Infrared Radiation in a Real Tropical Atmosphere
Final technical rept. 1 Nov 1975-30 Apr 1977
AVCO EVERETT RESEARCH LAB INC EVERETT MA
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Transmission of infrared radiation in the 8-13 and 16.5-21 micrometers spectral regions from 3 km altitude through the atmosphere to outer space has been evaluated. Analysis of tropical radiosonde atmospheric profiles of temperature and humidity shows that fluctuations in the total amount of water vapor above 3 km cause the transmission to vary by amounts from 10 to two orders of magnitude. Fluctuations in the effective temperature or pressure for absorption are shown to be small. The Curtis-Godson approximation is analyzed in detail for this problem. Also, effective parameters describing an atmospheric slant path are formulated for absorption by the water vapor continuum. The total amount of water vapor above 3 km varies chiefly as the trade wind inversion rises above or falls below that altitude it correlates poorly with the absolute humidity at 3 km. The atmospheric transmission can be obtained in real time from measurements of atmospheric emission. Fluctuations in the effective emission temperature, calculated from radiosonde data, are relatively small. However, further study of the effect of cirrus clouds on the transmission-emission relationship would be desirable.
- Atmospheric Physics