Medium scale TIDs observed by Radio interferometry and differential Doppler techniques

Abstract

Ionospheric irregularities have been observed with the Westerbork Synthesis Radio Telescope monitoring celestial radio sources and at the Royal Netherlands Meteorological Institute at De Bilt using differential Doppler measurements. This paper gives a description of the observing techniques used and of the analysis of the data. These observations were made during the first three months of 1983. The merits of our technique are compared with those of some other more commonly used techniques. Climatological characteristics of ionospheric waves are described and compared with similar observations carried out during the first three months of 1982. As in the 1982 data, the direction of propagation of medium scale TIDs is found to be mainly towards the southwest. A Fourier analysis of the amplitudes of the measured irregularities shows that typically a 12 h and a 24 h period with equal strength exist in the data. On the basis of the characteristics of medium scale TIDs we propose that the waves may be generated by atmospheric tides.