NCAR-based climate model joins seasonal forecasting effort

January 12, 2017 | An NCAR-based computer model known for global climate projections decades into the future recently joined a suite of other world-class models being used to forecast what may lie just a few months ahead.The Community Earth System Model has long been an invaluable tool for scientists investigating how the climate may change in the long term — decades or even centuries into the future. Last summer, CESM became the newest member of the North American Multi-Model Ensemble (NMME), an innovative effort that combines some techniques typically used in weather forecasting with those used in climate modeling to predict temperature and precipitation seasons in advance. The result is a bridge that helps span the gap between two-week forecasts and decades-long projections.The forecasted temperature anomalies (departures from average) over North America made by the entire NMME suite (top) and by CESM (middle). Observed temperature anomalies for the same period (bottom). Click to enlarge. (Images courtesy NOAA.) But NMME also builds another bridge: this one between operational forecasters, who issue the forecasts society depends on, and researchers. Now a collection of nine climate models, the NMME has proven it produces more accurate seasonal forecasts than any one model alone. It was adopted in May by the National Oceanic and Atmospheric Administration (NOAA) as one of the agency's official seasonal forecasting tools."What is so important about NMME is that it's bringing research to bear on operational forecasts," said Ben Kirtman, a professor of atmospheric sciences at the University of Miami who leads the NMME project. "The marriage between real-time prediction and research has fostered new understandings, identified new problems that we hadn't thought about before, and really opened up new lines of research."A new way to start a climate model runWeather models and climate models have a lot of things in common; for one, they both use mathematical equations to represent the physical processes going on in the atmosphere. Weather models, which are concerned with what’s likely to happen in the immediate future, depend on being fed accurate initial conditions to produce good forecasts. Even if a weather model could perfectly mimic how the atmosphere works, it would need to know what the atmosphere actually looks like now — the temperature and pressure at points across the country, for example — to determine what the atmosphere will look like tomorrow.Climate modelers, on the other hand, are often interested in broad changes over many decades, so the exact weather conditions at the beginning of a simulation are usually not as important. In fact, their impact is quickly drowned out by larger-scale trends that unfold over long time periods.In recent years, however, scientists have become interested in whether climate models — which simulate changes in ocean circulation patterns, sea surface temperatures, and other large-scale phenomena that have lingering impacts on weather patterns — could be initialized with accurate starting conditions and then used to make skillful seasonal forecasts.The NMME project is exploring this question. The global climate models that make up NMME project are all being initialized monthly to create multiple forecasts that stretch a year in advance. Along with CESM, those models include the NCAR-based Community Climate System Model, Version 4, which is being initialized by Kirtman's team at the University of Miami. (See a full list of models below.)Taken together, the individual model forecasts reveal information to forecasters about the amount of uncertainty in the seasonal forecast. If individual forecasts vary substantially, the future is less certain. If they agree, forecasters can have more confidence.The forecasted precipitation anomalies (departures from average) over North America made by the entire NMME suite (top) and by CESM (middle). Observed precipitation anomalies for the same period (bottom). Click to enlarge. (Images courtesy NOAA.)A valuable collection of dataCESM's first seasonal forecast as part of NMME, which was issued for July, August, and September 2016, was perhaps the most accurate of any in the ensemble. The forecast — which called for conditions to be warmer and drier than average across most of the United States — was issued after more than a year of work by NCAR scientists Joseph Tribbia and Julie Caron.All of the models in the NMME suite must be calibrated by running "hindcasts." By comparing the model's prediction of a historical season with what actually happened, the scientists can identify if the model is consistently off in some areas. For example, the model might generally predict that seasons will be wetter or cooler than they actually are for certain regions of the country. These tendencies can then be statistically corrected in future forecasts."We ran 10 predictions every month for a 33-year period and ran each prediction out for one year," Tribbia said. "You can learn a lot about how your model performs when you have so many runs."Once CESM was calibrated, it joined the NMME operational suite of models. But the data generated by the rigorous hindcasting process wasn't cast aside once the calibration was finished. Instead, every modeling group has saved not only monthly data, but also high-frequency daily data that are being stored at NCAR.The trove of historical predictions, along with the new predictions being generated in real-time, are an incredible resource for scientists interested in improving the techniques for initializing climate models and exploring what types of things can, and cannot, be predicted in advance."Predictability research can be a challenge. The NMME dataset allows you to check yourself in a robust way," Kirtman said. "If you think you've found a source of predictability in the hindcast mode, you can then try to do it in real time. It's really exciting — and it really holds your feet to the fire."This year, as much as 18.5 terabytes of NMME data were downloaded from NCAR monthly, according to NCAR's Eric Nienhouse, who oversees the data archive.Now that CESM is an active part of NMME, Tribbia and Caron will also be diving into the data."Now the fun begins," Caron said. "We get to start looking at the data to see how we're doing, and what we might change in the future to make our seasonal forecasts better."Models that make up NMME:NCEP CFSv2: National Centers for Environmental Prediction Climate Forecast System Version 2 (NOAA)CMC1 CanCM3: Canadian Meteorological Centre/Canadian Centre for Climate Modeling and AnalysisCMC2 CanCM4: Canadian Meteorological Centre/Canadian Centre for Climate Modeling and AnalysisGFDL FLOR: Geophysical Fluid Dynamics Laboratory Forecast-oriented Low Ocean Resolution (NOAA)GFDL CM2.1: Geophysical Fluid Dynamics Laboratory Coupled Climate Model Version 2.1 (NOAA)NCAR CCSM4: National Center for Atmospheric Research Community Climate System Model Version 4NASA GEOS5: NASA Goddard Earth Observing System Model Version 5NCAR CESM: National Center for Atmospheric Research Community Earth System ModelIMME: National Centers for Environmental Prediction International Multi-Model Ensemble (NOAA)Writer/contact:Laura Snider, Senior Science Writer  

Top stories of 2016

Zika risk estimated for U.S. citiesA multidisciplinary team of scientists studied the possible timing and location of Zika virus risk in the United States. A powerful new supercomputerThe new system for the NCAR-Wyoming Supercomputing Center is capable of more than 2.5 times the amount of scientific computing performed by its predecessor. SOARS turns 20The SOARS Program has been boosting diversity in Earth system science for two decades.Extreme downpours could quintuple 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.New NCAR climate exhibitThe exhibits at NCAR's Mesa Lab in Boulder provide the public with an engaging and scientifically accurate forum to learn about climate. Solar model pulls order out of chaosPushing a solar model to the highest resolution ever attempted brings order back to the Sun's magnetic tangle.Investigating air quality in KoreaNCAR scientists traveled to South Korea as part of a field campaign to investigate the region's air quality.U.S. water forecasts tap NCAR modelNOAA is using an advanced NCAR prediction system as the core of the new National Water Model.UCAR partners with AmazonUnidata has partnered with Amazon Web Services to make NEXRAD data from NOAA available in the cloud in near real time. Flights investigate Southern Ocean  The ORCAS field campaign is helping scientists better understand just how much carbon dioxide the icy waters are able to lock away.  Ocean temps predict U.S. heat wavesThe formation of a distinct pattern of sea surface temperatures in the Pacific Ocean can predict an increased chance of summertime heat waves up to 50 days in advance.3D-printed weather stations Scientists successfully installed the first wave of low-cost weather stations in Zambia with 3D-printed parts. Visualization of the year  Researchers at NCAR and the University of Miami are seeking clues about what really goes on inside a tornado using highly detailed computer simulations of wind fields.

NCAR & UCAR Scientists Highlight Advances in Weather, Water & Climate Research at AGU 2016

SAN FRANCISCO – Scientists with the National Center for Atmospheric Research (NCAR) and the University Corporation for Atmospheric Research (UCAR) will make dozens of presentations at the fall meeting of the American Geophysical Union (AGU) during the week of December 12–16.Media Q&AThe Path Forward from Paris, One Year LaterUCAR President Antonio J. Busalacchi, AGU President Margaret Leinen (Scripps Institution of Oceanography), and Carlos Nobre (Brazilian National Institute of Science & Technology for Climate Change) - related to Union Session U23ATuesday, December 13, 4 p.m. - Moscone West 3000 (Press Conference Room)Note: The Moscone West Q&A follows Union Session U23A with these participants in Moscone North Hall E from 1:40-3:40 p.m.Selected Talks MONDAY | TUESDAY | WEDNESDAY | THURSDAY | FRIDAYFull calendar, special events& exhibitsNCAR & UCAR at AGU 2016>@AtmosNewsLive | #NCARscience MONDAY, December 12Getting Space Weather Data and More From 'Noise' in GPS Signals: The COSMIC MissionsWilliam Schreiner, UCARSA11A-04: Satellite Constellations for Space Weather and Ionospheric Studies: Overview of the COSMIC and COSMIC-2 Missions8:45-9:00 a.m., Moscone West 2016Climate Change, Lyme, Zika, and Other Vector-Borne DiseasesAndrew Monaghan, NCARGC12A-02: Assessment of Climate Change and Vector-Borne Diseases in the United States10:35-10:50 a.m., Moscone West 2020Extreme Rainfall Could Increase Fivefold Across Parts of the U.S. Later This CenturyAndreas Prein, NCARGC13H-04: The Future Intensification of Hourly Precipitation Extremes2:25-2:40 p.m., Moscone West 3003Building Resilient Cities and Ecosystems: Food, Energy, and Water SecurityPatricia Romero-Lankao, NCARU13A-05: Urbanization, Extreme Climate Hazards, and Food/Energy/Water Security2:54-3:12 p.m., Moscone West 2022/2024TUESDAY, December 13Carbon Dioxide's Opposite Effects in the Upper AtmosphereStan Solomon, NCARSA21C-03: Climate Change in the Upper Atmosphere8:30-8:45 a.m., Moscone West 20163D-Printed Weather Stations Aid Forecasting in Developing NationsPaul Kucera, NCARH23F-1637: Development of Innovative Technology to Expand Precipitation Observations in Satellite Precipitation Validation in Under-developed Data-Sparse Regions1:40-6:00 p.m., Moscone South - Poster HallScenarios for Reaching the Paris Agreement TargetsBen Sanderson, NCARGC24D-02: Pathways to 1.5 Degrees: New GCM Simulations for Scenarios Which Meet the Paris Temperature Targets4:15-4:27 p.m., Moscone West 3003WEDNESDAY, December 14Seeing Into Tornadoes and Hurricanes with High-Resolution SimulationsGeorge Bryan, NCARIN31F-07: Insights into Tornadoes, Hurricanes from High-Resolution Simulations9:30-9:45 a.m., Moscone West 2000A Weather Resiliency Toolbox for Communities and BusinessesJames Done, NCARPA32A-03: Tools in Support of Planning for Weather and Climate Extremes10:58-11:11 a.m., Moscone South 304Exploring Unanswered Questions in the Evolution of Prehistoric Climate - The Emiliani LectureBette Otto-Bliesner, NCARPP32A-01: Resolving Some Puzzles of Climate Evolution Since the Last Glacial Maximum: A Melding of Paleoclimate Modeling and Data11:20 a.m.-12:20 p.m., Moscone West 2022/2024THURSDAY, December 15Novel Uses of Climate Information for Water Utility Planners David Yates, NCAR U42A-02: The Novel Use of Climate Information in Water Utility Planning 10:40-10:58 a.m., Moscone South 102What's In Wildfire Smoke? Jerome Barre, NCAR A42D-04: Quantifying Fire Emissions and Associated Aerosol Species Using Assimilation of Satellite Carbon Monoxide Retrievals 11:05-11:20 a.m., Moscone West 3004 <FRIDAY, December 16What's Causing Errors in Hurricane & Tropical Storm Forecasts? Chris Davis, NCAR A54F-06: On the Origin of Large Tropical Cyclone Track Errors 5:15-5:30 p.m., Moscone West 3012  Full calendar, special events & exhibit infoNCAR & UCAR at AGU 2016>@AtmosNewsLive | #NCARscience | #AGU16

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

A favorable forecast for Kenyan students

November 30, 2016 | As scientists expand a program to provide critically needed weather observations in developing countries, they are forging a partnership with local schoolchildren and their teachers.The students and teachers are helping to oversee and maintain innovative weather stations, built largely with 3D-printed parts, at four schools in Kenya. By transmitting information about temperature, rainfall, and other weather parameters, the stations can help alert communities to floods and other potential disasters, as well as provide improved weather forecasts to local farmers, who are deciding when to plant and fertilize crops.NCAR scientist Paul Kucera describes the various components of the 3D-PAWS at the Sirua Aulo Maasai High School. (©UCAR. Photo by Kristin Wegner. This image is freely available for media & nonprofit use.) The weather stations, known as 3D-PAWS (for 3D-Printed Automated Weather Stations), are built with components that can be easily replaced if they wear out in the field. They were designed by weather experts at the National Center for Atmospheric Research (NCAR) and its managing entity, the University Corporation for Atmospheric Research (UCAR)."In my 30 years of doing fieldwork, this is one of the best deployments I've ever had," said NCAR scientist Paul Kucera. "At every school, we were joined by hundreds of students and dozens of teachers who wanted to learn more about the weather stations and the value of these forecasts."The weather stations were installed as a partnership with the Global Learning and Observations to Benefit the Environment (GLOBE) program, an international science and education initiative that encompasses tens of thousands of schools. This approach means that 3D-PAWS serves the dual purpose of educating students and improving forecasts."This is a great partnership to now extend our weather stations to schools," said Kristin Wegner, a project manager with the GLOBE Implementation Office, based at UCAR. "There is so much enthusiasm among the teachers and students because it's such a great learning tool as well as helping their communities."Students will learn about local weather and climate by comparing their weather observations to those taken at other schools using science protocols established by GLOBE. They can also assess the impacts of climate change on society and the environment, as well as see how the observations help with farming, flood prediction, and other applications.The installments took place during GLOBE's biannual Lake Victoria Learning Expedition, in which students and scientists from around the world explore the environment around the lake and discuss potential research collaborations. The expedition was coordinated by GLOBE Africa Regional Coordinator Mark Brettenny and  GLOBE Kenya Assistant Country Coordinator Charles Mwangi. Schools also received equipment donated from Youth Learning as Citizen Environmental Scientists.Needed: more stationsLike many developing countries, Kenya does not have detailed forecasts, partly because weather stations are scarce. The density of stations in Africa is eight times lower than recommended by the World Meteorological Organization. Building out a network can be prohibitively expensive, with a single commercial weather station often costing $10,000 to $20,000, plus ongoing funding for maintenance and replacing worn-out parts.To fill this need, UCAR and NCAR scientists have worked for years to come up with a weather station that is inexpensive and easy to fix and can be adapted to the needs of the host country. The resulting 3D-PAWS are constructed out of plastic parts that are custom designed and can be run off a 3D printer, along with off-the-shelf sensors and a basic, credit card-sized computer developed for schoolchildren.The total cost is about $300 per station. As the stations age, the host country can easily have replacement parts printed.Funding for the project comes from the U.S. Agency for International Development's Office of Foreign Disaster Assistance and the U.S. National Weather Service.Scientists installed the 3D-PAWS in Zambia earlier this year. Kenya is the second country to receive them."We're looking forward to installing more stations," Wegner said. "Additional schools are already asking about them."FundersU.S. Agency for International Development's Office of Foreign Disaster Assistance U.S. National Weather Service.PartnerGlobal Learning and Observations to Benefit the Environment (GLOBE)Writer/contact:David Hosansky, Manager of Media Relations

Days of record-breaking heat ahead

BOULDER, Colo. — If society continues to pump greenhouse gases into the atmosphere at the current rate, Americans later this century will have to endure, on average, about 15 daily maximum temperature records for every time that the mercury notches a record low, new research indicates.That ratio of record highs to record lows could also turn out to be much higher if the pace of emissions increases and produces even more warming, according to the study led by scientists at the National Center for Atmospheric Research (NCAR).Over the last decade, in contrast, the ratio of record high temperatures to record lows has averaged about two to one."More and more frequently, climate change will affect Americans with record-setting heat," said NCAR senior scientist Gerald Meehl, lead author of the new paper. "An increase in average temperatures of a few degrees may not seem like much, but it correlates with a noticeable increase in days that are hotter than any in the record, and nights that will remain warmer than we've ever experienced in the past." The United States has experienced unusual warmth lately, as indicated by this July 22, 2016, weather map showing much of the country facing highs in the 90s and 100s and lows in the 70s. New research indicates that more record high temperatures may be in store. (Weather map by the National Oceanic and Atmospheric Administration's Weather Prediction Center.)The 15-to-1 ratio of record highs to lows is based on temperatures across the continental United States increasing by slightly more than 3 degrees Celsius (5.4 degrees Fahrenheit) above recent years, which is about the amount of warming expected to occur with the current pace of greenhouse gas emissions.The new research appears this week in the "Proceedings of the National Academy of Sciences." It was funded by the Department of Energy (DOE) and the National Science Foundation (NSF), which is NCAR's sponsor. The study was coauthored by NCAR scientist Claudia Tebaldi and by Dennis Adams-Smith, a scientist previously at Climate Central and now at the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory.Hotter days  In a 2009 study, Meehl and colleagues found that the ratio of record daily high temperatures to record daily low temperatures has steadily increased since the 1970s as average temperatures over the United States have warmed. Computer models at that time indicated that the ratio could continue to increase during this century, although the research team looked into just one scenario of future emissions. The scientists also found that the models were overstating the ratio of record highs to record lows in recent years, compared to observations.By digging further into the issue and analyzing why the models differed from observations, Meehl and his co-authors have now produced a better calibrated projection of future record-breaking daily highs across the U.S. They based their projections on the average temperature increase over the continental United States, rather than on a particular scenario of future emissions.By about 2065, for example, U.S. temperatures will rise by an average of slightly more than 3 degrees C (5.4 degrees F) if society maintains a “business as usual” increase in the emission of greenhouse gases. Under such a scenario, the ratio of record daily high temperatures to record daily lows will likely be about 15 to 1, although it could range anywhere from 7 to 1 up to 22 to 1, the study found.If temperatures increase even more this century, the ratio of record highs to record lows will jump substantially. For example, if temperatures climb more than 4 degrees C (7.2 degrees F), Americans could experience about 38 record highs for every record low. Such an outcome could occur if society does not make any efforts to mitigate the production of greenhouse gases."Every degree of warming makes a substantial amount of difference, with the ratio of record highs to record lows becoming much greater," Meehl said. "Even with much warmer temperatures on average, we will still have winter and we will still get record cold temperatures, but the numbers of those will be really small compared to record high maximums."If temperatures were not warming, Meehl said, the ratio of record highs to record lows would average out to about one to one.Instead, record high temperatures have already become a common occurrence in much of the country. The ratio of record highs to lows has averaged about 2 to 1 over the first decade of the 21st century, but there is considerable year-to-year variation. The ratio was about 5 to 1 in 2012, dropping to about 1 to 1 in 2013 and 2014, then almost 3 to 1 in 2015. The unusual warmth of 2016, resulting from both climate change and natural patterns such as El Niño, has led to 24,519 record daily maximums vs. 3,970 record daily minimums—a ratio of about 6 to 1.Precipitation and the warm 1930sA key part of the study involved pinpointing why the models in the 2009 study were simulating somewhat more daily record high maximum temperatures compared with recent observations, while there was good agreement between the models and the observed decreases in record low minimums. The authors focused on two sets of simulations conducted on the NCAR-based Community Climate System Model (version 4), which is funded by DOE and NSF and developed by climate scientists across the country.Their analysis uncovered two reasons for the disparity between the computer models and observations.First, the models tended to underestimate precipitation. Because the air is cooled by precipitation and resulting evapotranspiration — the release of moisture from the land and plants back to the atmosphere — the tendency of the computer models to create an overly dry environment led to more record high temperatures.Second, the original study in 2009 only went back to the 1950s. For the new study, the research team also analyzed temperatures in the 1930s and 1940s, which is as far back as accurate recordkeeping will allow. Because the Dust Bowl days of the 1930s were unusually warm, with many record-setting high temperatures, the scientists found that it was more difficult in subsequent years to break those records, even as temperatures warmed. However, even taking the warm 1930s into account, both the model-simulated and observed ratio of record highs to record lows have been increasing."The steady increase in the record ratio is an immediate and stark reminder of how our temperatures have been shifting and continue to do so, reaching unprecedented highs and fewer record lows," said Tebaldi. "These changes pose adaptation challenges to both human and natural systems. Only a substantial mitigation of greenhouse gas emissions may stop this increase, or at least slow down its pace."About the articleTitle: "US daily temperature records past, present, and future"Authors: Gerald A. Meehl, Claudia Tebaldi, and Dennis Adams-SmithJournal: Proceedings of the National Academy of Sciences

James Hurrell elected to AGU position

BOULDER, Colo. —James W. Hurrell, director of the National Center for Atmospheric Research (NCAR), has been elected incoming president of the Atmospheric Sciences Section of the American Geophysical Union (AGU). He will be formally installed as president-elect at the AGU's annual meeting in December."It is a great honor to be elected by peers throughout the atmospheric sciences community," Hurrell said. "This is a critical time for the atmospheric sciences as we seek to advance our knowledge of climate change, extreme weather events, air quality, and other issues that pose significant challenges to our society."NCAR Director James Hurrell. (©UCAR. Photo by Carlye Calvin. This image is freely available for media & nonprofit use.)The Atmospheric Sciences Section studies the physics, chemistry, and dynamics of the atmosphere, particularly the two layers closest to Earth’s surface: the stratosphere and troposphere. These layers are crucial to life because they regulate planetary surface temperature, play an integral role in the world’s water cycle, and screen the planet from high-energy radiation. Much of the research focuses on global climate change, as well as monitoring fluctuations in the ozone layer and better understanding and predicting weather events and the effects of emissions from human activities."New ideas and approaches to AGU’s strategic challenges can be found in the collective wisdom of the organization's diverse membership," Hurrell said. "As president-elect, I am committed to eliciting those ideas and finding effective methods to further develop and implement the best of them." An NCAR senior scientist, Hurrell was named director of the center in 2013. He has contributed to numerous national and international science planning initiatives, including extensive involvement in the World Climate Research Programme, as well as the assessment activities of the Intergovernmental Panel on Climate Change. He also has served on several National Academy of Sciences panels, and he has provided briefings and testimonies to Congress on climate change science.Hurrell is a Fellow of the AGU, as well as of the American Meteorological Society and the Royal Meteorological Society. His personal research has centered on empirical and modeling studies and diagnostic analyses to better understand climate, climate variability, and climate change."Jim's vision and energy, along with his skill at drawing on insights from across the atmospheric sciences community, will enable him to make substantial contributions to AGU," said Antonio J. Busalacchi, president of the University Corporation for Atmospheric Research (UCAR). "The UCAR community is excited over Jim's election and looks forward to his leadership in this important position."

Indonesian fires exposed 69 million to 'killer haze'

November 16, 2016 | NCAR scientist Christine Wiedinmyer is a co-author of a new study into the health effects of the 2015 Indonesian wildfires. This is an excerpt from a news release issued by Newcastle University.  Wildfires in Indonesia and Borneo exposed 69 million people to unhealthy air pollution, new research has shown.An image taken from space of smoke billowing from fires in Jambi Province on the Indonesian island of Sumatra. The false-color image was made with a combination of visible (green) and infrared light so that fires and freshly burned land stand out. (Image courtesy NASA.)The study, published today in Scientific Reports, gives the most accurate picture yet of the impact on human health of the wildfires which ripped through forest and peatland in Equatorial Asia during the autumn of 2015.The study used detailed observations of the haze from Singapore and Indonesia. Analysing hourly air quality data from a model at a resolution of 10km – where all previous studies have looked at daily levels at a much lower resolution - the team was able to show that a quarter of the population of Malaysia, Singapore and Indonesia was exposed to unhealthy air quality conditions between September and October 2015.Estimating between 6,150 and 17,270 premature deaths occurred as a direct result of the polluted haze, the research team – involving academics from the UK, US, Singapore and Malaysia – said the study confirmed the extent of this public health crisis.Read the full news release by Newcastle University.About the articleTitle: Population exposure to hazardous air quality due to the 2015 fires in Equatorial AsiaAuthors: P. Crippa, S. Castruccio, S. Archer-Nicholls, G. B. Lebron, M. Kuwata, A. Thota, S. Sumin, E. Butt, C. Wiedinmyer, and D. V. SpracklenJournal: Scientific Reports, DOI: 10.1038/srep37074


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