ABSTRACT
This paper describes the Nimbus-6 earth radiation budget experiment including its prelaunch calibration and in-flight performance. A preliminary assessment of the data shows the ERB measurement of the solar constant to be 1392 W/m(2) which is 1.6% higher than the expected value of 1370 W/m(2). Both values are traceable to the cavity radiometer scale. There is a disagreement between the fixed wide-angle and scanning narrow-angle measurements of planetary outgoing longwave radiation flux. Since the scanning channels are calibrated in-flight and show good agreement with previous observations of the Nimbus-3 satellite, the discrepancy is believed to be due to erroneous wide-angle flux estimates. The erroneous estimates may be caused by the misinterpretation of the transfer function for the wide-angle-earth-flux sensing thermopile detectors when viewing the earth which, unlike the prelaunch calibration source, does not fill the field of view of the detector and is not an isotropic radiation source. A field of view factor for the wide-angle channels is determined using an in-flight calibration procedure using the night-time scanning channel longwave radiation flux measurements as the absolute standard. The planetary global albedoes, longwave radiation fluxes, and net radiation are about 30%, 240 W/m(2), and -4 W/m(2) for the months of July and August 1975, which is in good agreement with previous Nimbus-3 estimates.
ABSTRACT
The Nimbus-5 infrared temperature profile radiometer (ITPR) experiment was designed to measure upwelling infrared radiation in appropriate spectral intervals and with sufficient geographical resolution for sounding the atmosphere's temperature distribution down to the earth's surface even under partly cloudy sky conditions. A primary scientific goal of the experiment was the specification of the mesoscale features of surface and atmospheric temperature and water vapor that are associated with intense weather systems. In this paper the ITPR instrument is described and some initial spacecraft results are given that demonstrate the success of the experiment in achieving its scientific goals.
ABSTRACT
The Nimbus III satellite carries the satellite infrared spectrometer (SIRS). It measures the radiance of the earth and the atmosphere in seven narrow spectral intervals in the 15-micrometer carbon dioxide band and in one interval of minimum absorption at 11.1 micrometers. Seven simultaneous equations are solved to obtain the vertical temperature profile; the eighth measurement is used to determine the boundary condition (cloud or surface temperature). Results agree with those obtained from conventional radiosondes.
ABSTRACT
The spectral interval centered at 899 cm(-1) with a bandpass of 8.75 cm(-1) is used for the measurements of surface and cloud-top temperatures from an altitude of 30 km. The continuum and selective absorption contribution to such measurements are discussed. The observations were obtained, using a balloon flight spectrometer, on two occasions: once from Palestine, Texas, in a tropical humid air mass, and once from Sioux Falls, South Dakota, in a cold arctic air mass. The results from these observations are compared with the screen temperatures under the balloon and with special surface temperature measurements made using a thermistor and a radiometer.
