Traveling planetary-scale waves in the E-region

Abstract

An analysis of E-region minimum virtual height data obtained from a network of ionosonde stations in the northern hemisphere at mid-latitudes shows the presence of long period (10–15 days) planetary-scale fluctuations for the six-month period, October 1970–March 1971. A lag correlation analysis of the data between stations reveals a slow westward drift of these waves moving on the average 17° of longitude per day during the first three months of this period. The longitudinal fluctuations of the higher latitude data are shown to be consistent with a wave one type of variation. From the peak intensity of the apparent wave one pattern on 1 January 1971, and from the cessation of movement of these waves after December, it is concluded that the 1970/71 major mid-winter stratospheric/mesospheric disturbance reached to at least the lower E-region and preceded the peak of the stratospheric warming at 30 mb by about 5 days. The planetary-scale fluctuations observed in the virtual height data are also shown to be well correlated with harmonic one of a zonal Fourier analysis of lower stratospheric radiance data from the SIRS instrument on the Nimbus IV weather satellite. The peak positive correlations with small lag are generally found to occur when the longitude of the radiance data is within approximately 45° of the higher latitude ionosonde stations. The ionospheric data from most of the lower latitude stations are found to be negatively correlated with the radiance data interpolated to within 45° of their longitude zone. These observed correlations are interpreted in terms of planetary-scale temperature changes in the lower E-region.