Meteorological Events that Produced the Highest Ground-Level Concentrations During Complex Terrain/Field Experiments

1986 ◽  
pp. 99-111
Author(s):  
Francis A. Schiermeier ◽  
Thomas F. Lavery ◽  
Donald C. DiCristofaro
Keyword(s):  
Complex Terrain ◽  
Field Experiments ◽  
Ground Level

Experimental Study of Gas Dispersion over Complex Terrain

2016 ◽  
Vol 821 ◽  
pp. 85-90 ◽  
Author(s):  
Petr Michálek ◽  
David Zacho
Keyword(s):  
Experimental Study ◽  
Complex Terrain ◽  
Dispersion Model ◽  
Concentration Field ◽  
Ground Level ◽  
Gas Emission ◽  
Gas Dispersion ◽  
Terrain Model ◽  
Flame Ionization ◽  
Ionization Detectors

Experimental study of gas dispersion over complex terrain model was performed in VZLU Prague. A complex terrain model was mounted into a boundary layer wind tunnel and equipped with ground-level gas emission source. Concentration field of the emitted gas was measured using comb suction probe and flame ionization detectors. The results will serve for verification and validation of a new computational dispersion model.

An Immersed Boundary Method for Simulation of Wind Flow Over Complex Terrain

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
S. Jafari ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Immersed Boundary Method ◽  
Complex Terrain ◽  
Stokes Equations ◽  
Ground Level ◽  
Rectangular Domain ◽  
Immersed Boundary ◽  
Test Case ◽  
Wind Flow ◽  
Wall Functions ◽  
Boundary Method

The accurate modeling of the wind resource over complex terrain is required to optimize the micrositing of wind turbines. In this paper, an immersed boundary method that is used in connection with the Reynolds-averaged Navier–Stokes equations with k-ω turbulence model in order to efficiently simulate the wind flow over complex terrain is presented. With the immersed boundary method, only one Cartesian grid is required to simulate the wind flow for all wind directions, with only the rotation of the digital elevation map. Thus, the lengthy procedure of generating multiple grids for conventional rectangular domain is avoided. Wall functions are employed with the immersed boundary method in order to relax the stringent near-wall grid resolution requirements as well as to allow the effects of surface roughness to be accounted for. The immersed boundary method is applied to the complex terrain test case of Bolund Hill. The simulation results of wind speed and turbulent kinetic energy show good agreement with experiments for heights greater than 5 m above ground level.

Seasonal differences in SO2 ground-level impacts from a power plant plume on complex terrain

2008 ◽  
Vol 149 (1-4) ◽  
pp. 445-455 ◽  
Author(s):  
J. L. Palau ◽  
J. Meliá ◽  
D. Segarra ◽  
G. Pérez-Landa ◽  
F. Santa-Cruz ◽  
...  
Keyword(s):  
Power Plant ◽  
Complex Terrain ◽  
Ground Level ◽  
Seasonal Differences

Response of three corn hybrids to defoliation of neighboring plants

1991 ◽  
Vol 71 (2) ◽  
pp. 311-315 ◽  
Author(s):  
B. L. Vasilas ◽  
J. J. Fuhrmann ◽  
R. W. Taylor
Keyword(s):  
Zea Mays ◽  
Field Experiments ◽  
Ground Level ◽  
Corn Hybrids ◽  
University Of Illinois ◽  
Relative Contribution ◽  
Hail Damage ◽  
Competition For Light ◽  
One Year ◽  
The University

Hail can cut completely through the whorl of young corn (Zea mays) plants causing complete defoliation. If only a portion of the stand is damaged, defoliated plants are subjected to shading by nondefoliated neighboring plants which benefit from reduced competition for light. Field experiments were conducted in 1986 and 1987 at the University of Illinois on a Flanagan silt loam (Aquic Argiudoll) to determine the relative contribution of both defoliated and nondefoliated plants to yield of the stand. Three hybrids were evaluated: Pioneer 3377, FR27 × FRMo17, and FRB73 × FR25. At the four-leaf stage the following treatments were imposed: cutting through the whorl of all plants 50 mm above ground level to effect complete defoliation (100-DEF) or cutting through the whorl of alternate plants (50-DEF). When compared to nondefoliated controls, the 100-DEF and 50-DEF treatments reduced grain yields on the average by 12.3 and 8.3%, respectively. No hybrid × defoliation interaction was detected for grain yield. With the 50-DEF treatment, compensation by nondefoliated plants was evident in the form of increased ears plant−1 and kernels ear−1, and 100-seed weight depending on the hybrid and year. Increased barrenness was a significant factor in decreased yields of defoliated plants only for FR27 × FRMo17 in one year. Key words: Zea mays L., hail damage, yield components, prolificacy, barrenness

scholarly journals Freezing and low temperature photoinhibition tolerance in cultivated potato and potato hybrids

2001 ◽  
Vol 10 (3) ◽  
pp. 153-163 ◽  
Author(s):  
M.M. SEPPÄNEN ◽  
O. NISSINEN ◽  
S. PERÄLÄ
Keyword(s):  
Low Temperature ◽  
Light Intensity ◽  
Field Experiments ◽  
Photosynthetic Apparatus ◽  
Ground Level ◽  
High Light Intensity ◽  
High Light ◽  
Freezing Stress ◽  
Ion Leakage ◽  
Frost Injury

Four Solanum tuberosum L. cultivars (Nicola, Pito, Puikula, Timo) and somatic hybrids between freezing tolerant S. commersonii and freezing sensitive S. tuberosum were evaluated for their tolerance to freezing and low temperature photoinhibition. Cellular freezing tolerance was studied using ion leakage tests and the sensitivity of the photosynthetic apparatus to freezing and high light intensity stress by measuring changes in chlorophyll fluorescence (FV/FM) and oxygen evolution. Exposure to high light intensities after freezing stress increased frost injury significantly in all genotypes studied. Compared with S. tuberosum cultivars, the hybrids were more tolerant both of freezing and intense light stresses. In field experiments the mechanism of frost injury varied according to the severity of night frosts. During night frosts in 1999, the temperature inside the potato canopy was significantly higher than at ground level, and did not fall below the lethal temperature for potato cultivars (from -2.5 to -3.0°C). As a result, frost injury developed slowly, indicating that damage occurred to the photosynthetic apparatus. However, as the temperature at ground level and inside the canopy fell below -4°C, cellular freezing occurred and the canopy was rapidly destroyed. This suggests that in the field visual frost damage can follow from freezing or non-freezing temperatures accompanied with high light intensity. Therefore, in an attempt to improve low temperature tolerance in potato, it is important to increase tolerance to both freezing and chilling stresses.

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.

scholarly journals Sweetpotato Clone Tolerance to Weed Interference

HortScience ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 229-232 ◽  
Author(s):  
Don R. La Bonte ◽  
Howard F. Harrison ◽  
Carl E. Motsenbocker
Keyword(s):  
Surface Area ◽  
Ipomoea Batatas ◽  
Field Experiments ◽  
Ground Level ◽  
Dry Mass ◽  
Light Interception ◽  
Weed Suppression ◽  
The Other ◽  
Weed Interference ◽  
Short Internode

Field experiments were conducted to assess how sweetpotato [Ipomoea batatas (L.) Lam.] clones interfere with weeds and how clones tolerate weed interference. Eleven clones with architecturally different canopies were evaluated for yield, canopy surface area and dry mass, weed dry mass, and light interception at ground level. A 2-fold difference in ground area covered by canopy surface area was observed among the eleven clones 42 days after planting, and a 3-fold difference in canopy dry mass at harvest. Yields were reduced from 14% to 68% by weed interference. The yields of high-yielding clones, `Beauregard', `Excel', L87-125, `Regal', `Centennial', and W-274, were reduced to a significantly greater extent by weeds than were yields of the other five clones. No differences were observed between clones for weed suppression as measured by weed dry mass at harvest and ground light interception. Short-internode and long-internode clones had similar competitive abilities. Yield of high-yielding clones was impacted more by weed interference than was that of low-yielding clones.

The Complex Terrain Measurement and Modeling Project of Land–Atmosphere Energy Exchanges (COMPLEX) Experiment

2020 ◽  
Author(s):  
Laura Herrera ◽  
Carlos Hoyos ◽  
Julián Urán
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Complex Terrain ◽  
Field Experiments ◽  
Air Pollutant ◽  
Turbulent Heat ◽  
Modeling Framework ◽  
Orographic Rainfall ◽  
Energy Exchanges

&lt;p&gt;The heterogeneity of the urban features, in addition to the inherent challenges added by highly complex terrain, has not allowed the scientific community to reach a complete understanding of the Atmospheric Boundary Layer (ABL) dynamics regarding the land-atmosphere interactions. The intricacies are higher when trying to simulate the observed interactions and their implications for air quality in a numerical modeling framework.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Over the last two decades, the ABL research community has dedicated several research efforts to study turbulent exchanges and ABL processes over complex terrain, and the implications of the particular features of these sites have on turbulence characteristics. A better knowledge of the ABL structure and dynamics is fundamental to understand processes such as air pollutant dispersion and disposal in the atmosphere, development and evolution of deep convection, and urban effects on meteorology. One of the aspects hindering our understanding is the lack of pertinent information from urbanized mountainous regions representative of the entire globe, useful to assess the different hypotheses and conceptual models of the Mountain Boundary Layer (MBL) dynamics. Most of the short- and long-term ABL field experiments in mountainous terrains have taken place over the high-latitude regions such as the Alps and the Rockies, and few over in the tropical Andes, where the Cordillera plays an essential role in controlling orographic rainfall intensification and the ventilation in inter-Andean valleys, resulting in knowledge gap regarding momentum, and latent and sensible heat flux exchanges over low-latitude, urban, complex terrain regions. In addition to a top-down approach, it is essential to follow a bottom-up strategy to study in detail the turbulent heat, mass, and momentum transfer in the Andean region.&lt;/p&gt;&lt;p&gt;The COMPLEX Experiment (COmplex terrain Measurement and modeling Project of Land-atmosphere Energy eXchanges) is a new effort focused on the long-term energy balance measurement campaign settled in the Aburr&amp;#225; Valley, a narrow highly complex mountainous-urban terrain located in the Colombian Andes. The primary purpose of this campaign is to identify the more relevant phenomenological features and processes responsible for ABL spatio-temporal variability, and land-atmosphere interactions in inter-Andean valleys. The long-term observational set-up includes eight sites equipped with turbulent flux sensors and net radiometers, in a cross-section of the valley, a microwave radiometer, a boundary layer radar, a scintillometer, and radiosonde intense observation periods (IOPs). We present the status of the COMPLEX experiment equipment deployment and preliminary results on the relationship of the transition between the stable boundary layer and the convective boundary layer and air quality in the region, and an exploration of the diurnal cycle of the different turbulent terms of the energy budget as a function of time and hill location.&lt;/p&gt;

Surface-layer scaling for thermally-driven up-slope flows

2020 ◽  
Author(s):  
Dino Zardi
Keyword(s):  
Boundary Layer ◽  
Numerical Simulations ◽  
Complex Terrain ◽  
Scaling Laws ◽  
Field Experiments ◽  
Layer Structure ◽  
Transport Processes ◽  
Future Research ◽  
Comprehensive Overview ◽  
Thermally Driven

&lt;p&gt;Sloping terrain of any inclination favour the development, under daytime heating, of thermally-driven organised flows, displaying peculiar boundary layer structures, and eventually triggering the development of atmospheric convection.&lt;/p&gt;&lt;p&gt;The ubiquitous occurrence of variously tilted surfaces - from gently sloping plains top steep cliffs, or valley sidewalls &amp;#8211; makes the understanding of such flows of utmost importance in view of the appropriate forecasting of the associated boundary layer transport processes. These may display quite a different structure from those, much better known, occurring over horizontal plain surfaces [1]. Also, they display a highly conceptual relevance, as the simplest, prototypal situations for many other thermally driven-flows over complex terrain [2]. Finally, with the increasing resolution of operational model runs, a more accurate parameterisation of these processes is required for a realistic simulation of their development in space and time. &amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;However, up-slope flows have received so far much less attention than downslope flows originating from cooling, which have been extensively investigated by means of theoretically analysis, field experiments and numerical simulations. Even the theoretical analysis on their onset and structure are rather limited (e.g. to gentle slopes: [3]). Analytical solutions, such as Prandtl&amp;#8217;s [4], rely on severely restrictive assumptions (parallel flow, constant or slowly varying eddy viscosity and diffusivity, along-slope invariance of the ambient factors). Extensions of such solutions relaxing those restrictions are still limited [5]. Even extensive high-resolution numerical simulations are rare, and not much progress has been made after Schumann&amp;#8217;s [6]. Further insight, especially on the conditions for flow separation, have been gained through laboratory-scale simulations [7], which however are limited to moderate flow situations.&lt;/p&gt;&lt;p&gt;The proposed presentation offers a comprehensive overview of our present understanding of these phenomena, ideas for scaling laws appropriate for these winds, and challenging open questions for future research.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;ol&gt;&lt;li&gt;Rotach, M. W., and D. Zardi, 2007: On the boundary layer structure over complex terrain: Key findings from MAP. Quart. J. Roy. Meteor. Soc., 133, 937-948.&lt;/li&gt; &lt;li&gt;Zardi, D. and C. D. Whiteman, 2013: Diurnal Mountain Wind Systems, Chapter 2 in &amp;#8220;Mountain weather research and forecasting &amp;#8211; Recent progress and current challenges&amp;#8221; (Chow, F. K., S. F. J. De Wekker, and B. Snyder Editors), Springer Atmospheric Sciences, Springer, Berlin.&lt;/li&gt; &lt;li&gt;Hunt, J. C. R., H. J. S. Fernando, and M. Princevac, 2003: Unsteady thermally driven flows on gentle slopes. J. Atmos. Sci., &lt;strong&gt;60&lt;/strong&gt;, 2169-2182.&lt;/li&gt; &lt;li&gt;Prandtl L. 1942. F&amp;#252;hrer durch die str&amp;#246;mungslehre, ch. V. Vieweg und Sohn [English translation: Prandtl, L., 1952: Mountain and Valley Winds in Stratified Air, in Essentials of Fluid Dynamics, Hafner Publishing Company, pp.422-425].&lt;/li&gt; &lt;li&gt;Zammett, R. J., and A. C. Fowler, 2007: Katabatic winds on ice sheets: A refinement of the Prandtl model. J. Atmos. Sci., &lt;strong&gt;64&lt;/strong&gt;, 2707&amp;#8211;2716.&lt;/li&gt; &lt;li&gt;Schumann U. 1990. Large-eddy simulation of the up-slope boundary layer. Quart. J. Roy. Meteor. Soc. &lt;strong&gt;116&lt;/strong&gt;, 637&amp;#8211;670.&lt;/li&gt; &lt;li&gt;Hilel Goldshmid, R.; Bardoel, S.L.; Hocut, C.M.; Zhong, Q.; Liberzon, D.; Fernando, H.J.S. Separation of Upslope Flow over a Plateau. Atmosphere 2018,&amp;#160;&lt;strong&gt;9&lt;/strong&gt;, 165.&lt;/li&gt; &lt;/ol&gt;

Evolution of Ground Level Scalar Concentrations Through a Compact Cylinder Array Embedded in the Atmospheric Surface Layer

2002 ◽  
Author(s):  
Heidi E. Miner ◽  
Adam Rasmussen
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
Field Experiments ◽  
Initial Conditions ◽  
Atmospheric Stability ◽  
Ground Level ◽  
Stability Conditions ◽  
Plume Dispersion ◽  
Gas Dispersion ◽  
Stable Conditions

Experiments for this study were designed to understand gas dispersion in the presence of surface mounted obstacles. To this end, model field experiments were conducted in a compact barrel array employing a spatial distribution of concentration sensors. Specific aims were to explore the effects of atmospheric stability and plume source initial conditions on the plume dispersion through the barrel array. The present results indicate a relaxation towards Gaussian behavior along the plume centerline. The rate of this Gaussian-like behavior is dependent upon atmospheric stability conditions. Plume dispersion through the array appears to be independent of source initial conditions under neutrally stable conditions.

Sign in / Sign up

Export Citation Format

Share Document