Measurements of Net Atmospheric Irradiance in the 0.7- to 2.8-Micrometer Infrared Region.
Abstract
The objective of this experiment was to measure atmospheric irradiance within the 0.7- to 2.8-micrometer infrared wavelength region from a balloon platform at altitudes ranging from 5 to 39 kilometers. An Epply precision spectral pyranometer pointed in a general downward direction and equipped with a 7-degree field of view field stop was successfully employed to collect irradiance data for a period of 34 hours on 23, 24, and 25 September 1976. The results showed that at low solar zenith angles and in the absence of clouds the atmospheric irradiance values usually remained within 2.2 x 1/100 cal/sqcm min and 2.6 x 1/100 cal/sqcm min. Clouds attenuated the irradiance down to magnitudes below 4 x 1/10000 cal/sqcm min which was the combined noise level of the pyranometer and associated electronics. At high solar zenith angles, specular reflections of sunlight which entered the pyranometer's field view caused enhancements of the measured irradiance to reach magnitudes greater than the instrument could measure (3.5 x 1/100 cal/sqcm min). No significant variations in irradiance were detected with changes in altitude above 5 kilometers or terrain viewed; therefore, the background intensity is attributed to the radiant emittance of the lower atmosphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1977
- Accession Number
- ADA041076
Entities
People
- Mike Izquierdo
- Roberto Rubio
Organizations
- United States Army Communications-Electronics Command