An Extension of the Split Window Technique for the Retrieval of Precipitable Water,
Abstract
The split window technique has been demonstrated to be a viable method of removing effects of atmospheric attenuation in order to make a more accurate estimate of surface properties. This technique has also been used to estimate low level water vapor fields. In this paper we make an extension to the split window technique such that it is possible to estimate total precipitable water. The essence of the split window technique is making observations of the earth in two differentially absorbing windows. We extend this technique by making observations in the split window under conditions where the atmospheric contribution to the upwelling radiance is essentially invariant, but the surface contribution changes markedly. Under these conditions it is possible to write a set of simultaneous equations and solve them for the transmittance of the split window, and from that deduce the quantity of the primary absorber, water. The conditions under which this extension is valid basically fall under two catagories; that of variation in time, and that of variation in space. Consecutive observations of a land surface from a geosynchronous satellite during the heating cycle of the day would be one example. Another would be observations from either a geosynchronous or polar orbiting satellite of immediately adjacent land and water surfaces will contrasting skin temperatures. This paper will present the theoretical considerations of this extension to the split window technique, as well as applications of the AVHRR instrument. Keywords: Remote Sensing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 03, 1986
- Accession Number
- ADA173008
Entities
People
- Larry M. Mcmillin
- Thomas J. Kleespies
Organizations
- Air Force Research Laboratory