| Time-Dependent Stochastic Inversion in Acoustic Tomography of the Atmosphere with Reciprocal Sound Transmission |
17-Oct-2008 |
14 pages |
| Authors:
Sergey N Vecherin; Vladimir E Ostashev; A Ziemann; D K Wilson; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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 | Time-dependent stochastic inversion (TDSI) was recently developed for acoustic travel-time tomography of the atmosphere. This type of tomography allows reconstruction of temperature and wind-velocity fields given the location of sound sources and receivers and the travel times between all source?receiver pairs. The quality of reconstruction provided by TDSI depends on the geometry of the transducer array. However, TDSI has not been studied for the geometry with reciprocal sound transmission. This ... |
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| Tomographic Reconstruction of Atmospheric Turbulence with the Use of Time-Dependent Stochastic Inversion |
01-Sep-2007 |
11 pages |
| Authors:
Sergey N Vecherin; Vladimir E Ostashev; A Ziemann; D K Wilson; K Arnold; M Barth; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Acoustic travel-time tomography allows one to reconstruct temperature and wind velocity fields in the atmosphere. In a recently published paper [S. Vecherin et al., J. Acoust. Soc. Am. 119, 2579 (2006)], a time-dependent stochastic inversion TDSI was developed for the reconstruction of these fields from travel times of sound propagation between sources and receivers in a tomography array. TDSI accounts for the correlation of temperature and wind velocity fluctuations both ... |
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| Quasi-Wavelet Models of Turbulent Temperature Fluctuations Boundary-Layer Meteorology |
07 JUL 2006 |
24 pages |
| Authors:
George H. Goedecke; D. K. Wilson; Vladimir E. Ostashev; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Here, we contribute to the continuing development of the quasi-wavelet (QW) model of turbulence that is currently being used in simulations of sound propagation and scattering in the turbulent atmosphere. We show that a QW model of temperature fluctuations exists for any physically reasonable temperature spectrum of isotropic homogeneous turbulence, including the widely used von Karman spectrum. We derive a simple formula for the QW shape that reproduces a given ... |
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| Time-Dependent Stochastic Inversion in Acoustic Travel-Time Tomography of the Atmosphere |
MAY 2006 |
11 pages |
| Authors:
Sergey N. Vecherin; Vladimir E. Ostashev; George H. Goedecke; D. K. Wilson; Alexander G. Voronovich; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Stochastic inversion is a well known technique for the solution of inverse problems in tomography. It employs the idea that the propagation medium may be represented as random with a known spatial covariance function. In this paper, a generalization of the stochastic inverse for acoustic travel-time tomography of the atmosphere is developed. The atmospheric inhomogeneities are considered to be random, not only in space but also in time. This allows ... |
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| Sound Propagation Through and Scattering by Internal Gravity Waves in a Stably Strategified Atmosphere |
DEC 2005 |
11 pages |
| Authors:
Vladimir E. Ostashev; Igor P. Chunchuzov; D. K. Wilson; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| A stably stratified atmosphere supports propagation of internal gravity waves (IGW). These waves result in highly anisotropic fluctuations in temperature and wind velocity that are stretched in a horizontal direction. As a result, (IGW) can significantly affect propagation of sound waves in nighttime boundary layers and infrasound waves in the stratosphere. In this paper, a theory of sound propagation through, and scattering by, (IGW) is developed. First, 3D spectra of ... |
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| Sound Propagation and Scattering in Nighttime Atmospheric Boundary Layers |
18 MAR 2005 |
10 pages |
| Authors:
V. E. Ostashev; G. H. Goedecke; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| In this project, we developed 3D models of temperature and wind velocity fluctuations in nighttime boundary layers (NBL) and, using these models, studied sound propagation and scattering. The 3D spectra of temperature and velocity fluctuations due to internal gravity waves in moderately and very stable NBL were obtained. The 3D spectra of turbulent temperature and wind velocity fluctuations in weakly stable, intermittent NBL were modeled with the use of the ... |
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| Equations for Finite-Difference, Time-Domain Simulation of Sound Propagation in Moving Inhomogeneous Media and Numerical Implementation |
FEB 2005 |
16 pages |
| Authors:
Vladimir E. Ostashev; D. K. Wilson; Lanbo Liu; David F. Aldridge; Neil P. Symons; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Finite-difference, time-domain (FDTD) calculations are typically performed with partial differential equations that are first order in time. Equation sets appropriate for FDTD calculations in a moving inhomogeneous medium with an emphasis on the atmosphere! are derived and discussed in this paper. Two candidate equation sets, both derived from linearized equations of fluid dynamics, are proposed. The first, which contains three coupled equations for the sound pressure, vector acoustic velocity, and ... |
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| Station Calibration and Regionalization in China and Surrounding Areas |
JAN 2005 |
72 pages |
| Authors:
Thomas Hearn; James Ni; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| NMSU seismologists, in conjunction with seismologists from the Institute of Geophysics of the China Seismological Bureau (IG/CSB), have collected seismic data to calibrate International Monitoring System stations in China and document propagation characteristics of regional phases in China. Much of the work is focused on the Annual Bulletin of Chinese Earthquakes. We obtained copies of these bulletins for 1983-1995. A tomographic image of Pn velocity beneath China was made and ... |
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| Sound Propagation Through Anisotropic, Inhomogeneous and Intermittent Turbulence |
AUG 2001 |
10 pages |
| Authors:
V. E. Ostashev; G. H. Goedecke; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Three-dimensional models of anisotropic and inhomogeneous spectra of temperature and wind velocity fluctuations in unstable atmospheric boundary layers have been developed, modified or extended. Furthermore, theories of sound propagation through anisotropic, inhomogeneous, and intermittent atmospheric turbulence have been developed. These theories allow consideration of different geometries of sound propagation: line-of-sight sound propagation, interference of the direct and ground reflected waves, sound scattering into a refractive shadow zone, and waveguide sound ... |
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| Development of the Modern Theory of Sound Propagation in the Turbulent Atmosphere |
30 NOV 1998 |
9 pages |
| Authors:
George H. Goedecke; Vladimir E. Ostashev; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The foundations of the modern theory of sound propagation and scattering in a homogeneous and isotropic atmospheric turbulence are developed: The sound scattering cross-section for von Karman spectra of temperature and wind velocity fluctuations is calculated; the rigouros theory of line of sight sound propagation in an atmosphere with Kolmogorov, Gaussian and von Karman spectra of temperature and wind velocity fluctuations is developed; a new theoretical formulation of the interference ... |
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| Uppermost Mantle Structure in the Middle East, Central Asia, Lake Baikal, and Far East from Pn Tomography and Sn Attenuation |
NOV 97 |
36 pages |
| Authors:
Thomas Hearn; James Ni; Richard Rapine; Christopher Reese; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| We have studied the propagation efficiencies of the Sn and Lg phases throughout China and produced summary maps. In addition, estimates of coda Q, Q for the Pn phase, and Q for the Lg phase for Tibet have been made. Sn has difficulty propagating across extended terrains in eastern China, the northern Tibetan plateau, and Mongolia. This makes it a difficult phase to use for nuclear monitoring purposes. Analysis of ... |
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| Regional Wave Propagation Characteristics in Southern Asia |
31 OCT 1997 |
40 pages |
| Authors:
Richard Rapine; Chris Reese; James Ni; Tom Hearn; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Lg Q values were determined for most parts of China. Higher Q values are seen from paths crossing the Tarim Platform. Lower Q values are found in Burma, southern Tibet, and along the mountains that border the eastern Tibetan Plateau. The overall low Q values found in China are similar to Q values found in the western United States. Large north-south variations were observed for the ... |
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| Regional Wave Propagation Characteristics in the Middle East and Southern Asia |
OCT 96 |
42 pages |
| Authors:
Richard Rapine; James Ni; Tom Hearn; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The regional seismic waves Pn, Sn and Lg were used to map lateral variations of attenuation in the crust and upper mantle. Propagation efficiencies of Sn and Lg were qualitatively analyzed by ranking their amplitudes relative to the P-wave coda. Efficient Sn propagation is observed in the Tien Shan, Tarim Platform, southern Tibet, Yangzi Paraplatform and Sino- Korean Platform. We have confirmed previous studies by finding a lack of Sn ... |
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| Uppermost Mantle Structure in Southern Eurasia from PN Tomography and Sn Attenuation |
JUN 96 |
60 pages |
| Authors:
Thomas M. Hearn; James F. Ni; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| This project has investigated the seismic characteristics of southern Eurasia through Pn travel time tomography and the regional mapping of attenuation for high frequency Sn and Lg waves. Pn tomography results indicate that much of the uppermost mantle beneath southern Eurasia has low P-wave velocity and a small amount of melt. Mapping of Sn propagation efficiency confirms that regions with low Pn velocity generally do not propagate Sn waves efficiently. ... |
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| Regional Wave Propagation Characteristics in China and Southern Asia, |
14 AUG 1995 |
9 pages |
| Authors:
James Ni; Richard Rapine; Jianxin Wu; Thomas Hearn; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Regional wave propagation studies are currently an important focus of research because of concerns over proliferation of nuclear weapons. Regional studies serve a twofold purpose: (1) regional data can provide stable yield estimates for underground nuclear explosions, and (2) regional data can discriminate between explosions and earthquakes. Yield and discrimination studies have often used the Sn and Lg regional phases. However, discriminants based on these types of regional data are ... |
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| Scattering Attenuation in Fractally Homogeneous Random Media, |
14 AUG 1995 |
9 pages |
| Authors:
C. Reese; J. Ni; T. Hearn; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Much of seismic nuclear monitoring depends on a proper understanding of attenuation and scattering of regional seismic waves. This report seeks to characterize wave scattering from both an observational and theoretical approach. A theory of wave propagation in fractally homogeneous random media is developed and applied to southern Tibet in order to quantify the analytical and statistical properties of crust and upper lithosphere heterogeneity. Seismic velocity heterogeneity is modeled by ... |
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| Laser Beam Aerosol Interactions |
28 FEB 95 |
9 pages |
| Authors:
Robert L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
|
| This report details experimental investigations undertaken to understand the interactions of aerosol particles with laser beams. Both optical and thermal interactions were examined, including elastic scattering and fluorescence, as well as a variety of nonlinear interactions. A number of new and significant experimental findings we made which are detailed in this report. These findings provide the experimental basis for potential applications in the fields of atmospheric probing, remote sensing, and ... |
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| A Survey of Nonlinear Dynamics (Chaos Theory) |
APR 91 |
103 pages |
| Authors:
Richard L. Ingraham; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The aim of this report is to give a survey of the whole field of nonlinear dynamics (chaos theory) in compressed form. The standard topics--such as stability and bifurcation of continuous and discrete time systems, Hamiltonian systems, measures of chaos through Lyapunov exponents, broad band power spectra, and algorithmic complexity and related entropies, and experimental realization of chaos ---are covered. But in addition, some topics seldom seen in short surveys ... |
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| Atmospheric Propagation of Laser Beams |
FEB 91 |
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| Authors:
Robert L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
|
 | The enclosed report describes experimental and theoretical results obtained under this contract. Experimental work emphasized nonlinear interactions of an intense laser beam with micrometer-sized liquid droplets, including nonlinear optical effects such as stimulated Raman scattering (SRS) and lasing, plasma studies, and superheating. Theoretical analyses served both to aid in the understanding of the experimental investigations and to undertake studies of related theoretical interest, notably analysis of the companion problem of ... |
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| Stimulated Raman Scattering in Micrometer-Sized Droplets: Time-Resolved Measurements |
JUN 88 |
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| Authors:
A. Biswas; P. Chylek; R. L. Armstrong; H. Latifi; E. Creegan; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Time resolved measurements of elastic scattering and stimulated Raman scattering (SRS) in micrometer sized water and carbon tetrachloride droplets irradiated with a pulsed, frequency doubled Nd:YAG laser (pulse width 8 nsec, lambda = 532 nm, peak intensity approx. 1 GW sq.cm.) are reported. Elastic scattering of light is instantaneous within our measurement error, estimated to be < + or - 3 nsec. On the other hand, the first Stokes shift ... |
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| Atmospheric Propagation of Laser Beams |
08 MAR 88 |
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| Authors:
Robert L. Armstrong; Leon J. Radziemski; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| This report describes work done under the cited ARO research grant. Experimental and theoretical results are described, papers and conference presentations resulting from this work are enumerated, and a list of personnel supported under this grant is provided. Keywords: Laser, Aerosols, Atmosphere, Spectroscopy, High energy, Plasma, Nonlinear optics. |
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| Non-Linear Effects on the Atmospheric Transmission of High-Flux Electromagnetic Beams, |
MAY 1987 |
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| Authors:
R. L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The propagation of an intense beam of electromagnetic radiation through the atmosphere is accompanied by a host of interactions between the beam and atmospheric constituents present along the propagation path. These interactions may have a significant influence on the characteristics of the propagation beam. This paper discusses aerosol-beam interactions which, in many cases of practical interest, are the dominant interactions between the atmosphere and the propagating beam. Theoretical analyses, numerical ... |
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| Propagation Effects on Pulsed Light Beams in Absorbing Media. |
01 JAN 1984 |
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| Authors:
R. L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The propagation of a pulsed light beam through a medium containing absorbing aerosol droplets is considered. A previous analysis of the droplet temperture, including both vaporization and conductivity effects, is used to obtain for a monodisperse distribution of droplet radii the beam intensity and the droplet temperature along the path. For sufficiently long pulses, a vaporization front may be defined by the leading edge of the steady-state droplet temperature regime. ... |
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| High Resolution Atmospheric Transmittance Study |
JAN 1982 |
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| Authors:
Robert L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| A theoretical description of line mixing in the Q-branch of an infrared rotation-vibration band is obtained in the weak coupling approximation. The resulting absorption band shape is applied to the case of the nu-2-band of CO2 near 667/cm. Theoretical absorption profiles are illustrated in selected spectral regions for several values of the pressure. (Author) |
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| Modification of Single Scattering Model AGAUS |
MAY 1981 |
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| Authors:
Edward Burlbaw; August Miller; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| An improved method for computation of phase functions has been implemented in computer code AGAUS to obtain more reliable results for large diameter particles under conditions of relatively high absorption. The new routine uses a partial backward recursion and the method of continued fractions. This represents an improvement over the forward recursion method. A brief outline of the later method is given for review and comparison. Results are presented which ... |
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| Atmospheric Extinction Model Modification Analysis. |
SEP 1979 |
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| Authors:
August Miller; Edward Burlbaw; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| This document summarized modifications of ASL supplied atmospheric extinction models carried out at NMSU. The particular modifications which have been examined and completed are the following: (1) Revision of the line-by-line model (ATRAN) to include an additional line-profile (the 'Gross' profile) for use at near-millimeter wavelengths, (2) Revision of the single-scattering aerosol code AGAUSX to provide for user supplied inputs and program outputs describing the polarization properties of incident and ... |
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| Studies on the Development of Algorithms for the Prediction of Time-Dependent Optical Properties of Aerosols. |
DEC 1978 |
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| Authors:
August Miller; George H. Goedecke; Richard C. Shirkey; Yugal K. Behl; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Most of the work done under the contract has been directed toward searches for ways in which existing aerosol IR transmittance modeling codes could be made computationally more efficient in order to enhance their utility in applications involving time dependent variations in aerosol properties. In the course of those studies, NMSU personnel have examined both rigorous and approximate methods for calculating both single and multiple scattering extinction and scattering effects, ... |
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| Calculation of Thermal Emission from Aerosols Using the Doubling Technique. |
NOV 1978 |
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| Authors:
August Miller; Richard C. Shirkey; Mary Ann Seagraves; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| The doubling approach to numerically solving the equation of radiative transfer in a plane-parallel atmosphere is reviewed and extended to include thermal emissions from an ambient medium. The matrix method used is that of Barkstrom and Querfeld and employs the familiar S and T operators to construct a thermal emission operator, E. This new operator is not internally dependent upon the temperature of the layer under consideration, thereby providing a ... |
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| Line Parameter Variations and the Profile Dependence of Atmospheric Transmittance. |
JUL 1978 |
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| Authors:
R. L. Armstrong; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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