on sea level rise.
The result, published in the journal Nature Geoscience today, March 16, has global implications because the ice flowing through Totten Glacier alone is equivalent to the entire volume of the more widely studied West Antarctic Ice Sheet. If Totten Glacier were to collapse completely, global sea levels would rise by at least 11 feet (3.3 meters). As in the West Antarctic Ice Sheet, complete collapse of Totten Glacier may take centuries, although the timing of retreat in both places is the subject of intensive research.
East Antarctica has appeared to be stable compared with the rapidly melting western side of the continent. The new finding shows that “Totten Glacier and the East Antarctic Ice Sheet are a much more interesting and dynamic part of the sea level rise story than we’d previously thought,” said co-author Dustin Schroeder, a scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California. Schroeder helped analyze data from an ice-penetrating radar to demonstrate that ocean water could access the glacier through the newfound troughs.
In some areas of the ocean surrounding Antarctica, warm water can be found below cooler water because it is saltier, and therefore heavier, than the shallower water. Seafloor valleys that connect this deep warm water to the coast can especially compromise glaciers, but this process had previously been seen only under the West Antarctic Ice Sheet. Deep warm water had been observed seaward of Totten Glacier, but there was no evidence that it could compromise coastal ice.
The newly discovered troughs are deep enough to give the deep warm water access to the huge cavity under the glacier. The deeper of the two troughs extends from the ocean to the underside of Totten Glacier in an area not previously known to be floating.
The data for this study were gathered as part of the International Collaboration for Exploration of the
Cryosphere through Airborne Profiling (ICECAP) project, which, together with the East Antarctic component of NASA’s Operation IceBridge mission, made the first comprehensive survey of the Totten Glacier Ice Shelf and nearby regions between 2008 and 2012. Other coauthors of the study come from research organizations and universities in Australia, France and England.
For more information on the new study, see:
To learn more about Operation IceBridge and ICECAP, visit:
The paper is available at: