NCAR

Food security report wins USDA award

BOULDER, Colo. — A comprehensive report warning of the impacts of climate change on the world's food security has won a top U.S. Department of Agriculture (USDA) award."Climate Change, Global Food Security, and the U.S. Food System," with co-authors from the National Center for Atmospheric Research (NCAR), provides an overview of recent research in climate change and agriculture. It warns that warmer temperatures and altered precipitation patterns can threaten food production, disrupt transportation systems, and degrade food safety, among other impacts, and that the world's poor and those living in tropical regions are particularly vulnerable.Michael Scuse, USDA acting deputy secretary (center), with members of the team of experts who produced the award-winning report, "Climate Change, Global Food Security, and the U.S. Food System." Those pictured are (back row from left): William Easterling (The Pennsylvania State University), Edward Carr (Clark University), and Peter Backlund (Colorado State University); front row from left: Rachel Melnick (USDA), Margaret Walsh (USDA), Scuse, Moffat Ngugi (U.S. Agency for International Development/USDA), and Karen Griggs (NCAR). (Photo by USDA.) The USDA this month named it as the winner of the 2016 Abraham Lincoln Honor Award for Increasing Global Food Security. The Abraham Lincoln Honor Award is the most prestigious USDA award presented by the Secretary of Agriculture, recognizing noteworthy accomplishments that significantly contribute to the advancement of the USDA's strategic goals, mission objectives, and overall management excellence.The report was produced as part of a collaboration between NCAR, the USDA, and the University Corporation for Atmospheric Research (UCAR), which manages NCAR on behalf of the National Science Foundation. It was written by 32 experts from 19 federal, academic, nongovernmental, intergovernmental, and private organizations in the United States, Argentina, Britain, and Thailand. The authors included three NCAR scientists, as well as eight experts affiliated with UCAR member universities."This award highlights the importance of addressing climate change in order to maintain the progress the world has made on food security in recent decades," said NCAR program director Lawrence Buja, who helped oversee production of the report. "Scientists will continue to study this critical issue and work with decision makers to co-develop the information they need about potential climate impacts on future production, distribution, and other aspects of our U.S. and global food systems."Published under the auspices of the U.S. Global Change Research Program, the reportfocuses on identifying climate change impacts on global food security through 2100. The authors emphasize that food security — the ability of people to obtain and use sufficient amounts of safe and nutritious food — will be affected by several factors in addition to climate change, such as technological advances, increases in population, the distribution of wealth, and changes in eating habits."Climate change has a myriad of potential impacts, especially on food, water, and energy systems," said UCAR President Antonio J. Busalacchi. "I commend the authors of this report for clearly analyzing this very complex issue in the agriculture sector, which has implications for all of society, from the least developed nations to the most advanced economies."Report authorsMolly Brown, University of Maryland*John Antle, Oregon State University*Peter Backlund, Colorado State University *Edward Carr, Clark UniversityBill Easterling, Pennsylvania State University*Margaret Walsh, USDA Office of the Chief Economist/Climate Change Program OfficeCaspar Ammann, NCARWitsanu Attavanich, Kasetsart UniversityChris Barrett, Cornell University*Marc Bellemare, University of Minnesota*Violet Dancheck, U.S. Agency for International DevelopmentChris Funk, U.S. Geological SurveyKathryn Grace, University of Utah*John Ingram, University of OxfordHui Jiang, USDA Foreign Agricultural ServiceHector Maletta, Universidad de Buenos AiresTawny Mata, USDA/American Association for the Advancement of ScienceAnthony Murray, USDA-Economic Research ServiceMoffatt Ngugi, U.S. Agency for International Development/USDA Foreign Agricultural ServiceDennis Ojima, Colorado State University*Brian O'Neill, NCARClaudia Tebaldi, NCAR*UCAR member universityReport project teamLawrence Buja, NCARKaren Griggs, NCAR 

Welcome Cheyenne: New supercomputer arrives in Wyoming

Sept. 19, 2016 | Last Monday, five semi trucks loaded down with NCAR's next supercomputer, Cheyenne, arrived at the NCAR-Wyoming Supercomputing Center after a long drive from Wisconsin. Staff from Silicon Graphics International Corp. (SGI), which built the computer along with the NCAR project team, have been working since on the hardware installation, which should be completed in about another week. Software installation and system integration work will begin after all the hardware has been installed and checked out.

Atmospheric rivers come into focus with high-res climate model

A high-resolution climate model based at the National Center for Atmospheric Research (NCAR) is able to accurately capture the ribbons of moist air that sometimes escape the sodden tropics and flow toward the drier mid-latitudes, allowing scientists to investigate how "atmospheric rivers" may change as the climate warms. These rivers in the sky can unleash drenching rains when they crash onto land. Because these downpours can alleviate droughts and also cause damaging floods, scientists are keenly interested in how their frequency, intensity, or path may be altered with climate change. But standard-resolution climate models have had difficulty realistically simulating atmospheric rivers and their impacts.In a pair of studies published this summer in the journal Geophysical Research Letters, NCAR scientists Christine Shields and Jeffrey Kiehl tested to see if a high-resolution climate model could do a better job. They found that a version of the NCAR-based Community Climate System Model 4.0 (CCSM4) with a resolution twice as high as normal does a good job of capturing the frequency with which atmospheric rivers made landfall over the last century as well as their locations and associated storms.Satellite images of water vapor over the oceans show atmospheric rivers hitting the U.S. West Coast in 2006 (top), 2009 (middle), and 2004 (bottom). (Images courtesy of NOAA.) Looking forward, the model projects that storms on the U.S. West Coast associated with a type of atmospheric river called the Pineapple Express, which sweeps moisture in from Hawaii, could linger and become more intense if greenhouse gas emissions are not mitigated.The studies also find that future changes to atmospheric rivers in general — including a possible increase in the number that make landfall in Southern California — will likely be dependent on how jet streams change in a warming world."Atmospheric rivers play an extremely important role in the Earth's water cycle. At any latitude, they account for only 10 percent of the air but they transport as much as 90 percent of the water that is moving from the tropics toward the poles," Kiehl said. "Understanding atmospheric rivers is critical to understanding how the entire climate system works."The how and why of future changesAtmospheric rivers were first discovered in the 1990s, and much of the early research was focused at understanding their detailed structure and the dynamics of how they form."We've gotten to a point in the science where we're able to track atmospheric rivers and detect them fairly well, and we can make some general statements about duration, intensity, and the precipitation associated with them," Shields said. "So the next step is really trying to understand how they might change in the future and, then, why they are changing."Shields and Kiehl suspected that the high-resolution version of the CCSM4 would be useful for answering those questions for a couple of reasons. Because the model has a resolution of about 50 kilometers (31 miles), it does a better job of capturing narrower phenomena, like the rivers. It also represents the complex terrain on the land surface that can trigger the atmospheric rivers to release rain or snow. As the rivers plow into the mountains of California, for example, they're forced higher into the atmosphere, where the moisture condenses and falls to the ground.As they'd hoped, the model did do a better job than a standard-resolution climate model at representing both the atmospheric rivers and their interactions with terrain. This allowed them to run the model forward to get a look at what rivers might do in the future if human-caused climate change continues unabated. What they found is that how — and why — atmospheric rivers change depends on the area of the world."Changes to atmospheric rivers in the future track with what the jets are doing," Shields said. "And that depends on your region."For example, the scientists found that the atmospheric rivers that hit California were influenced by changes to the subtropical jet, while atmospheric rivers that hit the United Kingdom were influenced by the polar jet.While understanding these connections gives scientist important insight into what factors may impact atmospheric rivers in the future, it's still a challenge for scientists to project how atmospheric rivers may actually change. That's because climate models tend to disagree about how jets will shift regionally as the climate warms.In the future, Shields and Kiehl plan to expand their analysis to other parts of the world, including the Iberian Peninsula."The climate change picture and what's going to happen to these atmospheric rivers really matter," Shields said. "They are a critical component of the hydrology in many places in the world."About the papers: Titles: "Simulating the Pineapple Express in the half degree Community Climate System Model, CCSM4," and "Atmospheric River Landfall-Latitude Changes in Future Climate Simulations"Authors: Christine A. Shields and Jeffrey T. KiehlJournal: Geophysical Research Letters, DOIs: 10.1002/2016GL069476 and 10.1002/2016GL070470Funders:National Science FoundationU.S. Department of EnergyWriter/contact:Laura Snider, Senior Science Writer and Public Information Officer 

In memoriam: Al Kellie

Sept. 13, 2016 | NCAR lost a beloved and respected colleague when CISL Director Al Kellie passed away unexpectedly in his sleep on Sept. 7, 2016. Al will be remembered for his considerable contributions to NCAR – especially his forward-looking stewardship of its high-performance computing resources – and for the way he truly cared for his employees both professionally and personally.

The 2-degree goal and the question of geoengineering

Sept. 7, 2016 | With world leaders agreeing to try to limit the increase in global temperatures, scientists at the National Center for Atmospheric Research (NCAR) are taking a look at whether geoengineering the climate could counter enough warming to help meet that goal. In a new study, the scientists found that if society doesn't make steep cuts in greenhouse gas emissions in the next couple of decades, injections of planet-cooling sulfates into the atmosphere could theoretically limit warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels. But such geoengineeing would mean a sustained effort stretching over more than a century and a half, and it would fail to prevent certain aspects of climate change."One thing that surprised me about this study is how much geoengineering it would take to stay within 2 degrees if we don't start reducing greenhouse gases soon," said NCAR scientist Simone Tilmes, the lead author.For the study, the research team focused on the potential impacts of geoengineering on temperatures, the drying of land surfaces, and Arctic sea ice. They did not examine possible adverse environmental consequences such as potential damage to the ozone layer. The sulfate injections also would not alleviate the impact of carbon dioxide emissions on ocean acidification.The research was published in the journal Geophysical Research Letters.Meeting an ambitious targetRepresentatives of 195 nations negotiated last fall's Paris Agreement, which sets an ambitious target of capping global warming at no more than 2 degrees. Scientists have found, however, that such a target will be extremely difficult to achieve. It would require society to begin dramatically reducing emissions of carbon dioxide and other greenhouse gases within a few years. Efforts to develop new technologies that could draw down carbon dioxide from the atmosphere would also be needed to succeed.Volcanic eruptions spew sulfates into the air, which can block incoming sunlight and have a cooling effect on the planet. One type of proposed geoengineering would rely on a similar method: injecting sulfates high in the atmopshere to try to cool the Earth. (Image courtesy of USGS.)The new study examined a scenario in which emissions continue growing at current rates until about 2040, when warming would reach 2 degrees. The authors found that, even if society then adopted an aggressive approach to reducing emissions and was able to begin drawing down carbon dioxide from the atmosphere, warming would reach 3 degrees by the end of the century.So they explored an additional possibility: injecting sulfate particles, like those emitted during volcanic eruptions, into the stratosphere. This approach to geoengineering, which is untested but has generated discussion for several years, would theoretically counter global warming because the sulfates would block incoming sunlight and shade the planet. This is why large volcanic eruptions can have a planet-cooling effect.The research team estimated that society would need to keep injecting sulfates for 160 years to stay within the target of 2 degrees. This would require a peak rate of 18 megatons of sulfur dioxide per year, or about 1.5 times the amount emitted by the massive eruption of Mt. Pinatubo in 1992.A different climateEven so, the climate would be noticeably altered under this scenario. Extreme hot days with geoengineering would be about twice as frequent in North America and other regions compared to present-day conditions. (In comparison, they would be about five to six times more frequent without geoengineering.) Summertime Arctic sea ice would retreat significantly with geoengineering, whereas it would disappear altogether if society relied solely on reducingcarbon dioxide in the atmosphere after 2040. Precipitation patterns would also change with geoengineering, causing drying in some regions."If society doesn't act quickly on emissions, we may be facing more uncertain methods like geoengineering to keep temperatures from going over the 2-degree target," Tilmes said. "But even with geoengineering, we'd still be looking at a climate that's different than today's. For the study, Tilmes and her colleagues used a pair of computer models: the NCAR-based Community Earth System Model and the Integrated Science Assessment Model at the University of Illinois. These enabled the authors to simulate climate conditions with different levels of greenhouse gases as well as stratospheric sulfates.The research was supported by the National Science Foundation and the Department of Energy.About the article:Title: Climate impacts of geoengineering in a delayed mitigation scenarioAuthors: Simone Tilmes, Benjamin Sanderson, and Brian O'NeillJournal: Geophysical Research Letters, DOI: 10.1002/2016gl070122Funders:National Science FoundationU.S. Department of EnergyWriter/contact:David Hosansky, Manager of Media Relations

NSF/NCAR research plane assisting with U.S. hurricane forecasts

BOULDER, Colo. — As the peak of hurricane season approaches, U.S. forecasters are deploying a high-altitude research aircraft operated by the National Center for Atmospheric Research (NCAR) to fly over and around storms to take critical observations.The NSF/NCAR Gulfstream-V readies for takeoff on a mission to study tropical storms. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) The deployment this week of the Gulfstream-V (G-V) aircraft is the result of a partnership between the National Science Foundation (NSF), which owns the plane, and the National Oceanic and Atmospheric Administration (NOAA), which issues forecasts. The NSF/NCAR G-V will take to the skies to support hurricane forecasts through October 12, while NOAA’s Gulfstream-IV (G-IV) undergoes unscheduled maintenance."It's critical to have detailed measurements of the atmosphere around a hurricane in order to ensure that forecasts are as accurate as possible," said Antonio (Tony) J. Busalacchi, president of the University Corporation for Atmospheric Research, which manages NCAR on behalf of NSF. "NCAR and its research partners have a proven track record of improving predictions of dangerous storms. Consistent with our role of managing NCAR, we take very seriously our ability and responsibility to share our advanced resources in support of NOAA's mission to protect life and property.""NSF is pleased that NCAR, using the G-V, is able to assist in this potentially lifesaving activity," said Roger Wakimoto, assistant director of the NSF Directorate for Geosciences. "The data gathered will help refine future hurricane forecasts.”Outfitted for critical observationsThe NSF/NCAR G-V can fly at high altitudes and deploy the same specialized sensors as the NOAA G-IV. These sensors take critical observations of atmospheric conditions for the NOAA National Hurricane Center.Studies show that such observations improve hurricane track forecasts in the U.S. global weather model (called the GFS) by about 15 percent during the 24 to 48 hours before landfall. Research also demonstrates that these data increase the accuracy of hurricane intensity forecasts.To take the observations, the NSF/NCAR G-V has been outfitted with the Airborne Vertical Atmospheric Profiling System (AVAPS). The system releases parachute-borne sensors, known as GPS dropsondes, that measure ambient temperature, pressure, humidity, wind speed, and wind direction at different altitudes as they fall through the atmosphere. Dropsondes were first developed at NCAR in the 1970s with NSF funding and have since been regularly updated. NOAA was an early adopter of the dropsondes for hurricane surveillance missions and research, and the development of the AVAPS system design in the 1990s was motivated in part by the capabilities of the NOAA G-IV.The NSF/NCAR G-V, which is available for flights over both the Atlantic and Pacific, will fly above a hurricane or other major storm at altitudes of up to 45,000 feet, as well as around the storm's edges. Its dropsonde launch system and software is similar to that of the NOAA G-IV.NCAR pilots will guide the aircraft on pre-planned flight tracks, dropping sondes approximately every 15 minutes. Data from the sondes will be processed by a NOAA technician onboard the plane, then sent to the Global Telecommunications System for immediate inclusion in hurricane forecast models."It is a special privilege for us to be able to help out our colleagues at NOAA by deploying the NSF/NCAR G-V in the hurricane surveillance missions this season," said Vanda Grubišić, director of NCAR's Earth Observing Laboratory, which operates the G-V. "Our Research Aviation Facility crews look forward to working with their NOAA colleagues and collecting important data in support of their mission."

Solar energy gets boost from new forecasting system

BOULDER, Colo. — A cutting edge forecasting system developed by a national team of scientists offers the potential to save the solar energy industry hundreds of millions of dollars through improved forecasts of the atmosphere.The new system, known as Sun4CastTM, has been in development for three years by the National Center for Atmospheric Research (NCAR) in collaboration with government labs, universities, utilities, and commercial firms across the country. Funded by the U.S. Department of Energy SunShot Initiative, the system greatly improves predictions of clouds and other atmospheric conditions that influence the amount of energy generated by solar arrays.After testing Sun4Cast at multiple sites, the research team has determined that it can be up to 50 percent more accurate than current solar power forecasts. This improved accuracy will enable utilities to deploy solar energy more reliably and inexpensively, reducing the need to purchase energy on the spot market. The amount of energy gathered by solar panels — such as these in Colorado's San Luis Valley — is influenced by factors including the position and types of clouds, the amount of snow on the ground, and relative humidity. The new Sun4Cast system greatly improves solar irradiance predictions, enabling utilities to deploy solar energy more reliably and inexpensively. (©UCAR. Photo by Sue Ellen Haupt, NCAR. This image is freely available for media & nonprofit use.)As a result, utilities across the United States may be able to save an estimated $455 million through 2040 as they use more solar energy, according to an analysis by NCAR economist Jeffrey Lazo.NCAR, which does not provide operational forecasts, makes the technology available so it can be adapted by utilities or private forecasting companies. The research is being highlighted in more than 20 peer-reviewed papers."These results can help enable the nation's expanding use of solar energy," said Sue Ellen Haupt, director of NCAR’s Weather Systems and Assessment Program, who led the research team. "More accurate predictions are vital for making solar energy more reliable and cost effective."The work builds on NCAR’s expertise in highly detailed atmospheric prediction, including the design of an advanced wind energy forecasting system."This type of research and development is important because it contributes to the reduction in costs for solar and wind energy and makes it easier for utilities to integrate renewables into the electrical grid," said William Mahoney, Deputy Director of NCAR's Research Applications Laboratory. "When it comes to balancing demand for power with supply, it's vital to be able to predict sources of energy as accurately as possible."Xcel Energy is already beginning to use the system to forecast conditions at several of its main solar facilities.“Our previous experience with the National Center for Atmospheric Research in developing a wind forecasting system has saved millions of dollars and has been highly beneficial for our customers," said Drake Bartlett, senior trading analyst for Xcel Energy – Colorado. "It is our sincere hope and belief that we will see positive atmospheric forecasting results for predicting solar generation as well, again to the benefit of our Xcel Energy customers."Energy forecasts out to 72 hoursUsing a combination of advanced computer models, atmospheric observations, and artificial intelligence techniques, Sun4Cast provides 0- to 6-hour nowcasts of solar irradiance and the resulting power production for specific solar facilities at 15-minute intervals. This enables utilities to continuously anticipate the amount of available solar energy.In addition, forecasts extend out to 72 hours, allowing utility officials to make decisions in advance for balancing solar with other sources of energy.Solar irradiance is notoriously difficult to predict. It is affected not just by the locations and types of clouds, but also a myriad of other atmospheric conditions, such as the amount of dust and other particles in the air, relative humidity, and air pollution. Further complicating the forecast, freshly fallen snow, nearby steep mountainsides, or even passing cumulus clouds can reflect sunlight in a way that can increase the amount of energy produced by solar panels.To design a system to forecast solar energy output, NCAR and its partners drew on an array of observing instruments, including satellites, radars, and sky imagers; specialized software; and mathematical and artificial intelligence techniques. Central to Sun4Cast is a new computer model of the atmosphere that simulates solar irradiance based on meteorological conditions. Called WRF-SolarTM, the model is derived from the NCAR-based Weather Research and Forecasting (WRF) model, which is widely used by meteorological agencies worldwide.The team tested the system in geographically diverse areas, including Long Island, New York; the Colorado mountains; and coastal California."We have to provide utilities with confidence that the system maintains a high degree of accuracy year-round in very different types of terrain," said Branko Kosovic, NCAR Program Manager for Renewable Energy.In addition to aiding the solar power industry, the work can also improve weather forecasting in general because of improved cloud prediction.NCAR's numerous partners on the project in the public and private sectors included:Government labs: National Renewable Energy Laboratory, Brookhaven National Laboratory, the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory, and other NOAA facilities; Universities: The Pennsylvania State University, Colorado State University, University of Hawaii, and University of Washington; Utilities: Long Island Power Authority, New York Power Authority, Public Service Company of Colorado, Sacramento Municipal Utility District (SMUD), Southern California Edison, and the Hawaiian Electric Company; Independent system operators: New York ISO, Xcel Energy, SMUD, California ISO, and Hawaiian Electric; and Commercial forecast providers: Schneider Electric, Atmospheric and Environmental Research, Global Weather Corporation, MDA Information Systems, and Solar Consulting Services.Computing time was provided by the New York State Department of Economic Development's Division of Science, Technology and Innovation on an IBM Blue Gene supercomputer at Brookhaven National Laboratory. Researchers also performed computing at the NCAR-Wyoming Supercomputing Center and the DOE National Energy Research Scientific Computing Center.About the SunShot InitiativeThe U.S. Department of Energy SunShot Initiative is a collaborative national effort that aggressively drives innovation to make solar energy fully cost-competitive with traditional energy sources before the end of the decade. Through SunShot, the Energy Department supports efforts by private companies, universities, and national laboratories to drive down the cost of solar electricity to $0.06 per kilowatt-hour.

US taps NCAR technology for new water resources forecasts

BOULDER, Colo. — As the National Oceanic and Atmospheric Administration (NOAA) this month launches a comprehensive system for forecasting water resources in the United States, it is turning to technology developed by the National Center for Atmospheric Research (NCAR) and its university and agency collaborators.WRF-Hydro, a powerful NCAR-based computer model, is the first nationwide operational system to provide continuous predictions of water levels and potential flooding in rivers and streams from coast to coast. NOAA's new Office of Water Prediction selected it last year as the core of the agency's new National Water Model."WRF-Hydro gives us a continuous picture of all of the waterways in the contiguous United States," said NCAR scientist David Gochis, who helped lead its development. "By generating detailed forecast guidance that is hours to weeks ahead, it will help officials make more informed decisions about reservoir levels and river navigation, as well as alerting them to dangerous events like flash floods."WRF-Hydro (WRF stands for Weather Research and Forecasting) is part of a major Office of Water Prediction initiative to bolster U.S. capabilities in predicting and managing water resources. By teaming with NCAR and the research community, NOAA's National Water Center is developing a new national water intelligence capability, enabling better impacts-based forecasts for management and decision making.The new WRF-Hydro computer model simulates streams and other aspects of the hydrologic system in far more detail than previously possible. (Image by NOAA Office of Water Prediction.) Unlike past streamflow models, which provided forecasts every few hours and only for specific points along major river systems, WRF-Hydro provides continuous forecasts of millions of points along rivers, streams, and their tributaries across the contiguous United States. To accomplish this, it simulates the entire hydrologic system — including snowpack, soil moisture, local ponded water, and evapotranspiration — and rapidly generates output on some of the nation's most powerful supercomputers.WRF-Hydro was developed in collaboration with NOAA and university and agency scientists through the Consortium of Universities for the Advancement of Hydrologic Science, the U.S. Geological Survey, Israel Hydrologic Service, and Baron Advanced Meteorological Services. Funding came from NOAA, NASA, and the National Science Foundation, which is NCAR's sponsor."WRF-Hydro is a perfect example of the transition from research to operations," said Antonio (Tony) J. Busalacchi, president of the University Corporation for Atmospheric Research, which manages NCAR on behalf of the National Science Foundation (NSF). "It builds on the NSF investment in basic research in partnership with other agencies, helps to accelerate collaboration with the larger research community, and culminates in support of a mission agency such as NOAA. The use of WRF-Hydro in an operational setting will also allow for feedback from operations to research. In the end this is a win-win situation for all parties involved, chief among them the U.S. taxpayers.""Through our partnership with NCAR and the academic and federal water community, we are bringing the state of the science in water forecasting and prediction to bear operationally," said Thomas Graziano, director of NOAA’s new Office of Water Prediction at the National Weather Service.Filling in the water pictureThe continental United States has a vast network of rivers and streams, from major navigable waterways such as the Mississippi and Columbia to the remote mountain brooks flowing from the high Adirondacks into the Hudson River. The levels and flow rates of these watercourses have far-reaching implications for water availability, water quality, and public safety.Until now, however, it has not been possible to predict conditions at all points in the nation's waterways. Instead, computer models have produced a limited picture by incorporating observations from about 4,000 gauges, generally on the country's bigger rivers. Smaller streams and channels are largely left out of these forecast models, and stretches of major rivers for tens of miles are often not predicted — meaning that schools, bridges, and even entire towns can be vulnerable to unexpected changes in river levels.To fill in the picture, NCAR scientists have worked for the past several years with their colleagues within NOAA, other federal agencies, and universities to combine a range of atmospheric, hydrologic, and soil data into a single forecasting system.The resulting National Water Model, based on WRF-Hydro, simulates current and future conditions on rivers and streams along points two miles apart across the contiguous United States. Along with an hourly analysis of current hydrologic conditions, the National Water Model generates three predictions: an hourly 0- to 15-hour short-range forecast, a daily 0- to 10-day medium-range forecast, and a daily 0- to 30-day long-range water resource forecast.The National Water Model predictions using WRF-Hydro offer a wide array of benefits for society. They will help local, state, and federal officials better manage reservoirs, improve navigation along major rivers, plan for droughts, anticipate water quality problems caused by lower flows, and monitor ecosystems for issues such as whether conditions are favorable for fish spawning. By providing a national view, this will also help the Federal Emergency Management Agency deploy resources more effectively in cases of simultaneous emergencies, such as a hurricane in the Gulf Coast and flooding in California."We've never had such a comprehensive system before," Gochis said. "In some ways, the value of this is a blank page yet to be written."A broad spectrum of observationsWRF-Hydro is a powerful forecasting system that incorporates advanced meteorological and streamflow observations, including data from nearly 8,000 U.S. Geological Survey streamflow gauges across the country. Using advanced mathematical techniques, the model then simulates current and future conditions for millions of points on every significant river, steam, tributary, and catchment in the United States.In time, scientists will add additional observations to the model, including snowpack conditions, lake and reservoir levels, subsurface flows, soil moisture, and land-atmosphere interactions such as evapotranspiration, the process by which water in soil, plants, and other land surfaces evaporates into the atmosphere.Scientists over the last year have demonstrated the accuracy of WRF-Hydro by comparing its simulations to observations of streamflow, snowpack, and other variables. They will continue to assess and expand the system as the National Water Model begins operational forecasts.NCAR scientists maintain and update the open-source code of WRF-Hydro, which is available to the academic community and others. WRF-Hydro is widely used by researchers, both to better understand water resources and floods in the United States and other countries such as Norway, Germany, Romania, Turkey, and Israel, and to project the possible impacts of climate change."At any point in time, forecasts from the new National Water Model have the potential to impact 300 million people," Gochis said. "What NOAA and its collaborator community are doing is trying to usher in a new era of bringing in better physics and better data into forecast models for improving situational awareness and hydrologic decision making."CollaboratorsBaron Advanced Meteorological Services Consortium of Universities for the Advancement of Hydrologic ScienceIsrael Hydrologic ServiceNational Center for Atmospheric ResearchNational Oceanic and Atmospheric AdministrationU.S. Geological SurveyFundersNational Science FoundationNational Aeronautics and Space AdministrationNational Oceanic and Atmospheric Administration

Climate change already accelerating sea level rise, study finds

BOULDER, Colo. — Greenhouse gases are already having an accelerating effect on sea level rise, but the impact has so far been masked by the cataclysmic 1991 eruption of Mount Pinatubo in the Philippines, according to a new study led by the National Center for Atmospheric Research (NCAR).Satellite observations, which began in 1993, indicate that the rate of sea level rise has held fairly steady at about 3 millimeters per year. But the expected acceleration due to climate change is likely hidden in the satellite record because of a happenstance of timing: The record began soon after the Pinatubo eruption, which temporarily cooled the planet, causing sea levels to drop.The new study finds that the lower starting point effectively distorts the calculation of sea level rise acceleration for the last couple of decades.The study lends support to climate model projections, which show the rate of sea level rise escalating over time as the climate warms. The findings were published today in the open-access Nature journal Scientific Reports.Mount Pinatubo's caldera on June 22, 1991. (Image courtesy USGS.)"When we used climate model runs designed to remove the effect of the Pinatubo eruption, we saw the rate of sea level rise accelerating in our simulations," said NCAR scientist John Fasullo, who led the study. "Now that the impacts of Pinatubo have faded, this acceleration should become evident in the satellite measurements in the coming decade, barring another major volcanic eruption."Study co-author Steve Nerem, from the University of Colorado Boulder, added: “This study shows that large volcanic eruptions can significantly impact the satellite record of global average sea level change. So we must be careful to consider these effects when we look for the effects of climate change in the satellite-based sea level record."The findings have implications for the extent of sea level rise this century and may be useful to coastal communities planning for the future. In recent years, decision makers have debated whether these communities should make plans based on the steady rate of sea level rise measured in recent decades or based on the accelerated rate expected in the future by climate scientists.The study was funded by NASA, the U.S. Department of Energy, and the National Science Foundation, which is NCAR's sponsor.Reconstructing a pre-Pinatubo worldClimate change triggers sea level rise in a couple of ways: by warming the ocean, which causes the water to expand, and by melting glaciers and ice sheets, which drain into the ocean and increase its volume. In recent decades, the pace of warming and melting has accelerated, and scientists have expected to see a corresponding increase in the rate of sea level rise. But analysis of the relatively short satellite record has not borne that out.To investigate, Fasullo, Nerem, and Benjamin Hamlington of Old Dominion University worked to pin down how quickly sea levels were rising in the decades before the satellite record began.Prior to the launch of the international TOPEX/Poseidon satellite mission in late 1992, sea level was mainly measured using tide gauges. While records from some gauges stretch back to the 18th century, variations in measurement technique and location mean that the pre-satellite record is best used to get a ballpark estimate of global mean sea level.Mount Pinatubo erupting in 1991. (Image courtesy USGS.)To complement the historic record, the research team used a dataset produced by running the NCAR-based Community Earth System Model 40 times with slightly different—but historically plausible—starting conditions. The resulting simulations characterize the range of natural variability in the factors that affect sea levels. The model was run on the Yellowstone system at the NCAR-Wyoming Supercomputing Center.A separate set of model runs that omitted volcanic aerosols — particles spewed into the atmosphere by an eruption — was also assessed. By comparing the two sets of runs, the scientists were able to pick out a signal (in this case, the impact of Mount Pinatubo's eruption) from the noise (natural variations in ocean temperature and other factors that affect sea level)."You can't do it with one or two model runs—or even three or four," Fasullo said. "There's just too much accompanying climate noise to understand precisely what the effect of Pinatubo was. We could not have done it without large numbers of runs."Using models to understand observationsAnalyzing the simulations, the research team found that Pinatubo's eruption caused the oceans to cool and sea levels to drop by about 6 millimeters immediately before TOPEX/Poseidon began recording observations.As the sunlight-blocking aerosols from Mount Pinatubo dissipated in the simulations, sea levels began to slowly rebound to pre-eruption levels. This rebound swamped the acceleration caused by the warming climate and made the rate of sea level rise higher in the mid- to late 1990s than it would otherwise have been.This higher-than-normal rate of sea level rise in the early part of the satellite record makes it appear that the rate of sea level rise has not accelerated over time and may actually have decreased somewhat. In fact, according to the study, if the Pinatubo eruption had not occurred—leaving sea level at a higher starting point in the early 1990s—the satellite record would have shown a clear acceleration."The satellite record is unable to account for everything that happened before the first satellite was launched, " Fasullo said. "This study is a great example of how computer models can give us the historical context that's needed to understand some of what we're seeing in the satellite record."Understanding whether the rate of sea level rise is accelerating or remaining constant is important because it drastically changes what sea levels might look like in 20, 50, or 100 years.“These scientists have disentangled the major role played by the 1991 volcanic eruption of Mt. Pinatubo on trends in global mean sea level,” said Anjuli Bamzai, program director in the National Science Foundation’s Division of Atmospheric and Geospace Sciences, which funded the research.  “This research is vital as society prepares for the potential effects of climate change."Because the study's findings suggest that acceleration due to climate change is already under way, the acceleration should become evident in the satellite record in the coming decade, Fasullo said.Since the original TOPEX/Poseidon mission, other satellites have been launched—Jason-1 in 2001 and Jason-2 in 2008—to continue tracking sea levels. The most recent satellite, Jason-3, launched on Jan. 17 of this year."Sea level rise is potentially one of the most damaging impacts of climate change, so it's critical that we understand how quickly it will rise in the future," Fasullo said. "Measurements from Jason-3 will help us evaluate what we've learned in this study and help us better plan for the future."The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.The graph shows how sea level rises and falls as ocean heat content fluctuates. After volcanic eruptions, the Earth cools and, in turn, the heat content in the ocean drops, ultimately lowering sea level.The solid blue line is the average sea level rise of climate model simulations that include volcanic eruptions. The green line is the average from model simulations with the effect of volcanic eruptions removed, and it shows a smooth acceleration in the rate of sea level rise due to climate change.The blue line between the start of the satellite record and present day makes a relatively straight line — just as we see from actual satellite observations during that time —  indicating that the rate of sea level rise has not accelerated. But in the future, barring another major volcanic eruption, scientists expect sea level to follow the gray dotted line, which is on the same accelerating path as the green line below it. Click to enlarge. (©UCAR. This graph is freely available for media & nonprofit use.) About the articleTitle: Is the detection of sea level rise imminent?Authors: J.T. Fasullo, R. S. Nerem, and B. HamlingtonJournal: Scientific Reports, DOI: 10.1038/srep31245 Funders:  NASANational Science FoundationU.S. Department of Energy Collaborators: Univesity of Colorado Boulder (UCAR member)Old Dominion University (UCAR member)Writer:Laura Snider, Senior Science Writer and Public Information Officer

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