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Physical Sciences and Mathematics Commons™

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Oceanography and Atmospheric Sciences and Meteorology

Florida Institute of Technology

2005

Articles 1 - 6 of 6

Full-Text Articles in Physical Sciences and Mathematics

Hyperspectral Simulation And Recovery Of Submerged Targets In Turbid Waters, Charles R. Bostater May 2005

Hyperspectral Simulation And Recovery Of Submerged Targets In Turbid Waters, Charles R. Bostater

Ocean Engineering and Marine Sciences Faculty Publications

Modeled hyperspectral reflectance signatures just above the water surface are obtained from radiative transfer models to create synthetic images of targets below the water surface. Images are displayed as 24 bit RGB images of the water surface using selected channels. Example model outputs are presented in this paper for a hyperspectral Monte Carlo and a hyperspectral layered analytical iterative model of radiative transport within turbid shallow water types. Images at the selected wavelengths or channels centered at 490, 530 and 680 nm suggests the two models provide quite similar results when displayed as RGB images. The techniques are demonstrated to …

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Local Adjustment Of The Background Error Correlation For Surface Analyses Over Complex Terrain, David T. Myrick, John D. Horel, Steven M. Lazarus Apr 2005

Local Adjustment Of The Background Error Correlation For Surface Analyses Over Complex Terrain, David T. Myrick, John D. Horel, Steven M. Lazarus

Aeronautics Faculty Publications

The terrain between grid points is used to modify locally the background error correlation matrix in an objective analysis system. This modification helps to reduce the influence across mountain barriers of corrections to the background field that are derived from surface observations. This change to the background error correlation matrix is tested using an analytic case of surface temperature that encapsulates the significant features of nocturnal radiation inversions in mountain basins, which can be difficult to analyze because of locally sharp gradients in temperature. Bratseth successive corrections, optimal interpolation, and three-dimensional variational approaches are shown to yield exactly the same …

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Evaluation Of A Wind Power Parameterization Using Tower Observations, Steven M. Lazarus, Jennifer Bewley Jan 2005

Evaluation Of A Wind Power Parameterization Using Tower Observations, Steven M. Lazarus, Jennifer Bewley

Ocean Engineering and Marine Sciences Faculty Publications

The spatial and temporal components of a published wind power parameterization method are evaluated using observed winds (9 m to 90 m) from 7 years of data collected at four towers in the Kennedy Space Center/Cape Canaveral Air Force Station network. The temporal component is governed by two parameterization inputs which represent the amplitude and mean of an assumed sinusoidal diurnal variation of the ratio of the 80 m to 10 m winds, respectively. Comparison with tower observations shows that the estimates of the mean ratio are robust but biased high, indicating that the temporal variation of the observations can …

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A Comparison Between Monte Carlo Simulations Of Runaway Breakdown And Terrestrial Gamma-Ray Flash Observations, Joseph R. Dwyer, David M. Smith Jan 2005

A Comparison Between Monte Carlo Simulations Of Runaway Breakdown And Terrestrial Gamma-Ray Flash Observations, Joseph R. Dwyer, David M. Smith

Aerospace, Physics, and Space Science Faculty Publications

Monte Carlo simulations of the runaway breakdown of air are used to calculate the spectra of terrestrial gamma-ray flashes (TGFs), which are then compared with RHESSI and CGRO/BATSE observations. It is found that the recent RHESSI spectrum is not consistent with a source altitude above 24 km but can be well fit by a source in the range of 15-21 km, depending upon the electric field geometry of the source. Because 15 km is not unusual for the tops of thunderstorms, especially at low latitudes, and is lower than typical minimum sprite altitudes, the RHESSI data imply that thunderstorms and …

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The Initiation Of Lightning By Runaway Air Breakdown, Joseph R. Dwyer Jan 2005

The Initiation Of Lightning By Runaway Air Breakdown, Joseph R. Dwyer

Aerospace, Physics, and Space Science Faculty Publications

A mechanism for lightning initiation by the sustained runaway breakdown of air is presented. Unlike earlior models that rely upon large cosmic-ray air showers, this mechanism uses the runaway electrons produced by the steady background of atmospheric cosmic-rays to amplify non-uniformities in the electric field. The ionization of air from the runaway electrons creates a region of discharge that propagates in the opposite direction of the electrons, enhancing the electric field in front of it to the point where a conventional breakdown can occur. As the discharged region grows, positron feedback can become important, dramatically increasing the flux of runaway …

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X-Ray Bursts Produced By Laboratory Sparks In Air, Joseph R. Dwyer, Hamid K. Rassoul, Ziad H. Saleh, Martin A. Uman, J. Jerauld, J. Anderson Plumer Jan 2005

X-Ray Bursts Produced By Laboratory Sparks In Air, Joseph R. Dwyer, Hamid K. Rassoul, Ziad H. Saleh, Martin A. Uman, J. Jerauld, J. Anderson Plumer

Aerospace, Physics, and Space Science Faculty Publications

X-ray observations were made during fourteen 1.5 to 2.0 m high-voltage discharges in air produced by a 1.5 MV Marx circuit. All 14 discharges generated x-rays in the ∼30 to 150 keV range. The x-rays, which arrived in discrete bursts, less than 0.5 microseconds in duration, occurred from both positive and negative polarity rod-to-plane discharges as well as from small, 5-10 cm series spark gaps within the Marx generator. The x-ray bursts usually occurred when either the voltages across the gaps were the largest or were in the process of collapsing. The bursts are remarkably similar to the x-ray bursts …

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