Role Of Conjugate and Local Terminators On the Electric Fields at Arecibo

Tuesday, 16 December 2014
Suman Ganguly1,2, Christiano G.M. Brum3, Nestor Aponte4, Eframir Franco1,2 and Sixto A. Gonzalez3, (1)Scientific Systems, LLC, Arlington, VA, United States, (2)Arecibo Observatory, HC3 BOX 53995, Arecibo, P.R. 00612, United States, (3)SRI International Menlo Park, Arecibo Observatory, Menlo Park, CA, United States, (4)SRI International Menlo Park, Menlo Park, CA, United States

Using some recent Plasma drift data at Arecibo, we present evidences of Electric Field (E) changes induced by sunrise and sunset transitions at both local and conjugate regions. Field perpendicular plasma drifts in the F region are used as unambiguous diagnostic of the Electric Field. The large time differences between the local ( 18.35 N, 66.75 W) and conjugate region (46.6 S, 64.7 W) sunrise and sunsets, particularly during the local winter at Arecibo,  allow identification of local and conjugate effects on the E field. We present evidences of a downward velocity started around the conjugate sunrise and reaching minimum around the local sunrise, when it turns around and merges with normal daytime behavior, controlled by the dynamo region. During sunset, the upward drift increase at local sunset and shows a dip at the conjugate sunset, when it turns around. Afterwards, the F region is isolated and behaves in regular night time fashion. The entire behavior can be explained by coupled behavior of the E and F region, where the terminator line switches the coupling and affects charge separation at the boundaries. Similar investigations using the summer data have been performed and confirm the interpretation of coupled electric circuit including the local and conjugate regions and intervening ionosphere along the field lines.