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  • 1
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    A study of the thermal and optical characteristics of radiometric channels for Earth radiation budget applications (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An improved dynamic electrothermal model for the Earth Radiation Budget Experiment (ERBE) total, nonscanning channels is formulated. This model is then used to accurately simulate two types of dynamic solar observation: the solar calibration and the so-called pitchover maneuver. Using a second model, the nonscanner active cavity radiometer (ACR) thermal noise is studied. This study reveals that radiative emission and scattering by the surrounding parts of the nonscanner cavity are acceptably small. The dynamic electrothermal model is also used to compute ACR instrument transfer function. Accurate in-flight measurement of this transfer function is shown to depend on the energy distribution over the frequency spectrum of the radiation input function. A new array-type field of view limiter, whose geometry controls the input function, is proposed for in-flight calibration of an ACR and other types of radiometers. The point spread function (PSF) of the ERBE and the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers is computed. The PSF is useful in characterizing the channel optics. It also has potential for recovering the distribution of the radiative flux from Earth by deconvolution.
    Keywords: GEOPHYSICS
    Type: NASA-CR-189783 , NAS 1.26:189783
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Infrared imaging - A validation technique for computational fluid dynamics codes used in STOVL applications (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The need for a validation technique for computational fluid dynamics (CFD) codes in STOVL applications has led to research efforts to apply infrared thermal imaging techniques to visualize gaseous flow fields. Specifically, a heated, free-jet test facility was constructed. The gaseous flow field of the jet exhaust was characterized using an infrared imaging technique in the 2 to 5.6 micron wavelength band as well as conventional pitot tube and thermocouple methods. These infrared images are compared to computer-generated images using the equations of radiative exchange based on the temperature distribution in the jet exhaust measured with the thermocouple traverses. Temperature and velocity measurement techniques, infrared imaging, and the computer model of the infrared imaging technique are presented and discussed. From the study, it is concluded that infrared imaging techniques coupled with the radiative exchange equations applied to CFD models are a valid method to qualitatively verify CFD codes used in STOVL applications.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 91-0675
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Earth Radiation Budget Experiment scanner radiometric calibration results (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Earth Radiation Budget Experiment (ERBE) scanning radiometers are producing measurements of the incoming solar, earth/atmosphere-reflected solar, and earth/atmosphere-emitted radiation fields with measurement precisions and absolute accuracies, approaching 1 percent. ERBE uses thermistor bolometers as the detection elements in the narrow-field-of-view scanning radiometers. The scanning radiometers can sense radiation in the shortwave, longwave, and total broadband spectral regions of 0.2 to 5.0, 5.0 to 50.0, and 0.2 to 50.0 micrometers, respectively. Detailed models of the radiometers' response functions were developed in order to design the most suitable calibration techniques. These models guided the design of in-flight calibration procedures as well as the development and characterization of a vacuum-calibration chamber and the blackbody source which provided the absolute basis upon which the total and longwave radiometers were characterized. The flight calibration instrumentation for the narror-field-of-view scanning radiometers is presented and evaluated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Long-term Monitoring of the Earth''s Radiation Budget; Apr 17, 1990 - Apr 18, 1990; Orlando, FL; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Comparison of the measured and predicted response of the Earth Radiation Budget Experiment active cavity radiometer during solar observations (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The Earth Radiation Budget Experiment consists of an array of radiometric instruments placed in earth orbit by the National Aeronautics and Space Administration to monitor the longwave and visible components of the earth's radiation budget. Presented is a dynamic electrothermal model of the active cavity radiometer used to measure the earth's total radiative exitance. Radiative exchange is modeled using the Monte Carlo method and transient conduction is treated using the finite element method. Also included is the feedback circuit which controls electrical substitution heating of the cavity. The model is shown to accurately predict the dynamic response of the instrument during solar calibration.
    Keywords: GEOPHYSICS
    Type: Applied Optics (ISSN 0003-6935); 28; 1327-133
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Transient conduction-radiation analysis of an absolute active cavity radiometer using finite elements (1987)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A NASA-developed finite element-based model of a generic active cavity radiometer (ACR) has been developed in order to study the dependence on operating temperature of the closed-loop and open-loop transient response of the instrument. Transient conduction within the sensing element is explored, and the transient temperature distribution resulting from the application of a time-varying radiative boundary condition is calculated. The results verify the prediction that operation of an ACR at cryogenic temperatures results in large gains in frequency response.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Symposium on Thermal Problems in Space-Based Systems; Dec 13, 1987 - Dec 18, 1987; Boston, MA; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Analysis of a nonisothermal, spherical detector for monitoring the earth's radiative energy budget. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Conference on Atmospheric Radiation; Aug 07, 1972 - Aug 09, 1972; Fort Collins, CO
    Format: text
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    NASA TECHNICAL REPORTS
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