270
270
Jun 20, 2010
06/10
by
Silver, S
texts
eye 270
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No Abstract Available
Topics: ATMOSPHERIC ATTENUATION, SOLAR RADIATION
The benefits of high data rates, high directionality, low sidelobes, small size, light weight, and low power of laser communications (lasercom) as compared to radio frequency (RF) communications make laser an attractive option for ship-to-ship communications. The realization of the option requires ship-to-ship lasercom system design and mission planning, which, in turn, necessitates a lasercom link budget analysis and a parametric analysis of lasercom system design and operational parameters....
Topics: Lasercom, Link Budget, Atmospheric Attenuation, Acquisition, Tracking and Pointing.
216
216
Jun 21, 2010
06/10
by
Putre, H. A
texts
eye 216
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Turbulent coaxial flow analysis for predicting fuel mass in reactor cavity
Topics: ATMOSPHERIC ATTENUATION, FLIGHT HAZARDS, METEOROLOGICAL PARAMETERS, VISIBILITY, COLLISION...
240
240
Jul 12, 2010
07/10
by
Thuiller, G.; Simon, P. C.; Pastiels, R.; Labs, D.; Meckel, H
texts
eye 240
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This instrument, at the present time in development, will fly on board Spacelab I in May 1983. Other flights are foreseen during the following missions. The instrument is composed of three double monochromators covering the range 170 to 3200 nm. The spectrometers have bandpasses of 1 nm up to 900 nm and 20 nm from 850 to 3200 nm with an accuracy 1/100 nm. Calibration lamps are included in the instrument to monitor any change of its sensitivity and wavelength scale.
Topics: ATMOSPHERIC ATTENUATION, SOLAR CONSTANT, VARIATIONS, BALLOON-BORNE INSTRUMENTS, CALIBRATING, OZONE,...
234
234
Jul 9, 2010
07/10
by
Kodin, Y.; Pipko, D
texts
eye 234
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The problems involved in a descent trajectory on Mars by the U.S.S.R. Mars 6 automatic spacecraft are discussed. Atmospheric conditions and possible water supplies on Mars are considered, and photographs of surface craters are included.
Topics: ATMOSPHERIC ATTENUATION, ELECTROMAGNETIC RADIATION, ALGORITHMS, ATMOSPHERIC SCATTERING,...
227
227
Jul 5, 2010
07/10
by
Warren, M. E
texts
eye 227
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The problem of ameliorating the discomfort of passengers on a large air transport subject to flight disturbances is examined. The longitudinal dynamics of the aircraft, including effects of body flexing, are developed in terms of linear, constant coefficient differential equations in state variables. A cost functional, penalizing the rigid body displacements and flexure accelerations over the surface of the aircraft is formulated as a quadratic form. The resulting control problem, to minimize...
Topics: ATMOSPHERIC ATTENUATION, LASERS, OPTICAL COMMUNICATION, ATMOSPHERIC COMPOSITION, LIGHT...
Weather severity has unfavorable effect on FSO transmission performance. The impact could result in poor quality of transmission and communication failure. This paper presents the analysis using multiple free space optic channels with amplification to mitigate haze attenuation. The visibility is progressively reduced due to the attenuation effects, causing the bit error rate to increase. Three designs of FSO system are proposed in this research as they are simulated and analysed thoroughly...
Topics: Atmospheric attenuation, Bit error rate (BER), Diameter aperture, Free space optics (FSO),...
415
415
Jul 12, 2010
07/10
by
NON
texts
eye 415
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No Abstract Available
Topics: DEEP SPACE NETWORK, FREQUENCY STANDARDS, MICROWAVE EQUIPMENT, MICROWAVE TRANSMISSION, ATMOSPHERIC...
352
352
Jul 12, 2010
07/10
by
Hilberg, R. H.; White, R. K
texts
eye 352
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No Abstract Available
Topics: ATMOSPHERIC ATTENUATION, CARBON DIOXIDE LASERS, RADIATION COUNTERS, SYNCHRONOUS SATELLITES, BEAMS...
857
857
Jul 6, 2010
07/10
by
Morenoff, J.; Roth, D. L.; Singleton, J. W
texts
eye 857
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The study to develop, implement, and maintain a space law library and information system is summarized. The survey plan; major interviews with individuals representative of potential sources, users and producers of information related to aerospace law; and system trade-off analyses are discussed along with the NASA/RECON system capability. The NASA publications of STAR and IAA are described, and the NASA legal micro-thesaurus is included.
Topics: ATMOSPHERIC ATTENUATION, INFRARED RADIATION, LIGHT (VISIBLE RADIATION), WAVE PROPAGATION,...
250
250
Jul 6, 2010
07/10
by
BLUM, E. J
texts
eye 250
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THE EXISTENCE OF AT LEAST TWO CLASSES OF RADIO TELESCOPES, COMPARISON AND CORRELATION, AND THE SENSITIVITY OF THEIR ANTENNAS AND RECEIVERS ARE DEMONSTRATED. COMPARISONS OF THE TWO TYPES AND METHODS OF SELECTING THE TYPE BEST SUITED FOR A PARTICULAR EXPERIMENT ARE DESCRIBED.
Topics: ATMOSPHERIC MODELS, RADIO WAVES, VENUS ATMOSPHERE, WAVE PROPAGATION, ATMOSPHERIC ATTENUATION,...
241
241
May 22, 2011
05/11
by
Ries, John C
texts
eye 241
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While General Relativity has been adopted as the standard theory of relativity, there are alternative theories, with important implications for gravitational physics, which can only be discounted with tests of sufficient accuracy. In addition to its contributions to lunar and solar system dynamics, Lunar Laser Ranging, in combination with other solar system data continues to refine some important limits. Satellite laser ranging tracking of geodetic satellites can provide similar tests, but the...
Topics: COMPUTERIZED SIMULATION, ENVIRONMENT SIMULATION, POSITION (LOCATION), SOUND LOCALIZATION, VIRTUAL...
Double scattering corrections for aureole radiances are calculated by adding the effects of two successive single scatterings. Atmospheric absorption, polarization, and variation of refractive index with altitude are ignored. Corrections due to spherical atmosphere were taken into account by the use of a generalized Chapman function. Realistic scattering phase functions based upon the Lorenz-Mie theory and model altitude-size distribution are used. The model distribution is assumed to be...
Topics: NASA Technical Reports Server (NTRS), LIGHT SCATTERING, SOLAR CORONA, ATMOSPHERIC ATTENUATION,...
A simple radiative transfer model of the particle layer found at 85 km over the summer poles is presented. The effects of the layer on the global radiative temperature, the polar region temperature, and the greenhouse effect are discussed. The estimated magnitude of the global radiative temperature change is 3.5 x .001 K to 2.2 x .01 K, depending on the value of the imaginary part of the particle index of refraction. The layer is shown to have a possible secondary influence on the temperature...
Topics: NASA Technical Reports Server (NTRS), MESOSPHERE, POLAR REGIONS, RADIATIVE TRANSFER, ATMOSPHERIC...
The hardware for the three Autonomous Visibility Monitoring (AVM) observatories was redesigned. Changes in hardware design include electronics components, weather sensors, and the telescope drive system. Operation of the new hardware is discussed, as well as some of its features. The redesign will allow reliable automated operation.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, HARDWARE, REMOTE SENSORS, SCHMIDT...
270
270
Jun 21, 2010
06/10
by
Crossman, E. R. F. W.; Szostak, H
texts
eye 270
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Man machine models for automobile steering control based on car/driver/highway interaction
Topics: ACOUSTIC ATTENUATION, ATMOSPHERIC ATTENUATION, JET AIRCRAFT NOISE, ACOUSTIC DUCTS, ACOUSTIC...
243
243
May 27, 2011
05/11
by
NON
texts
eye 243
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This bibliography lists reports, articles and other documents recently introduced into the NASA scientific and technical information database. Subject coverage includes: Aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life and flightcrew behavior and performance.
Topics: LOW VISIBILITY, LUMINANCE, FLEXIBILITY, ENHANCED VISION, ATMOSPHERIC ATTENUATION, VISUAL STIMULI,...
Absorption by Lorentz, Doppler, and Voight lines are compared for a range of atmospheric parameters. It is found that, for the intermediate path lengths, the use of the combined Lorentz-Doppler (Voight) profile is essential in calculating the atmospheric transmittance. A brief review of band models, to approximate the absorption over certain frequency interval, is presented. Expressions for total radiative energy emergent from the atmosphere are given which, with appropriate line or band...
Topics: NASA Technical Reports Server (NTRS), AIR POLLUTION, ATMOSPHERIC ATTENUATION, SPECTRAL BANDS,...
The results of 21 rocket flights of Arcas optical ozonesondes were combined to produce estimates of the mean ozone distribution and its variability; these estimates apply to a broad range of latitudes. The flights were launched from sites near the equator to 58 S and to 64 N, in the years from 1965 to 1971. The local-noon mean ozone densities in molecules/cubic centimeter are 7.0 to the 10th power at 50 km, 6.7 x 10 to the 11th power at 40 km, 3.1 x 10 to the 12th power at 30 km, and 3.1 x 10...
Topics: NASA Technical Reports Server (NTRS), ANNUAL VARIATIONS, DENSITY DISTRIBUTION, OZONE, ROCKET...
Satellite mounted microwave instruments and their use to measure surface pressure are investigated. Data cover instrument accuracy, atmospheric transmission, and meteorological parameter determinations.
Topics: NASA Technical Reports Server (NTRS), MICROWAVE EQUIPMENT, PRESSURE MEASUREMENT, REMOTE SENSORS,...
The primary objectives are to compare radiometer attenuation with beacon attenuation and to compare sky temperature estimates with calculations using simultaneous meteorological data. Secondary objectives are: (1) noise diode and reference load measurements and (2) to adjust for outside temperature and component temperature changes.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, BEACONS, CALIBRATING, RADIOMETERS,...
Topics: DTIC Archive, Betx, Howard T, CHICAGO UNIV IL LABS FOR APPLIED SCIENCES, *INFRARED RADIATION,...
There are no author-identified significant results in this report.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, ATMOSPHERIC SCATTERING, EARTH...
The various mechanisms which contribute to sound absorption in the atmosphere are identified and a technique for computing the contribution from each is presented. The similarities between sound absorption, laser fluorescence measurements, and the opto-acoustic effect are discussed. Finally, experimental sound absorption results are compared to predictions to test the microscopic energy transfer approach.
Topics: NASA Technical Reports Server (NTRS), ACOUSTIC ATTENUATION, ATMOSPHERIC ATTENUATION, SOUND...
The QUAC (Quick Atmospheric Correction) algorithm for in-scene-based atmospheric correction of VIS-SWIR (VISible-Short Wave InfraRed) Multi- and Hyperspectral Imagery (MSI and HSI) is reviewed and applied to radiometrically uncalibrated data. Quite good agreement was previously demonstrated for the retrieved pixel spectral reflectances between QUAC and the physics-based atmospheric correction code FLAASH (Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes) for a variety of HSI and...
Topics: DTIC Archive, SPECTRAL SCIENCES INC BURLINGTON MA, *MULTISPECTRAL, *ERROR CORRECTION CODES,...
When the en route noise of a representative aircraft powered by an eight-blade SR-7 propeller was previously calculated, the noise level was cited as a possible concern associated with the acceptance of advanced turboprop aircraft. Some potential methods for reducing the en route noise were then investigated and are reported. Source noise reductions from increasing the blade number and from operating at higher rotative speed to reach a local minimum noise point were investigated. Greater...
Topics: NASA Technical Reports Server (NTRS), NOISE REDUCTION, PROPELLER BLADES, PROPELLER NOISE, TURBOPROP...
Rain attenuation propagation data for 68 cities within the coverage area of the multiple beam and steerable antennas of the Advanced Communications Technology Satellite (ACTS) are presented. These data provide the necessary data base for purposes of communication link power budgeting and rain attenuation mitigation controller design. These propagation parameters are derived by applying the ACTS Rain Attenuation Prediction Model to these 68 locations. The propagation parameters enumerated in...
Topics: NASA Technical Reports Server (NTRS), ACTS, ATMOSPHERIC ATTENUATION, DATA BASES, PROPAGATION, RAIN,...
Remote sensing over long path lengths has become of greater interest in the terahertz frequency region. Applications such as pollution monitoring and detection of energetic chemicals are of particular interest. Although there has been much attention to atmospheric effects over narrow frequency windows, accurate measurements across a wide spectrum is lacking. The water vapor continuum absorption spectrum was investigated using Fourier Transform Spectroscopy. The continuum effect gives rise to an...
Topics: DTIC Archive, MASSACHUSETTS UNIV LOWELL SUBMILLIMETER-WAVE TECH LAB, *ATMOSPHERIC PHYSICS,...
First-principles atmospheric correction that converts Visible-NIRSWIR spectral imagery to surface reflectance requires an estimate of the scene visibility / aerosol optical depth. This paper describes aerosol upgrades to FLAASH, a first-principles atmospheric correction algorithm developed by Spectral Sciences, Inc. and the US Air Force Research Laboratory. FLAASH utilizes an automated band ratio method for retrieving an average scene visibility from dark pixels. The visibility estimate is...
Topics: DTIC Archive, SPECTRAL SCIENCES INC BURLINGTON MA, *INFRARED SPECTRA, *ATMOSPHERIC ATTENUATION,...
584
584
Jun 27, 2010
06/10
by
Jones, W. L.; Sivo, J. N.; Wanhainen, J. P
texts
eye 584
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comment 0
No Abstract Available
Topics: ATMOSPHERIC ATTENUATION, DIURNAL VARIATIONS, ATMOSPHERIC MODELS, DETECTION, EARTH RESOURCES...
ACTS counters fading by resource sharing between the users. It provides a large margin only for those terminals which are at risk by unfavorable atmospheric conditions. ACTS, as an experimental satellite, provides a 5 dB clear weather margin and 10 dB additional margin via rate reduction and encoding. For the uplink, this margin may be increased by exercising uplink power control. Some of the challenges faced by the radiowave propagation community are listed. The issue of needs for the...
Topics: NASA Technical Reports Server (NTRS), ACTS, ATMOSPHERIC ATTENUATION, SIGNAL FADING, SIGNAL...
483
483
Jul 23, 2010
07/10
by
NON
texts
eye 483
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Abstracts are provided for 85 patents and patent applications entered into the NASA scientific and technical information system during the period January 1987 through June 1987. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or patent application.
Topics: ATMOSPHERIC ATTENUATION, RADIOMETERS, RADIOSONDES, REMOTE SENSING, TEMPERATURE MEASUREMENT,...
A monitoring experiment was undertaken late 1968 to search for photon bursts of extraterrestrial origin. The experiment and the results of the observations to date are summarized. The method of detection employs ground-based photomultiplier tubes which are sensitive to the secondary fluorescence light that would be produced when the primary pulse is absorbed in the atmosphere.
Topics: NASA Technical Reports Server (NTRS), FLUORESCENCE, PHOTONS, SUPERNOVAE, ATMOSPHERIC ATTENUATION,...
Radio wave absorption data covering almost two years from Europe to Central Asia are presented. They are normalized by relating them to a reference absorption. Every day these normalized data are fitted to a mathematical function of geographical location in order to obtain a daily synopsis of radio wave absorption. A film of these absorption charts was made which is intended to reveal movements of absorption or absorption anomaly. In addition, radiance (temperature) data from the lower D-region...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, ELECTROMAGNETIC ABSORPTION, RADIO...
Attenuation and brightness temperature statistics at 20.6 and 31.65 GHz are analyzed for a year's worth of data. The data were collected in 1988 at Denver and Platteville, Colorado. The locations are separated by 49 km. Single-station statistics are derived for the entire year. Quality control procedures are discussed and examples of their application are given.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, BRIGHTNESS TEMPERATURE, RADIOMETERS,...
Effective atmospheric transmission spectra were calculated from 800 to 860 nanometers for laser sources with spectral widths of a few tenths of a nanometer. In this spectral region, the atmospheric absorption lines (water lines) have linewidths of a few hundredths of a nanometer, so that the transmission coefficient for a relatively wide laser pulse must be computed by taking a weighted average over the pulse spectral width. Laser spectral widths of several tenths of a nanometer are shown to...
Topics: NASA Technical Reports Server (NTRS), ABSORPTION, ATMOSPHERIC ATTENUATION, LINE SPECTRA, OPTICAL...
Four-dimensional atmospheric models previously developed for use as input to atmospheric attenuation models are evaluated to determine where refinements are warranted. The models are refined where appropriate. A computerized technique is developed that has the unique capability of extracting mean monthly and daily variance profiles of moisture, temperature, density and pressure at 1 km intervals to the height of 25 km for any location on the globe. This capability could be very useful to...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, ATMOSPHERIC MODELS, COMPUTER...
A detailed study of the charge composition of primary cosmic radiation for about 5000 charged nuclei from neon to iron with energies greater than 1.16 GeV/nucleon is presented. Values are obtained after corrections were made for detector dependences, atmospheric attenuation, and solar modulation. New values of 38.5, 32.4, 23.7, and 16.8 g/sq cm for the attenuation mean free paths in air for the same charge groups are presented.
Topics: NASA Technical Reports Server (NTRS), CHARGED PARTICLES, PRIMARY COSMIC RAYS, ATMOSPHERIC...
There are no author-identified significant results in this report.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, EARTH ATMOSPHERE, MULTISPECTRAL...
250
250
May 23, 2011
05/11
by
Sathish, Shamachary; Cantrell, John H.; Yost, William T
texts
eye 250
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The upper and lower bounds of the bulk, shear, and Young's moduli are calculated point-by-point along the radius of SCS-6 silicon carbide fibers using the Hashin-Shtrikman equations from considerations of the Auger spectra along the fiber radius. The calculated values are in agreement with measurements of the average Young modulus obtained over relatively large radial regions of the fiber using scanning acoustic microscopy (SAM). The validity of the Hashin-Shtrikman bounds calculations is...
Topics: APERTURES, TROPOSPHERE, TRANSMISSION LOSS, VARIATIONS, DEEP SPACE NETWORK, CALIBRATING,...
The attenuation suffered by an acoustic plane wave propagating from an elevated source to the ground, in excess of absorption losses, was studied. Reported discrepancies between attenuation measurements made in the field and theories which only account for absorption losses are discussed. It was concluded that the scattering of sound by turbulence results in a nonnegligible contribution to the total attenuation.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, PLANE WAVES, SOUND WAVES, WAVE...
A preliminary weather model is presented for optical propagation through the atmosphere. It can be used to compute the attenuation loss due to the atmosphere for desired link availability statistics. The quantitative results that can be obtained from this model provide good estimates for the atmospheric link budget necessary for the design of an optical communication system. The result is extended to provide for the computation of joint attenuation probability for n sites with uncorrelated...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, COMPUTER PROGRAMS, MATHEMATICAL...
The presence of selected atmospheric pollutants can be determined by transmitting an infrared beam of proper wavelength through the atmosphere, and detecting the reflections of the transmitted beam with a heterodyne radiometer transmitter-receiver using part of the laser beam as a local oscillator. The particular pollutant and its absorption line strength to be measured are selected by the laser beam wave length. When the round-trip path for the light is known or measured, concentration can be...
Topics: NASA Technical Reports Server (NTRS), AIR POLLUTION, ATMOSPHERIC COMPOSITION, COHERENT RADIATION,...
The pulsed dye laser offers a tunable oscillator, followed by three amplifiers. It is pumped by a dual frequency Nd:YAG laser. Tuning and spectral width are controlled by a holographic network connected to a high power telescope. The modified two wavelength dye laser allows for absorption lidar techniques for remote sensing of the atmosphere. Line switching is achieved by electrooptical commutation. A feasibility experiment was performed with the original oscillator. A model was then built, and...
Topics: NASA Technical Reports Server (NTRS), DYE LASERS, OSCILLATORS, TUNABLE LASERS, ATMOSPHERIC...
The amount and type of ground truth required for an altimeter experiment is a function of the uncertainty in the satellite orbit, the altimeter error budget and the type of operation being performed. Ground truth requirements will be discussed with reference to three areas of operation: the global mode, the high intensity mode and calibration.
Topics: NASA Technical Reports Server (NTRS), ALTIMETERS, ATMOSPHERIC ATTENUATION, PERFORMANCE TESTS,...
Some information is given on the ITALSAT millimetric waves propagation experiment, which is to be conducted with the ITALSAT satellite, whose launch is foreseen for the middle of 1990. The purpose of the experiment is one of experimenting with advanced technologies and techniques employing the 20/30 GHz bands in wideband telecommunications. Among the most qualified features of this system are the multispot antenna and the exchange function performed directly onboard. Details of the experiment...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, ITALIAN SPACE PROGRAM, MILLIMETER...
Significant findings during this report period are: (1) The feasibility of using techniques for obtaining and using atmospheric parameter to transform ERTS data into absolute target reflectance was demonstrated. (2) Ground-truth instrumentation must have a dynamic range of 100,000 for obtaining the full set of atmospheric parameters encountered in the field. (3) Atmospheric transmittance for January through May 1973 varied from 13 to 18 percent in the ERTS bands. (4) Energy scattered to the...
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, LANDSAT SATELLITES, SIGNAL...
Topics: DTIC Archive, Betz, Howard T, CHICAGO UNIV IL LABS FOR APPLIED SCIENCES, *INFRARED RADIATION,...
A viewgraph presentation describing the future of land remote sensing and the new technologies needed for clear views of the Earth is shown. The contents include: 1) Viewing the Earth; 2) Multi-Imagery; 3) May Missions and Sensors; 4) What is Needed; 5) Things to Think About; 6) Global Land Remote Sensing in Landsat 7 Era; 7) Seasonality; 8) Cloud Contamination; 9) NRC Decadal Study; 10) Atmospheric Attenuation; 11) Geo-Registration; 12) Orthorectification Required; 13) Band Registration with...
Topics: NASA Technical Reports Server (NTRS), LANDSAT 7, REMOTE SENSING, EARTH SURFACE, IMAGERY, PERIODIC...
Solar irradiance measurements made from a balloon on January 27, 1978 and February 10, 1980 show a change of 0.4% over similar measurements made in 1968. This change is greater than the uncertainty of the measurement and is felt to be the result of a change in the solar constant.
Topics: NASA Technical Reports Server (NTRS), ATMOSPHERIC ATTENUATION, SOLAR CONSTANT, VARIATIONS,...
