
Accession Number : AD0716774
Title : Tropospheric Effect on Electromagnetically Measured Range: Prediction from Surface Weather Data.
Descriptive Note : Technical memo.,
Corporate Author : JOHNS HOPKINS UNIV SILVER SPRING MD APPLIED PHYSICS LAB
Personal Author(s) : Hopfield,Helen S.
Report Date : JUL 1970
Pagination or Media Count : 41
Abstract : The height integral of tropospheric refractivity (n1), where n is refractive index, measures the range error in a vertically arriving electromagnetic signal. Such height integrals were studied, using meteorological balloon data from widely separated locations. Although the 'dry' part of (n1) at any point in the troposphere depends on both pressure and temperature (P/T), its height integral was found to be a linear function of surface pressure only, both theoretically and from observed data. The equivalent height for the quartic model of (n1)dry must therefore vary as surface temperature. Height parameters were computed from balloon data and were closely the same for all stations: a 'dry' height of 40.1 km at 0C, decreasing to zero near 0K. Using these, the model predicts vertical range error (dry part) within a few millimeters rms. Study of the very much smaller but more variable 'wet' contribution is continuing. (Author)
Descriptors : (*TROPOSPHERE, REFRACTIVE INDEX), (*RADIO WAVES, RANGE FINDING), RANGE(DISTANCE), MATHEMATICAL PREDICTION, METEOROLOGICAL BALLOONS, SATELLITES(ARTIFICIAL), INTEGRALS, SURFACE TEMPERATURE, REFRACTION, TABLES(DATA), BAROMETRIC PRESSURE
Subject Categories : Atmospheric Physics
Radiofrequency Wave Propagation
Distribution Statement : APPROVED FOR PUBLIC RELEASE