No abstract

General equations are presented for the diffuse scattering due to local ionic arrangements and displacements in systems with more than one ion per lattice point. Up to fourth-order terms are included. These are placed in a form easy to evaluate in specific cases; examples are given of a solid-solution oxide, and an oxide with vacant sites. Methods for employing these equations for the separation of the various contributions are discussed.

A brief review is given of the Boric-Sparks method of measuring and separating the diffuse scattering in alloys due to local displacements of atoms from lattice sites. Experimental techniques are reviewed with particular emphasis on simple computer controls, dead time, monochromators and specimens. After this, sources of error in the measurements are discussed and simple methods for assessing these errors presented. Equations for estimating higher-order terms than those included by Boric and Sparks are presented. It now appears that a thorough analysis of the errors needs to be made for each measurement prior to its publication. As this kind of experiment is readily automated and easily analyzed for errors with modern computers, this should now become standard procedure. It is also suggested that intensities in electron units be kept on file and made available when requested, as is done with structure factors.

The general consensus now is that some observations of Trimpis are not due to energetic electron precipitation from the magnetosphere\ but are a result of scattering from D region inhomogeneities caused directly by the electric _eld or EM radiation _eld of the lightning discharge[ In this connection a recent topic of interest is that of Sprites\ or cloud to ionosphere discharges "Dowden et al [ "0885#^Strangeways "0885#^Schonland and Craib "0816##[ These are believed to consist of narrow columns of enhanced electron density with a value

Abstract. In this paper, perturbations of the ionospheric Total Electron Content (TEC) are compared with geomagnetic oscillations. Comparison is made for a few selected periods, some during earthquakes in California and Japan and others at quiet periods in Israel and California. Anomalies in TEC were extracted using Global Positioning System (GPS) observations collected by GIL (GPS in Israel) and the California permanent GPS networks. Geomagnetic data were collected in some regions where geomagnetic observatories and the GPS network overlaps. Sensitivity of the GPS method and basic wave characteristics of the ionospheric TEC perturbations are discussed. We study temporal variations of ionospheric TEC structures with highest reasonable spatial resolution around 50 km. Our results show no detectable TEC disturbances caused by right-lateral strike-slip earthquakes with minor vertical displacement. However, geomagnetic observations obtained at two observatories located in the epicenter zone of a strong dip-slip earthquake (Kyuchu, M = 6.2, 26 March 1997) revealed geomagnetic disturbances occurred 6-7 h before the earthquake.