Abstract Turbulence structures and exchange of momentum heat in the nocturnal stable boundary layer (SBL) show distinct features under different stability conditions prompting interest their connection. Here eddy covariance data collected at four heights on a 62‐m meteorological tower over large open flat terrain are used to characterize SBL states associated turbulence structures. In characterized by strong near‐surface winds, turbulent sizes scale with observational experiences enhanced...

ABSTRACT The revised National Ambient Air Quality Standards for PM include fine particulate standards based upon mass measurements of PM25. It is possible in arid and semi-arid regions to observe significant coarse mode intrusion the PM2.5 measurement. In this work, continuous PM10, PM2.5, PM1.0 were measured during several windblown dust events Spokane, WA. PM2 5 constituted ~30% PM10 event days, compared with ~48% on non-dusty days preceding events. Both enhanced However, was not storms...

Rapid hydrogen peroxide (H2O2) decomposition is a significant limitation of catalyzed H2O2 propagations (i.e., modified Fenton’s reagent) for the remediation contaminated soil and groundwater by in situ chemical oxidation. Rates mediated seven trace minerals four iron manganese oxides were evaluated batch reactors containing slurries each 11 minerals. At pH 3, dominant catalysts on per surface area basis pyrolusite, goethite, hematite, while rates presence oxyhydroxide manganite mineral...

<h3>BACKGROUND</h3> The relationship between current concentrations of ambient air pollution and adverse health effects is controversial. We report a meteorological index stagnation that associated with daily visits to the emergency department for asthma in two urban areas. <h3>METHODS</h3> Data on values persistence were collected approximately years Spokane, Washington, USA 15 months Seattle, USA. represents number hours during 24 hour day when surface wind speeds are less than annual...

Abstract The first phase of an atmospheric tracer experiment program, designated Project Sagebrush, was conducted at the Idaho National Laboratory in October 2013. purpose to reevaluate results classical field experiments short-range plume dispersion (e.g., Prairie Grass) using newer technologies that are available for measuring both turbulence levels and concentrations. All releases were during daytime with conditions ranging from neutral unstable. key finding values horizontal spread...

Abstract In very stable boundary layers (VSBL), a “cocktail” of submeso motions routinely result in elevated mean wind speed maxima above the ground, acting as new source turbulence generation. This turbulent kinetic energy enhances mixing and causes profile distortion (WPD). As results, this transient adjusts classical log‐law. Addressing how WPD‐induced regulates flow structures, fluxes, transitions stability regimes across remains challenge. Eddy covariance data measured at four levels on...

Abstract. A number of numerical wind flow models have been developed for simulating at relatively fine spatial resolutions (e.g., ~ 100 m); however, there are very limited observational data available evaluating these high-resolution models. This study presents surface sets collected from an isolated mountain and a steep river canyon. The presented in terms four regimes: upslope, afternoon, downslope, synoptically driven regime. There were notable differences the two terrain types. For...

The Sagebrush experiment, led by NOAA's Field Research Division of the Air Resources Laboratory, consisted five releases (intensive observation periods, or IOPs) a chemically inert trace gas on days in October 2013. All occurred afternoon under either near neutral stability conditions with high wind speeds unstable low speeds. sampling network for tracer concentrations covered distances 200 m–3200 m from release location and samples were obtained 10-min averages. HYSPLIT, transport...

Concentration variability in the fast-response tracer dataset for continuous, near-surface, point source releases urban core from Joint Urban 2003 field study is analyzed. conditionally and unconditionally sampled time series characterized by probability densities, concentration fluctuation intensity, skewness, kurtosis. Significant day-night differences plume dispersion are observed. Relative to daytime, nighttime plumes were more likely have reduced intensities, higher normalized surface...

Abstract In this study we examined a data set of nearly two‐year collection and investigated the effects low‐level jets (LLJ) on near‐surface turbulence, especially wind direction changes, in nocturnal boundary layer. Typically, layer is thermally stratified stable. When profiles exhibit low gradient (in absence LLJ), it characterized by very weak turbulence large, abrupt, but intermittent changes (∆WD) layers near surface. contrast, presence LLJs can cause dramatic through inducing velocity...

Abstract Due to strong mean wind shear, the stable boundary layer (SBL) becomes vertically coupled. In a coupled SBL, large turbulent eddies enhance cross‐layer mixing and mix kinetic energy. However, gradients in momentum heat fluxes are frequently observed, degrading performance of Monin‐Obukhov similarity theory. It is shown that increased vertical variables (i.e., speed potential temperature) can cause flux gradients. This process operated upon by downward penetrating with altered phase...

Surface‐based radiometers can be used to assess the atmospheric aerosol burden. During 1998, two multifilter rotating shadow‐band (MFRSRs), operated by Washington State University (WSU) and USDA UV‐B program, were collect data on Columbia Plateau atmosphere. Analysis of these an automated Langley algorithm provided retrievals for total optical thickness, allowing calculation thickness (AOT) top‐of‐atmosphere (TOA) instrument signal. Statistical evaluation TOA signal permitted recalculation...

Accurate measurement of personal exposure to particulate matter and its constituents requires samplers that are accurate, compact, lightweight, inexpensive, convenient use. The organic mass sampler (PPOMS) has been developed meet these criteria. PPOMS uses activated carbon-impregnated foam as a combined 2.5-μm size-selective inlet denuder for assessment fine particle carbon. Proof the concept established by comparing carbon in particles collected with collocated Seattle, at central outdoor...

A codimension multifractal methodology was used to analyze and model scalar concentration fluctuations within sulfur hexafluoride tracer gas plumes from a line source in atmospheric surface-layer flows. Correspondence exhibited between the double trace moments parameters α C1 of experimentally measured plume characteristics peak-to-mean ratio fluctuation intensity. Data series were generated using an extremal Levy, stochastic model, with experimental as inputs. Uncertainties determined...

Abstract Large, rapid, and intermittent changes in wind direction were commonly observed low–wind speed conditions the very stable boundary layer during phase 2 of Project Sagebrush field tracer study. This paper investigates occurrence magnitude these explores their associated meteorological factors. The evidence indicates that occur mainly at speeds less than 1.5 m s −1 are with momentum sensible heat fluxes approaching zero shear conditions. results complete vertical decoupling. They only...

Dimensionally stable anodes (DSAs) demonstrate potential for the electrochemical treatment of industrial waste streams and disinfection effluent. Oxidation by laboratory‐prepared tin oxide DSAs was compared with that commercially available ruthenium oxide, iridium mixed metal DSAs, using hexanol as a probe molecule. The performance four similar in two‐chamber reactors, which anode cell separated from cathode Nafion membrane, allows transmission current between chambers, but not passage...

Abstract A field study was conducted of flows in the Birch Creek Valley eastern Idaho. There is a distinct topographic constriction that creates two subbasins: an upper and lower valley. The data were classified into one three groups based on synoptic influence (weak/absent, high wind speeds, other evidence influence). Gap commonly developed downwind association with weak/absent group but also occurred suggesting potential for more diverse origins. In general, frequency strength gap appeared...

Chemical speciation studies use sampling configurations that often require the deployment of denuder tubes various types to measure certain species or control particulate artifacts. Concurrent sets measurements on Teflon membrane and quartz filters in specific were used evaluate potential influence with glycerol-based coatings mass carbon downstream filters. Positive biases observed measurement gravimetric filters, respectively, sodium carbonate/glycerol citric acid/glycerol coated relative...