| Solar Flux Initialization Schemes for Distributed Surface Energy Budget Modeling |
AUG 2003 |
71 pages |
| Authors:
George G. Koenig; David H. Tofsted; ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
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 | It is a well-established fact that the state of the ground is driven in a large part by the downwelling solar and IR fluxes. Models developed to predict the state of the ground depend critically on these fluxes for initialization. When measured solar and infrared fluxes are not available they must be computed. We have compared the ground temperatures as computed by the thermal model SWOETHERM using different solar flux ... |
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| Navigation Through Fog: A Mathematical Analysis of Folded Path Propagation |
SEP 2002 |
56 pages |
| Authors:
David H. Tofsted; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM BATTLEFIELD ENVIRONMENT DIRECTORATE
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| Wendall Watkins of the U.S. Army Research Laboratory has a currently pending patent, which provides a technique for solving the problem of navigation through fog. This technique entails the use of laser illumination of retroreflective targets on airfield runways, stereo detection of the return signal, and debluming processing of the received imagery. The current analysis attempts a mathematical analysis of this same problem. Here, the propagation equations necessary to model ... |
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| Navigation Through Fog: A Mathematical Analysis of Folder Path Propagation |
SEP 2002 |
58 pages |
| Authors:
David H. Tofsted; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| The problem of navigation through fog was brought tragically to the fore during the summer of 1999 when John F. Kennedy Jr.'s plane crashed into the Atlantic off the coast of Martha's Vineyard. The key factor here was the inability to determine the vertical direction due to the lack of visual cues. Less catastrophic, but of more concern, are frequent delays caused by fog at America's major airports. It is ... |
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| Turbulence Simulation: On Phase and Deflector Screen Generation |
OCT 2001 |
68 pages |
| Authors:
David H. Tofsted; ARMY RESEARCH LAB WHITE SANDS NM COMPUTATIONAL AND INFORMATION SCIENCE DIRECTORATE
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| This report examines the topic of phase screen generation and introduces an alternative method of modeling propagation through turbulence based on an extended raytrace method involving passage through three- dimensionally varying refractive turbulence. The mathematics of propagation through turbulence are thoroughly detailed, including several derivations often left as exercises for the reader in other documentation. Chapter 2 contains an analysis of the interrelationships between Fourier transforms, Fourier series, and Fast ... |
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| Turbulence Simulation: Outer Scale Effects on the Refractive Index Spectrum |
NOV 2000 |
50 pages |
| Authors:
David H. Tofsted; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| An analysis of the commonly used refractive index power spectrum indicates that its method of simulating outer scale effects is deficient in two aspects: it approaches a nonzero value at zero frequency and is ambiguous regarding definition and usage of the outer scale in its functional form. To resolve these problems, a modified form of the refractive index spectrum is proposed which properly models the ... |
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| A Surface Energy Budget Model Modifying Heat Flow by Foliage Effects |
JUL 93 |
88 pages |
| Authors:
David H. Tofsted; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| Propagation of energy (either acoustic or electromagnetic energy) through the region of the atmosphere close to the earth's surface depends on estimates of the vertical structure of wind, pressure, temperature, humidity, and refractive index near the earth's surface. To help predict these vertical structures, the TGRAD model has been developed. The model is based on flux- profile methods, requiring simple meteorological inputs as functions of time. The model's original purpose ... |
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