Tornadoes, microbursts, and silver linings

Bob Henson • April 1, 2014 | It takes a sharp eye to find something positive in the wreckage of the worst swarm of U.S. tornadoes on record. Ted Fujita had just such an eye, and millions of Americans are safer in the air because of it. Theodore "Ted" Fujita was renowned for his meticulous work in observing and analyzing meteorological phenomena, including tornadoes and microbursts, through photographs and damage surveys as well as weather data. (Photo courtesy University of Chicago.) Fujita, who died in 1998, is known around the world for devising the Fujita Tornado Damage Scale, or F-scale. Now reworked as the Enhanced Fujita Tornado Damage Scale, it’s the system most commonly used to rank tornado strength based on observed damage. A prolific researcher, Fujita made many other contributions to meteorology that are less well known to the public. One standout is his conceptualization of microbursts, the small yet dangerous pockets of descending wind that even weak showers can produce. Fujita and colleagues at the University of Chicago joined with NCAR researchers in the late 1970s and 1980s in definitive work that clarified the danger posed to aviation by microbursts. The effort was a spectacular success—and it all started in the wake of a devastating round of tornadoes that struck 40 years ago this week. Insight from tragedy On April 3, 1974, the U.S. South and Midwest were raked by more than 140 tornadoes that killed more than 300 people. The sheer scope of this disaster, which Fujita dubbed the Jumbo Outbreak (it’s also referred to as the Super Outbreak), went beyond anything previously measured. Since then, the only comparable event was the rash of more than 300 tornadoes across much of the eastern United States on April 25–28, 2011, again killing more than 300 people. While conducting an aerial survey of damage from the Jumbo Outbreak, Fujita—already known among peers as a meticulous observer—noticed something strange. He recounted the experience in a 1985 monograph, The Microburst: The deadliest single tornado of the Jumbo Outbreak on April 3, 1974, plowed through Xenia, Ohio, killing 36 people. (Wikimedia Commons image.) “Unlike the swirling patterns of fallen trees, commonly seen from the air in the wake of tornadoes, hundreds of trees were blown outward in a starburst pattern. Trees near the starburst center were flattened or uprooted, spattered by a brownish topsoil.” Fujita reasoned that such damage was produced not by the inflowing, rising air in a tornado, but rather from a focused surge of descending air that suddenly diverges when it hits the ground. He likened this to flow from a garden hose. If the hose is pointed directly downward, the water will spray outward in all directions, but if the hose is angled just slightly, the water fans out toward one side, much like the damage observed by Fujita. Fujita concluded that about 15 percent of the jaw-dropping 2,598 linear miles of damage he mapped from the Super Outbreak was caused by these “outburst” winds, rather than by tornadoes. The next critical event occurred on the stormy day of June 24, 1975, when an Eastern Airlines plane crashed on approach at New York’s Kennedy International Airport, killing 113 people. Analyzing eyewitness reports and black-box data, and recalling the damage patterns he’d observed the year before, Fujita concluded that a “downburst” was likely responsible for the crash. (He later coined the term “microburst” to describe a downburst that was no more than 2.5 miles wide at ground level. See this comparison.) Quelling the critics with field data As with many transformative scientific ideas, Fujita’s concept came up against prominent detractors. Most researchers at the time believed that even strong downdrafts from thunderstorms ought to weaken before reaching the surface. Fujita also bucked convention in how he carried out his research. “The large majority of his downburst work was not published in peer-reviewed journals,” noted Jim Wilson (NCAR) and Roger Wakimoto (now NSF assistant director for the Directorate for Geosciences) in a 2001 retrospective for the Bulletin of the American Meteorological Society (see PDF). They wrote: “It is likely that [the publication process] would have been an irritating, time-consuming activity for Fujita. He probably realized reviewers would have questioned his unorthodox analysis procedures and heavy use of unstated assumptions.” As Fujita continued to gather data through aerial damage surveys in the late 1970s, he also enlisted the help of NCAR and its pair of portable Doppler radars, which were then among only a handful available in the world available for atmospheric research. With encouragement from Bob Serafin, who managed NCAR’s observing facilities at the time (and who later became NCAR director), NSF agreed to fund a field campaign. “At a time when many in the scientific community had serious doubts about Fujita’s downburst hypothesis, these two [entities (NSF and NCAR)] fully supported his efforts,” noted Wilson and Wakimoto. Several landmark field projects over the next decade made it clear that Fujita was on the right track. Descending air curls outward and upward as it slams into the ground in a microburst near Denver's former Stapleton International Airport on July 6, 1984, during the CLAWS project (Classify, Locate, Avoid Wind Shear). (Photo by Wendy Schreiber-Abshire, ©UCAR. This image is freely available for media & nonprofit use.) NIMROD, the Northern Illinois Meteorological Research on Downbursts, combined NCAR’s two radars with the CHILL radar (University of Chicago/Illinois State Water Survey). As NIMROD detected its first microburst, on May 29, 1978, Fujita and Wilson stepped outside and were almost blown into a nearby farm pond.  The radars and surface stations ended up detecting about 50 microbursts that spring and summer. JAWS, the Joint Airport Wind Shear project, took place in northeast Colorado in 1982, followed by CLAWS (Classify, Locate, and Avoid Wind Shear) in 1984. With three NCAR Doppler radars positioned more closely together, Fujita identified more than 180 microbursts and analyzed several in great detail through vertical cross sections. One of the stronger microbursts occurred near Denver’s former Stapleton Airport from a cloud with a radar reflectivity of just 17 dBZ—barely a detectable shower. (Fujita also saw his first-ever tornado that summer, near the town of Bennett.) MIST, the Microburst and Severe Thunderstorm project, brought the three NCAR Doppler radars to northern Alabama in 1986. This study focused on “wet” microbursts—those fed by great volumes of heavy rain, as opposed to the evaporation and cooling that produced the “dry” microbursts common in more arid regimes.   NCAR’s John McCarthy spent much of his time during the summers of 1984 and 1985 in the control tower of Denver’s Stapleton International Airport during the CLAWS project. (©UCAR. This image is freely available for media & nonprofit use.) Results from these field projects quickly convinced skeptics that microbursts were a bona fide threat to aviation. This initial awareness helped pilots and air traffic controllers stem the rate of major microburst-related accidents, which had been occurring every year or two in the 1970s and early 1980s. More intensive pilot training, much of it initiated by NCAR’s John McCarthy and sponsored by the Federal Aviation Administration, cemented the new concepts. Technology also made a huge difference. Building on research led by McCarthy, and with FAA support, NCAR teamed up with the Massachusetts Institute of Technology’s Lincoln Laboratory to develop software that generated wind-shear alerts, drawing on observations from surface weather stations near airports and a new network of airport-based Doppler radars. As the new tools and observing systems spread nationwide, microburst-related accidents became increasingly rare: the last major U.S. flight mishap attributed to wind shear occurred in 1995. RAL is still actively helping international governments and airport authorities procure wind shear systems. “The microburst/aircraft problem demonstrated how funding focused on a particular weather problem can lead to an operational solution,” says Wilson. The next challenges It’s likely that hundreds of deaths have been avoided thanks to Ted Fujita’s uncommon insight, his exhaustive documentation, and the careful field work carried out by NCAR scientists and their collaborators. Many of them remain active in research, savoring the microburst success even as they look to new areas where knowledge and technology can make transportation safer and more efficient. Much of this work now takes place within the framework of the FAA’s NextGen initiative, a comprehensive approach to aircraft navigation, weather information, and safety. Turbulence remains a vexing aviation problem. Even with no thunderstorms nearby, severe turbulence injured 11 people (two seriously) in February aboard a United Airlines flight en route from Denver to Billings, Montana. To date, around 200 United and Delta aircraft have tested an NCAR-developed system that automatically diagnoses turbulence and creates global maps of turbulence intensity. Southwest Airlines is expected to join the system later this year. Another NCAR software package uses Doppler radar data to remotely detect turbulence related to thunderstorms. Icing is another long-recognized hazard that’s being partially tamed by technology. An NCAR-developed system, now marketed by Vaisala, allows airports to monitor snowfall rate and other weather factors crucial to aircraft de-icing as they unfold. Two products developed at NCAR use current observations and short-range computer models to map out where in-flight icing conditions are expected to be most likely and most severe, both now and over the next 12 hours. NCAR is also collaborating with NOAA on a prototype system that would provide a global picture of predicted icing severity. This graphic display from the FIP-Severity software program depicts a two-hour icing severity forecast across the United States on March 15, 2011. The forecast is for a column extending from 1,000 to 30,000 feet above mean sea level. The shades of blue denote the level of severity, with dark blue indicating heavy icing. The red areas of "SLD threat" are warnings for the presence of supercooled large drops, an indicator of severe icing potential. Icing can create a significant hazard for some types of aircraft. (Image courtesy NOAA/NWS/ADDS.) Even though U.S. air travel is safer than ever, passengers can still encounter major inconvenience with long delays and cancelled flights. A new NCAR-based tool for air traffic awareness could help give airlines a probabilistic sense of where, when, and how many flights are likely to be hindered by thunderstorms. The system converts output from high-resolution computer forecast models into estimates of how much airspace capacity might be reduced—essentially switching the forecast product from weather itself to its impact on flights. The time frame of several hours into the future represents a sweet spot, with the probabilistic approach allowing for guidance beyond “nowcasting” of thunderstorms and other threats while giving traffic controllers and airlines a valuable planning window. The experimental project has been funded by NASA, the FAA, and most recently the National Weather Service. It’s also possible that some of the next transformative breakthroughs in transportation safety will occur on terra firma. Weather-related highway accidents kill thousands of Americans each year. NCAR’s Research Applications Laboratory—which emerged after the successful attack on the microburst problem—now includes a branch focused on surface transportation. Among their current projects is a winter-weather decision support system that uses weather and road data sent by specially equipped snowplows to help determine where plowing and sanding are most needed. When deployed on a larger scale, millions of “intelligent” vehicles might someday give drivers crucial advance notice of ice, rain, and other potential road hazards just around the bend.  As with microbursts and aircraft, there’s nothing like the power of plentiful data and thorough analyses to help keep people safe from weather’s worst.

New technology targets slick winter roads

BOULDER—In the annual battle to keep roads clear of snow and ice, snowplows are about to get much more intelligent. Officials in three states this winter are deploying hundreds of plows with custom-designed sensors that continually measure road and weather conditions. The new digital intelligence system, funded by the U.S. Department of Transportation and built by the National Center for Atmospheric Research (NCAR), is designed to reduce accidents and save states millions of dollars in winter maintenance costs. The system, known as the Pikalert™ Enhanced Maintenance Decision Support System (EMDSS), is being activated on major highways across Michigan, Minnesota, and Nevada. If it passes key tests, it will be transferred to private vendors and become available to additional states in time for next winter. “This offers the potential to transform winter driving safety,” said NCAR scientist Sheldon Drobot, who oversees the design of the system. “It gives road crews an incredibly detailed, mile-by-mile view of road conditions. They can quickly identify the stretches where dangerous ice and snow are building up.” The new system combines the sensor measurements with satellite and radar observations and computer weather models, giving officials an unprecedented near-real time picture of road conditions. With updates every five to fifteen minutes, EMDSS will enable transportation officials to swiftly home in on dangerous stretches even before deteriorating conditions cause accidents. “The U.S. Department of Transportation is committed to addressing the safety and mobility problems associated with adverse weather, especially through the use of intelligent transportation systems,” said Kenneth Leonard, director of the Department of Transportation's Intelligent Transportation Systems Joint Program Office. “This effort demonstrates the value of connected vehicle technologies, advanced weather prediction, and targeted decision support to enable state departments of transportation to more effectively maintain a high level of service on their roads.” Cars and trucks facing heavy snow on Interstate 84 in Oregon. A new digital intelligence system that equips snowplows with custom-designed sensors is helping transportation officials clear winter roads more quickly and effectively. (Image courtesy Wikimedia Commons/Oregon Department of Transportation.) Key information needed Motor vehicle accidents involving wintry conditions and other hazardous weather claim the lives of more than 4,000 people in the United States and injure several hundred thousand each year. To keep roads clear, a single state can spend tens of millions of dollars on maintenance operations over the course of one winter. But transportation officials often lack critical information about road conditions in their own states. They rely on ground-based observing stations that can be spaced more than 60 miles apart. As a result, they have to estimate conditions between weather stations. Snow and ice may build up more quickly along particular stretches of road because of shading, north-facing curves, higher elevation, or small-scale differences in weather conditions. If officials dispatch snowplows unnecessarily, or treat roads with sand, salt, or chemicals when not needed, they risk wasting money and harming the environment. If they do not treat the roads, however, drivers may face treacherous conditions. By equipping hundreds of snowplows and transportation supervisor trucks with sensors, officials can now get information along every mile of the roads traveled by the vehicles. The sensors collect weather data, such as temperature and humidity, as well as indirect indications of road conditions, such as the activation of antilock brakes or windshield wipers. Using GPS technology, the measurements are coded with location and time. They are transmitted via the Internet or dedicated radio frequencies or cellular networks to an NCAR database, where they are integrated with other local weather data, traffic observations, and details about the road’s surface material. The resulting data are subjected to quality control measures to weed out false positives (such as a vehicle slowing down because of construction rather than slippery conditions). The resulting detail about atmospheric and road conditions is relayed to state transportation officials to give them a near–real-time view of ice and snow buildup, as well as what to expect in the next few hours from incoming weather systems. Safer roads State transportation officials said the system will contribute significantly to safer roads. "Collecting atmosphere and road surface condition data from vehicles in near-real time provides another important layer of information never before available,” said Steven Cook, operations/maintenance field services engineer of the Michigan Department of Transportation. “With information like this, we can more accurately pinpoint changing road conditions in the winter that need treatment and alert drivers of potential hazardous conditions before they encounter them." “This additional location-specific information can help our maintenance crews provide a more effective and efficient response to weather events, resulting in improved road conditions and increased safety for all drivers,” added Denise Inda, the chief traffic operations engineer of the Nevada Department of Transportation. Drobot said he is looking forward to evaluating EMDSS. “We want to reduce that white-knuckle experience of suddenly skidding on ice,” Drobot said. EMDSS is the leading edge of a revolutionary approach to keeping motor vehicles safer in inclement weather. The next step, as early as next summer, will be to begin providing information to drivers about potentially hazardous conditions in their immediate vicinity, alerting them to slow down or take alternate routes. Several partners, including the universities of Nevada and Michigan and the firms Ameritrack and Synesis, relay information from the sensors to the main database at NCAR. Pikalert™ is a trademark of the University Corporation for Atmospheric Research.

Triggering turbulence in clear air

January 16, 2013 | Turbulence is the leading cause of injuries to passengers and crew aboard commercial aircraft, and it indirectly increases travel expenses by costing airlines tens of millions of dollars yearly. While much of the rough air occurs within clouds, planes sometimes unexpectedly encounter turbulence while cruising through regions of clear air. New research by NCAR researchers and collaborators points to gravity waves, which ripple unseen through the atmosphere, as the culprit in many cases of clear-air turbulence. If those waves can be forecast, the research suggests that planes in many cases could be rerouted around them. “Clear-air turbulence forecasting is one of the last great challenges of numerical weather prediction,” says Bob Sharman, who leads NCAR’s turbulence research team. “As we better understand what causes turbulence, we can begin developing systems to predict it.” Sharman presented the findings at December’s annual meeting of the American Geophysical Union. Gravity waves are a common atmospheric phenomenon. They are caused when air is forced upward, generally over mountains or in thunderstorms, and bumps up against the stable floor of the stratosphere. This sets off ripples that can travel hundreds of miles before breaking. (Gravity waves are unrelated to gravitational waves, which are perturbations in the gravitational field.) For their research, Sharman and colleagues from NCAR; the University of Melbourne in Australia; the University of California, Los Angeles; and the Naval Research Laboratory collected observations of turbulence from more than 100 commercial aircraft. The team then compared those reports to the locations of cloud and other possible sources of gravity waves. The observations, which measure the extent to which rough air causes up-and-down movements of an airplane, were recorded by a special onboard system devised by NCAR several years ago. Sharman and his team then used the NCAR-based version of the Weather Research and Forecasting model (WRF) to simulate atmospheric conditions associated with observed turbulence events. They found that gravity waves “break” against aircraft, much as ocean waves break on the beach. Although clear-air turbulence has traditionally been thought to be due mainly to areas of high wind shear associated with jet streams, the research indicates that gravity wave breaking events actually account for much of the observed turbulence. Gravity waves often break within a relatively shallow altitude range, so pilots might be able to avoid them if they knew where the waves were. But the waves cannot be detected by radars aboard commercial aircraft. For the next phase of their research, Sharman and his colleagues are using a computer model to better understand the initiation and evolution of gravity waves and gravity wave breaking. If they can successfully predict turbulence associated with gravity waves at least 85% of the time, the aviation industry may find it cost effective to reroute aircraft. Even if the planes did not take action to avoid the waves, pilots could often alert passengers about a bumpy ride ahead. “The goal is to make flying as safe and comfortable as possible,” Sharman says. The research is supported by NASA and the National Oceanic and Atmospheric Administration.

New airport system facilitates smoother take-offs and landings

BOULDER—For airline passengers who dread bumpy rides to mountainous destinations, help may be on the way. A new turbulence avoidance system has for the first time been approved for use at a U.S. airport and can be adapted for additional airports in rugged settings across the United States and overseas. The new turbulence avoidance system enables pilots to view areas of moderate (yellow) and severe (red) turbulence. (©UCAR. Screen capture from NCAR's Juneau Airport Warning System. This image is freely available for media & nonprofit use.) The system, developed by the National Center for Atmospheric Research (NCAR), provides information pilots can use to route aircraft away from patches of potentially dangerous turbulence. It uses a network of wind measuring instruments and computational formulas to interpret rapidly changing atmospheric conditions. The Federal Aviation Administration formally commissioned the system in July for Alaska’s Juneau International Airport. NCAR researchers can now turn their attention to adapting the system to other airports that often have notoriously severe turbulence, in areas ranging from southern California and the Mountain West to Norway and New Zealand. The Juneau system was patterned after a similar system, also designed by NCAR, that has guided aircraft for several years at Hong Kong’s heavily trafficked Chek Lap Kok Airport. “By alerting pilots to areas of moderate and severe turbulence, this system enables them to fly more frequently and safely in and out of the Juneau airport in poor weather,” says Alan Yates, an NCAR program manager who helped oversee the system’s development. “It allows pilots to plan better routes, helping to reduce the bumpy rides that passengers have come to associate with airports in these mountainous settings.” The system offers the potential to substantially reduce flight delays. In Alaska’s capital city, where it is known as the Juneau Airport Wind System or JAWS, it enables the airport to continue operations even during times of turbulence by highlighting corridors of smooth air for safe take-offs and landings. Al Yates (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) “The JAWS system has nearly eliminated all the risk of flying in and out of Juneau,” says Ken Williams, a Boeing 737 captain and instructor pilot with Alaska Airlines. “I wish the system would be deployed in other airports where there are frequent encounters with significant turbulence, so pilots can get a true understanding of what the actual winds are doing on the surrounding mountainous terrain as you approach or depart.” The project was funded by the Federal Aviation Administration. NCAR is sponsored by the National Science Foundation. Steep terrain, rough rides Turbulence has long been a serious concern for pilots approaching and departing airports in steep terrain. Rugged peaks can break up air masses and cause complex and rapidly changing patterns of updrafts and downdrafts, buffeting an aircraft or even causing it to unexpectedly leave its planned flight path. In Juneau, after several turbulence-related incidents in the early 1990s—including one in which a jet was flipped on its side during flight and narrowly avoided an accident—the FAA imposed strict rules of operation that effectively shut down the airport during times of atmospheric disturbance. The agency then asked NCAR to develop a system that would allow pilots to avoid regions of turbulence. Otherwise, Alaska’s capital would be isolated at many times from the rest of the state, since the only way to travel in and out of Juneau is by airplane or boat. The NCAR team used research aircraft and computer simulations to determine how different wind patterns—such as winds that come from the north over mountains and glaciers and winds that come from the southeast over water—correlated with specific areas of turbulence near the airport. To do this they installed anemometers and wind profilers at key sites along the coast and on mountain ridges. The team has installed ruggedized, heated instruments that can keep functioning even when exposed to extreme cold, wind, and heavy icing conditions. The Federal Aviation Administration accepted JAWS for operational use this year.    The five anemometer sites and three wind profiler sites around the airport transmit data multiple times every minute. Pilots can get near-real-time information about wind speed and direction, and a visual readout showing regions of moderate and severe turbulence in the airport’s approach and departure corridors, from the FAA’s Flight Service Station or online at a National Weather Service website, where an integrated display "app" is also available for download. “Juneau was an extremely challenging case, and we’re pleased that the new system met the FAA’s high standards,” Yates says. “We look forward to exploring opportunities to support development of turbulence avoidance systems at additional airports. Our goal is to improve flying safety and comfort for millions of passengers.”

Clouds and asphalt

August 21, 2012 | A single cloud can have dramatic effects on local weather conditions, but forecasting models do not fully capture individual clouds or cloud types. Now researchers at NCAR are developing tools that could enhance the precision of weather forecasts by taking clouds into account, with results that could help drivers, road crews, and others. “When you’re looking at storms or high-pressure systems across a large region, the cloud is like a little tiny speck of sand,” says Curtis Walker, a 2012 SOARS protégé at NCAR who is beginning a master’s program in atmospheric science at the University of Nebraska, Lincoln, this fall. “Today’s technology can’t really get a good grip on where an individual cloud might be or its impact on a small, localized area.” In addition, he notes, many current models are only generated every six hours, but clouds can move within minutes. Walker, under the direction of his science mentor, Michael Chapman, a scientific project manager at NCAR, applied the Naval Research Laboratory Cloud Classification algorithm, which uses satellite imagery to identify cloud types, pixel by pixel, over an 8-square-kilometer area. He classified cloud types into five categories: cirrus clouds, which are thin and feathery; mid-level, ‘alto’ clouds, which often occur in layers and have a “bubbled” or cellular appearance; stratus clouds, which are low-level clouds that produce fog or rain; cumuliform clouds, which include thunderstorm clouds that often form large, vertical towers; and clear conditions. The system gathers cloud data every 15 minutes. The researchers then overlaid cloud observations onto radiation measurements to quantify how much solar energy reaches Earth’s surface in the presence of different cloud types and sizes. The results can help forecasters anticipate how much heat from the Sun will reach the ground in the next few hours. Professional racing organizations have a keen interest in understanding how tires will grip the surface on race days, and municipalities and the aviation industry would also benefit from being able to more precisely predict atmospheric conditions. The ability to take clouds into account will also help the solar energy industry determine how much solar power can be harvested. Walker, Curtis L., “The Impact of Cloud Type on Surface Radiation and Road Pavement Temperature,” 2012: unpublished poster presentation: PDF

Weather-savvy cars and drivers

June 1, 2012  •  Driving: It’s many people’s least favorite aspect of winter. Whether it’s navigating roads covered in fresh snow or skidding on insidious black ice, winter transportation can be a white-knuckle experience. And whatever the season, even Siri, Apple’s personal digital assistant, can’t warn you that there’s a patch of fog lurking around the bend. Adverse weather is a factor in more than 1.5 million U.S. road accidents each year, resulting in more than 7,000 deaths. A prototype system being developed at NCAR could help reduce that toll by pooling and processing data gathered by weather-smart vehicles. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) In the future, however, a similar sort of digital intelligence may remove some of the stress factor from driving in dangerous conditions. NCAR scientists are developing a system in which wireless-enabled vehicles transmit automated updates about weather and road conditions to a central database, which then relays alerts to other drivers in the area. The goal is to reduce crashes, injuries, and deaths by giving drivers information about nearby hazards. “What you really want to know isn’t just the general weather conditions in the 20-mile zone around you—you want to know what’s going on at the next street corner. And should you go left or right at the light,” says NCAR scientist Sheldon Drobot. “This system will tell drivers what they can expect to run into in the next few seconds and minutes, giving them a critical chance to slow down or take other action.” The underlying science The prototype system, which is called the Vehicle Data Translator, is sponsored by the U.S. Department of Transportation’s Research and Innovative Technology Administration and Road Weather Management Program. The prototype Vehicle Data Translator aims to improve driving safety by warning motorists about nearby hazards. Information about adverse conditions would be automatically transmitted from vehicles to a remote data processing system. The system would incorporate weather information from other sources, including radars and satellites, and then send alerts to drivers in the area. (©UCAR. Illustration by Lex Ivey. This image is freely available for media & nonprofit use.*) Onboard equipment collects weather data, such as temperature, and indirect indications of road conditions, such as the activation of antilock brakes. This information is transmitted to a central database, where it is integrated with other local weather data and traffic observations, along with details about the road’s surface material. Incoming data will be anonymous to protect the privacy of drivers. The processed data would then be used to warn motorists about upcoming hazards and even suggest alternate routes. The system would also alert emergency managers to hazardous driving conditions and help road crews clear snow more efficiently. Field testing NCAR researchers Sheldon Drobot, Michael Chapman, and Brice Lambi install a sensor in a vehicle as part of testing for the Vehicle Data Translator system. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.*) In 2009, Drobot’s team first tested the system in the Detroit area, where drivers in 11 cars equipped with sensors sought out adverse winter road conditions. The researchers analyzed the reliability of the system by comparing data from the cars with weather observations from radars and satellites. They used this information to build the algorithms, or mathematical formulas, underlying the Vehicle Data Translator system. This past winter, the team took the project to Minnesota and Nevada, outfitting Department of Transportation snowplows and supervisor trucks with sensors. Eighty vehicles in Minnesota and 16 in Nevada measured temperature, pressure, humidity, and other weather variables as the drivers went about their routine jobs. The researchers will use the data to continue to develop the software, in hopes of having a system ready for operational field testing by winter 2012–13. Next year, the National Highway Traffic Safety Administration plans to use the results of these pilot tests to aid in determining whether the technology is mature enough to encourage vehicle manufacturers to include the equipment in new passenger vehicles. The system would then be made available to private vendors, according to Drobot. “We have a long history of transferring technology to public use. We want to see our efforts implemented in the real world,” he says.

When engine meets ice

May 11, 2012  •  With the help of deicing treatment on the ground and careful route selection in the air, commercial pilots now avoid most of the threat that ice will encase critical parts of a plane. But there’s another ice-related hazard gaining attention, one so low-profile up to now that the aviation community has yet to settle on what to call it. Ice and more For an overview of the development of tools at NCAR to predict in-flight icing, see the related feature in our in-depth package "From Science to Impact." It turns out that ice can not only build up on a plane’s wings; it can also do so inside sensitive parts of an aircraft engine. Pilots and scientists long dismissed this scenario, since the heat of an engine would presumably prevent any ice build-up. However, there’s growing evidence that icing resulting from ingestion of ice crystals can lead to brief engine shutdowns and interfere with pitot tubes, the heated devices attached to the fuselage that monitor a plane’s speed. Pitot icing from ice crystals may have been a factor in the loss of 228 people when an Airbus 330 plummeted into the South Atlantic Ocean after flying through storms off the Brazilian coast on June 1, 2009. Flight data recorder information retrieved from the black boxes of the aircraft has confirmed that the aircraft speed sensors malfunctioned directly before the accident and may have contributed to the events culminating in the apparent fatal stall. The final report from the French accident investigation bureau is expected to be released within months. About 150 cases of partial or complete engine power loss (as it’s often labeled within the industry) from the last several decades have now been linked to the still-mysterious phenomenon of icing in the engine compressor. In nearly all cases, the engines were restarted within a minute or two, and passengers were none the wiser, but the rising tally of events is a worrisome flag for the aviation community. Although the events span a wide range of locations and altitudes, there are enough common threads to give hope that a warning and avoidance system might be feasible. A field project in early 2013 will study engine-related icing with flights from a base in Darwin, Australia, where offshore thunderstorms form so reliably that World War II pilots gave them a name: Hector, also known as "Hector the Convector." (Photo © Jacci Rose Ingham.) NCAR is part of an international team looking into the science of engine icing events in the multiyear Study of High Ice Water Content Regions of Deep Convection (HIWC). The focus of HIWC will be a three-month field campaign (January to March 2013) based in Darwin, Australia, where intense thunderstorms occur each summer. As a Gulfstream II jet operated by a NASA contractor weaves its way through anvil regions that extend from the tops of vast oceanic storm complexes, it will gather data on areas with high concentrations of minuscule ice crystals—the conditions that appear to be most effective in getting ice into engines. The data will be used to evaluate proposed certification envelopes, now out for industry review, from the Federal Aviation Administration (FAA) and the European Aviation Safety Agency. The observations will also provide a rich and unique data set for improving understanding of deep convective clouds, including thunderstorms. The field work is being organized by NASA, Environment Canada, the Australian Bureau of Meteorology, and the FAA, with forecasting tools developed by NCAR (see below). Other parties sponsoring and contributing to the overall HIWC effort include Transport Canada, National Research Council Canada, the aircraft manufacturers Boeing and Airbus, and Science Engineering Associates. The tropical connection Ice and the tropics might seem like an incongruous pair, but cold-topped thunderstorms are common at low latitudes, and Darwin is a well-chosen launch pad for the HIWC field phase. The largest global share of engine icing reports is from the vicinity of Southeast Asia. Since 2000, air traffic across the Pacific has increased more than fivefold, which may be an important factor. Another is the region’s toasty seawater, the warmest on Earth for such a large area, which helps fuel massive mesoscale convective systems (MCSs). Over land, deep convection is well known to have intense cores associated with actively building cells that may include copious lightning, strong updrafts, and hail. Aircraft typically avoid these potential hazards by vectoring around areas of high reflectivity indicated on the pilot’s radar. However, in oceanic deep convection, these high-reflectivity areas are less commonly seen at high altitude, and lightning is rare. A Gulfstream II jet operated by a NASA contractor for HIWC will sample parts of thunderstorms laden with large numbers of small ice crystals. (Image courtesy NASA Glenn Research Center.) To learn more about engine event cases, Environment Canada and its industry counterparts have sifted through the scientific literature and available data from research flights and carried out a number of interviews with engine event pilots. They’ve concluded that aircraft are flying directly across large MCSs through oceanic updraft areas without noting high radar reflectivity regions on their radars or experiencing highly vigorous updrafts. At the same time, these aircraft are encountering very high ice concentrations associated with the deep lift and condensation of moist tropical air. This hypothesis is supported by the data from exploratory flights conducted with an industry test aircraft out of Darwin in 2010, where surprisingly high values of ice concentration were commonly observed in the absence of strong radar returns at altitude. Investigators will take a more detailed look at such conditions during the 2013 Darwin flights. The project chose the Gulfstream II in part because its engines have no history of ice accretion events. HIWC will also minimize risk by incrementally exposing the aircraft and engines to progressively longer periods of flight into regions with large amounts of ice. “Our intention is to get in, sample, get out, do some evaluations on the engines, then go back in,” says Tom Ratvasky, an HIWC principal investigator based at NASA’s Glenn Research Center. Once this build-up process is completed, he adds, longer paths through dense ice clouds can be flown with greater confidence to meet the science plan objectives.  The secrets of accretion Although many questions remain about what makes an engine icing event happen, it’s believed that tiny ice crystals—perhaps many of them smaller than 0.004 inches (100 microns)—accumulate in large enough numbers to counterbalance the heat of an engine’s interior. Pilot reports are also helping shed light on what’s happening during engine power-loss events. In many cases, pilots report they have seen and heard “rain on the windscreen,” a spattering most likely caused by tiny crystals melting on impact. Although temperatures are quite cold at these altitudes, sometimes as frigid at –58°F (–50°C), many aircraft have reported encountering air that’s up to 54°F (30°C) warmer than that just before an engine power-loss event, followed by a rapid temperature drop as the plane flies onward. These temperature changes, although initially misinterpreted as an atmospheric phenomenon, are in fact another example of a malfunction caused by ice crystals—in this case, the crystals accumulating and melting in the heated instrument housing where the temperature sensor resides. “We’ve been able to replicate those temperature anomalies in a couple of ground test facilities,” says Ratvasky. “I’m really interested in finding these in flight.” By getting to the root of accretion events, HIWC stands to make headway on some longstanding questions about cloud physics. While many field studies have explored oceanic storms, few have taken aircraft into the updrafts at the heart of these storms. There’s only skimpy data on how water droplets and ice crystals evolve and interact in these regions, and models cannot yet simulate the processes. HIWC is also being shaped by laboratory work. At a lab run by the National Research Council Canada (NRC) lab in Ottawa, researchers are injecting ice crystals into a warm tunnel the width of a shoebox, attempting to replicate what happens to ice inside the compressor section of an engine. Later this year, NASA Glenn will conduct initial validation tests in its Propulsion Systems Laboratory, a facility recently upgraded to allow ice crystals to be pulled into an actual operating jet engine at altitude conditions. Ratvasky and colleagues have worked to define and organize all aspects of the flight program, including pulling together instruments for the G-II flights. The HIWC aircraft will be equipped with six underwing pylons to house nine particle measurement probes, a variety of systems to measure bulk liquid and total water content, a next-generation pilot’s radar, and a research cloud radar. The team has worked for four years to improve the reliability and accuracy of cloud physics instruments in the harsh environment linked to high ice water content, including tests in a calibrated high-speed ice simulation wind tunnel at the NRC. A new isokinetic evaporator was designed by NRC and Environment Canada as the primary tool for measuring total water content in the HIWC field phase. It’s capable of measuring up to 10 grams of ice per cubic meter at flight speeds of 450 mph (200 meters per second) to the accuracy demanded by industry sponsors. Predicting engine-ice risk The NCAR team that’s worked on forecasts of in-flight icing for years (see sidebar) is now applying its toolbox to the problem of predicting regions fertile for ice crystal icing. The immediate goal for the 2013 HIWC field campaign is to prepare a nowcasting system, dubbed ALPHA (Algorithm for Prediction of HIWC Areas). The group carried out a two-week nowcasting exercise this past March with local forecasters in Darwin to prep for next year’s field phase. Julie Haggerty is leading the effort at NCAR to develop nowcasting tools for the HIWC project. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) “Right now we’re using some of the basic observations from people who have analyzed the 150 engine power-loss events to date,” says Julie Haggerty, the NCAR project lead and another principal investigator for HIWC. “We’re using routinely available sources of meteorological data and trying to pinpoint where a model or a satellite product shows evidence of HIWC conditions.” There are plenty of clues from satellite imagery pointing to where convection is strongest. For example, when powerful updrafts punch through a storm’s shield of ice crystals, they can produce a bright bubble of cumulus called an overshooting top. However, the zones of interest to HIWC, those packed with many tiny ice crystals, don’t lend themselves to easy recognition from satellites. Even when an aircraft enters such a zone, the small size of the ice crystals may produce only an innocuous signal on radar, often as weak as 20 dBz (decibels of reflectivity) or less. (The strength of the signal returning from an object drops by a thousandfold if the object’s diameter is cut in half.) Even if a region prone to engine icing were easy to spot, it might not last for long. It’s believed that some zones of high ice content may span less than 20 miles (32 kilometers) and exist for less than an hour. That adds to the challenge facing NCAR’s forecast development team and HIWC itself. “We’re specifically trying to find regions that are small scale and short lived,” says Haggerty. If the project does live up to its promise, it could lead to new regulations on how aircraft engines are built and new flight guidance for pilots, perhaps building on the ALPHA system now being created at NCAR. There could also be improvements in the weather prediction models that are small-scale enough to resolve clouds. Participants are stressing the power of teamwork in making progress on the insidious, understudied problem of engine core icing. “This is by far one of the most collaborative efforts I’ve seen,” says NASA’s Ratvasky. “There’s no way any one organization could do this project by itself.”

Keeping aircraft safe from ice

April 27, 2012  •  When flight instructor Scott Dennstaedt studied possible routes for a recent flight from Denver to Bend, Oregon, he checked standard aviation forecasts—plus a pair of high-precision NCAR atmospheric maps that track potentially hazardous icing conditions. Thanks to that information, he determined that he could safely fly above icing and storms that would develop at lower altitudes along the route. An aircraft coated with ice that formed in freezing rain. (Photo courtesy NASA Glenn Research Center.) “The NCAR products helped us make a good decision,” Dennstaedt says. “We were able to integrate them with other weather guidance to really understand where the vertical extent of the clouds was that day.”  NCAR’s online icing maps, developed at the request of the Federal Aviation Administration, represent a major advance in the nation’s effort to ensure flying safety. An independent report commissioned by the FAA credited them with preventing an average of eight accidents a year, saving lives and reducing costs by more than $60 million annually. “These products help make flying safer because dispatchers and pilots of smaller aircraft can choose flight paths that avoid icing conditions,” says Marcia Politovich, who oversees in-flight icing research at NCAR. “For commercial airlines, the information we provide enables them to avoid the delays and excessive fuel costs associated with in-flight icing.” Marcia Politovich leads NCAR's icing research. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.) Icy weather, including ice pellets and cloud droplets that freeze on contact, can affect air travel anywhere in the country, at any time of the year, and especially during colder months. When ice builds up on aircraft wings, it can increase the drag on the airplane and make it difficult to stay aloft. Icing has played a role in a number of high-profile crashes, including the 1959 crash that killed Buddy Holly and other rock ‘n roll legends. A study by the National Transportation Safety Board in 2002 found that in-flight icing was responsible for dozens of accidents a year, mostly among smaller, general aviation aircraft. Cancellations and delays due to icy weather can also cost airlines millions of dollars. Even when aircraft are certified to fly through icing conditions, the risk can prompt pilots to detour for hundreds of miles. In the late 1980s, as the number of commuter aircraft was expected to increase sharply, the FAA approached NCAR to see if it would be possible to identify and even forecast regions in clouds with high potential for icing conditions. At that time, meteorologists engaged in basic research had already spent decades studying cloud physics and the processes by which some droplets remain liquid even at subfreezing temperatures. Those “supercooled” droplets are especially dangerous because they can freeze on an airplane’s wing. Rock 'n roll pioneers Buddy Holly (above), Ritchie Valens, and the Big Bopper died in a 1959 small plane crash that occurred in moderate to heavy icing conditions. (Photo courtesy Wikimedia Commons.) “The main issue is the mix of supercooled droplets and ice particles in a cloud, which is extremely important to understanding how an aircraft ices up,” says John Hallett. A professor emeritus at the University of Nevada and the Desert Research Institute, Hallett has studied cloud processes since the 1950s.  “If there are enough of the supercooled droplets in the wrong place, the aircraft will crash.” A series of field projects funded by the National Science Foundation and other agencies in the last 20 years helped scientists further understand how environmental conditions such as the amount and type of dust in the air can profoundly affect icing conditions by changing the temperature at which the droplets freeze. To create the icing maps, a team of scientists at NCAR and their collaborators in the university community refined computer models to better capture the physics of cloud droplets and ice particles. The researchers also developed artificial intelligence techniques to evaluate observations from ground-based radar, pilot reports, and satellites. The FAA in 2002 approved the first version of an NCAR icing map, known as Current Icing Potential (CIP). The map, which regularly updates estimates of current icing conditions, enables dispatchers and pilots to make fly/no-fly decisions, plan flights, change routes, and select altitudes. The agency has since approved a companion NCAR product, Forecast Icing Potential (FIP), that predicts regions of icing and the likely severity. The products are constantly upgraded, and Politovich notes that additional research will provide even more guidance to the aviation community. “There are still a lot of mysteries about the freezing process,” she says. “As we dig deeper and get a better feel for which types of particles in clouds are associated with which geographic regions and times of year, we can produce more information about the size of droplets and ice crystals. That would tell us which aircraft are likely to be most affected along a particular route. This is the kind of information the aviation community is asking for.”

Research that reaps results

April 27, 2012  •  There hasn’t been a single U.S. airline flight downed by wind shear in more than 15 years. That’s no accident. It’s the result of painstaking work by NCAR and colleagues across a community of researchers who produced a world-leading system for warning pilots about wind shear at airports. When a rain shaft enters drier air, the rain-cooled parcel of air may gather momentum and produce a microburst. The strongly contrasting winds over short distances generated by microbursts caused a number of U.S. aviation disasters before NCAR and partners developed a warning system for wind shear. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.*) This is just one example of how a unique, collaborative ecosystem of end-to-end science can yield positive, powerful impacts. Many facets of everyday life, from boarding a plane to turning on the lights or driving down the highway, are becoming safer and more cost-effective with the help of technologies rooted in atmospheric science. This includes research carried out at NCAR, the 100-plus members and affiliates of UCAR, and the federal agencies that support and collaborate on this work, including the National Science Foundation, NCAR’s primary sponsor. When scientists carry out basic research, it’s not always clear how it will play out. It’s a safe bet that Albert Einstein wasn’t thinking of compact discs when he laid out the theoretical foundations for lasers nearly a century ago. Today, basic research in the United States—60% of which is federally funded, and most of which takes place at universities—is an impressive economic engine “Innovations that flow from university-based basic research are at the root of countless companies,” notes the Science Coalition in its 2010 report Sparking Economic Growth. NCAR director Roger Wakimoto. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.*) “The transfer of research to applications is a fundamental aspect of NCAR’s mission,” says NCAR director Roger Wakimoto. “Basic research has always been at the core of activities that take place within the university community and NCAR. However, weather and climate impact people’s lives in profound ways, so it is both exciting and necessary that much of our work in atmospheric sciences has direct applications to society.” In order to understand the atmosphere, scientists rely heavily on supercomputing power and far-flung observations, plus the software and connectivity to model the atmosphere and get results to users. All of these areas have advanced by leaps and bounds in recent years. With the help of new technologies, plus years of foundational research, forecasting has gone light years beyond “fair and warmer.” For example:  Building on knowledge gained from field studies of how snowflakes and ice crystals form within high, cold clouds, NCAR developed a system to warn private pilots—whose smaller aircraft might not include deicing equipment—where and when dangerous ice accumulations could encrust their planes in flight. The resulting forecasts, supported by the Federal Aviation Administration (FAA), now help avert an average of eight accidents per year, saving lives as well as some $60 million. Decades of study to unravel the complex, turbulent wind flow just above Earth’s surface have fed into a system that offers pinpoint forecasts of how much energy might be gleaned, hour by hour, from a wind turbine. If the wind suddenly becomes too weak or strong for turbines to operate, a utility might have to fire up a conventional power plant or buy power on the open market. The NCAR forecasts saved research sponsor Xcel Energy $6 million in 2010 alone by making such decisions more efficient and accurate. Utilities as a whole can benefit from the findings published in association with this work. Every day, the nation is crisscrossed by millions of potential weather sensors: cars and trucks. A system developed at NCAR promises to create “weather-smart vehicles” that can transmit weather data anonymously to a central point where road conditions can be analyzed and extended to the near future. Once this technology is in place, your weather-smart car could flash a warning message on the dashboard letting you know of treacherous ice or severe weather just ahead. The system’s development is being funded by the Federal Highway Administration (FHWA) and the U.S. Department of Transportation. The design for this parachute-borne dropsonde, which samples atmospheric conditions as it descends, is among more than 100 patented innovations developed at NCAR. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.*) Streamlining the path to progress The end-to-end science fostered by NCAR and UCAR hasn’t always been the norm. After World War II, universities and federally sponsored labs began producing a wealth of basic research. However, they were often discouraged by custom or by law from applying their results to the real world. Attitudes began changing with NASA’s space missions and its Technology Utilization Program, launched in 1962, which became known for its increasingly fruitful crop of spinoffs. In 1980, Congress passed the Bayh-Dole Act, which gave the green light for universities to create programs that would bring their own research into practical applications. An explosion of tech transfer followed, especially in biotechnology and health services. Today’s lithium-ion battery, for example, emerged from research on materials science carried out at the University of Texas at Austin in the 1980s. A number of UCAR’s member institutions jumped at this new chance to transfer their technology. In turn, that inspired UCAR to see how it might help bring the gains made in atmospheric science more directly to society. After surveying its members to get their views, UCAR launched its own spinoff: the UCAR Foundation, established in 1986. The foundation serves as a bridge between industry and the R&D that takes place at NCAR and at UCAR via its community programs. Through the foundation, private firms can acquire the rights to take a promising technology and adapt it for commercial uses. The foundation has licensed everything from highly specialized software to educational training modules. With more than 140 patents assigned to NCAR- and UCAR-based researchers in the last 20 years, there’s plenty more for innovative firms to mine. Part of the foundation’s licensing revenue flows back to NCAR and UCAR to support additional research—and perhaps another end-to-end story.  A university-based springboard The structure of NCAR and UCAR—unique among the nation’s science disciplines—paves the way for innovation to bring impact to everyday life. NCAR’s research is unusually wide-ranging, from the flow of magnetism within the Sun to the flow of heat in the ocean. Much of NCAR’s work is carried out with collaborators at universities and labs across the nation and beyond, which further expands the breadth of the science. After hundreds were killed in aircraft accidents related to wind shear in the 1970s and 1980s, several field programs investigated the issue, including the FAA-funded CLAWS (Classify, Locate, and Avoid Wind Shear), led by NCAR's John McCarthy. The goal was to develop a prototype system for forecasting microbursts and other wind shear events and for providing timely advisory information to pilots. Here McCarthy is seen working in the control tower at Denver's former Stapleton International Airport during CLAWS in the summer of 1984. (©UCAR. This image is freely available for media & nonprofit use.*) NCAR’s Research Applications Laboratory (RAL), with more than 240 staff serving a variety of funder-clients, is well equipped to take knowledge produced by this collaborative web and transmute it into technology ready to be adapted for real-world use. The seeds of the lab were planted after a series of airline disasters, including the crash of Eastern Air Lines Flight 66, which plummeted to the ground on approach to New York’s Kennedy Airport on June 24, 1975, killing 113 people. Eminent meteorologist Ted Fujita (University of Chicago) studied this and other accidents and concluded that wind shear produced by powerful downdrafts was likely to blame. Many doubted the idea, but field projects in 1978 and 1982 that were organized by NCAR, the University of Chicago, and other partners confirmed the deadly power of what Fujita dubbed microbursts. The cluster of scientists at the center of those projects went on to design the successful warning system for wind shear, and their activities gradually expanded and diversified to become the heart of NCAR’s applied research efforts. “Because the wind shear work led to a dramatic reduction in microburst-related airline accidents, the FAA decided it was time to tackle more aviation hazards,” notes RAL deputy director William Mahoney. These new focal points have included other thunderstorm hazards, plus turbulence, icing on the ground and in the air, and ceiling and visibility prediction. “As the research portfolio expanded, other U.S. and even foreign government agencies decided to take advantage of RAL’s research-to-operations experience to solve problems," says Mahoney. A tornado uprooted trees and damaged buildings in Norman, Oklahoma—home to the National Weather Center—on April 13, 2012. (Photo by Bob Henson, UCAR.) RAL now works on a wide array of topics, including water resources, homeland security, and other realms of societal benefit, including the potential for enhanced climate information to benefit agriculture and human health and the optimal ways to build weather warnings and outlooks that save lives. Even the way a hurricane warning is worded could make the difference in how people respond, as NCAR research has found. There’s no limit in sight to the ways that improved weather and climate forecasts can benefit people and communities. “As society continues to become more global, more diverse, and more weather- and climate-vulnerable, the value of research to enhance the benefits of weather and climate information to society only continues to grow,” says Jeff Lazo, an economist in RAL. According to Lazo and colleagues, the combined effects of “good” and “bad” weather can cause U.S. economic output in a given year to be as much as $240 billion higher or lower than the long-term average. “Weather affects nearly every economic sector and pretty much every activity and decision we undertake as individuals from day to day,” he says. The value of innovative weather forecasts to public health goes far beyond seeking shelter from a storm. NCAR scientists are working with African colleagues in meteorology and public health to enhance regional forecasts of the onset of the rainy season across meningitis-prone areas. The disease is associated with dry, dusty conditions that precede seasonal rains, so when those rains are predicted more accurately, vaccines are targeted more effectively. Precipitation and innovation Kelvin Droegemeier. (Photo courtesy University of Oklahoma) From his vantage point as a student, researcher, professor, and administrator, Kelvin Droegemeier has seen how real-world benefits emerge from the lab, field, and desktop (not to mention supercomputers). A past chair of the UCAR Board of Trustees, Droegemeier is currently vice president for research at the University of Oklahoma and holder of OU’s Weathernews Chair Emeritus of Applied Meteorology. He’s been a leader in the development of fine-scale modeling of thunderstorms, where it’s critical to understand how tiny cloud droplets and ice crystals can lead to baseball-sized hail and hurricane-strength winds. “Basic research in cloud physics has been an important foundation for some of the most advanced capabilities we now enjoy in the detection and prediction of high-impact local weather,” he says. In 2011 and 2012, Doppler weather radars operated across the country by the National Weather Service are being upgraded to dual-polarization systems, which will allow them to better distinguish rain, hail, and storm debris. Droegemeier points out that the “dual-pol” capabilities in these and other radars rely heavily on basic research in cloud and precipitation physics. That same research is also combining with recent advances in computer modeling to give scientists the ability to simulate the fine-scale physical activity going on within clouds. Such cloud-resolving models now represent a wide variety of cloud physics processes using sophisticated schemes linked with radiation and other model physics, says Droegemeier. And, he adds, "global climate change, hydrology, ecology, and a host of other research disciplines rely heavily upon basic research in cloud and precipitation physics for both understanding and predicting important components of the Earth system.”  

Winter weather: Story tips from NCAR and UCAR

BOULDER—Improved forecasting of winter storms and innovative technological systems to help keep winter drivers safe are among the goals of new work at the National Center for Atmospheric Research (NCAR) and collaborating organizations. Help with winter driving hazards. Drivers could one day get warnings from the Vehicle Data Translator system, now in development and testing. (©UCAR. Illustration by Lex Ivey. See related background story for uncropped and high-resolution versions.) Winter research extends from the tropics to Alaska and from the ground to the outer atmosphere. Areas of focus include the evolution of winter storms, wintertime events in the stratosphere that can jeopardize technological systems, improved tools to measure snowfall, projecting future spring snowpack in the Western states, and more. In Depth: Winter Weather, a special report, provides background, photos, interactives, and video about winter-related research from NCAR and UCAR. Research highlights Keeping drivers safe. NCAR is helping develop and test an innovative technological system that will eventually help protect drivers from sudden surprises like black ice, fog, and other hazardous weather conditions. The prototype system, called the Vehicle Data Translator and sponsored by the U.S. Department of Transportation, gathers detailed information about weather and road conditions from moving vehicles and relays alerts to other vehicles in the area.“The goal is to reduce crashes, injuries, and deaths by giving drivers information about nearby hazards,” says NCAR scientist Sheldon Drobot. “The system will tell drivers what they can expect to run into in the next few seconds and minutes, giving them a critical chance to slow down or take other action.” | Winter driving: where the rubber meets the road > Improving snow forecasts. Scientists are making headway on deciphering the mechanisms that lead to snow formation within winter storms. One of the key findings from a recent field project, led by the University of Illinois and supported in part by NCAR aircraft and ground-based instruments, is that small pockets of rising air near the tops of winter storms may play a large role in generating snowfall on the ground. This research could one day help forecasters analyze how a storm is evolving and what to expect.National Weather Service meteorologists are already being briefed on the preliminary findings, according to Bob Rauber, head of the Department of Atmospheric Sciences at the University of Illinois at Urbana–Champaign and leader of the recent field project. | Where snow is born: getting on top of winter storms > Could “Snowtober” happen again? Why did parts of the Northeast get buried by record snow last month? An analysis shows that the historic storm was fueled by a combination of a strong jet stream, unusually warm waters southeast of New England, and copious amounts of low-level moisture extending south toward the remnants of Hurricane Rina. Yet, no record low temperatures were set. | The October snow blitz: What made "Snowtober" so unusual? Measuring snow depth. Recent snowstorms have served as reminders of how difficult it is to accurately measure snow, given the effects of drifting, melting, and widely varying types of snowflakes. To replace old-fashioned yardsticks, scientists are developing a battery of high-tech tools, such as ultrasonic sensors and GPS-based technologies. Better snow measurements will help decision makers project water availability during the following summer, especially in mountainous areas that rely on runoff for agriculture and other needs. |  Accumulated wisdom: How to measure snow > Projecting future snowpack. Recent research indicates that spring snowpack in many mountainous regions of Western states may disappear this century as temperatures warm. A new video and animation shows the outlook for spring snowpack in the West through 2100. | Spring snowpack in a warmer world > Protecting GPS signals. While storms and other winter events pound the lower atmosphere, the stratosphere is home to a different wintertime phenomenon: sudden warming events. Scientists are using computer models and observations to learn about these events, which can threaten radio communications, GPS signals, and other sensitive technological systems. | Winter's stratospheric reach > Linking the Indian Ocean to U.S. storms. An international field project in the Indian Ocean this winter, involving NCAR and numerous other organizations, seeks to better understand an atmospheric phenomenon known as the Madden-Julian Oscillation that affects global weather and climate patterns. The research could lead to improved long-term forecasts of winter storms in North America. | Scientists probe Indian Ocean for clues to worldwide weather patterns > Training forecasters. The University Corporation for Atmospheric Research (UCAR), which manages NCAR, trains meteorologists on atmospheric processes associated with winter storms. The classes, part of a wide spectrum of in-person and distance training run by UCAR’s COMET Program, are designed to improve forecasters’ skills in predicting winter weather. The COMET Program also links university researchers with National Weather Service meteorologists to carry out studies of mutual interest, such as a recent project to improve winter forecasts in the Anchorage area. | Predicting snow in the Anchorage bowl >


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