ARCTIC ABSORPTION AT OBLIQUE INCIDENCE OBSERVED AT 32 MC ON RIOMETERS AND SCATTER SIGNALS

• Main Authors: Collins, William, Mitchell, Joseph, Rockmaker, Phillip, Farrell, James, Albright, William, Santos, Winifred De Los, Schreiber, Roberta, Hepner, John, Steel, D. N.
• Other Authors: PAGE COMMUNICATIONS ENGINEERS INC WASHINGTON DC
• Format: Text
• Language: English
• Published: 1961
• Subjects: Test Facilities; Equipment and Methods; *SCATTERING; *ABSORPTION; *EXTRATERRESTRIAL RADIO WAVES; IONOSPHERE; AURORAE; COMMUNICATION AND RADIO SYSTEMS; POLAR REGIONS; Arctic; Greenland
• Online Access: http://www.dtic.mil/docs/citations/AD0273725; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0273725

Ionospheric absorption in the arctic was studied using riometers and ionospheric scatter signals at 32 mc. Oblique measurement were made in all cases on three antennas at Sondrestrom, Greenland, pointing NW, SE, and SW. several events in the period September 1960 through October 1961 areANALYZED. Total ionospheric absorption is inferred from riometer measurements, while lowlevel absorption is inferred from the scatter signal-intensity variations. Auroral absorption observations indicated that the size of absorbing areas usually does not exceed 10,000 sq km. Evidence of noise generated in the aurora is discussed. Polar-cap absorption events showed severe absorption, often exceeding 30 db at oblique incidence. Polar-cap absorption effects were more intense in the auroral zone, probably because of a strong dependence on solar zenith angle, although the effects persisted longer at the higher latitudes. Good correlation between the onset of the events on the various antennas showed the effects to be widespread. The signal and noise absorption variations, when compared with a simple model, indicate considerable variation of scattering and/ or absorption heights dring the events.