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Arking, A.

Publications and source records attributed to Arking, A..

35 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

A Fourier approach to cloud motion estimation

A Fourier phase-difference technique for cloud motion estimation from pairs of pictures is described, and results obtained using this technique are compared with the results of a Fourier-domain cross-correlation scheme. The phase-difference technique makes use of the phase of the cross-spectral density and allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. When objects being tracked do not change their shape, size, and orientation to more than a limited degree, both techniques are effective. The phase difference technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects; in these circumstances, the cross-correlation scheme is preferable. It is suggested that the Fourier transform phase difference estimation methods can be applied in problems such as landmark matching.

Arking, A.↗
NASA NTRS1978

An infrared radiation routine for use in numerical atmospheric models

Previous methods for calculating radiative fluxes due to water vapor and CO2 absorption bands are extended to take into consideration the entire water vapor and CO2 bands, including e-type absorption in the window region and the overlapping of different absorptions. Cooling rate profiles in the water vapor bands for a tropical atmosphere were computed by a detailed line-by-line method and by a far-wing approximation method, and the error of both methods is less than 0.2 C/day. Cooling rate profiles in the 15 micron band including overlapping of CO2 absorption with water vapor were calculated by a method in which flux transmittance is computed by means of a linear expansion and the multiplication rule, and maximum errors of 0.3 C/day were found in comparison with the exact line-by-line method.

Chow, M.-D.↗
NASA NTRS1977

A Fourier approach to cloud motion estimation

A Fourier technique is described for estimating cloud motion from pairs of pictures using the phase of the cross spectral density. The method allows motion estimates to be made for individual spatial frequencies, which are related to cloud pattern dimensions. Results obtained are presented and compared with the results of a Fourier domain cross correlation scheme. Using both artificial and real cloud data show that the technique is relatively sensitive to the presence of mixtures of motions, changes in cloud shape, and edge effects.

Arking, A.↗
NASA NTRS1977

Fast but accurate techniques for calculating radiative terms in numerical atmospheric models and in remote sensing applications

Methods were developed for calculating radiative terms with relatively high accuracy but with sufficient speed, so that they can be used in numerical atmospheric models or in high volume processing of satellite measured radiances for remote sensing of atmospheric and surface parameters. Comparison with commonly used methods in both types of applications indicate improvements in calculating transmittances of factors between two and three, and in calculating radiances and cooling rates of factors between two and seven.

Arking, A.↗
NASA NTRS1976

A new formulation for anisotropic radiative transfer problems. I - Solution with a variational technique

The equations of radiative transfer in anisotropically scattering media are reformulated as linear operator equations in a single independent variable. The resulting equations are suitable for solution by a variety of standard mathematical techniques. The operators appearing in the resulting equations are in general nonsymmetric; however, it is shown that every bounded linear operator equation can be embedded in a symmetric linear operator equation and a variational solution can be obtained in a straightforward way. For purposes of demonstration, a Rayleigh-Ritz variational method is applied to three problems involving simple phase functions. It is to be noted that the variational technique demonstrated is of general applicability and permits simple solutions for a wide range of otherwise difficult mathematical problems in physics.

Cheyney, H., III↗
NASA NTRS1976

The proper weighting function for retrieving temperatures from satellite measured radiances

One class of methods for converting satellite measured radiances into atmospheric temperature profiles, involves a linearization of the radiative transfer equation: delta r = the sum of (W sub i) (delta T sub i) where (i=1...s) and where delta T sub i is the deviation of the temperature in layer i from that of a reference atmosphere, delta R is the difference in the radiance at satellite altitude from the corresponding radiance for the reference atmosphere, and W sub i is the discrete (or vector) form of the T-weighting (i.e., temperature weighting) function W(P), where P is pressure. The top layer of the atmosphere corresponds to i = 1, the bottom layer to i = s - 1, and i = s refers to the surface. Linearization in temperature (or some function of temperature) is at the heart of all linear or matrix methods. The weighting function that should be used is developed.

Arking, A.↗
NASA NTRS1975

Meteorological satellite accomplishments

Meteorological satellites include experimental satellites operated by NASA and operational satellites operated by the National Oceanic and Atmospheric Administration (NOAA). The operational system currently provides pictures of the entire globe, temperature measurements throughout the world, and wind measurements in selected parts of the Atlantic and Pacific oceans. Aspects of vertical sounding are discussed along with questions of parameter extraction technique development, macroscale phenomena, the heat budget of the earth-atmosphere system and the climate, and studies of ocean surface and hydrology.

Allison, L. J.↗
NASA NTRS1974

Meteorological satellite accomplishments

The various types of meteorological satellites are enumerated. Vertical sounding, parameter extraction technique, and both macroscale and mesoscale meteorological phenomena are discussed. The heat budget of the earth-atmosphere system is considered, along with ocean surface and hydrology.

Allison, L. J.↗
NASA NTRS1972

The influence of line shape and band structure on temperatures in planetary atmospheres

Numerical experiments are performed to examine the effects of line shape and band structure on the radiative equilibrium temperature profile in planetary atmospheres. In order to accurately determine these effects, a method for calculating radiative terms is developed which avoids the usual approximations. It differs from the more commonly used methods in that it allows arbitrary dependence of the absorption coefficient on wave number, without requiring tedious line by line integration and without the constraints of band models. The present formulation is restricted to homogeneous atmospheres but the concept can be extended to the more general case. The numerical experiments reveal that the line shape and band structure of the absorbing gases have a large effect on temperatures in the higher layers of the atmosphere (corresponding to the stratosphere and mesosphere). The more nongrey the spectrum (that is, the higher the peaks and the deeper the troughs in the spectrum), the lower the temperature.

Arking, A.↗