Accession Number : AD0706410

Title :   SHORT-TERM PREDICTIONS ON THE COURSE OF POLAR CAP ABSORPTION.

Descriptive Note : Final rept. (Part 1), 1 Apr 68-31 May 69,

Corporate Author : DARTMOUTH COLL HANOVER N H THAYER SCHOOL OF ENGINEERING

Personal Author(s) : Owren,Leif

Report Date : DEC 1969

Pagination or Media Count : 127

Abstract : The physical and empirical facts of polar cap absorption (PCA) produced by solar proton events are reviewed. A description of PCA, its measurement, and the solar-terrestrial environment is included. The physical conditions of the lower ionosphere during PCA are discussed together with the frequency law of PCA, nightime recoveries, the polar cap distribution of absorption, and arctic HF propagation during PCA. A procedure for short-term prediction of the future course of PCA is developed, based on single frequency riometer measurements and computer processing of the data. The application of the prediction technique is illustrated by a detailed discussion of two PCA events. It is concluded that for most PCA events satisfactory short-term predictions can be made from riometer observations.

Descriptors :   (*SOLAR RADIATION, PROTONS), (*IONOSPHERIC DISTURBANCES, POLAR REGIONS), (*IONOSPHERIC PROPAGATION, BLACKOUT(PROPAGATION)), HIGH FREQUENCY, ABSORPTION, SOLAR FLARES, RIOMETERS, MATHEMATICAL PREDICTION, STATISTICAL ANALYSIS, COMPUTER PROGRAMS

Subject Categories : Astrophysics
      Atmospheric Physics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE