Building roads to match tomorrow's weather

April 20, 2017 | When engineers design roads, bridges, and other types of transportation infrastructure, they need to account for local weather patterns. Extreme heat or freeze-thaw cycles can lead to ruts and cracks in roads, and heavy rains can overwhelm inadequate drainage systems, washing out bridges and flooding key transportation corridors.But how should engineers design new transportation projects, which may last for a half-century, if climate change will greatly alter weather patterns? The extent to which temperatures and precipitation may change in the future has become a major concern for the transportation industry.To address this issue, climate scientists at the National Center for Atmospheric Research (NCAR) are launching an innovative collaboration with civil and environmental engineers at Carnegie Mellon University and the RAND Corporation. They're using global and regional computer models, along with statistical techniques, to generate projections of future climate in ways that will be most helpful to infrastructure designers and planners, especially when it comes to drainage.A girl looks at a washed-out road in Louisville, Colorado, after damaging floods in 2013. Engineers are teaming up with climate scientists to design transportation infrastructure that can withstand shifting weather patterns. (Photo by David Hosansky.)The three-year project, funded by the National Science Foundation, will focus on Pittsburgh and several other cities across the country that will likely be affected in different ways by future climate."Our overriding goal is to enable transportation agencies to maximize the lifetime performance of new infrastructure while minimizing the costs to ensure its resilience to extreme weather events," said NCAR scientist Linda Mearns, the principal investigator on the project.Several recent studies led by NCAR scientists have underscored the extent to which climate change may affect future temperature and precipitation extremes in the United States. One concluded that, if emissions of greenhouse gases continue along a business-as-usual course, record daily high temperatures will outpace record daily lows by about 15 to 1 later in the century. A second study, also looking at emissions continuing on a business-as-usual path, concluded that incidents of extreme rainfall may increase by as much as five times in parts of the country.More detail means more uncertaintyTo conduct the new project, Mearns and her colleagues are working closely with local transportation officials and other stakeholders. Rather than analyzing the overall ways that climate is likely to change in the target cities, they're focusing on information that will be most useful to the design and construction of drainage infrastructure and other transportation systems."This requires very active engagement with stakeholders," Mearns said. "It's working together to determine what they want versus what we can actually provide and coming up with measures of uncertainty that are meaningful for them. This is in the realm of true coproduction of knowledge."For example, an engineer designing a drainage system along a highway might want an estimate of how much precipitation will fall in 15-minute increments. Although climate models do not provide such detailed information, Mearns and her colleagues can provide a partial answer by using a combination of techniques to produce projections of future precipitation every hour to several hours, as well as characterizing the uncertainty around those projections.A major challenge is that more detailed projections have greater uncertainty. While climate models consistently show that emissions of greenhouse gases lead to higher average global temperatures, the outlook is less clear for temperature and precipitation patterns by region. The type of information most needed by infrastructure planners and designers—projections of extreme temperatures and precipitation for specific locations and time periods—is even more uncertain. As a result, the study team will have to make compromises between the need for high-resolution data and the need for reliable data.Mearns said it's critical to give engineers a clear understanding of the uncertainty of a particular projection in order to prevent transportation projects from being based on a false sense of precision in climate projections. "The challenge," she said, "is developing sound engineering strategies for extremes under uncertainty."In addition to Mearns, the NCAR scientists working on the project include Seth McGinnis, Melissa Bukovsky, Rachel McCrary, and Doug Nychka. The Carnegie Mellon team is being led by Costa Samaras, who directs the school's Center for Engineering and Resilience for Climate Adaptation.“This project is a unique interdisciplinary collaboration that will advance the ways engineers and climate scientists will work together in the future,” said Samaras. “Infrastructure can last for many decades, and engineers need to design infrastructure to be resilient at the end of the infrastructure life span as well as in the beginning. Working with NCAR is critical to advancing the research needed to transform the way we design infrastructure in the United States."The benefit of different techniquesTo generate climate projections, Mearns and her colleagues will use two types of techniques to translate the coarse resolution of a global computer model, which typically simulates climate processes that are larger than about 100 miles, into the localized weather events that are of interest to transportation experts.One of these techniques, known as dynamical downscaling, will use a combination of three coarser-resolution global climate models and two higher-resolution regional models (including the NCAR-based Weather Research and Forecasting model, or WRF). This will enable the researchers to simulate the entire globe in coarse resolution while zooming in on selected regions with much higher resolution. This approach doesn't need as much supercomputing power as trying to simulate the entire globe in high resolution, although it still can be computationally intensive.The other technique, known as statistical downscaling, involves developing statistical relationships between large-scale atmospheric patterns and local temperatures and precipitation. This technique, which requires even less computing, can help scientists link conditions in a global model (such as a large area of low pressure) to a localized weather event (such as intermittent downpours).The combined approaches will enable the scientists to generate projections for at least every six hours, and possibly—with the use of additional specialized techniques—as frequently as every hour. Using both the dynamical and statistical approaches also will enable the team to better understand the uncertainties around future climate as well as evaluate the relative strengths of the techniques."Transportation systems are critical to the U.S. economy, and they represent some of the largest investments of our tax dollars," Mearns said. "We want to make sure that they'll hold up to a future climate."FunderNational Science FoundationPartnersCarnegie Mellon UniversityRAND CoroporationWriter/contactDavid Hosansky, Manager of Media Relations

Our People - Rory Kelly

April 19, 2017 | On weekdays in winter, while most people are still sleeping, Rory Kelly is driving to a ski area in the dark, slipping into his ski mountaineering gear, and training for two hours before heading back to Boulder for his job as a software engineer in NCAR's Computational and Information Systems Laboratory (CISL).

Drones need aviation forecasts, too

UAS Weather ForumWhat: An opportunity for stakeholders from the UAS community -- including manufacturers, operators, regulators, and researchers -- to come together to discuss weather effects on drones and the support needed to mitigate those impacts.When: 9 a.m. - 12 p.m., Monday, May 8, 2017Where: XPONENTIAL, Kay Bailey Hutchison Convention Center, Dallas Click here for more information.April 13, 2017 | The possible future uses for drones are spectacularly diverse. Unmanned aircraft systems (UAS) could make door-to-door deliveries, search for a lost hiker, survey agricultural crops, inspect infrastructure, or collect scientific data from difficult-to-reach places, among other things. Already Amazon is experimenting with drone delivery of packages, for example, and BNSF Railway is testing the use of drones to inspect hundreds of miles of railroad tracks.Yet the ultimate success of efforts like these may hinge on a good weather forecast. The National Center for Atmospheric Research (NCAR), long a trusted provider of critical weather information to the aviation industry, is beginning to lend its expertise to the UAS community as well.Staff in NCAR's Research Applications Laboratory are already working with NASA to provide low-level turbulence forecasts for NASA's project to create a UAS Traffic Management (UTM) system, which would be similar to the air traffic control system for crewed airplanes. And in May, the NCAR team is hosting a UAS Weather Forum in Dallas. The forum will be co-located with XPONENTIAL, a conference on "all things unmanned" that is organized by the Association of Unmanned Vehicle Systems International."As the aircraft get smaller and smaller, the challenges of providing the needed weather information increase," said NCAR scientist Matthias Steiner, deputy director of RAL's Aviation Applications Program. "These small UAS's are more sensitive to winds, temperature, turbulence, precipitation — essentially the full range of weather — than larger planes flying at higher altitudes."NASA engineers prepare to launch a remotely piloted aircraft during practice runs for an Unmanned Aircraft Systems Traffic Management test. (Image courtesy NASA.)Weather impacts on dronesDrones, at least the small ones allowed under current Federal Aviation Administration rules, fly in the lowest few hundred feet of the atmosphere, where weather can be highly dynamic and less predictable.This layer of the atmosphere is heavily affected by land surface and topography. Consider, for example, wind as it blows through a city. The buildings force the wind to speed through "urban canyons" and swirl into tight eddies behind structures. Uneven heating — the sunny side of the street warming more than the shady side, for example — can create circulating downdrafts and updrafts.Piloting a drone through a built-up area could be tricky without a detailed understanding of the local atmospheric circulation patterns. And even with that information, it's important to understand how different drones will be affected. The tinier and lighter the drone, the more vulnerable it is to the vagaries of the weather, just as a small Cessna is more vulnerable to turbulence than a giant 747. And the type of drone, such as a fixed wing or a quadcopter, matters as well because each has a different ability to respond.The concern is not just crashing on the ground; severe weather conditions could also lead to a collision in the sky. NASA's UTM project is exploring the possibility of managing a high volume of drones by essentially assigning individual UAS's to a lane of airspace. But weather will affect the ability of a drone to stay in its lane. An abrupt updraft, for instance, could force a drone that is supposed to fly at a lower altitude into the higher-altitude lane assigned to another UAS (or a crewed aircraft in mixed airspace), increasing the possibility of a collision between the two.Weather can have less obvious impacts on drone operation as well. Extremely cold weather, headwinds, or turbulence that requires a lot of flight control adjustments could drain the aircraft's battery more quickly, reducing its range and, potentially, its ability to return home. Facilitating a community dialogueThese kinds of weather challenges would likely not surprise a seasoned aviator. But many of the organizations interested in using drones today come to the UAS community from the technology side, not the aviation side, and may lack a full understanding of the impacts that atmospheric conditions can have on flight.This is where NCAR has expertise to offer. For decades, NCAR has been providing the aviation industry with the tools they need to increase flight safety, including wind shear alerts, turbulence forecasts, and information on inflight icing potential.In an effort to stay on top of the latest weather challenges facing the aviation industry, NCAR launched the Friends and Partners in Aviation Weather Forum in 1997. The meeting, now held twice yearly, is an opportunity for stakeholders from the operational, regulatory, and research sectors to come together."We created these meetings as a means of fostering dialogue," Steiner said. "We want to know: 'What are your operational sensitivities? How can we help you?' Now we are emulating these forums with the UAS community. "The UAS Weather Forum at the XSPONENTIAL conference on May 8 is the first effort at starting a similar meeting—and fostering the dialogue needed to advance drone safety, even in the face of challenging weather conditions."We want drone operators to know NCAR is a partner that can help them address their weather impacts," Steiner said.Writer/contact: Laura Snider, Senior Science Writer and Public Information Officer

UCAR congressional briefing on wildland fires

WASHINGTON, D.C. — Scientists and fire experts are making landmark progress in developing new tools to improve the management and prediction of wildland fires, a panel of experts said at a congressional briefing today. The developments offer the potential of better protecting vulnerable residents and property from these extreme events, as well as reducing their costs. The briefing, sponsored by the University Corporation for Atmospheric Research (UCAR), highlighted the development of new observing tools and advanced computer models to better understand wildland fires. "We're at a turning point where new technologies and advances in basic research are enabling us to tackle a major real-world problem," said UCAR President Antonio J. Busalacchi. "Federal and state agencies, firefighters, and scientists are all working together to develop a new generation of tools that will keep firefighters safer, reduce the costs of these massive conflagrations, and better safeguard lives and property."Bureau of Land Management firefighter near Burns, Oregon, in September 2011. (Photo by Dave Toney, BLM Oregon.)UCAR is a consortium of 110 universities that manages the National Center for Atmospheric Research (NCAR) on behalf of the National Science Foundation. NCAR's wildland fire research includes working with Colorado on an advanced prediction system.Toll of wildland fires The costs of forest, grass, and other types of wildland fires are increasing dramatically. In 2016 alone, more than 67,000 wildfires consumed 5.5 million acres across the nation. The U.S. Forest Service spends more than $2.5 billion annually on fire management, an increase of more than 60 percent over the last decade. The total losses can run many times higher: Last year's Chimney Tops 2 fire in Gatlinburg, Tennessee, left 14 people dead and destroyed more than 2,400 structures at a cost of $500 million. "The money spent by the federal government on suppressing the fires is only a fraction of the overall costs, such as the destruction of houses and other property," said Michael Gollner, assistant professor at the University of Maryland's Department of Fire Protection Engineering. "There are more large-scale fires than there used to be, and those are the most dangerous blazes that are particularly expensive and destructive." Donald Falk, assistant professor of the University of Arizona's School of Natural Resources and the Environment, warned that decades of fire suppression coupled with drier and warmer temperatures in some regions will lead to longer fire seasons and more major fires. "The problem is not going away," he said. "It's going to get bigger, and we're going to have to live with it without breaking the bank." Wildland fires are extremely difficult to predict because they are influenced by local topography and vegetation, as well as by atmospheric conditions that, in turn, are affected by a blaze's heat and smoke. To better anticipate fire risk as well as predict a fire once it has started, scientists are harnessing new technologies. These include specialized satellite instruments and unmanned aerial vehicles to observe the blazes, as well as specialized computer models that incorporate weather-fire interactions, the density and condition of vegetation, landscape features such as elevation and topography, and the physics of fires. The researchers are working with federal and state agencies, emergency managers, and firefighters to adapt the new capabilities for real-time decision support. "Practitioners and scientists are bringing their expertise and knowledge to the table in order to create new evolutions of technology that will result in safer and more effective firefighting, enhance how we predict events and their potential impacts, and better plan for ways to prevent those wildfires we consider harmful," said Todd Richardson, state fire management officer of the Bureau of Land Management's Colorado office. "Having better guidance prior to planning your fire operations can provide critical information to the tactical operations and fire management," said William Mahoney, interim director of NCAR's Research Applications Laboratory. "Taking advantage of these important data sources and integrating these research areas provides tremendous opportunities to advance wildland fire management." The event is the latest in a series of UCAR congressional briefings that draw on expertise from the university consortium and public-private partnerships to provide insights into critical topics in the Earth system sciences. Past briefings have focused on predicting space weather, aviation weather safety, the state of the Arctic, hurricane prediction, potential impacts of El Niño, and new advances in water forecasting.

A tribute to Steve Worley

April 14, 2017 | At the 30-year mark of his career at NCAR, Steve Worley is announcing his plans to begin a phased retirement. From now into 2018, Steve will be transferring his responsibilities in CISL’s Data Support Section (DSS) to DSS staff and assisting with Doug Schuster’s transition to DSS Manager. Steve will reduce his working hours to 60 percent in July 2017, and in September 2017 he will conclude his third year as Chair of NCAR’s Data Stewardship Engineering Team (DSET).

Scientists link recent California droughts and floods to distinctive atmospheric waves

BOULDER, Colo. — The crippling wintertime droughts that struck California from 2013 to 2015, as well as this year's unusually wet California winter, appear to be associated with the same phenomenon: a distinctive wave pattern that emerges in the upper atmosphere and circles the globe.Scientists at the National Center for Atmospheric Research (NCAR) found in a recent study that the persistent high-pressure ridge off the west coast of North America that blocked storms from coming onshore during the winters of 2013-14 and 2014-15 was associated with the wave pattern, which they call wavenumber-5. Follow-up work showed that wavenumber-5 emerged again this winter but with its high- and low-pressure features in a different position, allowing drenching storms from the Pacific to make landfall. "This wave pattern is a global dynamic system that sometimes makes droughts or floods in California more likely to occur," said NCAR scientist Haiyan Teng, lead author of the California paper. "As we learn more, this may eventually open a new window to long-term predictability." The high- and low-pressure regions of wavenumber-5 set up in different locations during January 2014, when California was enduring a drought, and January 2017, when it was facing floods. The location of the high and low pressure regions (characterized by anticylonic vs. cyclonic upper-level air flow) can act to either suppress or enhance precipitation and storms. The black curves illustrate the jet streams that trap and focus wavenumber-5. (Image by Haiyan Teng and Grant Branstator, ©UCAR. This image is freely available for media & nonprofit use.)  The finding is part of an emerging body of research into the wave pattern that holds the promise of better understanding seasonal weather patterns in California and elsewhere. Another new paper, led by NCAR scientist Grant Branstator, examines the powerful wave pattern in more depth, analyzing the physical processes that help lead to its formation as well as its seasonal variations and how it varies in strength and location.The California study was published in the Journal of Climate while the comprehensive study into the wave patterns is appearing in the Journal of the Atmospheric Sciences. Both papers were funded by the National Science Foundation, which is NCAR's sponsor, as well as by the Department of Energy, the National Oceanic and Atmospheric Administration, and NASA.The new papers follow a 2013 study by Teng and Branstator showing that a pattern related to wavenumber-5 tended to emerge about 15-20 days before major summertime heat waves in the United States.Strong impacts on local weather systemsWavenumber-5 consists of five pairs of alternating high- and low-pressure features that encircle the globe about six miles (10 kilometers) above the ground. It is a type of atmospheric phenomenon known as a Rossby wave, a very large-scale planetary wave that can have strong impacts on local weather systems by moving heat and moisture between the tropics and higher latitudes as well as between oceanic and inland areas and by influencing where storms occur.The slow-moving Rossby waves at times become almost stationary. When they do, the result can be persistent weather patterns that often lead to droughts, floods, and heat waves. Wavenumber-5 often has this stationary quality when it emerges during the northern winter, and, as a result, is associated with a greater likelihood of persistent extreme events.To determine the degree to which the wave pattern influenced the California drought, Teng and Branstator used three specialized computer models, as well as California rainfall records and 20th century data about global atmospheric circulation patterns. The different windows into the atmosphere and precipitation patterns revealed that the formation of a ridge by the California coast is associated with the emergence of the distinctive wavenumber-5 pattern, which guides rain-producing low-pressure systems so that they travel well north of California.Over the past winter, as California was lashed by a series of intense storms, wavenumber-5 was also present, the scientists said. But the pattern had shifted over North America, replacing the high-pressure ridge off the coast with a low-pressure trough. The result was that the storms that were forced north during the drought winters were, instead, allowed to make landfall.Clues to seasonal weather patternsForecasters who predict seasonal weather patterns have largely looked to shifting sea surface temperatures in the tropical Pacific, especially changes associated with El Niño and La Niña. But during the dry winters of 2013-14 and 2014-15, those conditions varied markedly: one featured the beginning of an El Niño while the sea surface temperatures during the other were not characteristic of either El Niño or La Niña.The new research indicates that the wave pattern may provide an additional source of predictability that sometimes may be more important than the impacts of sea surface temperature changes. First, however, scientists need to better understand why and when the wave pattern emerges.In the paper published in Journal of the Atmospheric Sciences, Branstator and Teng explored the physics of the wave pattern. Using a simplified computer model of the climate system to identify the essential physical processes, the pair found that wavenumber-5 forms when strong jet streams act as wave guides, tightening the otherwise meandering Rossby wave into the signature configuration of five highs and five lows."The jets act to focus the energy," Branstator said. "When the jets are present, the energy is trapped and cannot escape." But even when the jets are present, the wavenumber-5 pattern does not always form, indicating that other forces requiring study are also at play.The scientists also searched specifically for what might have caused the wave pattern linked to the severe California drought to form. In the paper published in the Journal of Climate, the pair found that extremely heavy rainfall from December to February in certain regions of the tropical Pacific could double the probability that the extreme ridge associated with wavenumber-5 will form. The reason may have to do with the tropical rain heating parts of the upper atmosphere in such a way that favors the formation of the wavenumber-5 pattern.But the scientists cautioned that many questions remain."We need to search globally for factors that cause this wavenumber-5 behavior," Teng said, "Our studies are just the beginning of that search."About the articlesTitle: Causes of Extreme Ridges That Induce California DroughtAuthors: Haiyan Teng and Grant BranstatorJournal: Journal of Climate, DOI: 10.1175/JCLI-D-16-0524.1
Title: Tropospheric Waveguide Teleconnections and Their SeasonalityAuthors: Grant Branstator and Haiyan TengJournal: Journal of the Atmospheric Sciences, DOI: 10.1175/JAS-D-16-0305.1Writer:David Hosansky, Manager of Media Relations

Oceanography Brown Bag - Andy Hogg

Lee Waves, Spontaneous Generation and Ocean Mixing
Andy Hogg
Australian National University


Mixing in the ocean interior is thought to be controlled by breaking of internal waves generated at the surface and at the seafloor. The usual paradigm is that energy is transported into the ocean interior by waves, where they can contribute to the background mixing that controls ocean stratification. In this talk I will examine potential contributions to ocean mixing from:

Planetary waves, first found on Earth, are discovered on Sun

BOULDER, Colo. — The same kind of large-scale planetary waves that meander through the atmosphere high above Earth's surface may also exist on the Sun, according to a new study led by a scientist at the National Center for Atmospheric Research (NCAR).Just as the large-scale waves that form on Earth, known as Rossby waves, influence local weather patterns, the waves discovered on the Sun may be intimately tied to solar activity, including the formation of sunspots, active regions, and the eruption of solar flares."The discovery of magnetized Rossby waves on the Sun offers the tantalizing possibility that we can predict space weather much further in advance," said NCAR scientist Scott McIntosh, lead author of the paper.The study will be published next week in the journal Nature Astronomy. Co-authors are William Cramer of Yale University, Manuel Pichardo Marcano of Texas Tech University, and Robert Leamon of the University of Maryland, College Park.The research was funded by the National Science Foundation (NSF), which is NCAR's sponsor, and by NASA.An unprecedented view of the SunOn Earth, Rossby waves are associated with the path of the jet stream and the formation of low- and high-pressure systems, which in turn influence local weather events.The waves form in rotating fluids — in the atmosphere and in the oceans. Because the Sun is also rotating, and because it's made largely of plasma that acts, in some ways, like a vast magnetized ocean, the existence of Rossby-like waves should not come as a surprise, said McIntosh, who directs NCAR's High Altitude Observatory.And yet scientists have lacked the tools to distinguish this wave pattern until recently. Unlike Earth, which is scrutinized at numerous angles by satellites in space, scientists historically have been able to study the Sun from only one viewpoint: as seen from the direction of Earth.But for a brief period, from 2011 to 2014, scientists had the unprecedented opportunity to see the Sun's entire atmosphere at once. During that time, observations from NASA's Solar Dynamics Observatory (SDO), which sits between the Sun and the Earth, were supplemented by measurements from NASA's Solar TErrestrial RElations Observatory (STEREO) mission, which included two spacecraft orbiting the Sun. Collectively, the three observatories provided a 360-degree view of the Sun until contact was lost with one of the STEREO spacecraft in 2014. McIntosh and his co-authors mined the data collected during the window of full solar coverage to see if the large-scale wave patterns might emerge."By combining the data from all three satellites we can see the entire sun and that's important for studies like this because you want the measurements to all be at the same time," said Dean Pesnell, SDO project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. "They’re pushing the boundary of how we use solar data to understand the interior of the sun and where the magnetic field of the sun comes from."Coronal bright points identified in images of the Sun taken simultaenously from three distinct vantage points in space. From left, images were captured by STEREO-Behind, SDO, and STEREO-Ahead. (Image courtesy Scott McIntosh, NCAR.)Finding waves in the dataThe team used images taken by instruments on SDO and STEREO to identify and track coronal bright points. These small bright features dot the entire face of the Sun and have been used to track motions deeper in the solar atmosphere.The scientists plotted the combined data on Hovmöller diagrams, a diagnostic tool developed by meteorologists to highlight the role of waves in Earth's atmosphere. What emerged from the analysis were bands of magnetized activity that propagate slowly across the Sun — just like the Rossby waves found on Earth.The discovery could link a range of solar phenomena that are also related to the Sun's magnetic field, including the formation of sunspots, their lifetimes, and the origin of the Sun’s 11-year solar cycle. "It's possible that it's all tied together, but we needed to have a global perspective to see that," McIntosh said. "We believe that people have been observing the impacts of these Rossby-like waves for decades, but haven't been able to put the whole picture together."With a new understanding of what the big picture might really look like, scientists could take a step closer to predicting the Sun's behavior."The discovery of Rossby-like waves on the Sun could be important for the prediction of solar storms, the main drivers of space weather effects on Earth," said Ilia Roussev, program director in NSF's Division of Atmospheric and Geospace Sciences.  "Bad weather in space can hinder or damage satellite operations, and communication and navigation systems, as well as cause power-grid outages leading to tremendous socioeconomic losses. Estimates put the cost of space weather hazards at $10 billion per year.”But to advance our predictive capabilities, scientists must first gain a better understanding of the waves and the patterns that persist on them, which would require once again having a 360-degree view of the Sun."To connect the local scale with the global scale, we need to expand our view," McIntosh said. "We need a constellation of spacecraft that circle the Sun and monitor the evolution of its global magnetic field."About the articleTitle: The detection of Rossby-like waves on the SunAuthors: Scott W. McIntosh, William J. Cramer, Manuel Pichardo Marcano, and Robert J. Leamon  Journal: Nature Astronomy, DOI: 10.1038/s41550-017-0086Writer:Laura Snider, Senior Science Writer and Public Information Officer

Space weather warnings could arrive earlier with NCAR coronagraph

March 22, 2017 | A research instrument atop the Mauna Loa volcano in Hawaii could be used to provide earlier warnings to astronauts when dangerous high-energy particles are blasted out of the Sun's corona. The K-Coronagraph (K-Cor), owned and operated by the National Center for Atmospheric Research (NCAR), could flag these space weather events nearly 20 minutes faster than coronagraphs based in space, according to a new, NASA-led study. Coronagraphs use a disk to block the blinding light of the Sun's face in order to create an artificial solar eclipse, enabling scientists to study the very dim solar atmosphere known as the corona.The K-Cor instrument installed at the Mauna Loa Solar Observatory.  (©UCAR. Courtesy of the High Altitude Observatory. This image is freely available for media & nonprofit use.)"While there are lots of advantages to having a coronagraph in space — above the clouds and the distortion of Earth's atmosphere — there are also important advantages to having a coronagraph on the ground," said Joan Burkepile, a co-author of the study and a scientist at NCAR's High Altitude Observatory.Ground-based instrumentation costs a fraction of space-based hardware, and images can be acquired more frequently (seconds compared to minutes) and then distributed in near real time. K-Cor is also the only coronagraph that is observing the low corona in white light. This allows it to detect the very early stages of the solar activity that drives space weather.Elements of a space weather warning There are several types of space weather events originating on the Sun that can produce impacts on Earth. The new paper, published in the journal Space Weather, examines solar energetic particles (SEPs), which are accelerated into space by fast-moving explosive events known as coronal mass ejections (CMEs). The fastest SEPs can reach Earth in less than a half hour after leaving the Sun.Unlike the CMEs themselves, SEPs do not cause the geomagnetic storms that can disrupt power grids and GPS systems on Earth. But they can harm astronauts and spacecraft, and they can block high latitude communications and increase radiation over the Earth’s poles, forcing airlines to reroute flights from shorter polar paths to longer lower latitude routes.The potential of SEPs to cause damage is associated with their energy and the amount of particles produced. CMEs that are fast and produce a particular type of radio emission tend to generate more dangerous SEPs. Therefore the ability to measure the early speed of a CME — and, later, to determine if there was an accompanying radio burst — can allow scientists to provide a warning that damaging space weather is on the way.A coronagraph can be used to measure the speed and acceleration of a CME, but only if it can capture multiple images closely spaced in time. Even then, those images would have to be provided quickly to space weather forecasters on Earth to be part of a useful warning system.Existing space-based coronagraphs, like those onboard the SOlar and Heliospheric Observatory (SOHO) and the Solar TErrestrial RElations Observatory (STEREO), take too few images and send those images back to Earth too infrequently to be used for this type of an operational warning system.But K-Cor, which has been operating at NCAR's Mauna Loa Solar Observatory (MLSO) since 2013, can deliver on both counts. The coronagraph can take a new image every 15 seconds, and those images are processed and available on the internet less than 15 minutes later. With the installation of a new, faster computer at MLSO — a project that is currently underway — the lag until the images are widely available could shrink to just a few minutes.Scientists at NASA Goddard Space Flight Center also are working to develop software that could automatically identify the formation of a CME in the data and flag it, a necessary step toward actually using K-Cor in an operational capacity.A successful test caseIn the new study, the researchers used an SEP event that occurred on Jan. 1, 2016, as a test case to see if K-Cor could be used to provide early warnings for these kinds of events. They found that K-Cor could have provided a warning 19 minutes earlier than any other instrument. But K-Cor has drawbacks, too."You can only see the Sun so many hours in a day from one ground-based site," Burkepile said. "On a good day, we get 10 hours of data, but you're at the mercy of the weather and the sky conditions."To address this, NASA or other agencies would need to deploy a half-dozen ground-based coronagraphs spaced longitudinally around the globe. Alternatively, agencies could deploy a single space-based coronagraph — if it could be engineered, like K-Cor, with the ability to measure white light, take frequent pictures, and communicate quickly with Earth.Either way, scientists would also need to prevent warnings that are false positives. While K-Cor can see the formation of a CME quite early, it takes many more minutes before other instruments can detect whether or not there will be an accompanying radio burst, which increases the likelihood that a damaging SEP event will occur."The first sign of a fast-moving CME event is really much more like a storm watch issued here on Earth," Burkepile said. "We have to wait until we have evidence of a radio burst to upgrade the watch to a storm warning."In the top row, an eruption from the Sun on Jan. 1, 2016, is captured in composite by the Solar Dynamics Observatory (in gold), the K-Coronagraph (in blue), and the Solar Helophysics Observatory (red). (Image courtesy of Joan Burkepile, NCAR.)  About the articleTitle: Solar energetic particle warnings from a coronagraphAuthors: O. C. St. Cyr, A. Posner, and J. T. BurkepileJournal: Space Weather, DOI: 10.1002/2016SW001545Writer/contact:Laura Snider, Senior Science Writer and Public Information Officer  


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