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W. L. Smith

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W. L. Smith

Abstract

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W. L. Smith

The importance of global atmospheric temperature soundings determined from satellite radiometric measurements has long been recognized by the scientific community. Several remote sounding techniques have been proposed for determining the thermal structure of the atmosphere. This paper reviews the physical concepts of various satellite sounding methods showing empirical results to demonstrate their viability.

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W. L. Smith

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W. L. Smith and H. B. Howell

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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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W. A. SCHULZ and D. L. SMITH

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W. L. Smith and H. M. Woolf

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A new technique is formulated for using eigenvectors of covariance matrices to retrieve atmospheric parameters from spectral radiance observations. The eigenvector method permits the use of all spectral radiances in a simultaneous solution for cloud-free infrared sounding radiances from cloud-contaminated observations as well as for the vertical profiles of temperature, moisture and cloudiness. The effects of random observation errors are minimized without suppressing the influence of any real information structure contained in the spectral radiance distribution. Also, since the method provides for the most economical representation of any variable from a number of “terms required” point of view, computer storage and computation requirements are much less than those of other methods.

The eigenvector method is tested using radiance observations synthesized for the Nimbus-6 infrared and microwave sounding instruments. Although the method has been successfully applied for the routine processing of observations obtained from the Nimbus-6 satellite, these results will be presented in a future report.

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W. L. Smith and C. M. R. Platt

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Cloud altitudes specified from the Infrared Temperature Profile Radiometer on the Nimbus 5 satellite are compared with simultaneous observations by radiosonde and ground-based ranging measurements conducted with the lidar system at CSIRO in Aspendale, Victoria, Australia, during September 1976. The results show that the cloud altitudes deduced by the CO2 channel absorption method are in general agreement with the lidar and radiosonde determinations, regardless of the cloud opacity and amount.

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ROBERT L. SMITH and DAVID W. HOLMES

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The U.S. Weather Bureau has been experimenting with a radar operating on the Doppler principle to determine whether apparatus of this type would detect and uniquely identify tornadoes. The principles of Doppler radar as applied to meteorology and results of recent experiments with equipment of this type are discussed. Calculations of anomalous wind speeds of 206 m.p.h. in a funnel cloud and 94 m.p.h. in a dust devil are presented in detail. In addition, data have been gathered from squall lines and isolated thunderstorms. Recommendations are made for an optimum Doppler radar system for the detection of tornadoes.

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W. L. SMITH, H. M. WOOLF, and W. J. JACOB

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A least squares regression method is formulated for obtaining global temperature and geopotential height profiles from satellite radiation measurements, particularly those obtained by the Sate1lite Infra-Red Spectrometer (SIRS) aboard the Nimbus 3 satellite launched Apr. 14, 1969. Regression equations relating temperature and geopotential height to spectral radiance observations are derived. A method accounting for the influence of clouds, mountains, and hot terrain on the solutions is described. Results obtained from Nimbus 3 radiance data are presented.

The procedure described herein has been successfully applied to Nimbus 3 SIRS observations on a real-time basis. The temperature and geopotential heights obtained are being used operationally by the National Meteorological Center in their objective constant pressure analyses. Numerous meteorological results are given to demonstrate the usefulness of this new sounding tool.

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