An article by ATG’s Senior Scientist Dr. Brian Viner, in collaboration with scientists from the USDA Forest Service Savannah River, Ohio State University (College of Health Sciences), and the University of Georgia School of Public Health, has been accepted for publication in the Journal of Environmental Radioactivity. The article is titled: Predicted cumulative dose to firefighters and the offsite public from natural and anthropogenic radionuclides in smoke from wildland fires at the Savannah River Site, South Carolina USA. More details about the study and its findings can be found in the abstract below.
Abstract: The contaminated ground surface at Savannah River Site (SRS) is a result of the decades of work that has been performed maintaining the country’s nuclear stockpile and performing research and development on nuclear materials. The volatilization of radionuclides during wildfire results in airborne particles that are dispersed within the smoke plume and may result in doses to downwind firefighters and the public. To better understand the risk that these smoke plumes present, we have characterized four regions at SRS in terms of their fuel characteristics and radiological contamination on the ground. Combined with general meteorological conditions describing typical and extreme burn conditions, we have simulated potential fires in these regions and predicted the potential radiological dose that could be received by firefighting personnel and the public surrounding the SRS. In all cases, the predicted cumulative dose was a small percent of the US Department of Energy regulatory limit (0.25 mSv). These predictions were conservative and assumed that firefighters would be exposed for the duration of their shift and the public would be exposed for the entire day over the duration of the burn. Realistically, firefighters routinely rotate off the firefront during their shift and the public would likely remain indoors much of the day. However, we show that even under worst-case conditions the regulatory limits are not exceeded. We can infer that the risks associated with wildfires would not be expected to cause cumulative doses above the level of concern to either responding personnel or the offsite public.
SRNL is dedicated to maintaining the scientific and technological vitality of the lab, fostering creativity and enhancing core lab capabilities through the Laboratory Directed Research and Development (LDRD) initiative. Each year, this program provides funding for innovative research projects in various areas that range from National Security to Environmental Stewardship. The very competitive selection process begins with a ‘pitch’ presentation of the proposed research, followed by a written proposal submission to a committee that selects projects to be funded under each of the areas supported by LDRD. In previous years, ATG scientists have been active participants of this program; and this year was no exception with three research projects presented at the End of the Year Review and Poster Session held at SRS on October 3, 2017.
The project titled Advanced Cloud Forecasting for Solar Energy’s Impact on Grid Modernization was presented by Dr. David Werth. This project studies the impacts of short-term variability in solar irradiance on solar power production. A comprehensive solar monitoring station was established to measure direct and indirect solar irradiance, infrared irradiance, and output from an adjacent solar panel. These data were used to study the impact of cloud type and aerosols on local solar irradiance and solar power production, and to evaluate a method to forecast the amount and variability of daily solar irradiance by using analog weather predictions, i.e. looking at weather conditions from the past to predict short term future weather conditions. Results show good agreement between analog forecasts and observations. Based on this project, ATG currently has the capability to create daily solar forecasts using the analog technique.
Dr. Robert Kurzeja, presented the project Evaluation and Uncertainty of a New Method to Detect Suspected Nuclear and WMD Activity. This study focused on assessing the ability to detect signals from Weapons of Mass Destruction (WMD) and nuclear activity using a time series of chemical or radiological measurements, and to calculate probability of origin of the signal in question using Bayesian statistics. Testing of this method with 2013 data from a Comprehensive Test Ban Treaty site showed small uncertainty values in the calculated probability of origin for the suspect activity. This evaluation also proved that the method remains reliable under conditions when chemical signals are weak, hence proving to be an important method to detect concealed nuclear activity.
Finally, Dr. Robert Buckley discussed Advanced Atmospheric Modeling Techniques for Non-Proliferation Applications. In an extension to work done the previous year (also under LDRD), this project evaluates atmospheric transport models and compares 3 ensemble techniques: standard ensemble, adaptive programming, and data assimilation (Ensemble Kalman Filter), on a small spatial scale and complex terrain. Field data collected during field tracer experiments conducted at Diablo Canyon, CA were used to evaluate the different techniques. Results of ensemble model against observations show improvement in downwind concentration estimations using the Kalman Filter and Adaptive Programming ensemble techniques. These results demonstrate the importance of adapting model physics to specific location and time, and assimilating local data into the simulation to obtain better transport accuracy.
New and exciting projects led by, or in collaboration with ATG members were also awarded funding for this upcoming year (2018) during the presentation.
This summer SRNL welcomed approximately 140 interns to conduct research projects around the site. Among this group, 3 interns joined and collaborated with Atmospheric Technologies Group (ATG) to work on exciting projects, the results of which were presented on SRNL Interns’ Research Poster Session this past Thursday, July 26th at the Applied Research Center.
Michael Stewart, from the University of South Carolina, studied solar power generation, under the guidance of ATG’s David Werth. His research examined the intermittency of power output and the contribution of direct and indirect radiation to photovoltaic (PV) power generation. Results suggest that although direct radiation is a major contributor to power generation, indirect radiation is also significant. Additionally, a large variation in PV output over a short time scale was observed, as well as significant spatial variation across Savannah River Site. Future research will examine a bimodal distribution of power generation against indirect and direct radiation that was observed during this study.
Nicolet Chovancak, also from the University of South Carolina, focused on our STREAMII aqueous model under the mentorship of Grace Maze (ATG) and Vidya Samadi (USC). Her project, titled Uncertainty Analysis in Streamflow Data, looked at the change in transport and fate of materials given the uncertainty in the monthly stream flow values currently used by the model. Her findings show that the variation in transport times and maximum concentration is not large when minimum, average, and maximum flow values are compared.
Additionally, Beth Mitchell from Winthrop University – working for her second year as intern with the SRNL Chief Information Office and Scientific Computing - continued her work on developing and updating the ATG webpage. In 2016, under the mentorship of Cory Herbst and Andrew Kail, Beth had created the ATG business page that is currently active. This year, her efforts focused on updating ATG’s weather web page and forecast input pages. The web page Beth created is expected to go live as the new official weather web page soon!
It is with very heavy hearts that we announce the passing of our esteemed friend and colleague Matt J. Parker. Our group, and the entire meteorological enterprise, has had a sudden and big loss. Below is a tribute to Matt given by ATG Group Manager Chuck Hunter, during the Funeral Service on March 24, 2017:
It’s my honor and privilege to speak to the life of Matt Parker on behalf of his work family – the Atmospheric Technologies group at SRNL.
I first met Matt in the fall of 1988. He was a grad student at North Carolina State University at the time, and had come down for several weeks with a group from State to participate in a DOE-sponsored nighttime field data collection experiment that was being coordinated by Dr. Allen Weber of our group. We were impressed by Matt and so we hired him the following year after completing his Master’s degree.
Dr. Weber was a former professor at NC State, and he always took a very nurturing approach with young scientists – mentoring them with their work and encouraging them to become active in our professional society, the American Meteorological Society. So, as the new young scientist in our group, Allen naturally took Matt under his wing. And as many of us here today would later come to appreciate, this experience would have a very profound and life-long impact on Matt. When it was our turn, we all very much appreciated Allen’s advice and wise counsel, but mostly we would just nod with a bit of ambivalence at Allen’s not so subtle prodding that, first: we become active in the Society and, and then, more importantly, work towards obtaining the professional status of Certified Consulting Meteorologist.
But not Matt Parker! With Allen, Matt was all in. Both feet.
Throughout this journey, he enthusiastically took his mentor to heart when it came to serving the young scientist – whether it be in his AMS activities or in his work with us at SRNL, it was vitally important to Matt to reach out to the students, the interns, the new hires to provide advice and counsel, cajole them to become AMS certified, guide them through their work without an air of condescension, to readily offer praise and encouragement.
Family was always most important to Matt – both his personal family and his professional family. And even though Matt earned wonderful individual accolades, I know personally through my many, often lengthy, conversations with him, that as far as his professional life, his work family came first. Certainly, he took great pride in his own achievements, but part of his motivation to pursue these goals was to contribute to the greater good of our group through greater recognition and creating contacts that would help our team develop new business.
He was the consummate teammate, willing to give selflessly to achieve our common goals.Whether he was just a contributor to the project or leading the project, you could count on Matt to give his full effort, reach out to pull in the right set of skills, then work together to achieve the desired result. Always with diligence and excellence.
Matt firmly believed that we were the best meteorology group throughout the Department of Energy or anywhere else for that matter. Naturally, I believe that to be that case as well.
But whatever our group’s status may be, it’s in no small part because of our world class meteorological measurements and observations program, a program that thrived under Matt’s technical expertise and leadership, and more importantly how effective he was in nurturing the small cadre of engineering specialists that turned his ideas into reality in the field.
Because of his caring relationship with his specialists – and, his ability to explain technical details in ways that led to the job at hand being thoroughly understood, there are no bigger fans of Matt Parker than the three guys that supported Matt over the years. Without fail, I would get e-mail from Matt praising their work after a major job was completed.
Our work group at SRNL has always been close, and Matt was a beloved member of our workplace family. We’ve now lost a close family member and it hurts. And although it sounds clichéd, we’re determined to pull together to carry on his work, our work, because we know Matt would have wanted it this way….
March 24, 2017
Reid Memorial Presbyterian Church
Founded in 1919, AMS is the nation’s premier scientific and professional organization promoting and disseminating information about the atmospheric, oceanic and hydrologic sciences. The membership includes scientists, researchers, educators, broadcast meteorologists, students, and other professionals in the fields of weather, water and climate. As president, he will represent the Society’s 13,000 members (both domestically and abroad), and will lead the AMS Council, the governing body of the organization. The president also determines the theme for the Annual Meeting. Parker will preside over the 2018 event in Austin, TX under the theme ‘Transforming Communication in the Weather, Water, and Climate Enterprise: Focusing on Challenges Facing Our Sciences’.
Parker plans to use his leadership position to provide outreach to industry, academia and the public; and to enhance partnerships with other countries to share measurement and forecast data. “Relationships with colleagues abroad are critical for ensuring sharing of measurement and modeling data, as well as enhancing ‘universal’ professional development principles. Weather and climate know no geopolitical boundaries.” - He adds.
The official SRNL Press Release can be accessed here:
ATG members, David Werth and Robert Buckley, recently submitted an article on emission signals from nuclear detonations. The article titled ‘Characterizing the detectability of emission signals from North Korean nuclear detonation’ has now been accepted for publication in the Journal of Environmental Radioactivity Volumes 169-170, pages 214 – 220.
Abstract: The detectability of emission sources, defined by a low-level of mixing with other sources, was estimated for various locations surrounding the Sea of Japan, including a site within North Korea. A high-resolution meteorological model coupled to a dispersion model was used to simulate plume dynamics for four periods, and two metrics of airborne plume mixing were calculated for each source. While emissions from several known sources in this area tended to blend with others while dispersing downwind, the North Korean plume often remained relatively distinct, thereby making it potentially easier to unambiguously ‘backtrack’ it to its source. Ref. Journal of Environmental Radioactivity 169-170 (2017) 214e220. Doi: 10.1016/j.jenvrad.2016.12.002
Intermediate Time-Scale Response of Atmospheric CO2 following Prescribed Fire in a Longleaf Pine Forest by B. Viner, M. Parker, G. Maze, P. Varnadoe, M. LeClerc, G. Starr, D. Aubrey, G. Zhang, and H. Duarte was published in the Journal of Geophysical Research: Biogeosciences (online)
Abstract - Fire plays an essential role in maintaining the structure and function of longleaf pine ecosystems. While the effects of fire on carbon cycle have been measured in previous studies for short periods during a burn and for multi-year periods following the burn, information on how carbon cycle is influenced by such changes over the span of a few weeks to months has yet to be quantified. We have analyzed high-frequency measurements of CO2 concentration and flux, as well as associated micrometeorological variables, at three levels of the tall Aiken AmeriFlux tower during and after a prescribed burn. Measurements of the CO2 concentration and vertical fluxes were examined as well as calculated net ecosystem exchange (NEE) for periods prior to and after the burn. Large spikes in both CO2 concentration and CO2 flux during the fire and increases in atmospheric CO2 concentration and reduced CO2 flux were observed for several weeks following the burn, particularly below the forest canopy. Both CO2 measurements and NEE were found to return to their pre-burn states within 60-90 days following the burn when no statistical significance was found between pre-burn and post-burn NEE. This study examines the micrometeorological conditions during a low-intensity prescribed burn and its short-term effects on local CO2 dynamics in a forested environment by identifying observable impacts on local measurements of atmospheric CO2 concentration and fluxes. Ref: Journal of Geophysical Research: Biogeosciences DOI:10.1002/2016JG003351
Matt Parker was the featured speaker at a seminar sponsored by the Department of Chemistry and Physics at Augusta University in Augusta, GA. Matt's talk, 'Atmospheric Research at the Savannah River National Laboratory', touched on the wide variety of applied studies conducted by ATG related to emergency response, long-range atmospheric transport, climate change impacts and renewable wind and solar energy, and included discussion of some of the advanced modeling techniques and innovative meteorological monitoring technologies currently being developed. Matt also discussed the ties between weather, climate and human health as well as his work as the President Elect of the American Meteorological Society. Comments on career development for students were also covered.
The paper ‘On dispersion above a forest – measurements and methods’ by B. B. Hicks, C. H. Hunter, and A. H. Weber was published in the Journal of the Air and Waste Management Association (Aug 2016).
Abstract - High frequency (10 hz) measurements over a mixed conifer/deciduous forest at the Savannah River Site in South Carolina using sonic anemometry reveal that on-site and real-time measurements of the velocity component standard deviations, σv and σw, are preferred for dispersion modeling. Such data are now easily accessible, from the outputs of cost-effective and rugged sonic anemometers. The data streams from these devices allow improvements to conventional methodologies for dispersion modeling. In particular, extrapolation of basic input data from a nearby location to the site of the actual release can be facilitated. In this regard reliance on the velocity statistics σv and σw appears to be preferred to the conventional σθ and σϕ. In the forest situations addressed here, the uncertainties introduced by extrapolating initializing properties (u, θ, σθ, and σϕ, or alternatively, σv and σw) from some location of actual measurement to some nearby location where an actual release occurs are similar to those associated with the spread of the plume itself and must be considered in any prediction of the likelihood of downwind concentration (exposure) exceeding some critical value, i.e., a regulatory standard. Consideration of plume expansion factors related to meander will not necessarily cause predicted downwind maxima within a particular plume to be decreased; however, the probability of exposure to this maximum value at any particular location will be reduced. Three-component sonic anemometers are affordable and reliable, and are now becoming a standard for meteorological monitoring programs subject to regulatory oversight. The time has come for regulatory agencies and the applied dispersion community to replace the traditional discrete sets of dispersion coefficients based on Pasquill stability by the direct input of measured turbulence data. Ref.- J Air Waste Manag Assoc. 2016 Aug;66(8):768-85. doi: 10.1080/10962247.2016.1178189.
Brian Viner and Sydney Goodlove (ATG summer intern) presented a poster at the AMS 32nd Conference on Agricultural and Forest Meteorology entitled ‘Using Atmosphere-Forest Flux Measurements to Examine Potential for Reduced Downwind Dose ‘(poster). Wind and moisture flux data from ATG’s forest flux tower (the Aiken Ameriflux Tower) are being used as input to coupled Gaussian dispersion model (above canopy) and a 2-D advection diffusion model (within canopy) to characterize the fate of an airborne plume of radioactive tritium oxide (H3O) as it interacts with a forested surface. For a short-term release (a few hours), we expect this interaction will lead to an effective removal of material from the airborne plume, resulting in lower concentration and radiological dose to the affected public than would otherwise be obtained from standard models used in nuclear facility safety analysis. The goal is to define an ‘effective’ deposition velocity to account for these interaction in the standard models.
Plume characteristics above and within the forest were evaluated 10 km from the release point. A greater fraction of the plume was predicted to mix into the forest under very stable conditions (E/F Stability) or very unstable conditions (A/B Stability). Less mixing was predicted for near-neutral conditions (C/D Stability). Increased mixing during the day is attributed to increased turbulence during the day; the vertical convective turbulence in addition to the mechanical turbulence at the forest top combine to mix a greater fraction of the plume downward. In stable conditions, a narrow, highly concentrated plume constrained near the forest top creates a larger gradient between the atmosphere and forest airspace, increasing the downward flux of the plume into the forest. The next stage of this project will be to analyze the rates of mixing into the forest under these conditions to determine the appropriate estimates deposition velocity. This work is being funded primarily from a Nuclear Safety Research and Development Grant from the National Nuclear Security Administration (NNSA).
David Werth presented the paper ‘Novel Ensemble Atmospheric Modeling Techniques for the Simulation of Large-Scale Dispersion’ at the 20th George Mason University Conference on Atmospheric Transport and Dispersion Modeling. Abstract - Tracer release simulations have historically been performed using a single high-resolution meteorological simulation, making use of both 1) model parameters estimated by the user, and 2) observations from weather stations. Our knowledge of the initial atmospheric state is often guided by a small number of weather observations, while model ‘free’ parameters are often poorly constrained. Thus, a single model solution can be considered to be only one possible representation of the meteorology.
Ensemble modeling - running multiple simulations with various plausible values of such inputs - is used to allow for uncertainty in poorly understood model parameters or in sparse weather observations. This standard ensemble approach provides a range of possible model solutions, but may still experience systematic model errors. Our current research explores alternatives to the standard ensemble approach through the development of two novel methods: (1) minimizing model error through adaptive (physics-based) programming techniques and (2) reducing ensemble variance by applying an ensemble Kalman filter to optimize the assimilation of observational data. We will show that substantial improvement in transport accuracy can be achieved when a model is adapted to a particular location and time.
Chuck Hunter attended a bi-monthly meeting of the SRS Citizens Advisory Board in Savannah, GA to present an invited talk ‘Assessing Public Health Risks from SRS Air Emissions’. In a 2014 report, the Agency for Toxic Substance and Disease Registry concluded that radiological and most of the toxic air pollutant emissions from SRS facilities were unlikely to pose adverse health effects among members of the public. Nonetheless, the report identified eight toxic air pollutants for which an evaluation could not be completed due to insufficient data. The presentation to the CAB summarized results from a followup modeling study that examined an additional 10 years of emissions data for each of these eight chemicals, pursuant to ASTDR recommendations. In all cases, the modeling results indicated that it would be highly unlikely for the public to be exposed to concentrations exceeding either a concentration reference standard above which a non-cancer health effect could be expected, or producing an additional carcinogenic risk greater than one in 10,000.
Dr. Allen Weber was remembered for his long-standing contributions to the Chapter and founder of this highly successful annual event. Allen worked in ATG for more than 30 years and was integral to forging ATG’s long-standing mission.