Some peculiarities in the field structure of ipcl geomagnetic pulsations at coastal high-latitude observatories

Simultaneous observations of long-period (1-6 mHz) high-latitude geomagnetic pulsations of the ipcl type at four polar observatories, located at close geomagnetic latitudes in the Northern and Southern hemispheres, Dumont d'Urville (DRV), Scott Base (SBA), Mould Bay (MBC), and Cambridge Bay (CBB), are examined. Anomalously large values of the vertical field component at DRV and anomalously small values at MBC, respectively, have been found and interpreted as st result of field distortion by geoelectric irregularities in the vicinity of the observation point. The geomagnetic coast effect, which originates due to longshore sea currents and manifests itself in an anomalous increase in the Z/X ratio at coastal stations, is most pronounced at DRV. The diurnal variation in the Z/X ratio caused apparently by a difference in origin between;the daytime and nighttime geomagnetic pulsations, has been found.