Abstract
Abstract. The characteristics of dayside ionospheric convection are studied using Northern Hemispheric SuperDARN data and DMSP particle and flow observations when the interplanetary magnetic field (IMF) was strongly northward during 13:00–15:00 UT on 2 March 2002. Although IMF Bx was positive, which is believed to favour Southern Hemisphere high-latitude reconnection at equinox, a four-cell convection pattern was observed and lasted for more than 1.5 h in the Northern Hemisphere. The reconnection rate derived from an analysis of the Northern Hemisphere SuperDARN data illustrates that the high-latitude reconnection was quasi-periodic, with a period between 4–16 min. A sawtooth-like and reverse-dispersed ion signature was observed by DMSP-F14 in the sunward cusp convection at around 14:41 UT, confirming that the high-latitude reconnection was pulsed. Accompanying the pulsed reconnection, strong antisunward ionospheric flow bursts were observed in the post-noon LLBL region on closed field lines, propagating with the same speed as the plasma convection. DMSP flow data show that a similar flow pattern and particle precipitation occurred in the conjugate Southern Hemisphere.
Highlights
IntroductionIt has been well established that the orientation of the interplanetary magnetic field (IMF) plays an important role in controlling the dayside reconnection (e.g. Heppner, 1972; Reiff and Burch, 1985; Moore et al, 2002), and thereby the large-scale convection-driven flow patterns
In this paper we present SuperDARN and DMSP satellite observations when the interplanetary magnetic field (IMF) was strongly northward
The IMF Bx was positive during most of the interval of interest, which is believed to favour Southern Hemisphere lobe reconnection at equinox, a four-cell convection pattern occurred in the Northern Hemisphere and lasted for at least 1.5 h, with periodic flow bursts in the post-noon antisunward convection region associated with low-latitude boundary layer (LLBL) precipitation on closed field lines
Summary
It has been well established that the orientation of the interplanetary magnetic field (IMF) plays an important role in controlling the dayside reconnection (e.g. Heppner, 1972; Reiff and Burch, 1985; Moore et al, 2002), and thereby the large-scale convection-driven flow patterns When the IMF is northward, lobe reconnection, or highlatitude reconnection between lobe field lines and the IMF begins, resulting in a multi-celled flow pattern, with a region of sunward flow in the dayside polar cap The first type is lobe reconnection, which takes place only in one hemisphere, referred to as “lobe stirring” (Reiff, 1982), or lobe reconfiguration, which results in circulatory lobe convection cells in the polar cap. Another type, often referred to as lobe merging, occurs first in one hemisphere and the overdraped field lines reconnect in the opposite hemisphere. It gives us an excellent opportunity to study the temporal variations of lobe reconnection and its associated ionospheric convection in detail
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