Research using NASA data is giving new insight into one of the processes causing Greenland's ice sheet to lose mass. A team of scientists used satellite observations and ice thickness measurements gathered by NASA's Operation IceBridge to calculate the rate at which ice flows through Greenland's glaciers into the ocean. The findings of this research give a clearer picture of how glacier flow affects the Greenland Ice Sheet and shows that this dynamic process is dominated by a small number of glaciers.

Over the past few years, Operation IceBridge measured the thickness of many of Greenland's glaciers, which allowed researchers to make a more accurate calculation of ice discharge rates. In a new study published in the journal Geophysical Research Letters, researchers calculated ice discharge rates for 178 Greenland glaciers more than one kilometer (0.62 miles) wide.

Ice sheets grow when snow accumulates and is compacted into ice. They lose mass when ice and snow at the surface melts and runs off and when glaciers at the coast discharge ice into the ocean. The difference between yearly snowfall on an ice sheet and the sum of melting and discharge is called a mass budget. When these factors are equal, the mass budget is balanced, but for years the Greenland Ice Sheet has had a negative mass budget, meaning the ice sheet is losing mass overall.

For years the processes of surface melt and glacier discharge were roughly equal in size, but around 2006 surface melt increased and now exceeds iceberg production. In recent years, computer model projections have shown an increasing dominance of surface melt, but a limited amount of glacier thickness data made pinpointing a figure for ice discharge difficult.

Ice discharge is controlled by three major factors: ice thickness, glacier valley shape and ice velocity. Researchers used data from IceBridge's ice-penetrating radar – the Multichannel Coherent Radar Depth Sounder, or MCoRDS, which is operated by the Center for Remote Sensing of Ice Sheets at the University of Kansas, Lawrence, Kan. – to determine ice thickness and sub-glacial terrain, and images from satellite sources such as Landsat and Terra to calculate velocity. The team used several years of observations to ensure accuracy. "Glacier discharge may vary considerably between years," said Ellyn Enderlin, glaciologist at the University of Maine, Orono, Maine and the study's lead author. "Annual changes in speed and thickness must be taken into account."

Being able to study Greenland in such a large and detailed scale is one of IceBridge's strengths. "IceBridge has collected so much data on elevation and thickness that we can now do analysis down to the individual glacier level and do it for the entire ice sheet," said Michael Studinger, IceBridge project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "We can now quantify contributions from the different processes that contribute to ice loss."

With data on glacier size, shape and speed, researchers could calculate each glacier's contribution to Greenland's mass loss and the total volume of ice being discharged from the Greenland Ice Sheet. Of the 178 glaciers studied, 15 accounted for more than three-quarters of ice discharged since 2000, and four accounted for roughly half. Considering the large size of some of Greenland's glacier basins, such as the areas drained by the Jakobshavn, Helheim and Kangerdlugssuaq glaciers, this was not exactly surprising.

What they also found was that the size of these basins did not necessarily correlate with glacier discharge rate, shuffling the order of Greenland's largest glaciers. Previously Helheim Glacier was thought to be Greenland's third largest glacier, but this study puts it in fifth place and adds two southeast Greenland glaciers, Koge Bugt and Ikertivaq South to the list of big ice-movers.

Glacier thickness measurements and this study's calculation methods have the potential to improve future supercomputer model projections of the Greenland Ice Sheet. And with a new picture of which glaciers contribute most to mass loss, IceBridge will be able to more effectively target areas in future campaigns, promising more and better data to add to the research community's body of knowledge.

Using data from NASA's Van Allen Probes, researchers have tested and improved a model to help forecast what's happening in the radiation environment of near-Earth space -- a place seething with fast-moving particles and a space weather system that varies in response to incoming energy and particles from the sun.

When events in the two giant doughnuts of radiation around Earth – called the Van Allen radiation belts -- cause the belts to swell and electrons to accelerate to 99 percent the speed of light, nearby satellites can feel the effects. Scientists ultimately want to be able to predict these changes, which requires understanding of what causes them.

Now, two sets of related research published in the Geophysical Research Letters improve on these goals. By combining new data from the Van Allen Probes with a high-powered supercomputer model, the new research provides a robust way to simulate events in the Van Allen belts.

"The Van Allen Probes are gathering great measurements, but they can't tell you what is happening everywhere at the same time," said Geoff Reeves, a space scientist at Los Alamos National Laboratory, or LANL, in Los Alamos, N.M., a co-author on both of the recent papers. "We need models to provide a context, to describe the whole system, based on the Van Allen Probe observations."

Prior to the launch of the Van Allen Probes in August 2012, there were no operating spacecraft designed to collect real-time information in the radiation belts. Understanding of what might be happening in any locale was forced to rely mainly on interpreting historical data, particularly those from the early 1990s gathered by the Combined Release and Radiation Effects Satellite, or CRRES.

Imagine if meteorologists wanted to predict the temperature on March 5, 2014, in Washington, D.C. but the only information available was from a handful of measurements made in March over the last seven years up and down the East Coast. That's not exactly enough information to decide whether or not you need to wear your hat and gloves on any given day in the nation's capital.

Thankfully, we have much more historical information, models that help us predict the weather and, of course, innumerable thermometers in any given city to measure temperature in real time. The Van Allen Probes are one step toward gathering more information about space weather in the radiation belts, but they do not have the ability to observe events everywhere at once. So scientists use the data they now have available to build supercomputer simulations that fill in the gaps.

The recent work centers around using Van Allen Probes data to improve a three-dimensional model created by scientists at LANL, called DREAM3D, which stands for Dynamic Radiation Environment Assimilation Model in 3 Dimensions. Until now the model relied heavily on the averaged data from the CRRES mission.

One of the recent papers, published Feb. 7, 2014, provides a technique for gathering real-time global measurements of chorus waves, which are crucial in providing energy to electrons in the radiation belts. The team compared Van Allen Probes data of chorus wave behavior in the belts to data from the National Oceanic and Atmospheric Administration's Polar-orbiting Operational Environmental Satellites, or POES, flying below the belts at low altitude. Using this data and some other historical examples, they correlated the low-energy electrons falling out of the belts to what was happening directly in the belts.

"Once we established the relationship between the chorus waves and the precipitating electrons, we can use the POES satellite constellation – which has quite a few satellites orbiting Earth and get really good coverage of the electrons coming out of the belts," said Los Alamos scientist Yue Chen, first author of the chorus waves paper. "Combining that data with a few wave measurements from a single satellite, we can remotely sense what's happening with the chorus waves throughout the whole belt."

The relationship between the precipitating electrons and the chorus waves does not have a one-to-one precision, but it does provide a much narrower range of possibilities for what's happening in the belts. In the metaphor of trying to find the temperature for Washington on March 5, it's as if you still didn't have a thermometer in the city itself, but can make a better estimate of the temperature because you have measurements of the dewpoint and humidity in a nearby suburb.

The second paper describes a process of augmenting the DREAM3D model with data from the chorus wave technique, from the Van Allen Probes, and from NASA's Advanced Composition Explorer, or ACE, which measures particles from the solar wind. Los Alamos researchers compared simulations from their model – which now was able to incorporate real-time information for the first time – to a solar storm from October 2012.

"This was a remarkable and dynamic storm," said lead author Weichao Tu at Los Alamos. "Activity peaked twice over the course of the storm. The first time the fast electrons were completely wiped out – it was a fast drop out. The second time many electrons were accelerated substantially. There were a thousand times more high-energy electrons within a few hours."

Tu and her team ran the DREAM3D model using the chorus wave information and by including observations from the Van Allen Probes and ACE. The scientists found that their supercomputer simulation made by their model recreated an event very similar to the October 2012 storm.

What's more the model helped explain the different effects of the different peaks. During the first peak, there simply were fewer electrons around to be accelerated.

However, during the early parts of the storm the solar wind funneled electrons into the belts. So, during the second peak, there were more electrons to accelerate.

"That gives us some confidence in our model," said Reeves. "And, more importantly, it gives us confidence that we are starting to understand what's going on in the radiation belts." 

NASA is partnering with the California Department of Water Resources (DWR) to develop and apply new technology and products to better manage and monitor the state's water resources and respond to its ongoing drought.

NASA scientists, DWR water managers, university researchers and other state resource management agencies will collaborate to apply advanced remote sensing and improved forecast modeling to better assess water resources, monitor drought conditions and water supplies, plan for drought response and mitigation, and measure drought impacts.

"Over the past two decades, NASA has developed capabilities to measure and provide useful information for all components of Earth's freshwater resources worldwide," said Michael Freilich, director of NASA's Earth Science Division in Washington. "Working with partners like DWR, we are leveraging NASA's unique Earth monitoring tools and science expertise to help managers address the state's water management challenges."

In January, Gov. Edmund G. Brown Jr. declared a drought state of emergency and directed state officials to take all necessary actions to prepare for water shortages as 2014 shapes up to be one of the driest years on record in California.

NASA and DWR began exploring opportunities to apply remote sensing data and research to the process of water resource management through a partnership established with funding from the 2009 American Recovery and Reinvestment Act. Ongoing collaborations include monitoring California delta levees; mapping fallowed agricultural lands; and improving estimates of precipitation, water stored in winter snowpack, and changes in groundwater resources. The agencies also are working to combine data from NASA satellites and DWR's network of agricultural weather stations to improve estimates of crop water requirements for California farmers seeking to better manage irrigation.

"We value the partnership with NASA and the ability of their remote sensing resources to integrate data over large spatial scales, which is useful for assessing drought impacts," said Jeanine Jones, Interstate Water Resources Manager, DWR, Sacramento.  "Early detection of land subsidence hot spots, for example, can help forestall long-term damage to water supply and flood control infrastructure."

In April, NASA and DWR will resume flights of NASA's Airborne Snow Observatory to map the snowpack of the Tuolumne River Basin in the Sierra Nevada and the Uncompahgre watershed in the Upper Colorado River Basin. The Tuolumne watershed is the primary water supply for 2.6 million San Francisco Bay Area residents.

The airborne observatory measures how much water is in the snowpack and how much sunlight the snow absorbs, which affects how fast the snow melts. These data enable accurate estimates of how much water will flow out of a basin when the snow melts. Last year, observatory data helped water managers optimize reservoir filling and more efficiently allocate water between power generation, water supplies and ecological uses.

Another pilot project is demonstrating the feasibility of using satellite imagery to track the extent of fallowed land -- cultivated land intentionally allowed to lie idle during growing season -- in California's Central Valley. NASA is working with DWR, the U.S. Department of Agriculture, the U.S. Geological Survey (USGS) and California State University at Monterey Bay to establish an operational fallowed land monitoring service as part of a California drought early warning information system. New methods using time-series of crop data from NASA and USGS satellites can provide information on land fallowing and reductions in planted acreage early in the year. The team is preparing to produce data and maps of fallowed acreage in the Central Valley beginning this April to help monitor the impacts of the ongoing drought.

Faced with an inability to fully irrigate their crops due to drought, Central Valley farmers often must prioritize use of limited available water supplies to sustain perennial crops. Taking land out of production reduces farm income and agricultural sales and increases unemployment. Timely and accurate knowledge of the extent of fallowing can give decision makers vital insights into the severity of drought impacts and provide a basis for sound drought response decisions.

Another NASA project mapped areas of subsidence, or ground sinking, in the San Joaquin Valley from 2007 to 2011 caused by decreased groundwater levels. Groundwater is increasingly important in water resource management, yet knowledge of groundwater levels is not uniformly available. Satellite-based and airborne interferometric synthetic aperture radar can monitor groundwater levels by measuring surface deformation due to the withdrawal and recharge of aquifers.

Satellite radar maps produced to date reveal significant areas of subsidence. NASA produced regional maps of the rate and total amount of subsidence, along with animations and detailed histories of individual locations that can help deduce year-to-year changes in groundwater storage. Researchers hope to extend the data to the present day to give state water managers updates on how subsidence has progressed during the drought and detect possible new areas of concern. The data can be used to focus on problem areas where too much water is being pumped. The maps also help managers of infrastructure that can be affected by subsidence, such as aqueducts, flood-control channels and the California High-Speed Rail Authority.

NASA is teaming with DWR, University of California at San Diego and others to conduct airborne campaigns, satellite studies and analyses of weather and climate models to enhance understanding and improve forecasts of atmospheric rivers. These narrow, low-altitude, elongated corridors of water vapor account for most major flooding events, provide about 40 percent of California's freshwater, and often are "drought busters." They help scientists understand and predict the global water cycle and its regional extremes.

NASA satellite data and modeling studies have contributed to a better description and understanding of the Madden-Julian Oscillation, a recurring pattern of tropical weather and climate that impacts weather in Earth's mid-latitudes, including California. Weather forecast models now demonstrate the ability to forecast this pattern as much as four weeks in advance, potentially providing new, long-lead precipitation forecast information for California. The NASA team is working with the global weather and climate forecast communities to enable and improve routine forecasts of this phenomenon.

Three of the five new Earth science missions NASA is scheduled to launch this year will contribute to water cycle research and water-related national policy decisions.

The Global Precipitation Measurement (GPM) Core Observatory, a joint satellite project with the Japan Aerospace Exploration Agency scheduled for launch Thursday, Feb. 27, will inaugurate an unprecedented international satellite constellation that will produce the first nearly global observations of rainfall and snowfall. The new information will help answer questions about our planet's life-sustaining water cycle, and improve water resource management and weather forecasting.

ISS-RapidScat, scheduled to launch to the International Space Station (ISS) in June, will extend the data record of ocean winds around the globe. The data are a key factor in climate research, weather and marine forecasting and tracking of storms and hurricanes.

The Soil Moisture Active Passive (SMAP), launching in November, will inform water resource management decisions on water availability. SMAP data also will aid in predictions of plant growth and agricultural productivity, improve short-term weather forecasts and long-term climate change projections, and advance our ability to monitor droughts and predict floods and mitigate their related impacts on people's lives.

NASA also plans to launch four additional water-related satellites in the next seven years: The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2); Gravity Recovery and Climate Experiment (GRACE) Follow-on; Surface Water Ocean Topography mission; and the NASA-Indian Space Research Organisation Synthetic Aperture Radar mission. These satellite missions join more than a dozen NASA airborne sensors focused on regional-scale issues, understanding detailed Earth science processes and calibrating and validating NASA satellites.

NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

NASA researchers are part of an international team working to improve aviation safety by studying high altitude ice crystals during a flight campaign now under way in Darwin, Australia.

NASA and its North American partners are supporting the European Airbus-led High Altitude Ice Crystals (HAIC)/High Ice Water Content (HIWC) field campaign in the "land down under" through March. The primary goal of the campaign is to fly into weather that produces specific icing conditions so researchers can study the characteristics present.  NASA's Glenn Research Center in Cleveland is supplying an isokinetic probe, as well as instrument and meteorological ground support. Mounted under the wing of a French Falcon 20 aircraft, the probe measures the total water content in clouds that have high concentrations of ice crystals in the vicinity of oceanic and continental thunderstorms.

"The data captured during the HAIC/HIWC campaign will add to the ground-based icing research our agency has already conducted in Glenn's Propulsion Systems Laboratory where a full scale engine was tested under high altitude ice crystal icing conditions," said Tom Ratvasky, Glenn's project scientist supporting the campaign.

NASA's Langley Research Center in Hampton, Va., and NASA's Goddard Institute for Space Studies in New York, are also participating. Engineers and scientists from Langley are contributing sensors expertise. One team is analyzing data from the Falcon's onboard weather radar. Another is capturing satellite imagery to help forecast where the jet might encounter the best icing conditions. Goddard scientists are providing expertise in cloud resolving modeling, using the in-situ flight data to improve current cloud modeling algorithms to predict the high ice concentrations in these environments.

"The aviation industry around the world is very interested in this research. That's because ice crystals at high altitudes are not normally detected by onboard weather radar and visibly do not appear to be a danger to pilots," said Steve Harrah, HAIC/HIWC weather radar principal investigator at NASA Langley.

"However, if those crystals are ingested into a turbofan engine and reach its core, they can cause a temporary loss of power - with no warning," added Ratvasky.

Turbofan engines ingesting ice crystals is not new. However, its impact on aviation is becoming more widely known because of an increase in exposure to these conditions caused by increases in worldwide commercial aviation traffic, flying at higher altitudes with more efficient bypass engines.

"The research that will be compiled during the flight campaign will build on what we know about ice crystal icing at high altitudes and help us better understand the physical processes that cause high concentrations of crystals in certain areas," said Ratvasky.  "What we learn will help inform aviation regulatory agencies internationally and help further development of technologies that may one day detect the presence of ice crystals or mitigate ice crystals' effects when encountered during flight."

New research using data from NASA's Van Allen Probes mission helps resolve decades of scientific uncertainty over the origin of ultra-relativistic electrons in Earth's near space environment, and is likely to influence our understanding of planetary magnetospheres throughout the universe.

Understanding the processes that control the formation and ultimate loss of such relativistic electrons is a primary science objective of the Van Allen Probes and has astronauts performing activities outside a spacecraft.important practical applications, because of the enormous amounts of radiation trapped within the two Van Allen radiation belts. The belts, consisting of high-energy electrons and protons discovered above Earth's upper atmosphere in 1958 by James Van Allen, can pose a significant hazard to satellites and spacecraft, as well to 

Such electrons in the Earth's outer radiation belt can exhibit pronounced increases in intensity, in response to activity on the sun, and changes in the solar wind — but the dominant physical mechanisms responsible for such radiation belt electron acceleration has remained unresolved for decades.

Two primary candidates for electron acceleration exist, one external and one internal. From outside the belts, a theoretical process known as inward radial diffusive transport has been developed. From within the belts, scientists hypothesize that the electrons are undergoing strong local acceleration from very low frequency plasma waves. Controversies also exist as to the very nature of the wave acceleration: Is it stochastic – that is, a linear and diffusive process – or is it non-linear and coherent?

In research published Dec. 19, 2013, in Nature, lead author Richard Thorne and colleagues report on high-resolution measurements, made by the Van Allen Probes, which suggest that local acceleration is at work. The team observed high-energy electrons during a geomagnetic storm of Oct. 9, 2012, which they analyzed together with a data-driven global wave model. Their analysis reveals that linear, stochastic scattering by intense, natural very low-frequency radio waves -- known as chorus waves -- in Earth's upper atmosphere can account for the observed relativistic electron build-up.

"The successful point-by-point comparison of radiation belt features observed by the Van Allen Probes with the predictions of the state of the art model developed by Richard Thorne and his group dramatically demonstrates the significance of in situ particle acceleration within Earth's radiation belts," said David Sibeck, mission scientist for the Van Allen Probes at NASA's Goddard Space Flight Center in Greenbelt, Md.

The detailed modeling reported in Nature, together with previous observations reported earlier this year in the journal Science [link to article ] of peaks in electron phase space density by Geoff Reeves at Los Alamos National Laboratory in New Mexico and colleagues, demonstrates the remarkable efficiency of natural wave acceleration in Earth's near space environment. Their research shows that radial diffusion was not responsible for the observed acceleration during this storm, said Thorne, a scientist at the University of California at Los Angeles.

The local wave acceleration process is a universal physical process and should also be effective in the magnetospheres of Jupiter, Saturn and other magnetized plasma environments in the cosmos, Thorne said. He thinks the new results from the detailed analysis at Earth will influence future modeling of other planetary magnetospheres.

"This new finding is of paramount importance to unlocking the multitude of processes behind particle behavior in the belts," says Barry Mauk, project scientist for the Van Allen Probes at the Johns Hopkins Applied Physics Laboratory in Laurel, Md. "To have one of the primary science objectives of the mission met within just over a year of launch is a testament to the quality and quantity of the data the instruments on the probes are gathering, and to the teams analyzing them."

Page 10 of 13