ATMOSPHERIC ABSORPTIONS OVER LONG SLANT PATHS IN THE STRATOSPHERE
DENVER UNIV CO DEPT OF PHYSICS
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The variation of the infrared solar spectrum with altitude was observed during a series of balloon flights made from Fairbanks, Alaska. Spectra were obtained at various altitudes with solar zenith angles ranging from 49 degrees to 92 degrees. These spectra were used to determine the atmospheric transmittance to be expected at high altitudes and particularly over very long slant paths in the stratosphere. The transmittance data are presented in this report. The spectral region scanned during this flight covered the 2.7 mu region. The major atmospheric absorptions in this region are due to carbon dioxide and water vapor. The paths traversed by the solar radiation in reaching the spectrometer when the solar zenith angle is greater than 90 degrees are such that a major portion of the air mass traversed by the radiation is traversed in a relatively narrow altitude interval close to the minimum height of the ray. Thus these long paths provide a method of sampling the absorption to be expected in relatively narrow layers. The water vapor absorptions obtained under these conditions have been used to determine the amount of water vapor present in these layers in the stratosphere. These data are compared with the mixing ratios determined on the basis of the change in these absorptions during a flight with small solar zenith angle. The agreement is within the accuracy of the measurement and shows no indication that the data of the normal flight are inaccurate due to contamination. The profile indicates the increased mixing ratio above the tropopause noted on other flights at other geographic locations.
- Atmospheric Physics