Winter Anomalous Radio Wave Absorption Days at 32 Degrees N Latitude and Prevalent Solar Radiation

摘要

A study was made to determine whether the winter anomaly recurs at 32 degrees N latitude or during quiet solar days. The series of A-1 measurements of ionospheric D-region electromagnetic wave absorption recorded at White Sands Missile Range in December 1970, January 1971, and February 1971 and used to detect the anomaly are reported here. A criterion to identify anomalous high absorption days is defined and subsequently used in conjunction with the A-1 measurements to establish the occurrence of 11 winter anomalous days. Zurich sunspot numbers and solar flux input at 8.8 GHz and 15.4 GHz are used as solar activity indicators. Days with at least one standard deviation more than the computed three months solar flux and/or sunspot average are classified as solar active days. The earth's daily maximum magnetic field intensity is also reported and used to identify geomagnetically active days. Of the 11 anomalous absorption days detected at 32 degrees N latitude, five were found to occur on days of enhanced solar radiation, while the other six anomalous days occurred on quiet solar days. (Author)