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H. B. Howell

Abstract

Results of multiple-scattering calculations of diffuse reflection and diffuse transmission from scattering layers of different particle size and/or index of refraction are presented. Comparison of the results for each scattering model indicates the extent to which earlier calculations (for one cloud model) are generally applicable.

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H. Jacobowitz
and
H. B. Howell

Abstract

No abstract available.

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H. B. Howell
and
H. Jacobowitz

Abstract

A matrix method for multiple-scattering problems, which was the subject of earlier papers, is extended to include the state of polarization in the description of both singly and multiply scattered raditaion. Comparisons of numerical results from the extended matrix method with published values obtained by two other methods are presented (for the special cue of a Rayleigh scattering layer of optical depth τ = 0.25). The values of total intensity (Stokes parameter I) calculated by the matrix method show excellent agreement with published values, while the values of the Stokes parameters Q) and U show slight systematic deviations. For the particular case studied, the numerical results indicate that the inclusion of polarization affects the values of I by less than 10%, and in many cases by less than 17%.

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W. L. Smith
and
H. B. Howell

Abstract

In this paper, the algorithm used for calculating the water vapor distribution from SIRS-B spectral radiances is given. Examples are presented illustrating the effects of errors in the water vapor absorption coefficients and the specified temperature profile on the retrieval of the water vapor profile. Comparisons of satellite-derived and radiosonde-observed water vapor profiles indicate that the errors of the SIRS-derived relative humidity in the middle troposphere (i.e., the 400–600 mb layer) are less than 20%. Relative humidity errors in the lower troposphere (600–1000 mb) are somewhat larger but still less than 30%.

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S. TWOMEY
and
H. B. HOWELL

Abstract

Instability limits the usefulness of indirect sounding, i.e. the deduction of a physical distribution from a set of observations which represent an integral transform of the former. A method is presented which allows a stable, but smoothed, solution to be obtained in certain cases. As an illustration of the application of the method, the deduction of vertical ozone distribution from measurements of the spectral distribution of scattered ultraviolet radiation is discussed. Graphs showing results from several possible methods of inversion are included to show the difficulties associated with such indirect measurements.

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S. Twomey
,
H. Jacobowitz
, and
H. B. Howell

Abstract

If the radiation field is approximated by a discrete distribution at points or latitude circles on the unit sphere, matrix relationships can be written between incident and reflected or transmitted radiation fields. The reflection and transmission matrices thus defined are shown to satisfy algebraic equations which can be used to compute the properties of thick layers by building up the thick layers from thinner sublayers, the starting point being a layer so thin that it is effectively a single scattering layer only.

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S. Twomey
,
H. Jacobowitz
, and
H. B. Howell

Abstract

Results of calculations of diffuse reflection and transmission of cloud-model layers are presented. These calculations which are based on matrix methods developed by the authors and discussed in a previous paper include the effects of cloud thickness, absorption, drop-size distribution, liquid water content, and directions of the incident and emergent radiation.

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W. L. Smith
,
H. B. Howell
, and
H. M. Woolf

Abstract

It is shown that the partial interferogram measurement technique, originally developed to separate the trace gas emissions from a spectral signal dominated by background radiation (from the earth's surface) and emissions from major constituents (H2O and CO2), has application to the vertical sounding problem. The interferometric technique will enable relatively high vertical temperature profile resolution to be achieved and will provide absolute accuracies of temperature approaching, and at same levels exceeding, 1°C.

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W. L. Smith
,
W. C. Shen
, and
H. B. Howell

Abstract

A seven-channel Multi-spectral Scanning Radiometer (MSR) was flown aboard the NASA Convair-990 aircraft during the GARP Atlantic Tropical Experiment (GATE) from June–September, 1974. The radiometer measures the total shortwave (0.2–5 μm) and longwave (5–50 μm) components of radiation and the radiation in specific absorption band and window regions that modulate the total radiation flux. Measurements of the angular distribution of radiation, including the upward and downward components, were obtained. The principal scientific objective of the MSR experiment was to obtain the atmospheric absorption data required for precise computations of radiative heating profiles from atmospheric state parameters. The method used to construct the infrared radiation heating computational model based on in situ GATE MSR observations is described. Radiative heating profiles computed with this model for both cloudy and cloudless atmospheres were compared with direct observations by flux radiometers and with profiles computed with the Rodgers and Walshaw model. The results indicate that the empirically based computational model should provide tropospheric radiative heating profiles sufficiently accurate for diagnostic and prognostic applications of GATE data.

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S. Twomey
,
H. B. Howell
, and
T. A. Wojciechowski

Abstract

No abstract available.

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