scholarly journals Project Sagebrush: Revisiting the Value of the Horizontal Plume Spread Parameter σy

2016 ◽  
Vol 55 (6) ◽  
pp. 1305-1322 ◽  
Author(s):  
D. Finn ◽  
K. L. Clawson ◽  
R. M. Eckman ◽  
H. Liu ◽  
E. S. Russell ◽  
...  
Keyword(s):  
Field Experiments ◽  
National Laboratory ◽  
Field Studies ◽  
Tracer Experiment ◽  
Horizontal Wind ◽  
Plume Dispersion ◽  
Atmospheric Conditions ◽  
Stability Class ◽  
Wind Speeds ◽  
Range Of Values

AbstractThe first phase of an atmospheric tracer experiment program, designated Project Sagebrush, was conducted at the Idaho National Laboratory in October 2013. The purpose was to reevaluate the results of classical field experiments in short-range plume dispersion (e.g., Project Prairie Grass) using the newer technologies that are available for measuring both turbulence levels and tracer concentrations. All releases were conducted during the daytime with atmospheric conditions ranging from neutral to unstable. The key finding was that the values of the horizontal plume spread parameter σy tended to be larger, by up to a factor of ~2, than those measured in many previous field studies. The discrepancies tended to increase with downwind distance. The values of the ratio σy/σθ, where σθ is the standard deviation of the horizontal wind direction, also trend near the upper limit or above the range of values determined in earlier studies. There was also evidence to suggest that the value of σy began to be independent of σθ for σθ greater than 18°. It was also found that the commonly accepted range of values for σθ in different stability conditions might be limiting, at best, and might possibly be unrealistically low, especially at night in low wind speeds. The results raise questions about the commonly accepted magnitudes of σy derived from older studies. These values are used in the parameterization and validation of both older stability-class dispersion models as well as newer models that are based on Taylor’s equation and modern PBL theory.

The influence of surface atmospheric conditions on the range and area reached by animal vocalizations.

1997 ◽  
Vol 200 (3) ◽  
pp. 421-431 ◽  
Author(s):  
D Larom ◽  
M Garstang ◽  
K Payne ◽  
R Raspet ◽  
M Lindeque
Keyword(s):  
Sound Propagation ◽  
Computer Modelling ◽  
Low Frequency ◽  
Field Studies ◽  
Atmospheric Conditions ◽  
Frequency Sound ◽  
Wind Speeds ◽  
Calling Behaviour ◽  
Animal Vocalizations ◽  
Temperature Inversions

Low-level vertical changes in temperature and wind exert powerful and predictable influences on the area ensonified by animal vocalizations. Computer modelling of low-frequency sound propagation in measured atmospheric conditions predicts that the calls of the savanna elephant at these frequencies can have ranges exceeding 10 km and that the calls will be highly directional in the presence of wind shear. Calling area is maximized under temperature inversions with low wind speeds. Calling area changes substantially over 24 h periods; on any given day, the calling area undergoes an expansion and contraction which may be as large as one order of magnitude. This cycle is modulated by topography, regional weather patterns, seasonality and possibly by climate variation. Similar influences affect the somewhat higher-frequency calls of lions and may be a selective pressure towards their crepuscular and nocturnal calling behaviour. Coyotes and wolves, which also live in areas with strong and prevalent nocturnal temperature inversions, show similar calling patterns, maximizing their chances of being heard over the longest possible distances. The pronounced dawn and evening vocalization peaks in other animals including birds, frogs and insects may reflect the same influences in combination with other factors which selectively limit high-frequency sound propagation. Atmospheric conditions therefore need to be taken into account in many field studies of animal behaviour. A simplified method for estimating sound propagation during field studies is presented.

scholarly journals River Breezes for Pollutant Dispersion in GoAmazon2014/5

2018 ◽  
Author(s):  
Adan S. S. Medeiros ◽  
Igor O. Ribeiro ◽  
Marcos V. B. Morais ◽  
Rita V. Andreoli ◽  
Jorge A. Martins ◽  
...  
Keyword(s):  
Pollutant Dispersion ◽  
Atmospheric Composition ◽  
Horizontal Wind ◽  
Data Sets ◽  
Plume Dispersion ◽  
Wind Fields ◽  
Wind Speeds ◽  
Pollutant Concentrations ◽  
First Case ◽  
Apparent Influence

Abstract. The effect of river breezes on pollutant plume dispersion or canalization in the central Amazon was evaluated. A pollution plume changes atmospheric composition downwind of Manaus, a city of 2 million people positioned at the confluence between two wide rivers. Herein, to evaluate the effects of river breezes, two cases were modeled at the mesoscale for March 2014. The first case, "with rivers" (wR), simulated the transport and chemistry of the Manaus pollution plume as the rivers were in reality. The second case, "without rivers" (woR), carried out simulations for which all rivers and floodable areas were replaced by forest. The three main conclusions are as follows: (1) Between the two cases, alterations in wind speeds were maximum at local noon, and river breezes influenced horizontal wind fields from surface up to 150 m in altitude, suggesting a capping height of 150 m on most days for the influence of river breezes on pollutant concentrations. In agreement with this modeling result, data sets collected at 500 m by aircraft flights showed no apparent influence of the underlying rivers on plume dispersion. The flights traversed the plume downwind of Manaus during the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) Experiment. (2) Between the wR and wOR cases, changes to downwind concentrations of O3, NOx, and CO pollutants were

scholarly journals Relationship between the NO<sub>2</sub> photolysis frequency and the solar global irradiance

2009 ◽  
Vol 2 (4) ◽  
pp. 1537-1573 ◽  
Author(s):  
I. Trebs ◽  
B. Bohn ◽  
C. Ammann ◽  
U. Rummel ◽  
M. Blumthaler ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Field Experiments ◽  
Global Radiation ◽  
Ground Level ◽  
Field Studies ◽  
Atmospheric Conditions ◽  
Global Irradiance ◽  
Tropical Environments ◽  
Photolysis Frequency

Abstract. Representative values of the atmospheric NO2 photolysis frequency, (j(NO2)), are required for the adequate calculation and interpretation of NO and NO2 concentrations and exchange fluxes near the surface. Direct measurements of j(NO2) at ground level are often not available in field studies. In most cases, modeling approaches involving complex radiative transfer calculations are used to estimate j(NO2) and other photolysis frequencies for air chemistry studies. However, important input parameters for accurate modeling are often missing, most importantly with regard to the radiative effects of clouds. On the other hand, solar global irradiance ("global radiation", G) is nowadays measured as a standard parameter in most field experiments and in many meteorological observation networks around the world. A linear relationship between j(NO2) and G was reported in previous studies and has been used to estimate j(NO2) from G in the past 30 years. We have measured j(NO2) using spectro- or filter radiometers and G using pyranometers side-by-side at several field sites. Our results cover a solar zenith angle range of 0–90°, and are based on nine field campaigns in temperate, subtropical and tropical environments during the period 1994–2008. We show that a second-order polynomial function (intercept=0): j(NO2)=(1+α)×(B1×G+B2×G2), with α defined as the site-dependent UV-A surface albedo and the polynomial coefficients (including uncertainty ranges): B1=(1.47±0.03)×10−5 W−1 m2 s−1 and B2=(−4.84±0.31)×10−9 W−2 m4 s−1 can be used to estimate ground-level j(NO2) directly from G, independent of solar zenith angle under all atmospheric conditions. The absolute j(NO2)↓ residual of the empirical function is ±6×10−4 s−1 (95.45% confidence level). The relationship is valid for sites below 800 m a.s.l. and under low background albedo conditions. It is not valid in alpine regions, above snow or ice and sandy or dry soil surfaces. Our function can be applied to estimate chemical life times of the NO2 molecule with respect to photolysis, and is useful for surface-atmosphere exchange and photochemistry studies close to the ground, e.g., above fields with short vegetation and above forest canopies.

Corrosion and performance of dust palliatives : laboratory and field studies

2021 ◽  
Author(s):  
Lulu Edwards ◽  
Charles Weiss ◽  
J. Newman ◽  
Fred Nichols ◽  
L. Coffing ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Field Trials ◽  
Ground Vehicle ◽  
Wind Speeds ◽  
Corrosion Studies ◽  
Air Impingement ◽  
And Performance ◽  
Rotary Wing

This report details laboratory and field experiments on BioPreferred® dust suppressants to assess performance and corrosion characteristics. Numerous bio-based dust suppressant products are marketed, but little data are available to assess performance for dust abatement and corrosion of common metals. A laboratory study used an air impingement device and the Portable In-Situ Wind ERosion Laboratory (PI-SWERL) to simulate wind speeds similar to those in field conditions for rotary wing aircraft. Laboratory corrosion studies used metal coupons imbedded in soil treated with dust palliative. Field trials were conducted using ground vehicle traffic to minimize cost and lower safety concerns while increasing surface wear from repetitive traffic. These studies clearly show that bio-based products demonstrate low corrosion potential with similar dust abatement performance to synthetic-based agents.

scholarly journals On the Exchange of Momentum over the Open Ocean

2013 ◽  
Vol 43 (8) ◽  
pp. 1589-1610 ◽  
Author(s):  
James B. Edson ◽  
Venkata Jampana ◽  
Robert A. Weller ◽  
Sebastien P. Bigorre ◽  
Albert J. Plueddemann ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Wind Speed ◽  
Field Experiments ◽  
Field Studies ◽  
Wave Age ◽  
Wind Speeds ◽  
Smooth Flow ◽  
Direct Covariance ◽  
Wave Slope ◽  
Using Data

Abstract This study investigates the exchange of momentum between the atmosphere and ocean using data collected from four oceanic field experiments. Direct covariance estimates of momentum fluxes were collected in all four experiments and wind profiles were collected during three of them. The objective of the investigation is to improve parameterizations of the surface roughness and drag coefficient used to estimate the surface stress from bulk formulas. Specifically, the Coupled Ocean–Atmosphere Response Experiment (COARE) 3.0 bulk flux algorithm is refined to create COARE 3.5. Oversea measurements of dimensionless shear are used to investigate the stability function under stable and convective conditions. The behavior of surface roughness is then investigated over a wider range of wind speeds (up to 25 m s−1) and wave conditions than have been available from previous oversea field studies. The wind speed dependence of the Charnock coefficient α in the COARE algorithm is modified to , where m = 0.017 m−1 s and b = −0.005. When combined with a parameterization for smooth flow, this formulation gives better agreement with the stress estimates from all of the field programs at all winds speeds with significant improvement for wind speeds over 13 m s−1. Wave age– and wave slope–dependent parameterizations of the surface roughness are also investigated, but the COARE 3.5 wind speed–dependent formulation matches the observations well without any wave information. The available data provide a simple reason for why wind speed–, wave age–, and wave slope–dependent formulations give similar results—the inverse wave age varies nearly linearly with wind speed in long-fetch conditions for wind speeds up to 25 m s−1.

scholarly journals Large Contributions from Biogenic Monoterpenes and Sesquiterpenes to Organic Aerosol in the Southeastern United States

2018 ◽  
Author(s):  
Lu Xu ◽  
Havala O. T. Pye ◽  
Jia He ◽  
Yunle Chen ◽  
Benjamin N. Murphy ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Organic Aerosol ◽  
Atmospheric Model ◽  
Average Concentration ◽  
Mass Spectrometry Data ◽  
World Health ◽  
Atmospheric Conditions ◽  
Considerable Uncertainty ◽  
Health Organization

Abstract. Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are critical precursors of OA. The OA generation from these precursors predicted by models has considerable uncertainty owing to a lack of appropriate observations as constraints. Here, we perform novel lab-in-the-field experiments, which allow us to study OA formation under realistic atmospheric conditions and offer a connection between laboratory and field studies. Based on the lab-in-the-field experimental approach and positive matrix factorization analysis on aerosol mass spectrometry data, we provide a measure of OA from monoterpenes and sesquiterpenes in the southeastern U.S. Further, we use an upgraded atmospheric model and reproduce the measured OA concentration from monoterpenes and sesquiterpenes at multiple sites in the southeastern U.S., building confidence in the observed attribution of monoterpene SOA. We show that the annual average concentration of OA from monoterpenes and sesquiterpenes in the southeastern U.S. is ~ 2.1 µg m−3. This amount is substantially higher than represented in current regional models and accounts for 21 % of World Health Organization PM2.5 standard, indicating a significant contributor of environmental risk to the 77 million habitants in the southeastern U.S.

scholarly journals Relationship between the NO<sub>2</sub> photolysis frequency and the solar global irradiance

2009 ◽  
Vol 2 (2) ◽  
pp. 725-739 ◽  
Author(s):  
I. Trebs ◽  
B. Bohn ◽  
C. Ammann ◽  
U. Rummel ◽  
M. Blumthaler ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Surface Albedo ◽  
Field Experiments ◽  
Global Radiation ◽  
Ground Level ◽  
Field Studies ◽  
Atmospheric Conditions ◽  
Global Irradiance ◽  
Photolysis Frequency

Abstract. Representative values of the atmospheric NO2 photolysis frequency j(NO2) are required for the adequate calculation and interpretation of NO and NO2 concentrations and exchange fluxes near the surface. Direct measurements of j(NO2) at ground level are often not available in field studies. In most cases, modeling approaches involving complex radiative transfer calculations are used to estimate j(NO2) and other photolysis frequencies for air chemistry studies. However, important input parameters for accurate modeling are often missing, most importantly with regard to the radiative effects of clouds. On the other hand, solar global irradiance ("global radiation", G) is nowadays measured as a standard parameter in most field experiments and in many meteorological observation networks around the world. Previous studies mainly reported linear relationships between j(NO2) and G. We have measured j(NO2) using spectro- or filter radiometers and G using pyranometers side-by-side at several field sites. Our results cover a solar zenith angle range of 0–90°, and are based on nine field campaigns in temperate, subtropical and tropical environments during the period 1994–2008. We show that a second-order polynomial function (intercept = 0): j(NO2)=(1+α)× (B1×G+B2×G2), with α defined as the site-dependent UV-A surface albedo and the polynomial coefficients: B1=(1.47± 0.03)×10-5 W−1 m2 s−1 and B2=(-4.84±0.31)×10-9 W−2 m4 s−1 can be used to estimate ground-level j(NO2) directly from G, independent of solar zenith angle under all atmospheric conditions. The absolute j(NO2) residual of the empirical function is ±6×10-4 s−1(2σ). The relationship is valid for sites below 800 m a.s.l. and with low surface albedo (α<0.2). It is not valid in high mountains, above snow or ice and sandy or dry soil surfaces.

scholarly journals Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 321
Author(s):  
Stefan Cristian Prazaru ◽  
Giulia Zanettin ◽  
Alberto Pozzebon ◽  
Paola Tirello ◽  
Francesco Toffoletto ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Generalist Predators ◽  
Predator Species ◽  
Potted Plants ◽  
Naturally Occurring ◽  
Orius Majusculus ◽  
Limited Effectiveness ◽  
Pest Outbreaks ◽  
The Impact

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

Predicting cooling tower plume dispersion

1997 ◽  
Vol 211 (4) ◽  
pp. 291-297 ◽  
Author(s):  
B E A Fisher
Keyword(s):  
Cooling Tower ◽  
Industrial Process ◽  
Local Environment ◽  
Meteorological Conditions ◽  
Performance Criteria ◽  
Plume Dispersion ◽  
Cooling Towers ◽  
Atmospheric Conditions ◽  
Operating Characteristics

An assessment of the effects of visible cooling tower plumes on the local environment can be a necessary part of any proposal for a new large industrial process. Predictions of the dispersion of plumes from cooling towers are based on methods developed for chimney emissions. However, the kinds of criteria used to judge the acceptability of cooling tower plumes are different from those used for stack plumes. The frequency of long elevated plumes and the frequency of ground fogging are the two main issues. It is shown that events associated with significant plume visibility are dependent both on the operating characteristics of the tower and on the occurrence of certain meteorological conditions. The dependence on atmospheric conditions is shown to be fairly complex and simple performance criteria based on the exit conditions from the tower are not sufficient for assessments.

scholarly journals Molecular-level evidence for marine aerosol nucleation of iodic acid and methanesulfonic acid

2021 ◽  
Author(s):  
An Ning ◽  
Ling Liu ◽  
Lin Ji ◽  
Xiuhui Zhang
Keyword(s):  
Molecular Level ◽  
Methanesulfonic Acid ◽  
Field Studies ◽  
Nucleation Mechanism ◽  
Polar Regions ◽  
Atmospheric Conditions ◽  
Iodic Acid ◽  
Quantum Chemical Approach ◽  
Marine Areas ◽  
First Time

Abstract. Both iodic acid (HIO3, IA) and methanesulfonic acid (CH3S(O)2OH, MSA) have been identified by field studies as important precursors of new particle formation (NPF) in marine areas. However, the mechanism of NPF in which IA and MSA are jointly involved is still unclear. Hence, we investigated the IA-MSA nucleation system under different atmospheric conditions and uncovered the corresponding nucleating mechanism at a molecular level for the first time using quantum chemical approach and Atmospheric Cluster Dynamics Code (ACDC). The findings showed that MSA can stabilize IA clusters via both hydrogen and halogen bonds. Moreover, the joint nucleation rate of IA-MSA system is significantly higher than that of IA self-nucleation, particularly in relatively cold marine regions with sparse IA and rich MSA. For the IA-MSA nucleation mechanism, in addition to self-nucleation of IA, the IA-MSA-involved clusters can also directly participate in the nucleation process, and their contribution is particularly prominent in the polar regions with rich MSA and sparse IA. The IA-MSA nucleation mechanism revealed in this work may help to elucidate some missing sources of marine NPF.

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