%0 Journal Article
%@holdercode {isadg {BR SPINPE} ibi 8JMKD3MGPCW/3DT298S}
%@nexthigherunit 8JMKD3MGPCW/3ETL868
%@archivingpolicy denypublisher denyfinaldraft24
%X The dawn-to-dusk convection electric field increases during the growth phase of substorms, driving DP2 currents composed of two-cell current vortices in high latitude and leading to an increase in the eastward electrojet at the dayside dip equator (EEJ). During the expansion phase of substorms, electric field and currents are often reversed in direction to the normal DP2 currents at subauroral to equatorial latitudes when the convection electric field reduces abruptly. The reversed current at the dayside dip equator appears as a counterelectrojet (CEJ) and causes an equatorial enhancement of the negative bay in the afternoon sector. Conversely, the convection electric field increases during substorms as deduced from sawtooth events, causing an increase in the EEJ. In this study, by analyzing isolated substorms with magnetometer array data and SuperDARN (Super Dual Auroral Radar Network) convection maps, we deduce that the reversed electric field and currents develop at the subauroral-to-equatorial latitudes at the onset of substorms, while the convection electric field increases at auroral latitudes. These observations imply that both the region 1 and region 2 field aligned currents (R1 and R2 FACs) develop on the dayside concurrently with the current wedge responsible for the midlatitude positive bay at midnight. The substorm-associated R2 FACs are strong enough to cause the reversed current at the subauroral latitude and the CEJ at the equator. We also deduce that the dayside equatorial CEJ begins simultaneously with or even earlier than the midlatitude positive bay at midnight while the midlatitude positive bay onset is delayed by several minutes as the station departs from the midnight meridian. These observations suggest that the substorm begins with the intensification of the R2 FACs responsible for the equatorial CEJ.
%@mirrorrepository sid.inpe.br/mtc-m19@80/2009/08.21.17.02.53
%8 Sept.
%N A09217
%T Polar-equatorial ionospheric currents driven by the region 2 field-aligned currents at the onset of substorms
%@electronicmailaddress hashi@kiui.ac.jp
%@secondarytype PRE PI
%K High-latitude convection, Magnetically disturbed conditions, HF radar observations, Electric-fields, Magnetospheric substorms, Expansion phase, Growth-phase, Penetration, Signatures, Transmission.
%@usergroup administrator
%@usergroup banon
%@usergroup marciana
%@usergroup tereza@sid.inpe.br
%@group
%@group
%@group
%@group DAE-CEA-INPE-MCT-BR
%@e-mailaddress tereza@sid.inpe.br
%@secondarykey INPE--PRE/
%@issn 0926-9851
%2 sid.inpe.br/mtc-m19/2011/11.24.17.07.35
%@affiliation Department of Environmental Management, Kibi International University, Takahashi, Japan
%@affiliation Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
%@affiliation National Institute of Information and Communications Technology, Koganei, Japan
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%B Journal of Applied Geophysics
%@versiontype publisher
%4 sid.inpe.br/mtc-m19/2011/11.24.17.07
%@documentstage not transferred
%D 2011
%V 116
%@doi 10.1029/2011JA016442
%A Hashimoto, K. K.,
%A Kikuchi, T.,
%A Watari, S.,
%A Abdu, M. A.,
%@dissemination WEBSCI; AGU; MGA; COMPENDEX.
%@area CEA