RAL

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

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.

From GOES-16 to the world

March 6, 2017 | As atmospheric scientists around the world look forward to seeing extraordinarily detailed images from the new GOES-16 satellite, the University Corporation for Atmospheric Research (UCAR) and National Center for Atmospheric Research (NCAR) are preparing for central roles in disseminating the satellite's data.The first of a series of next-generation National Oceanic and Atmospheric Administration (NOAA) satellites, GOES-16 was launched in November and is expected to become fully operational late this year. It will immediately improve weather forecasts with its rapid, high-resolution views of hurricanes, thunderstorms, and other severe events, as well as provide a breakthrough lightning mapping system and more detailed monitoring of geomagnetic disturbances caused by the Sun."Scientists are rightfully excited because this is a revolutionary system," said Mohan Ramamurthy, director of UCAR's Unidata Program. "It's going to truly transform weather forecasting and research."GOES-16 captured this view of the mid-Atlantic and New England states on Jan. 15. (Image by National Oceanic and Atmospheric Administration.) Data from GOES-16 will be transmitted to a new downlink facility at the NCAR Mesa Lab. Unidata, which provides data, software tools, and support to enhance Earth system science education and research, will then make that data widely available.  As the only open-access and free source of GOES data in real time, Unidata's services have become indispensable to scientists as well as to operational forecasters in regions that lack their own downlink facilities, such as parts of Latin America.In addition, NCAR's Earth Observing Laboratory (EOL) will produce customized data products from GOES-16 to support field campaigns. EOL currently uses observations from GOES satellites and other sources to help scientists make critical decisions as they're taking measurements in the field.More data than everFor years, NCAR and UCAR have provided real-time data from a series of NOAA satellites known as GOES (Geostationary Operational Environmental Satellite). These satellites, which provide views of the Americas and adjoining ocean regions, are part of a global network of satellites whose observations are shared by forecasters and researchers worldwide.But the advantages of GOES-16 also create new challenges. The satellite has three times as many spectral channels as its predecessors, each with four times more resolution. It can scan the entire Western Hemisphere every 15 minutes and simultaneously generate images of severe weather every 30-60 seconds. All this data will amount to about 1 terabyte per day, more than 100 times the amount of data produced by an existing GOES satellite. And even more data can be expected when NOAA launches additional advanced GOES satellites in coming years.Thanks to a NOAA grant, UCAR and NCAR have installed a direct broadcast receiving station to receive the data, as well as the computers and electronics needed to process and transmit it. In addition to Unidata and EOL, NCAR's Research Applications Laboratory helps operate the downlink facilities for existing GOES satellites and relies on satellite data for the development of specialized forecasting products.The volume of information means that Unidata will continue to move toward making data available in the cloud. It will store GOES-16 data for about 10 days and is in discussions with Amazon over long-term storage options.EOL will customize GOES-16 observations for worldwide field projects, which advance understanding of Earth system science, including weather, climate, and air quality. Such projects deploy teams of scientists with aircraft, ships, ground-based instruments, and other tools. They rely on detailed forecasts and real-time updates about evolving atmospheric conditions."The data from GOES 16 will provide invaluable information for flight planning and decision making during field projects," said EOL director Vanda Grubišić. "This will enable scientists to gather additional observations, further advancing our understanding of the atmosphere and related aspects of the Earth system."EOL will also include the GOES data in their field catalog, along with measurements from field campaigns and other observations. This catalog is widely used by scientists when analyzing results from past campaigns or planning new ones.Other scientists say they are looking forward to the new capabilities that GOES-16 offers."The observations collected by the Geostationary Lightning Mapper on GOES-16 have the potential to help advance our understanding of hurricanes and their intensity changes," said Kristen Corboseiero, a professor in the Department of Atmospheric and Environmental Sciences at the University of Albany-SUNY. "Being able to access this data through Unidata will streamline and expedite our research."In Costa Rica, agencies are planning to use the GOES-16 data from Unidata for weather forecasting and research. In addition, the data will help with monitoring water levels for hydropower to avoid possible power cuts during the dry season, as well as for observing volcanic ash that can affect aviation and farming near San Jose."Several institutions will be using the new GOES-16 data in ways that will help safeguard society from potential natural disasters as well as avoiding energy shortages," said Marcial Garbanzo Salas, an atmospheric sciences professor at the Universidad de Costa Rica (University of Costa Rica). "This is extremely important to us, and we're very pleased that Unidata will be making it available."Writer/contact:David Hosansky, Media Relations ManagerFunder:National Oceanic and Atmospheric Administration

Slower snowmelt in a warming world

BOULDER, Colo. — As the world warms, mountain snowpack will not only melt earlier, it will also melt more slowly, according to a new study by scientists at the National Center for Atmospheric Research (NCAR).The counterintuitive finding, published today in the journal Nature Climate Change, could have widespread implications for water supplies, ecosystem health, and flood risk."When snowmelt shifts earlier in the year, the snow is no longer melting under the high sun angles of late spring and early summer," said NCAR postdoctoral researcher Keith Musselman, lead author of the paper. "The Sun just isn't providing enough energy at that time of year to drive high snowmelt rates."Snowpack in the Colorado Rockies as seen from the NSF/NCAR C-130 research aircraft. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)The study was funded by the National Science Foundation, NCAR's sponsor.The findings could explain recent research that suggests the average streamflow in watersheds encompassing snowy mountains may decline as the climate warms — even if the total amount of precipitation in the watershed remains unchanged. That's because the snowmelt rate can directly affect streamflow. When snowpack melts more slowly, the resulting water lingers in the soil, giving plants more opportunity to take up the moisture. Water absorbed by plants is water that doesn't make it into the stream, potentially reducing flows.Musselman first became interested in how snowmelt rates might change in the future when he was doing research in the Sierra Nevada. He noticed that shallower, lower-elevation snowpack melted earlier and more slowly than thicker, higher-elevation snowpack. The snow at cooler, higher elevations tended to stick around until early summer — when the Sun was relatively high in the sky and the days had grown longer — so when it finally started to melt, the melt was rapid.Musselman wondered if the same phenomenon would unfold in a future climate, when warmer temperatures are expected to transform higher-elevation snowpack into something that looks much more like today's lower-elevation snowpack. If so, the result would be more snow melting slowly and less snow melting quickly. To investigate the question, Musselman first confirmed what he'd noticed in the Sierra by analyzing a decade's worth of snowpack observations from 979 stations in the United States and Canada. He and his co-authors — NCAR scientists Martyn Clark, Changhai Liu, Kyoko Ikeda, and Roy Rasmussen — then simulated snowpack over the same decade using the NCAR-based Weather Research and Forecasting (WRF) model.Once they determined that the output from WRF tracked with the observations, they used simulations from the model to investigate how snowmelt rates might change in North America around the end of the century if climate change continues unabated."We found a decrease in the total volume of meltwater — which makes sense given that we expect there to be less snow overall in the future," Musselman said. "But even with this decrease, we found an increase in the amount of water produced at low melt rates and, on the flip side, a decrease in the amount of water produced at high melt rates."While the study did not investigate the range of implications that could come from the findings, Musselman said the impacts could be far-reaching. For example, a reduction in high melt rates could mean fewer spring floods, which could lower the risk of infrastructure damage but also negatively affect riparian ecosystems. Changes in the timing and amount of snowmelt runoff could also cause warmer stream temperatures, which would affect trout and other fish species, and the expected decrease in streamflow could cause shortages in urban water supplies."We hope this study motivates scientists from many other disciplines to dig into our research so we can better understand the vast implications of this projected shift in hydrologic patterns," Musselman said.About the articleTitle: Slower snowmelt in a warmer worldAuthors: Keith N. Musselman, Martyn P. Clark, Changhai Liu, Kyoko Ikeda, and Roy RasmussenJournal: Nature Climate Change, DOI: 10.1038/nclimate3225WriterLaura Snider, Senior Science Writer and Public Information OfficerFunderNational Science Foundation

High-resolution regional modeling (no supercomputer needed)

Annual precipitation over Colorado as modeled by the low-resolution, global Community Earth System Model (top) compared to the high-resolution, regional Weather Research and Forecasting model (below). (Images courtesy Ethan Gutmann, NCAR.) February 13, 2017 | In global climate models, the hulking, jagged Rocky Mountains are often reduced to smooth, blurry bumps. It's a practical reality that these models, which depict the entire planet, typically need to be run at a relatively low resolution due to constraints on supercomputing resources. But the result, a virtual morphing of peaks into hills, affects the ability of climate models to accurately project how precipitation in mountainous regions may change in the future — information that is critically important to water managers.To address the problem, hydrologists have typically relied on two methods to "downscale" climate model data to make them more useful. The first, which uses statistical techniques, is fast and doesn't require a supercomputer, but it makes many unrealistic assumptions. The second, which uses a high-resolution weather model like the Weather Research and Forecasting model (WRF), is much more realistic but requires vast amounts of computing resources.Now hydrologists at the National Center for Atmospheric Research (NCAR) are developing an in-between option: The Intermediate Complexity Atmospheric Research Model (ICAR) gives researchers increased accuracy using only a tiny fraction of the computing resources."ICAR is about 80 percent as accurate as WRF in the mountainous areas we studied," said NCAR scientist Ethan Gutmann, who is leading the development of ICAR. "But it only uses 1 percent of the computing resources. I can run it on my laptop."Drier mountains, wetter plainsHow much precipitation falls in the mountains — and when — is vitally important for communities in the American West and elsewhere that rely on snowpack to act as a frozen reservoir of sorts. Water managers in these areas are extremely interested in how a changing climate might affect snowfall and temperature, and therefore snowpack, in these regions.But since global climate models with low resolution are not able to accurately represent the complex topography of mountain ranges, they are unsuited for answering these questions.For example, as air flows into Colorado from the west, the Rocky Mountains force that air to rise, cooling it and causing moisture to condense and fall to the ground as snow or rain. Once these air masses clear the mountains, they are drier than they otherwise would have been, so there is less moisture available to fall across Colorado's eastern plains.Low-resolution climate models are not able to capture this mechanism — the lifting of air over the mountains — and so in Colorado, for example, they often simulate mountains that are drier than they should be and plains that are wetter. For a regional water manger, these small shifts could mean the difference between full reservoirs and water shortages."Climate models are useful for predicting large-scale circulation patterns around the whole globe, not for predicting precipitation in the mountains or in your backyard," Gutmann said.Precipitation in millimeters over Colorado between Oct. 1 and May 1 as simulated by the Weather Research and Forecasting model (WRF), the Intermediate Complexity Atmospheric Research model (ICAR), and the observation-based Parameter-Elevation Regressions on Independent Slopes Model. (Images courtesy Ethan Gutmann.)A modeling middle groundA simple statistical fix for these known problems may include adjusting precipitation data to dry out areas known to be too wet and moisten areas known to be too dry. The problem is that these statistical downscaling adjustments don't capture the physical mechanisms responsible for the errors. This means that any impact of a warming climate on the mechanisms themselves would not be accurately portrayed using a statistical technique.That's why using a model like WRF to dynamically downscale the climate data produces more reliable results — the model is actually solving the complex mathematical equations that describe the dynamics of the atmosphere. But all those incredibly detailed calculations also take an incredible amount of computing.A few years ago, Gutmann began to wonder if there was a middle ground. Could he make a model that would solve the equations for just a small portion of the atmospheric dynamics that are important to hydrologists — in this case, the lifting of air masses over the mountains — but not others that are less relevant?"I was studying statistical downscaling techniques, which are widely used in hydrology, and I thought, 'We should be able to do better than this,'" he said. "'We know what happens when you lift air up over a mountain range, so why don’t we just do that?'"Gutmann wrote the original code for the model that would become ICAR in just a few months, but he spent the next four years refining it, a process that's still ongoing.100 times as fastLast year, Gutmann and his colleagues — Martyn Clark and Roy Rasmussen, also of NCAR; Idar Barstad, of Uni Research Computing in Bergen, Norway; and Jeffrey Arnold, of the U.S. Army Corps of Engineers — published a study comparing simulations of Colorado created by ICAR and WRF against observations.The authors found that ICAR and WRF results were generally in good agreement with the observations, especially in the mountains and during the winter. One of ICAR's weaknesses, however, is in simulating storms that build over the plains in the summertime. Unlike WRF, which actually allows storms to form and build in the model, ICAR estimates the number of storms likely to form, given the atmospheric conditions, a method called parameterization.Even so, ICAR, which is freely available to anyone who wants to use it, is already being run by teams in Norway, Austria, France, Chile, and New Zealand."ICAR is not perfect; it's a simple model," Gutmann said. "But in the mountains, ICAR can get you 80 to 90 percent of the way there at 100 times the speed of WRF. And if you choose to simplify some of the physics in ICAR, you can get it close to 1,000 times faster."About the articleTitle: The Intermediate Complexity Atmospheric Research Model (ICAR)Authors: Ethan Gutmann, Idar Barstad, Martyn Clark, Jeffrey Arnold, and Roy RasmussenJournal: Journal of Hydrometeorology, DOI: 10.1175/JHM-D-15-0155.1Funders:U.S. Army Corps of EngineersU.S. Bureau of ReclamationCollaborators:Uni Research Computing in NorwayU.S. Army Corps of EngineersWriter/contact: Laura Snider, Senior Science Writer

Scientists take to the skies to test cloud seeding

February 7, 2017 | Does cloud seeding successfully increase snowfall? This winter, scientists with the National Center for Atmospheric Research (NCAR) are taking part in a field project in Idaho that will help answer the question.The project, called SNOWIE (Seeded and Natural Orographic Wintertime Clouds — the Idaho Experiment), is taking place from Jan. 7 to March 17 in the Payette Basin region north of Boise. A public-private partnership, SNOWIE is led by scientists at the University of Wyoming and other universities in collaboration with NCAR, with funding from the National Science Foundation (which is NCAR's sponsor) and the Idaho Power Company.The research team is using airborne and ground-based radars, high-resolution snow gauges, and computer modeling to gain insights into what happens after clouds are seeded with silver iodide. Snow from winter storms develops when ice crystals form on dust and other particles known as "ice nuclei." In cloud seeding, silver iodide is used to make artificial nuclei to encourage snowflakes to form.Silver iodide is released during the SNOWIE field project in such a way that it disperses downwind to the east, with its highest concentrations forming a zigzag pattern (shown in red). This allows scientists to fly a research aircraft from west to east through both seeded and unseeded regions and compare differences in ice crystal formation. (Image by Lulin Xue, ©UCAR. This image is freely available for media & nonprofit use.)NCAR scientists are focusing much of their work on observations taken by a University of Wyoming King Air plane that is flying though plumes of silver iodide released by a seeding aircraft. The silver iodide disperses downwind in a zigzag pattern, enabling the King Air to intercept it multiple times. The scientists will compare the formation of ice crystals in regions of clouds that are seeded with those that are not.The results can also be used to improve the NCAR-based Weather Research and Forecasting model (WRF), especially its simulation of cloud microphysics related to cloud seeding.Although scientists think that cloud seeding and other types of weather modification can increase precipitation in certain circumstances, the effects are difficult to quantify."NCAR's role in these weather modification experiments is to provide an unbiased viewpoint," said NCAR scientist Sarah Tessendorf, a principal investigator on SNOWIE. "The project uses observations and computer models to determine what is happening during a cloud seeding program and whether it is effective as a water augmentation tool."For more about the project, see the NSF news release.Writer/contactDavid Hosansky, Manager of Media RelationsFundersNational Science FoundationIdaho Power CompanyPartnersUniversity of WyomingIdaho Power CompanyUniversity of Colorado BoulderUniversity of Illinois at Urbana-ChampaignBoise State UniversityCenter for Severe Weather ResearchWeather Modification, Inc.

RAL Seminar: Lightning Safety Impacts on Airline and Airport Operations, Dr. Matthias Steiner

Thunderstorms and lightning pose a safety risk to personnel working outdoors. Airport and airline operators, therefore, employ safety procedures that include observations and warnings of the onset and duration of lightning hazards. Ramp closures (i.e., bringing people inside) are needed to ensure the safety of outdoor personnel servicing gate-side aircraft. Yet halting outdoor work delays air traffic and can cause ripple effects beyond the impacted airport.

RAL Seminar: Coupling the Physical and Social Sciences Toward Understanding the Transmission Dynamics of Aedes-Borne Viruses

Aedes aegypti mosquitoes are the primary vectors for dengue, yellow fever, chikungunya and Zika viruses. In recent decades, this mosquito and a closely related vector, Aedes albopictus, have expanded rapidly in the Americas, including the United States due to changing environmental and human conditions. Viruses transmitted by Aedes mosquitoes are a growing threat in the United States as evidenced by the proliferation of dengue viruses and the recent introductions of Zika and chikungunya viruses.

Two NCAR scientists honored by American Geophysical Union

BOULDER, Colo. — Martyn Clark, senior scientist at the National Center for Atmospheric Research (NCAR), will be honored next week as a Fellow of the American Geophysical Union (AGU) for his exceptional contribution to Earth science.Clark is an expert in the numerical modeling and prediction of hydrologic processes. His current research includes developing new modeling methods to improve streamflow forecasts and better understand climate change impacts on regional water resources. Clark, who grew up in Christchurch, New Zealand, has authored or co-authored 135 journal articles since receiving his Ph.D. from the University of Colorado in 1998.NCAR Senior Scientist Martyn Clark (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)"This well-deserved honor reflects Martyn's eminent work in the increasingly critical area of water-resource prediction and management," said NCAR Director James W. Hurrell.Clark said he was delighted to see NCAR's hydrologic modeling recognized. "Hydrology is beginning to play a much stronger role in addressing important interdisciplinary science questions about Earth System change, such as how changes in the terrestrial water cycle affect biological productivity and how groundwater can buffer water stress in ecosystems and human societies. It's exciting to advance modeling capabilities in these areas."NCAR Senior Scientist Bette Otto-Bliesner. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)Clark is among 60 individuals from eight countries recognized as Fellows this year; only one in one thousand AGU members receive this recognition in any given year. Nearly 40 percent of this year's fellows are from the 110 member colleges and universities of the University Corporation for Atmospheric Research (UCAR), which manages NCAR. This year's class will be honored next Wednesday at the 2016 AGU Fall Meeting in San Francisco.NCAR Senior Scientist Bette Otto-Bliesner, who was named an AGU Fellow last year, is being honored by her peers in the Paleoceanography and Paleoclimatology Focus Group and Ocean Sciences Section by being asked to give the 2016 Emiliani Lecture. She will give the lecture next Wednesday at the AGU Fall Meeting on the topic of "Resolving Some Puzzles of Climate Evolution Since the Last Glacial Maximum: A Melding of Paleoclimate Modeling and Data."The AGU, dedicated to advancing Earth and space sciences for the benefit of society, is a not-for-profit, professional organization representing 60,000 members in more than 140 countries. 

Extreme downpours could increase fivefold across parts of the U.S.

BOULDER, Colo. — At century's end, the number of summertime storms that produce extreme downpours could increase by more than 400 percent across parts of the United States — including sections of the Gulf Coast, Atlantic Coast, and the Southwest — according to a new study by scientists at the National Center for Atmospheric Research (NCAR).The study, published today in the journal Nature Climate Change, also finds that the intensity of individual extreme rainfall events could increase by as much as 70 percent in some areas. That would mean that a storm that drops about 2 inches of rainfall today would be likely to drop nearly 3.5 inches in the future."These are huge increases," said NCAR scientist Andreas Prein, lead author of the study. "Imagine the most intense thunderstorm you typically experience in a single season. Our study finds that, in the future, parts of the U.S. could expect to experience five of those storms in a season, each with an intensity as strong or stronger than current storms."The study was funded by the National Science Foundation (NSF), NCAR's sponsor, and the Research Partnership to Secure Energy for America.“Extreme precipitation events affect our infrastructure through flooding, landslides and debris flows,” said Anjuli Bamzai, program director in NSF’s Directorate for Geosciences, which funded the research.  “We need to better understand how these extreme events are changing. By supporting this research, NSF is working to foster a safer environment for all of us.”The figure shows the expected increase in the number of summertime storms that produce extreme precipitation at century's end compared to the period 2000 - 2013. (©UCAR. Courtesy Andreas Prein, NCAR. This image is freely available for media & nonprofit use.)A year of supercomputing timeAn increase in extreme precipitation is one of the expected impacts of climate change because scientists know that as the atmosphere warms, it can hold more water, and a wetter atmosphere can produce heavier rain. In fact, an increase in precipitation intensity has already been measured across all regions of the U.S. However, climate models are generally not able to simulate these downpours because of their coarse resolution, which has made it difficult for researchers to assess future changes in storm frequency and intensity.For the new study, the research team used a new dataset that was created when NCAR scientists and study co-authors Roy Rasmussen, Changhai Liu, and Kyoko Ikeda ran the NCAR-based Weather Research and Forecasting (WRF) model at a resolution of 4 kilometers, fine enough to simulate individual storms. The simulations, which required a year to run, were performed on the Yellowstone system at the NCAR-Wyoming Supercomputing Center.Prein and his co-authors used the new dataset to investigate changes in downpours over North America in detail. The researchers looked at how storms that occurred between 2000 and 2013 might change if they occurred instead in a climate that was 5 degrees Celsius (9 degrees Fahrenheit) warmer — the temperature increase expected by the end of the century if greenhouse gas emissions continue unabated.Prein cautioned that this approach is a simplified way of comparing present and future climate. It doesn't reflect possible changes to storm tracks or weather systems associated with climate change. The advantage, however, is that scientists can more easily isolate the impact of additional heat and associated moisture on future storm formation."The ability to simulate realistic downpours is a quantum leap in climate modeling. This enables us to investigate changes in hourly rainfall extremes that are related to flash flooding for the very first time," Prein said. "To do this took a tremendous amount of computational resources."Impacts vary across the U.S.The study found that the number of summertime storms producing extreme precipitation is expected to increase across the entire country, though the amount varies by region. The Midwest, for example, sees an increase of zero to about 100 percent across swaths of Nebraska, the Dakotas, Minnesota, and Iowa. But the Gulf Coast, Alabama, Louisiana, Texas, New Mexico, Arizona, and Mexico all see increases ranging from 200 percent to more than 400 percent.The study also found that the intensity of extreme rainfall events in the summer could increase across nearly the entire country, with some regions, including the Northeast and parts of the Southwest, seeing particularly large increases, in some cases of more than 70 percent.A surprising result of the study is that extreme downpours will also increase in areas that are getting drier on average, especially in the Midwest. This is because moderate rainfall events that are the major source of moisture in this region during the summertime are expected to decrease significantly while extreme events increase in frequency and intensity. This shift from moderate to intense rainfall increases the potential for flash floods and mudslides, and can have negative impacts on agriculture.The study also investigated how the environmental conditions that produce the most severe downpours might change in the future. In today's climate, the storms with the highest hourly rainfall intensities form when the daily average temperature is somewhere between 20 and 25 degrees C (68 to 77 degrees F) and with high atmospheric moisture. When the temperature gets too hot, rainstorms become weaker or don't occur at all because the increase in atmospheric moisture cannot keep pace with the increase in temperature. This relative drying of the air robs the atmosphere of one of the essential ingredients needed to form a storm.In the new study, the NCAR scientists found that storms may continue to intensify up to temperatures of 30 degrees C because of a more humid atmosphere. The result would be much more intense storms."Understanding how climate change may affect the environments that produce the most intense storms is essential because of the significant impacts that these kinds of storms have on society," Prein said.About the articleTitle: The future intensification of hourly precipitation extremesAuthors: Andreas F. Prein, Roy M. Rasmussen, Kyoko Ikeda, Changhai Liu, Martyn P. Clark, and Greg J. HollandJournal: Nature Climate Change, DOI: 10.1038/NCLIMATE3168Writer:Laura Snider, Senior Science Writer and Public Information Officer

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