GEOELECTRIC POWER SPECTRA OVER OCEANIC DISTANCES

We present initial results of simultaneous measurements of the geoelec tric potential as measured across two long cable routes in the Pacific (Guam to Philippines and California to Hawaii) separated by approxima tely 6h in local time and approximately 30-degrees in latitude. Over t he frequency range approximately 10(-5) to 1.67 x 10(-3) Hz the power levels tend to be enhanced near local noon along the two routes, espec ially during geomagnetic quiet intervals. During the seven days analyz ed, geoelectric power levels up to 10(4) (mV/km)2/km were measured on a geomagnetically disturbed day. The power levels at the longest perio ds, approximately 17m to approximately 150m, are generally found to be largest along the route at lower geomagnetic latitudes (Guam to Phili ppines) when comparisons are made at equivalent local times. In contra st, the power levels for periods in the hydromagnetic wave region (per iods less than or similar to 5m) tend to be larger at all local times for the higher geomagnetic latitude route. The nightside geoelectric p ower levels along the higher latitude route tend to increase with incr easing geomagnetic activity.