Abstract
The rocketborne SPIRE (SPectral InfraRed Experiment) probe was launched from Poker Flat Research Range, Alaska, on Sept 28, 1977 to measure infrared atmospheric emission from the earth’s limb.1 The payload included two coaligned, telescoped, circular-variable-filter (CVF) spectrometers. The short-wavelength spectrometer, cooled to 77° K, covered the spectral region between 1.4μm and 7.0μm while the long-wavelength instrument, cooled to 4° K, made measurements between 9.0μm and 16.5μm. The payload reached an altitude of 285 km. The earthlimb was continuously spatially scanned from hard earth to local horizontal at 0.5 deg/sec while taking a spectrum at 2 scans/sec. The spectrometers measured the earthlimb emission during 12 vertical spatial scans at different azimuths. In doing so the emission was measured from the night (scan 8), terminator (scans 1 through 7), and daylit (scans 9 through 12) sectors of the earthlimb. For a given tangent height day scans correspond to different solar elevation angles. The emission from the a 1Δg (v′=0) --> x3Σg (v″=1) transition of O2 at 1.58μm is observed during the day scans only and increases in radiance with solar elevation angle (Figure 1). This shows that the only important process lending to the production of O2(1Δg) is the photodissociation of ozone. The emissions from ozone at 9.8μm (ν3 band), as well as the 4.8μm v1 + v3 combination band, are measured during both day and night (Figure 2). Around 80 km tangent height, the daytime 9.6μm emission is smaller than the nighttime value by a factor of about 5, because of the decreased daytime ozone density due to photodissociation. Below 50 km tangent height the daytime and nighttime emissions do not show a significant variation, in spite of the fact that some daytime ozone is photodissociated to O2(1Δg) which is observed at 1.58μm. The observed emissions from ozone and O2(1Δg) state are discussed in terms of modelled time-dependent ozone concentrations along the line-of-sight.
© 1983 Optical Society of America
PDF ArticleMore Like This
B. D. Green, G. E. Caledonia, R. M. Nadile, and A. T. Stair
TuC10 Optical Techniques for Remote Probing of the Atmosphere (RPA) 1983
J. A. Betts, C. M. Lovejoy, and L. J. Marabella
TUM9 Conference on Lasers and Electro-Optics (CLEO:S&I) 1983
Henry Nebel, P. P. Wintersteiner, R. H. Picard, R. D. Sharma, and J. R. Winick
ThE.15 Optical Remote Sensing of the Atmosphere (ORS) 1993