STUDY OF GEOELECTROMAGNETIC DISTURBANCES IN QUEBEC, 1 - GENERAL RESULTS

With the aim to better understand the flow of geomagnetically induced currents in the power system and to be able to prevent GIC inconvenien ces in the future, Hydro-Quebec carried out measurements of the geoele ctromagnetic field in Quebec at five sites, spread over 250 km, from 1 992 to 1994. This included magnetometers and the use of 25 km long pho ne cables to measure the electric field. The largest disturbances were found to occur when the auroral electrojet moved close to the recordi ng sites. The magnetic disturbances varied little over the five sites, but the electric fields varied greatly from site to site due to chang es in the local geology. An analysis: of events with electric fields E greater than or equal to 1 V/km found an approximate linear relations hip between E and horizontal dB/dt. The directions of these electric f ields were roughly east-west, consistent with the electrojet as the ca use of the disturbances.