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W. L. Smith and H. M. Woolf

Abstract

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, 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, H. M. Woolf, and H. E. Fleming

Abstract

The method of real-time retrieval of atmospheric temperature profiles from Nimbus IV Satellite Infrared Spectrometer observations currently used in dynamical weather analysis-forecast operation is described. Each vertical temperature profile is determined by its deviation from a “guess” profile. The deviation is expressed as a linear combination of differences between the measured radiances and those computed from the guess profile. The coefficients are estimated, by matrix inversion, from the weighting functions (i.e., derivatives of atmospheric transmittance functions), which are regularized by the ratio of the expected variance of the measurement errors to the expected variance of the errors in the guess profile. The deviations are iterated until the variance of the radiance residuals is less than the expected variance of the measurement errors.

For weather analysis-forecast operation the dynamical forecast is used as the first guess; therefore, the calculated profiles should differ from the forecast profiles only when the measurable error in the forecast exceeds the instrumental noise level. The retrieved profiles are those which deviate least from the forecast in order to satisfy all the radiance observations. This property is well suited to dynamical forecasting in that it does not tend to produce erroneous atmospheric waves.

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A. J. MILLER, S. TEWELES, and H. M. WOOLF

Abstract

Monthly mean values of the geostrophic angular momentum transport at 500 mb. have been computed as a function of latitude and zonal wave number (1 through 10) for a 10-yr. period.

The total transport is found to be in good agreement with previous calculations; at the same time several wave numbers exhibit considerable individuality. Equatorward transport by wave 2 at high latitudes extends farther south, and is much larger in magnitude, than the transport by any of the other wave numbers. Also, the negative transport in low latitudes is in distinct contrast to the behavior of the other waves. Wave 3, on the other hand, transports momentum poleward in mid-latitudes at a rate at least twice as great as that of any other wave number.

An additional finding is that in July and August, waves 1 through 5 are relatively inactive in transporting momentum, while waves 6 through 10 accomplish substantial transport near the latitude of the summertime maximum westerlies.

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A. J. Miller, H. M. Woolf, and F. G. Finger

Abstract

Results of comparisons of wind and temperature data obtained by closely spaced launchings of Japanese MT-135 and American ARCAS meteorological rocket systems are presented. In general, smoothed temperature profiles show a certain disagreement that is unexplained at this time. Perturbation profiles of wind and temperature indicate a degree of correlation that tends to substantiate the existence of small-scale features.

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F. G. FINGER, H. M. WOOLF, and C. E. ANDERSON

Abstract

A method of numerical objective analysis has been developed for application to stratospheric constant-pressure data at the 100-, 50-, 30-, and 10-mb. levels (approximately 16, 20, 24, and 31 km., respectively). This system evolved from successive modifications of the programs employed for operational objective analysis of lower-level charts at the National Meteorological Center. For use with stratospheric data, the Automatic Data Processing portion of these programs was expanded to correct for the errors in high-level rawinsonde temperatures and heights caused by short and long-wave radiational effects on the temperature sensor. In addition, procedures for vertical extrapolation of rawinsonde reports and merging of off-time data were incorporated to compensate for the scarcity of reports at a given observation time.

General degradation of stratospheric data with increasing height necessitated more stringent data rejection criteria within the entire system. It was also essential that increased emphasis be placed on wind observations as an analysis parameter. The resulting charts have shown that the objective system employed produces analyses of acceptable quality. Improvements are continually being developed and incorporated to increase the efficacy and objectivity of the procedures and the quality and usefulness of the product.

The main purposes of the computerized system are to provide good quality stratospheric analyses for anticipated operational requirements and to satisfy the needs of research. Daily analysis of Northern Hemisphere charts is being performed during the IQSY and is expected to continue after the end of the period. These maps are recorded for distribution on microfilm and also on punched-card decks containing grid-point data.

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

Abstract

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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W. L. Smith, H. E. Revercomb, R. O. Knuteson, F. A. Best, R. Dedecker, H. B. Howell, and H. M. Woolf

Abstract

The characteristics of the ER-2 aircraft and ground-based High Resolution Interferometer Sounder (HIS) instruments deployed during FIRE II are described. A few example spectra are given to illustrate the HIS cloud and molecular atmosphere remote sensing capabilities.

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Wayne F. Feltz, William L. Smith, Robert O. Knuteson, Henry E. Revercomb, Harold M. Woolf, and H. Ben Howell

Abstract

The Atmospheric Emitted Radiance Interferometer (AERI) is a well-calibrated ground-based instrument that measures high-resolution atmospheric emitted radiances from the atmosphere. The spectral resolution of the instrument is better than one wavenumber between 3 and 18 μm within the infrared spectrum. The AERI instrument detects vertical and temporal changes of temperature and water vapor in the planetary boundary layer. Excellent agreement between radiosonde and AERI retrievals for a 6-month sample of coincident profiles is presented in this paper. In addition, a statistical seasonal analysis of retrieval and radiosonde differences is discussed. High temporal and moderate vertical resolution in the lowest 3 km of the atmosphere allows meteorologically important mesoscale features to be detected. AERI participation in the Department of Energy Atmospheric Radiation Measurement program at the Southern Great Plains Cloud and Radiation Testbed (SGP CART) has allowed development of a robust operational atmospheric temperature and water vapor retrieval algorithm in a dynamic meteorological environment near Lamont, Oklahoma. Operating in a continuous mode, AERI temperature and water vapor retrievals obtained through inversion of the infrared radiative transfer equation provide profiles of atmospheric state every 10 min to 3 km in clear sky or below cloud base. Boundary layer evolution, cold or warm frontal passages, drylines, and thunderstorm outflow boundaries are all recorded, offering important meteorological information. With important vertical thermodynamic information between radiosonde locations and launch times, AERI retrievals provide data for planetary boundary layer research, mesoscale model initialization, verification, and nowcasting. This paper discusses retrieval performance at the SGP CART site, as well as interesting meteorological case studies captured by AERI profiles. The AERI system represents an important new capability for operational weather- and airport-monitoring applications.

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William L. Smith, Wayne F. Feltz, Robert O. Knuteson, Henry E. Revercomb, Harold M. Woolf, and H. Ben Howell

Abstract

The surface-based Atmospheric Emitted Radiance Interferometer (AERI) is an important measurement component of the Department of Energy Atmospheric Radiation Measurement Program. The method used to retrieve temperature and moisture profiles of the plantetary boundary layer from the AERI’s downwelling spectral radiance observations is described.

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