Mapping Agricultural Decision Making Across The U.S. Corn Belt, 2017 University of Nebraska, Lincoln
Mapping Agricultural Decision Making Across The U.S. Corn Belt, Tonya Haigh, Eugene Takle, Jeffrey Andresen, Melissa Widhalm, J. Stuart Carlton, Jim Angel
Decision calendars help identify opportunities for inserting climate information into a decision process as well as points where other considerations might overrule use of the climate information. Developers of decision calendars are challenged, though, by a potentially infinite number of modifications required to address spatial variability in agricultural decision making. Variability in climate, soils, and agricultural production systems across a region may result in deviations in decision-making times.
Observing The Quantumbehavior Of Light In An Undergraduate Laboratory, 2017 Utah State University
Observing The Quantumbehavior Of Light In An Undergraduate Laboratory, M. S. Neel, J. J. Thorn, V. W. Donato, G. S. Bergreen, Robert E. Davies, M. Beck
While the classical, wavelike behavior of light (interference and diffraction) has been easily observed in undergraduate laboratories for many years, explicit observation of the quantum nature of light (i.e., photons) is much more difficult. For example, while well-known phenomena such as the photoelectric effect and Compton scattering strongly suggest the existence of photons, they are not definitive proof of their existence. Here we present an experiment, suitable for an undergraduate laboratory, that unequivocally demonstrates the quantum nature of light. Spontaneously downconverted light is incident on a beamsplitter and the outputs are monitored with single-photon counting detectors. We observe a ...
Identification Of Extreme Precipitation Threat Across Midlatitude Regions Based On Short-Wave Circulations, 2017 Utah State University
Identification Of Extreme Precipitation Threat Across Midlatitude Regions Based On Short-Wave Circulations, Shih-Yu (Simon) Wang, Robert E. Davies, Robert R. Gillies
The most severe thunderstorms, producing extreme precipitation, occur over subtropical and midlatitude regions. Atmospheric conditions conducive to organized, intense thunderstorms commonly involve the coupling of a low-level jet (LLJ) with a synoptic short wave. The midlatitude synoptic activity is frequently modulated by the circumglobal teleconnection (CGT), in which meridional gradients of the jet stream act as a guide for short Rossby waves. Previous research has linked extreme precipitation events with either the CGT or the LLJ but has not linked the two circulation features together. In this study, a circulation-based index was developed by combining (a) the degree of the ...
Connecting Subseasonal Movements Of The Winter Mean Ridge In Western North America To Inversion Climatology In Cache Valley, Utah, Shi-Yu (Simon) Wang, Robert R. Gillies, Randy Martin, Robert E. Davies, Marty R. Booth
A 10-yr record of PM2.5 (particulate matter of aerodynamic diameter ≤ 2.5 μm), collected in Cache Valley near downtown Logan, Utah, reveals a strong peak in the PM2.5 concentration climatology that is tightly localized in mid-January. The cause of this subseasonal variation in the PM2.5 climatology is investigated through dynamical downscaling and large-scale diagnostics. Climatological analysis of the U.S. winter mean ridge reveals a mid-January subseasonal shift in the zonal direction, likely in response to variations in the Rossby wave source over the central North Pacific Ocean. This displacement of the winter mean ridge, in turn ...
Pakistan’S Two-Stage Monsoon And Links With The Recent Climate Change, 2017 Utah State University
Pakistan’S Two-Stage Monsoon And Links With The Recent Climate Change, Shih-Yu (Simon) Wang, Robert Davies, Wan Ru Huang, Robert R. Gillies
Meteorological conditions related to the Pakistan floods of 2010 were examined in the context of monsoon dynamics and large‐scale circulations. Case and climatological analyses suggest that summer precipitation in northern Pakistan comprises two distinct phases: (1) a premonsoon trough phase (July) whose rainfall is more episodic and intense, occurring prior to arrival of the monsoon trough, and (2) a monsoon trough phase (August) whose rainfall is persistent, yet less episodic, driven by northward migration of the monsoon trough. Analyses of conditional instability, moisture flux, and circulation features support a persistent increase in conditional instability during the July premonsoon trough ...
Final Report: Evaluation Of The Morphoedaphic Index And Sediment Diatoms For Inference Of Pre-European Settlement Total Phosphorus Concentration In Epa Region 10 Lakes, Rich Miller, Aaron Hook, Richard Petersen, Mark D. Sytsma
Mark D. Sytsma
Water quality in many Northwest lakes has declined over the past century due, in part, to increased anthropogenic nutrient loading (Edmonson and Lehman, 1981). Under the Clean Water Act, resource managers such as the Washington Department of Ecology, Oregon Department of Environmental Quality, and tribes are responsible for restoring and protecting the integrity of these waters. Targets for restoration or criteria for impairment are not well defined, however, and may naturally vary by geology, hydrology, morphometry, and climate. One way to determine whether lakes are impaired and to identify restoration targets is to assess lake reference conditions (EPA 2000). Reference ...
Atmospheric Mercury Concentrations And Speciation Measured From 2004 To 2007 In Reno, Nevada, Usa, 2017 Utah State University
Atmospheric Mercury Concentrations And Speciation Measured From 2004 To 2007 In Reno, Nevada, Usa, Seth N. Lyman, Mae Sexauer Gustin
Atmospheric elemental, reactive and particulate mercury (Hg) concentrations were measured north of downtown Reno, Nevada, USA from November 2004 to November 2007. Three-year mean and median concentrations for gaseous elemental Hg (Hg0) were 1.6 and 1.5 ng m−3 (respectively), similar to global mean Hg0 concentrations. The three-year mean reactive gaseous Hg (RGM) concentration (26 pg m−3) was higher than values reported for rural sites across the western United States. Well defined seasonal and daily patterns in Hg0 and RGM concentrations were observed, with the highest Hg0 concentrations measured in winter and early morning, and RGM concentrations ...
A Review Of Passive Sampling Systems For Ambient Air Mercury Measurements, 2017 Utah State University
A Review Of Passive Sampling Systems For Ambient Air Mercury Measurements, Jiaoyan Huang, Seth N. Lyman, Jelena Stamenkovic Hartman, Mae Sexauer Gustin
Atmospheric mercury (Hg) temporal and spatial patterns must be measured accurately in order to adequately understand the role of this pathway as it relates to Hg toxicity and exposure of humans and wildlife to Hg. It is also important to understand the distribution of the different chemical forms (elemental, oxidized, or particle bound) and specific compounds in air (e.g., HgCl2, HgBr2, HgO, Hg(NO3)2, and HgSO4). However, the current automated and passive sampling methods of measurement have limitations and artifacts impacting our ability to achieve this task. Both abiotic and biotic systems have been developed to measure the ...
A Passive Sampler For Ambient Gaseous Oxidized Mercury Concentrations, 2017 Utah State University
A Passive Sampler For Ambient Gaseous Oxidized Mercury Concentrations, Seth N. Lyman, Mae Sexauer Gustin, Eric M. Prestbo
This paper reports on the development of a passive sampler for estimating gaseous oxidized mercury concentrations. Atmospheric gaseous oxidized mercury concentrations calculated from passive sampler data were correlated with those obtained using an automated analyzer (r2 = 0.71, p < 0.01, n = 110 for one-week deployments; r2 = 0.89, p < 0.01, n = 22 for two-week deployments). Sampler uptake was not significantly affected by changes in temperature, humidity, or ozone concentration, but it was slightly dependent on wind speed. As such, an equation for correcting data due to this factor was developed based on wind tunnel and field data. The ...
Speciation Of Atmospheric Mercury At Two Sites In Northern Nevada, Usa, 2017 Utah State University
Speciation Of Atmospheric Mercury At Two Sites In Northern Nevada, Usa, Seth N. Lyman, Mae Sexauer Gustin
Gaseous elemental mercury (Hg0), reactive gaseous mercury (RGM), and mercury bound to particles (Hgp) were measured during seasonal 1- or 2-week data collection campaigns at two Mercury Deposition Network sites (NV02 and NV99) in northern Nevada, USA. The sites are rural but are located in an area of diverse natural and anthropogenic mercury sources that include undisturbed and mining mercury-disturbed enriched substrates, coal-fired power plants, ore processing facilities, and industrial facilities. Concentrations of Hg0 averaged over all campaigns were 3.0±1.7 ng m−3 at NV02 and 2.5±3.1 ng m−3 at NV99, higher than ...
Release Of Mercury Halides From Kcl Denuders In The Presence Of Ozone, 2017 Utah State University
Release Of Mercury Halides From Kcl Denuders In The Presence Of Ozone, Seth N. Lyman, Daniel A. Jaffe, Mae S. Gustin
KCl-coated denuders have become a standard method for measurement of gaseous oxidized mercury, but their performance has not been exhaustively evaluated, especially in field conditions. In this study, KCl-coated and uncoated quartz denuders loaded with HgCl2 and HgBr2 lost 29–55% of these compounds, apparently as elemental mercury, when exposed to ozone (range of 6–100 ppb tested). This effect was also observed for denuders loaded with gaseous oxidized mercury at a field site in Nevada (3–37% of oxidized mercury lost). In addition, collection efficiency decreased by 12–30% for denuders exposed to 50 ppb ozone during ...
The Magnitude Of The Snow-Sourced Reactive Nitrogen Flux To The Boundary Layer In The Uintah Basin, 2017 Utah State University
The Magnitude Of The Snow-Sourced Reactive Nitrogen Flux To The Boundary Layer In The Uintah Basin, Maria Zakto, Joseph Erbland, Joel Savarino, Lei Geng, Lauren Easley, Andrew Schauer, Timothy Bates, Patricia K. Quinn, Bonnie Light, David Morison, Hans D. Osthoff, Seth Lyman, William Neff, Bin Yuan, Becky Alexander
Reactive nitrogen (Nr = NO, NO2, HONO) and volatile organic carbon emissions from oil and gas extraction activities play a major role in wintertime ground-level ozone exceedance events of up to 140 ppb in the Uintah Basin in eastern Utah. Such events occur only when the ground is snow covered, due to the impacts of snow on the stability and depth of the boundary layer and ultraviolet actinic flux at the surface. Recycling of reactive nitrogen from the photolysis of snow nitrate has been observed in polar and midlatitude snow, but snow-sourced reactive nitrogen fluxes in mid-latitude regions have not yet ...
Testing And Application Of Surrogate Surfaces For Understanding Potential Gaseous Oxidized Mercury Dry Deposition, Seth N. Lyman, Mae Sexauer Gustin, Eric M. Prestbo, Phillip I. Kilner, Eric Edgerton, Ben Hartsell
Currently there is no standard method for measurement of atmospheric mercury dry deposition. While all operationally defined forms of atmospheric mercury (elemental, oxidized, and particulate) can be dry deposited, oxidized forms are of concern due to high deposition velocities, water solubility, and reactivity. This paper describes the development of a surrogate surface for characterizing potential dry deposition of gaseous oxidized mercury (GOM). Laboratory tests showed that the surface collected HgCl2, HgBr2, and HgO with equal efficiency, and deposition was not significantly influenced by temperature, humidity, or ozone concentrations. Deposition of mercury to surfaces in field deployments was correlated with GOM ...
Progress On Understanding Atmospheric Mercury Hampered By Uncertain Measurements, 2017 Utah State University
Progress On Understanding Atmospheric Mercury Hampered By Uncertain Measurements, Daniel A. Jaffe, Seth N. Lyman, Helen M. Amosl, Mae Sexauer Gustin, Jiaoyan Huang, Noelle E. Selin, Leonard Levin, Arnout Ter Schure, Robert P. Mason, Robert Talbot, Andrew Rutter, Brandon Finley, Lyatt Jaeglé, Viral Shah, Crystal Mcclure, Jesse Ambrose, Lynne Gratz, Steven Lindberg, Peter Weiss-Penzias, Guey-Rong Sheu, Dara Feddersen, Milena Horvat, Ashu Dastoor, Anthony J. Hynes, Huiting Mao, Jeroen E. Sonke, Franz Slemr, Jenny A. Fisher, Ralf Ebinghaus, Yanxu Zhang, Grant Edwards
Mercury (Hg) is a potent neurotoxin and globally reducing environmental levels is seen as paramount for protecting human and wildlife health. In 2013, many countries finalized the negotiations on, and have now signed, the Minamata Convention on Mercury, which commits participating countries to reduce emissions and use of mercury. Successful implementation of the treaty will require adequate verification through global monitoring.
Sources Of Gaseous Oxidized Mercury And Mercury Dry Deposition At Two Southeastern U.S. Sites, 2017 Utah State University
Sources Of Gaseous Oxidized Mercury And Mercury Dry Deposition At Two Southeastern U.S. Sites, Peter S. Weiss-Penzias, Mae S. Gustin, Seth N. Lyman
Wet deposition measurements have shown that relative to other parts of the US, the southeastern region has the highest mercury (Hg) inputs. The source of this Hg has been investigated by multiple researchers and is suggested to be derived from local, regional and global sources. Here we focus on trying to understand potential sources of Hg to this area during periods dominated by dry gaseous oxidized mercury (GOM) deposition. Dry deposition of GOM to a surrogate surface was measured in conjunction with speciated atmospheric Hg, and ancillary parameters from September 2007 through September 2008 at two sites located within 25 ...
Seasonal And Diel Variation Of Atmospheric Mercury Concentrations In The Reno (Nevada, Usa) Airshed, 2017 Utah State University
Seasonal And Diel Variation Of Atmospheric Mercury Concentrations In The Reno (Nevada, Usa) Airshed, Jelena Stamenkovic, Seth Lyman, Mae S. Gustin
This paper describes total gaseous mercury (TGM) concentrations measured in Reno, Nevada from 2002 to 2005. The 3-year mean and median air Hg concentrations were 2.3 and 2.1 ng m−3, respectively. Mercury concentrations exhibited seasonality, with the highest concentrations in winter, and the lowest in summer and fall. A well-defined diel pattern in TGM concentration was observed, with maximum daily concentrations observed in the morning and minimum in the afternoon. A gradual increase of TGM concentration was observed in the evening and over night. The early morning increase in TGM was likely due to activation of local ...
Determinants Of Atmospheric Mercury Concentrations In Reno, Nevada, U.S.A., 2017 Utah State University
Determinants Of Atmospheric Mercury Concentrations In Reno, Nevada, U.S.A., Seth N. Lyman, Mae Sexauer Gustin
Concentrations of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate-bound mercury (PBM) were measured along with ancillary variables 9 km east of downtown Reno, Nevada, U.S.A. from November 2006 through March 2009. Mean two-year (February 2007 through January 2009) GEM, GOM, and PBM concentrations were 2.0 ± 0.7 ng m− 3 (± standard deviation), 18 ± 22 pg m− 3, and 7 ± 7 pg m− 3, respectively. Data collected were compared with observations made at another location just north of the city at 169 m higher elevation. At both locations higher concentrations of GEM and PBM occurred ...
Do We Understand What The Mercury Speciation Instruments Are Actually Measuring? Results Of Ramix, 2017 Utah State University
Do We Understand What The Mercury Speciation Instruments Are Actually Measuring? Results Of Ramix, Mae Sexauer Gustin, Jiaoyan Huang, Matthieu B. Miller, Christianna Peterson, Daniel A. Jaffe, Jesse Ambrose, Brandon D. Finley, Seth N. Lyman, Kevin Call, Robert Talbotl, Dara Feddersen, Huiting Mao, Steven E. Lindberg
From August 22 to September 16, 2012, atmospheric mercury (Hg) was measured from a common manifold in the field during the Reno Atmospheric Mercury Intercomparison eXperiment. Data were collected using Tekran systems, laser induced fluorescence, and evolving new methods. The latter included the University of Washington-Detector for Oxidized Mercury, the University of Houston Mercury instrument, and a filter-based system under development by the University of Nevada-Reno. Good transmission of total Hg was found for the manifold. However, despite application of standard protocols and rigorous quality control, systematic differences in operationally defined forms of Hg were measured by the sampling systems ...
Observations Of Speciated Atmospheric Mercury At Three Sites In Nevada: Evidence For A Free Tropospheric Source Of Reactive Gaseous Mercury, Peter Weiss-Penzias, Mae Sexauer Gustin, Seth Lyman
Air mercury (Hg) speciation was measured for 11 weeks (June–August 2007) at three sites simultaneously in Nevada, USA. Mean reactive gaseous Hg (RGM) concentrations were elevated at all sites relative to those reported for locations not directly influenced by known point sources. RGM concentrations at all sites displayed a regular diel pattern and were positively correlated with ozone (O3) and negatively correlated with elemental Hg (Hg0) and dew point temperature (Tdp). Superimposed on the diel changes were 2- to 7-day periods when RGM concentrations increased across all three sites, producing significant intersite correlations of RGM daily means (r = 0 ...
Mercury Exchange Between The Atmosphere And Low Mercury Containing Substrates, 2017 Utah State University
Mercury Exchange Between The Atmosphere And Low Mercury Containing Substrates, Mae Sexauer Gustin, Mark Engle, Jody Ericksen, Seth N. Lyman, Jelena Stamenkovic, Mei Xin
Mercury is emitted to the air from Hg-enriched and low Hg-containing (natural background) substrates. Emitted Hg can be geogenic, or can be derived from the re-emission of Hg that was previously deposited to the soil from the atmosphere. Atmospheric Hg can be derived from natural and/or anthropogenic sources and can be deposited by wet or dry processes. It is important to understand the relative magnitude of emission, deposition, and re-emission of Hg associated with terrestrial ecosystems with natural background soil Hg concentrations because these landscapes cover large terrestrial surface areas. This information is also important for developing biogeochemical mass ...