RESEARCH CONCERNING INFRARED EMISSIVITY (I) ATMOSPHERIC OPTICAL NOISE MEASUREMENTS (II)
Abstract
In an effort to determine the limits of detectibility and discrimination of ground objects, investigations were conducted concerning the effective emissivities of various terrain objects. Since these were very nearly the same, examples were sought wherein discrimination disappeared. It was found that such effects occurred. They were termed washout. This occurred most often at sunrise and sunset. The second limiting factor on discrimination appeared to be variations in emission that were not associated with the source. These were termed atmospheric optical noise. Many previous investigators had observed this phenomenon, which was called scintillation, twinkle, and various other names. This investigation was concerned primarily with the infrared and was the first to report such measurements beyond 1 micron wavelength. The atmospheric optical noise was dependent on the weather, being greatest on sunny days and least on over-cast nights. It is shown to be independent of wavelength. It does depend on height above the surface, on frequency and on area of the receiver. An explanation of the phenomena is given in terms of a theory by Tatarski. This is based on inhomogeneities in the index of refraction of the air due to turbulence. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 1962
- Accession Number
- AD0287517
Entities
People
- Eric Ellis
- Nathan Ginsburg
- Roy Paulson
Organizations
- Syracuse University