OSCILLATIONS IN D-REGION ABSORBTION AT PERIODS OF ONE TO TWO MONTHS

J. L. Stanford, and (1)R. C. Saksena, Department of Atmospheric, Oceanic, and Planetary Physics, University of Oxford, Oxford OX1 3PU, U.K.

(1) National Physical Laboratory, Hillside Road, New Delhi 110012, India

J. Atmos. & Terrestrial Phys., 51, 975-981 (1989)

Abstract

One to two month oscillations in D-region absorption are found in seven years of daily f-min data from low latitude stations at Singapore (1N, 104E) and Rarotonga (21S, 160W). Coherency (cross-spectral) analyses reveal that solar flux variations account for much of the f-min variance at these periods. Over the range of periods from 10 to 200 days, statistically significant linear correlation is found between the f-min time series and contemporaneous 10.7cm solar flux measurements at periods of 16-19 days, the 26-29 day solar rotation band, and a broad band covering 43-80 day periods.