The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Richard H. Johnson - One of the best experts on this subject based on the ideXlab platform.
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A scale-discriminating vorticity budget for a Mesoscale vortex in a midlatitude, continental Mesoscale convective system
Journal of the Atmospheric Sciences, 2003Co-Authors: Jason C. Knievel, Richard H. JohnsonAbstract:Abstract The authors employ data from the NOAA Wind Profiler Network to present a scale-discriminating vorticity budget for a Mesoscale convective vortex (MCV) that was generated by a Mesoscale convective system (MCS) in Oklahoma and Kansas on 1 August 1996. A spatial bandpass filter was used to divide observed wind into Mesoscale and synoptic components. Then the authors sought sources and sinks of vorticity in those two components over 9 h of the MCV's lifetime. The vorticity budget reveals that both the Mesoscale and synoptic winds supplied significant vorticity to the MCV. The vortex's origin could not be proved, but data weakly suggest that tilting may have been mostly responsible. Convergence of absolute vorticity by the Mesoscale wind was the reason the MCV grew deeper and stronger as the MCS weakened. Finally, tilting of synoptic and Mesoscale vorticity by gradients in Mesoscale vertical motion was responsible for a secondary deepening of the MCV as the MCS dissipated. The budget suggests that, if...
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The Kinematics of a Midlatitude, Continental Mesoscale Convective System and Its Mesoscale Vortex
Monthly Weather Review, 2002Co-Authors: Jason C. Knievel, Richard H. JohnsonAbstract:The authors present a unique, scale-discriminating study of the environment-relative circulations within a Mesoscale convective system (MCS) and Mesoscale convective vortex (MCV). The MCS, a leading convective line and trailing stratiform region that became asymmetric, passed through the National Oceanic and Atmospheric Administration (NOAA) Profiler Network (NPN) in Kansas and Oklahoma on 1 August 1996. The MCV appeared in the MCS’s stratiform region just prior to the system’s mature stage and grew to a depth of over 12 km as the MCS dissipated. The MCV did not apparently survive to the next day. A spatial bandpass filter was used to divide observed wind into a component that was predominantly synoptic background wind and a component that was predominantly a Mesoscale perturbation on that background wind. A Mesoscale updraft, Mesoscale downdraft, and divergent outflows in the lower and upper troposphere were evident after the synoptic background wind was removed, so these four circulations were internal and fundamental to the MCS. The Mesoscale perturbation in wind in the middle troposphere extended farther behind the MCS than ahead of it, consistent with analytic studies and numerical simulations of gravity waves generated by heat sources characteristic of MCSs with leading convective lines and trailing stratiform regions. Deepening of the MCV appeared to be reflected in the vertical wind shear at the vortex’s center: as the MCV strengthened, the Mesoscale shear through its lower part decreased, perhaps as wind became more vortical at increasing altitudes. Mesoscale and synoptic vertical shears were of similar magnitude, so an average of environmental soundings outside an MCS probably does not accurately represent the shear that affects an MCV. This suggests the need to reevaluate how the kinematical settings of MCVs are diagnosed.
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Mesoscale Processes and Severe Convective Weather
Meteorological Monographs, 2001Co-Authors: Richard H. Johnson, Brian E. MapesAbstract:Severe convective weather events—tornadoes, hailstorms, high winds, flash floods—are inherently Mesoscale phenomena. While the large-scale flow establishes environmental conditions favorable for severe weather, processes on the Mesoscale initiate such storms, affect their evolution, and influence their environment. A rich variety of mesocale processes are involved in severe weather, ranging from environmental preconditioning to storm initiation to feedback of convection on the environment. In the space available, it is not possible to treat all of these processes in detail. Rather, we will introduce several general classifications of Mesoscale processes relating to severe weather and give illustrative examples. Although processes on the Mesoscale are often intimately linked with those on smaller and larger scales, we will exclude from discussion those that obviously lie outside the Mesoscale domain (e.g., baroclinic waves on the synoptic scale or charge separation in clouds on the microscale).
Yuh Lang Lin - One of the best experts on this subject based on the ideXlab platform.
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Mesoscale dynamics
Mesoscale Dynamics, 2007Co-Authors: Yuh Lang LinAbstract:Mesoscale weather systems are responsible for numerous natural disasters, such as damaging winds, blizzards and flash flooding. A fundamental understanding of the underlying dynamics involved in these weather systems is essential in forecasting their occurrence. This 2007 book provides a systematic approach to this subject. The opening chapters introduce the basic equations governing Mesoscale weather systems and their approximations. The subsequent chapters cover four major areas of Mesoscale dynamics: wave dynamics, moist convection, front dynamics and Mesoscale modelling. This is an ideal book on the subject for researchers in meteorology and atmospheric science. With over 100 problems, and password-protected solutions available to instructors at www.cambridge.org/9780521808750, this book could also serve as a textbook for graduate students. Modelling projects, providing hands-on practice for building simple models of stratified fluid flow from a one-dimensional advection equation, are also described.
Yvette Richardson - One of the best experts on this subject based on the ideXlab platform.
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Mesoscale Meteorology in Midlatitudes
Mesoscale Meteorology in Midlatitudes, 2010Co-Authors: Paul Markowski, Yvette RichardsonAbstract:Mesoscale Meteorology in Mid-Latitudes presents the dynamics of Mesoscale meteorological phenomena in a highly accessible, student-friendly manner. The book's clear mathematical treatments are complemented by high-quality photographs and illustrations. Comprehensive coverage of subjects including boundary layer Mesoscale phenomena, orographic phenomena and deep convection is brought together with the latest developments in the field to provide an invaluable resource for Mesoscale meteorology students. Mesoscale Meteorology in Mid-Latitudes functions as a comprehensive, easy-to-use undergraduate textbook while also providing a useful reference for graduate students, research scientists and weather industry professionals. CN - 0000
Hugh Alan Bruck - One of the best experts on this subject based on the ideXlab platform.
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Characterization and control of plastic deformation in Mesoscale premolded components to realize in-mold assembled Mesoscale revolute joints†
Polymer Engineering and Science, 2009Co-Authors: Arvind Ananthanarayanan, S. K. Gupta, Hugh Alan BruckAbstract:This article reports a mold design strategy and a detailed mechanics-based modeling approach to characterize and control the plastic deformation of premolded components during in-mold assembly of Mesoscale revolute joints. The following new results are reported in this article. First, a Mesoscale mold design with varying cavity shape is described to perform in-mold assembly of the Mesoscale revolute joint. Second, a transient computational fluid dynamics (CFD) modeling approach to determine the forces experienced by the Mesoscale parts due to injection molding is described. Finally, a mechanics-based model approach developed using a combination of experimental materials property data and the CFD results as input to a finite element simulation of the deformation response of the Mesoscale part is presented for the determination of critical mold design parameters that are necessary for repeatable fabrication of articulating Mesoscale revolute joints. Using the advances reported in this article a Mesoscale revolute joint has been successfully molded. To the best of our knowledge, this is the first demonstration of in-mold assembly process using a varying cavity shape mold tocreate an articulating Mesoscale revolute joint. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
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Development of in-Mold Assembly process for realizing Mesoscale revolute joints
Transactions of the North American Manufacturing Research Institution of SME, 2007Co-Authors: Arvind Ananthanarayanan, Hugh Alan Bruck, Z. Yu, S. K. Gupta, K.p. RajurkarAbstract:In-Mold Assembly process at the Mesoscale presents several manufacturing challenges. Results reported in this paper demonstrate the technical feasibility of creating rigid body Mesoscale revolute joints using In-Mold Assembly process. The following new results are reported in this paper. First, we describe a mold design with varying cavity shape to perform In-Mold Assembly. This mold design uses an accurate mold piece positioning method to avoid damage to delicate Mesoscale parts during the cavity change step. Second, we describe a mold insert fabrication process for making mold inserts with the desired surface characteristics for Mesoscale molding. Finally, we describe methods to limit the adhesion at the interfaces and hence create articulated revolute joint. Using the advances reported In this paper we have successfully molded a Mesoscale revolute joint. To the best of our knowledge, this is the first demonstration of In-Mold Assembly process using a varying cavity shape mold to create a Mesoscale revolute joint.
James A. Yoder - One of the best experts on this subject based on the ideXlab platform.
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High frequency and Mesoscale variability in SeaWiFS chlorophyll imagery and its relation to other remotely sensed oceanographic variables
Deep-Sea Research Part II: Topical Studies in Oceanography, 2004Co-Authors: B. Mete Uz, James A. YoderAbstract:In its typical use for the study of large scale and relatively slow variability of phytoplankton biomass, ocean-color imagery is often binned in space and in time, and variability within the bin is discarded as noise. Since small- to Mesoscale processes at time scales as short as a day may play a significant role in global cycles of carbon and nutrients, characterizing variability at these scales is necessary. With the first four years of nearly continuous daily imagery from the SeaWiFS instrument, we investigated patterns of variability at the Mesoscales, operationally defined as that within a 2×2-degree neighborhood. We show that Mesoscale variability of chlorophyll concentration (Chl) is high near the coasts, in dynamically active areas, and at the oligotrophic centers of subtropical gyres. High apparent variability over the oligotrophic ocean is a surprising contrast to the low variability in composite imagery at the same locations and may be due to increased relative noise at low mean Chl. Low correlation between pairs of images as little as 1 day apart in the oligotrophic ocean is consistent with a noise artifact, or alternatively may indicate that the observed variability is due to high-frequency phenomena. Spatial patterns of variability observed when data are binned into narrow ranges of mean Chl, suggest oceanographic origins. Patterns of variability in Chl and in sea-surface height have little correlation, suggesting that eddy pumping or turbulent diffusion along temporarily slanted isopycnal surfaces are not the major sources of Chl variability. The correlation between Mesoscale anomalies of Chl and sea-surface temperature is not always negative as would have been the case if anomalies were produced mainly by the entrainment of colder, nutrient-rich thermocline waters into the euphotic layer. Instead, we find roughly zonal bands of alternating negative and positive correlations determined by the relative directions of the background gradients of Chl and SST. Thus the most obvious influence of Mesoscale motion on the distribution of Chl is advection of the existing gradients. Both long-term means and local anomalies of scatterometric winds from QuikSCAT are also correlated with mean Chl. Much of this correlation appears to be due to changes in the relationship between surface roughness and wind speed, brought on by factors like surface films, thermal stability of the air column, and surface currents. Our analyses show the feasibility of using ocean-color imagery to study Mesoscale variability but also identify areas where there is room for major improvements. Minimization of speckling due to imperfect atmospheric correction, in particular, would significantly enhance the utility of SeaWiFS data at Mesoscales. © 2004 Elsevier Ltd. All rights reserved.
