Characteristics of counter-Sq SFE (SFE) at the dip equator CPMN stations A05306

Abstract

The solar flare effect (SFE) at dip equatorial latitudes sometimes shows the counter-Sq variation around local noon. In this paper, we refer to this type of SFE as SFE*. Observations obtained by the Circum-pan Pacific Magnetometer Network (CPMN) reveal some previously unknown characteristics of SFE*. Some of these features are the following: (1) the counter-Sq SFE variation is observed in limited longitude (local time) and latitude sectors (i.e., LT ≈ 1030-1300, \DipLat.\ ≲, 1.5°) (2) outside this limited region, the amplitude of SFE(Z/) and preflare S q(H) have a linear relationship (3) SFE* is observed during the significant depression of the horizontal magnetic field at dip equatorial latitudes, which indicates the presence of westward electric fields whose origin remains to be understood. Copyright 2009 by the American Geophysical Union.