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Articles 1321 - 1350 of 1383

Full-Text Articles in Physical Sciences and Mathematics

Full-Wave Modeling Of Small-Scale Gravity Waves Using Airborne Lidar And Observations Of The Hawaiian Airglow (Aloha-93) O(¹S) Images And Coincident Na Wind/Temperature Lidar Measurements, Michael P. Hickey Ph.D., Michael J. Taylor, Chester S. Gardner, Christian R. Gibbons Mar 1998

Full-Wave Modeling Of Small-Scale Gravity Waves Using Airborne Lidar And Observations Of The Hawaiian Airglow (Aloha-93) O(¹S) Images And Coincident Na Wind/Temperature Lidar Measurements, Michael P. Hickey Ph.D., Michael J. Taylor, Chester S. Gardner, Christian R. Gibbons

Publications

Measurements were made of mesospheric gravity waves in the OI (5577 Å) nightglow observed from Maui, Hawaii, during the Airborne Lidar and Observations of Hawaiian Airglow (ALOHA-93) campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of four waves through the mesopause region and calculated the O(¹S) nightglow response to the waves. Mean winds derived from Na wind/temperature lidar observations were employed in the computations. Wave amplitudes were calculated based on the requirement that the observed and …

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Nonlinear Modes Of Liquid Drops As Solitary Waves, Andrei Ludu, J. P. Draayer Mar 1998

Nonlinear Modes Of Liquid Drops As Solitary Waves, Andrei Ludu, J. P. Draayer

Publications

The nonlinear dynamic equations of the surface of a liquid drop are shown to be directly connected to Korteweg–de Vries (KdV) systems, giving traveling solutions that are cnoidal waves. They generate multiscale patterns ranging from small harmonic oscillations (linearized model), to nonlinear oscillations, up through solitary waves. These non-axis-symmetric localized shapes are also described by a KdV Hamiltonian system. Recently such “rotons” were observed experimentally when the shape oscillations of a droplet became nonlinear. The results apply to droplike systems from cluster formation to stellar models, including hyperdeformed nuclei and fission.

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Yang's Gravitational Theory, Brendan Guilfoyle, Brien C. Nolan Mar 1998

Yang's Gravitational Theory, Brendan Guilfoyle, Brien C. Nolan

Publications

Yang's pure space equations generalize Einstein's gravitational equations, while coming from gauge theory. We study these equations from a number of vantage points: summarizing the work done previously, comparing them with the Einstein equations and investigating their properties. In particular, the initial value problem is discussed and a number of results are presented for these equations with common energy-momentum tensors.

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A Search For Optical Afterglow From Grb 970828, P. J. Groot, T. J. Galama, J. Van Paradijs, C. Kouveliotou, R. A. M. J. Wijers, J. Bloom, N. Tanvir, R. Vanderspek, J. Greiner, A. J. Castro-Tirado, J. Gorosabel, T. Von Hippel, M. Lehnert, K. Kuijken, H. Hoekstra, N. Metcalfe, C. Howk, C. Conselice, J. Telting, R. G. M. Rutten, J. Rhoads, A. Cole, D. J. Pisano, R. Naber, R. Schwarz Jan 1998

A Search For Optical Afterglow From Grb 970828, P. J. Groot, T. J. Galama, J. Van Paradijs, C. Kouveliotou, R. A. M. J. Wijers, J. Bloom, N. Tanvir, R. Vanderspek, J. Greiner, A. J. Castro-Tirado, J. Gorosabel, T. Von Hippel, M. Lehnert, K. Kuijken, H. Hoekstra, N. Metcalfe, C. Howk, C. Conselice, J. Telting, R. G. M. Rutten, J. Rhoads, A. Cole, D. J. Pisano, R. Naber, R. Schwarz

Publications

We report on the results of R-band observations of the error box of the g-ray burst of 1997 August 28 made between 4 hr and 8 days after this burst occurred. No counterpart was found varying by more than 0.2 mag down to R 5 23.8. We discuss the consequences of this nondetection for relativistic blast wave models of g-ray bursts and the possible effect of redshift on the relation between optical absorption and the low-energy cutoff in the X-ray afterglow spectrum.

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Ion Bernstein Waves Driven By Two Transverse Flow Layers, Mark Anthony Reynolds, G. Ganguli Jan 1998

Ion Bernstein Waves Driven By Two Transverse Flow Layers, Mark Anthony Reynolds, G. Ganguli

Publications

The interaction between two narrow layers of E3B flow is investigated, along with their stability properties. The mode frequencies, growth rates, and eigenfunctions are calculated. It is found that the instability due to a single layer is robust to the inclusion of a second layer. Specifically, when the separation between the layers is on the order of the ion-cyclotron radius, there is strong coupling between the two layers and the second layer is destabilizing. In addition, when the flow velocities are in opposite directions a wide variety of modes is possible, including near-zero-frequency modes, resulting in broadband structure in both …

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Inversion Of Plasmaspheric Euv Remote Sensing Data From The Stp 72-1 Satellite, R.R. Meier, A.C. Nicholas, J.M. Picone, D.J. Melendez-Alvira, G. Ganguli, Mark Anthony Reynolds, E.C. Roelof Jan 1998

Inversion Of Plasmaspheric Euv Remote Sensing Data From The Stp 72-1 Satellite, R.R. Meier, A.C. Nicholas, J.M. Picone, D.J. Melendez-Alvira, G. Ganguli, Mark Anthony Reynolds, E.C. Roelof

Publications

Observations of the extreme ultraviolet emission of helium ions at 30.4 nm can be used to study the global shape of the plasmasphere and its dynamical response to geomagnetic forcing. In order to retrieve number densities of plasmaspheric He+ from such observations, we have developed a new inversion technique based on discrete inverse theory, which uses the optical data to optimize a parameterized model of the He+ distribution. We apply this inversion technique to several orbits of data obtained from the Naval Research Laboratory extreme ultraviolet photometric experiment launched on the STP 72-1 satellite in October 1972. The inversion is …

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New Technique Of Stereolithography To Local Curing In Thermosensitive Resins Using Co(2) Laser, A. L.J. Munhoz, P. R.S. Wagner, M. C.F. Ierardi, A. E. Kiel, M. A.F. Scarparo, S. D. Allen Jan 1998

New Technique Of Stereolithography To Local Curing In Thermosensitive Resins Using Co(2) Laser, A. L.J. Munhoz, P. R.S. Wagner, M. C.F. Ierardi, A. E. Kiel, M. A.F. Scarparo, S. D. Allen

Publications

A theoretical and experimental study of thermosensitive resins used in thermal stereolithography is presented. The process of local curing through the application of infrared radiation, which has proved to be useful in a new technique for the making of prototypes by means of selective heating with C02 laser (10.6um), is studied. The ideal composition of the thermosensitive resins has proved to be 10 parts epoxy, 1.4 part diethylene triamine (the curing agent) and 0.7 part silica powder. A physical theoretical model is applied for control of the parameters which influence the confinement of the curing in the irradiated bulk. A …

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Automated Classification Of Stellar Spectra. Ii: Two-Dimensional Classification With Neural Networks And Principal Components Analysis, Ted Von Hippel, Coryn A.L. Bailer-Jones, Mike Irwin Oct 1997

Automated Classification Of Stellar Spectra. Ii: Two-Dimensional Classification With Neural Networks And Principal Components Analysis, Ted Von Hippel, Coryn A.L. Bailer-Jones, Mike Irwin

Publications

We investigate the application of neural networks to the automation of MK spec- tral classification. The data set for this project consists of a set of over 5000 optical (3800–5200°A) spectra obtained from objective prism plates from the Michigan Spec- tral Survey. These spectra, along with their two-dimensional MK classifications listed in the Michigan Henry Draper Catalogue, were used to develop supervised neural network classifiers. We show that neural networks can give accurate spectral type classifications (68 = 0.82 subtypes, rms= 1.09 subtypes) across the full range of spectral types present in the data set (B2–M7). We show also that …

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Stellar Populations And The White Dwarf Mass Function: Connections To Supernova Ia Luminosities, Ted Von Hippel, G. D. Bothum, R. A. Schommer Sep 1997

Stellar Populations And The White Dwarf Mass Function: Connections To Supernova Ia Luminosities, Ted Von Hippel, G. D. Bothum, R. A. Schommer

Publications

We discuss the luminosity function of SNe Ia under the assumption that recent evidence for dispersion in this standard candle is related to variations in the white dwarf mass function (WDMF) in the host galaxies. We develop a simple parameterization of the WDMF as a function of age of a stellar population and apply this to galaxies of different morphological types. We show that this simplified model is consistent with the observed WDMF of Bergeron et al. (1992) for the solar neighborhood. Our simple models predict that WDMF variations can produce a range of more than 1.8 mag in MB(SN …

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Breakdown Of The Iron Passive Layer By Use Of The Scanning Electrochemical Microscope, David O. Wipf, John W. Still Aug 1997

Breakdown Of The Iron Passive Layer By Use Of The Scanning Electrochemical Microscope, David O. Wipf, John W. Still

Publications

The scanning electrochemical microscope (SECM) is used to generate localized corrosion at passivating iron surfaces by using the tip to generate Cl– ions. Use of the SECM allows the rapid establishment of a locally aggressive chemical environment at a pre-selected site on the iron surface. The susceptibility for passive-layer breakdown and corrosion initiation was examined as a function of the time between the start of the passive-layer growth and the formation of Cl- ions. The breakdown of the passive-layer was found to depend strongly on the passivation potential and the site of Cl- formation on the iron …

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Physical Parameterization Of Stellar Spectra: The Neural Network Approach, Coryn A.L. Bailer-Jones, Ted Von Hippel, Mike Irwin, Gerard Gilmore Jul 1997

Physical Parameterization Of Stellar Spectra: The Neural Network Approach, Coryn A.L. Bailer-Jones, Ted Von Hippel, Mike Irwin, Gerard Gilmore

Publications

We present a technique which employs artificial neural networks to produce physical parameters for stellar spectra. A neural network is trained on a set of synthetic optical stellar spectra to give physical parameters (e.g. Teff, log g, [M/H]). The network is then used to produce physical parameters for real, observed spectra. Our neural networks are trained on a set of 155 synthetic spectra, generated using the spectrum program written by Gray (Gray & Corbally 1994, Gray & Arlt 1996). Once trained, the neural network is used to yield Teff for over 5000 B–K spectra extracted from a set of photographic …

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Numerical Simulations Of Gravity Waves Imaged Over Arecibo During The 10-Day January 1993 Campaign, Michael P. Hickey Ph.D., R. L. Walterscheid, Michael J. Taylor, William Ward, G. Schubert, Qihou Zhou, Francisco Garcia, Michael C. Kelly, G. G. Shepherd Jun 1997

Numerical Simulations Of Gravity Waves Imaged Over Arecibo During The 10-Day January 1993 Campaign, Michael P. Hickey Ph.D., R. L. Walterscheid, Michael J. Taylor, William Ward, G. Schubert, Qihou Zhou, Francisco Garcia, Michael C. Kelly, G. G. Shepherd

Publications

Recently, measurements were made of mesospheric gravity waves in the OI (5577 Å) nightglow observed from Arecibo, Puerto Rico, during January 1993 as part of a special 10-day campaign. Clear, monochromatic gravity waves were observed on several nights. By using a full-wave model that realistically includes the major physical processes in this region, we have simulated the propagation of two waves through the mesopause region and calculated the O(¹S) nightglow response to the waves. Mean winds derived from both UARS wind imaging interferometer (WINDII) and Arecibo incoherent scatter radar observations were employed in the computations as were the …

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The Circulating Processor Model Of Parallel Systems, Amy Apon, Lawrence Dowdy May 1997

The Circulating Processor Model Of Parallel Systems, Amy Apon, Lawrence Dowdy

Publications

This paper introduces the circulating processor model for parallel computer systems. The circulating processor model is a product form queuing network model where the processors are allowed to circulate between the parallel applications instead of the more traditional circulating task model. Certain behaviors of parallel systems are better captured using this new approach. The circulating processor model may be load dependent or load dependent. The load dependent circulating processor model is exact for systems which contain a single parallel application. An exact error is calculated for the load independent circulating processor model for systems which contain a single parallel application. …

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Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales Jan 1997

Velocity–Space Drag And Diffusion In A Model, Two-Dimensional Plasma, Mark Anthony Reynolds, B.D. Fried, G.J. Morales

Publications

The quasilinear fluctuation integral is calculated for a two-dimensional, unmagnetized plasma ~composed of charged rods!, and is expressed in terms of Fokker–Planck coefficients. It is found that in two dimensions, the enhanced fluctuations generated by fast electrons lead to anomalously large transport coefficients. In particular, the effect of a small population of fast electrons is only weakly dependent on their density. In three dimensions, the effect of fast electrons is masked by the dominant approximation, but higher-order terms describe processes similar to those in two dimensions, and these terms can become significant for weakly stable plasmas. The differences between two …

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Effect Of Diurnal Convection On Trapped Thermal Plasma In The Outer Plasmasphere, Mark Anthony Reynolds, G. Ganguli, J.A. Fedder, D.J. Melendez-Alvira Jan 1997

Effect Of Diurnal Convection On Trapped Thermal Plasma In The Outer Plasmasphere, Mark Anthony Reynolds, G. Ganguli, J.A. Fedder, D.J. Melendez-Alvira

Publications

A kinetic, multi‐species model of the plasmasphere is constructed that includes the effect of convection and corotation electric fields on trapped particles in drifting flux tubes. The resulting morphology of the outer plasmasphere is significantly different from the morphology obtained using the assumption of diffusive equilibrium. The difference is due primarily to the contraction and expansion of the region of velocity space accessible to the trapped particles, and has implications for the interpretation of remote sensing experiments.

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Gdr In Superdeformed Nuclei, F. Camera, A. Bracco, A. Atac, R. Bark, I. G. Bearden, J. J. Gaardhoje, B. Herskind, M. Kmiecik, S. Leoni, M. Mattiuzzi, A. Maj, G. Turri Jan 1997

Gdr In Superdeformed Nuclei, F. Camera, A. Bracco, A. Atac, R. Bark, I. G. Bearden, J. J. Gaardhoje, B. Herskind, M. Kmiecik, S. Leoni, M. Mattiuzzi, A. Maj, G. Turri

Publications

A search for the gamma decay of the Giant Dipole Resonance built on superdeformed nuclear configurations was made. The superdeformed states of the Eu-143 nucleus were populated using the reaction Pd-110(Cl-37, 4n)Eu-143 at a beam energy of 165 MeV. High energy gamma-rays were detected in 8 large BaF2 scintillators in coincidence with discrete transitions measured with part of the NORDBALL array (17 HPGe detectors and a 2 pi multiplicity filter). Spectra of high-energy gamma-rays gated by low-energy transitions from states fed by the superdeformed bands show an excess yield in the 7-10 MeV region with respect to those gated by …

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Wiyn Data Distribution And Archiving, Rob Seaman, Ted Von Hippel Jan 1997

Wiyn Data Distribution And Archiving, Rob Seaman, Ted Von Hippel

Publications

The NOAO/IRAF Save the Bits archive has been operating for over three years at Kitt Peak National Observatory and at the National Solar Observatory's nighttime program. Since that time, the W. M. Keck Observatory and the Cerro Tololo Inter-American Observatory have also adopted the software. These first generation Save the Bits installations rely on Exabyte tapes as the archival medium, typically using pairs of drives to produce duplicate copies of the data for heightened protection against data loss. The upgrade of Save the Bits that is currently in progress to support writable CD-R drives is discussed. In addition to another …

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Experimental Results Of Neutron Fluence Outside An Iron Shield In The Forward Direction, M. M.C. Torres, A. J. Elwyn, D. Fein, E. James, K. Johns, W. Davis, D. P. Ciampa, E. Mierkiewicz Sep 1996

Experimental Results Of Neutron Fluence Outside An Iron Shield In The Forward Direction, M. M.C. Torres, A. J. Elwyn, D. Fein, E. James, K. Johns, W. Davis, D. P. Ciampa, E. Mierkiewicz

Publications

This work represents the first systematic study at a high energy accelerator of the depth dependence of neutron fluence in longitudinal shielding.

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Reduction And Acetylation Of 2,4-Dinitrotoluene By A Pseudomonas Aeruginosa Strain, Daniel R. Noguera, David L. Freedman Jul 1996

Reduction And Acetylation Of 2,4-Dinitrotoluene By A Pseudomonas Aeruginosa Strain, Daniel R. Noguera, David L. Freedman

Publications

Aerobic and anoxic biotransformation of 2,4-dinitrotoluene (DNT) was examined by using a Pseudomonas aeruginosa strain isolated from a plant treating propellant manufacturing wastewater. DNT biotransformation in the presence and absence of oxygen was mostly reductive and was representative of the type of cometabolic transformations that occur when a high concentration of an easily degradable carbon source is present. P. aeruginosa reduced both nitro groups on DNT, with the formation of mainly 4-amino-2-nitrotoluene and 2-amino-4-nitrotoluene and small quantities of 2,4-diaminotoluene. Acetylation of the arylamines was a significant reaction. 4-Acetamide-2-nitrotoluene and the novel compounds 2-acetamide-4-nitrotoluene, 4-acet-amide-2-aminotoluene, and 2,4-diacetamidetoluene were identified as DNT …

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The Metallicity Dependence Of The Stellar Luminosity And Initial Mass Functions: Hst Observations Of Open And Globular Clusters, Ted Von Hippel, Gerard Gilmore, Nial R. Tanvir, David Robinson, Derek H.P. Jones Jul 1996

The Metallicity Dependence Of The Stellar Luminosity And Initial Mass Functions: Hst Observations Of Open And Globular Clusters, Ted Von Hippel, Gerard Gilmore, Nial R. Tanvir, David Robinson, Derek H.P. Jones

Publications

Using HST and the WFPC2 we have acquired very deep V- and I-band photometry of stars in NGC 2420 and NGC 2477 to study cluster luminosity functions at approximately solar metallicity. We have determined these cluster luminosity functions down to MI = 10.5 (0.2 M⊙) and find that the luminosity function of NGC 2420 turns over at MI ≈ 9.0, and possibly stops altogether by MI ≈ 9.5. The luminosity function of NGC 2477 may flatten at MI ≥ 9.5. We compare our open cluster luminosity functions to the solar neighborhood field star luminosity function of Kroupa, Tout \& Gilmore …

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Main Sequence Masses And Radii From Gravitational Redshifts, Ted Von Hippel Feb 1996

Main Sequence Masses And Radii From Gravitational Redshifts, Ted Von Hippel

Publications

Modern instrumentation makes it possible to measure the mass to radius ratio for main sequence stars in open clusters from gravitational redshifts. For stars where independent information is available for either the mass or the radius, this application of general relativity directly determines the other quantity. Applicable examples are: 1) measuring the radii of solar metallicity main sequence stars for which the mass - luminosity relation is well known, 2) measuring the radii for stars where model atmospheres can be used to determine the surface gravity (the mass to radius squared ratio), 3) refining the mass - radius relation for …

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An Almost Periodic Function Of Several Variables With No Local Minimum, Gregory S. Spradlin Jan 1996

An Almost Periodic Function Of Several Variables With No Local Minimum, Gregory S. Spradlin

Publications

No abstract provided.

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High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, Mark Anthony Reynolds Jan 1996

High-Frequency Fluctuations Of A Modulated, Helical Electron Beam, Mark Anthony Reynolds

Publications

The high-frequency electromagnetic field generated by a density-modulated, helical electron beam propagating in a magnetized plasma is calculated. The magnetic fluctuations are found to exhibit spatially localized ~evanescent! resonances at harmonics of the electron-cyclotron frequency, whose width is determined by the pitch angle of the beam, and whose existence is a consequence of the helical geometry. In addition, electrostatic modes are radiated near the hybrid frequencies, and electromagnetic modes are radiated above the upper-hybrid frequency. The predicted frequency spectrum and mode structure in configuration space are in good agreement with experimental observations of discrete emission lines at the electron-cyclotron harmonics.

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The Application Of Artificial Neural Networks To Stellar Classification, Coryn A. L. Jones, Mike Irwin, Ted Von Hippel Jan 1996

The Application Of Artificial Neural Networks To Stellar Classification, Coryn A. L. Jones, Mike Irwin, Ted Von Hippel

Publications

We are working on a project to automate the multi-parameter classification of stellar spectra using Principal Components Analysis (PCA) and Artificial Neural Networks. We present here the usefulness of PCA as a form of spectral data compression, and our results to date of classification on the MK system.

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A Chemical-Dynamical Model Of Wave-Driven Sodium Fluctuations, Michael P. Hickey Ph.D., John M.C. Plane Oct 1995

A Chemical-Dynamical Model Of Wave-Driven Sodium Fluctuations, Michael P. Hickey Ph.D., John M.C. Plane

Publications

A comprehensive chemical-dynamical model is used to investigate the interaction of gravity waves with twenty minor species involved in the atomic sodium chemistry in the mesopause region. We find that chemistry becomes important on the underside of the sodium layer, primarily below 85 km altitude, where the relative importance of chemistry in wave-driven sodium fluctuations increases with increasing wave period and increasing horizontal wavelength. We also find that for altitudes below 80 km an adequate determination of the effects of chemistry in these fluctuations requires the inclusion of several reactions related to ozone chemistry. However, the atomic Na density is …

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New Sources For The Hot Oxygen Geocorona: Solar Cycle, Seasonal, Latitudinal, And Diurnal Variations, Michael P. Hickey Ph.D., P. G. Richards, D. G. Torr Sep 1995

New Sources For The Hot Oxygen Geocorona: Solar Cycle, Seasonal, Latitudinal, And Diurnal Variations, Michael P. Hickey Ph.D., P. G. Richards, D. G. Torr

Publications

This paper demonstrates the variability of thermospheric sources of hot oxygen atoms. Numerical calculations were performed for day and night, high and low solar activity, summer and winter, and low- and middle-latitude conditions. Under most conditions, reactions involving metastable species are more important hot O sources than previously considered dissociative recombination of O2+ and NO+. All the hot O sources are an order of magnitude lower at midnight than at noon. At night, dissociative recombination of O2+and NO+ are the most important sources. Quenching of vibrationally excited N2 (N2*) by O is the most important metastable source at night. Above …

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Experiences Of Wfpc-2 Photometry And Psf Modelling, Nial Tanvir, David Robinson, Ted Von Hippel Mar 1995

Experiences Of Wfpc-2 Photometry And Psf Modelling, Nial Tanvir, David Robinson, Ted Von Hippel

Publications

The wide-field chips in WFPC-2 have ~0.0996 arcsec pixels, which is larger than the FWHM of the point spread function (PSF). This poor sampling of WFPC-2 images, means that simple stellar aperture photometry is competitive with profile fitting for moderately crowded fields. One of the problems which must be addressed with profile fitting photometry is that of allowing for variations of the PSF as a function of position on the image. The equivalent problem for aperture photometry is obtaining aperture corrections as a function of position. The aperture correction must be added to each aperture magnitude in order to account …

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An Independent Calibration Of Stellar Ages: Hst Observations Of White Dwarfs At V=25, Ted Von Hippel, Gerard Gilmore, D.H.P. Jones Mar 1995

An Independent Calibration Of Stellar Ages: Hst Observations Of White Dwarfs At V=25, Ted Von Hippel, Gerard Gilmore, D.H.P. Jones

Publications

The white dwarf luminosity function of a stellar cluster will have a sharp trunca- tion at a luminosity which is determined by the time since formation of the first white dwarfs in that cluster. Calculation of the dependence of this limiting luminosity on age requires relatively well-understood physics and is independent of stellar evolutionary models. Thus, measurement of the termination of the white dwarf luminosity func- tion provides an independent method to determine the age of a cluster, and thereby to calibrate stellar evolutionary ages. We have obtained HST WFPC2 data in two open clusters, identified the white dwarf sequence, …

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Wave-Modified Mean Exothermic Heating In The Mesopause Region, Michael P. Hickey Ph.D., R. L. Walterscheid Nov 1994

Wave-Modified Mean Exothermic Heating In The Mesopause Region, Michael P. Hickey Ph.D., R. L. Walterscheid

Publications

We employ a model of wave-driven OH nightglow fluctuations to calculate the effects of gravity waves on the chemical exothermic heating due to reactions involving odd hydrogen and odd oxygen species in the mesopause region. Using a model based on time means and deviations from those means, it is demonstrated that gravity waves contribute to the time-average exothermic heating. The effect can be significant because the fractional fluctuations in minor species density can be substantially greater than the fractional fluctuation of the major gas density. Our calculations reveal that the waves mitigate the exothermic heating, demonstrating their potential importance in …

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Simulations Of The Effects Of Water Vapor, Cloud Liquid Water, And Ice On Amsu Moisture Channel Brightness Temperatures, Bradley M. Muller, Henry E. Fuelberg, Xuwu Xiang Oct 1994

Simulations Of The Effects Of Water Vapor, Cloud Liquid Water, And Ice On Amsu Moisture Channel Brightness Temperatures, Bradley M. Muller, Henry E. Fuelberg, Xuwu Xiang

Publications

Radiative transfer simulations are performed to determine how water vapor and nonprecipitating cloud liquid water and ice particles within typical midlatitude atmospheres affect brightness temperatures T-B's of moisture sounding channels used in the Advanced Microwave Sounding Unit (AMSU) and AMSU-like instruments. The purpose is to promote a general understanding of passive top-of-atmosphere T-B's for window frequencies at 23.8, 89.0, and 157.0 GHz, and water vapor frequencies at 176.31, 180.31, and 182.31 GHz by documenting specific examples. This is accomplished through detailed analyses of T-B's for idealized atmospheres, mostly representing temperate conditions over land. Cloud effects are considered in terms of …

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