Options
Different responses of northern and southern high latitude ionospheric convection to IMF rotations: A case study based on SuperDARN observations
Language
English
Obiettivo Specifico
2A. Fisica dell'alta atmosfera
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/27 (2009)
Issued date
2009
Abstract
We use SuperDARN data to study high-latitude
ionospheric convection over a three hour period (starting at
22:00 UT on 2 January 2003), during which the Interplanetary
Magnetic Field (IMF) flipped between two states, one
with By >>|Bz| and one with Bz >0, both with negative Bx .
We find, as expected from previous works, that day side ionospheric
convection is controlled by the IMF in both hemispheres.
For strongly northward IMF, we observed signatures
of two reverse cells, both in the Northern Hemisphere
(NH) and in the Southern Hemisphere (SH), due to lobe reconnection.
On one occasion, we also observed in the NH
two viscous cells at the sides of the reverse cell pair. For
duskward IMF, we observed in the NH a large dusk clockwise
cell, accompanied by a smaller dawn cell, and the signature
of a corresponding pattern in the SH. On two occasions,
a three cell pattern, composed of a large clockwise
cell and two viscous cells, was observed in the NH. As regards
the timings of the NH and SH convection reconfigurations,
we find that the convection reconfiguration from a
positive Bz dominated to a positive By dominated pattern
occurred almost simultaneously (i.e. within a few minutes)
in the two hemispheres. On the contrary, the reconfiguration
from a By dominated to a northward IMF pattern started
in the NH 8–13 min earlier than in the SH. We suggest that
part of such a delay can be due to the following mechanism:
as IMF Bx <0, the northward-tailward magnetosheath magnetic
field reconnects with the magnetospheric field first tailward
of the northern cusp and later on tailward of the southern
cusp, due to the IMF draping around the magnetopause.
ionospheric convection over a three hour period (starting at
22:00 UT on 2 January 2003), during which the Interplanetary
Magnetic Field (IMF) flipped between two states, one
with By >>|Bz| and one with Bz >0, both with negative Bx .
We find, as expected from previous works, that day side ionospheric
convection is controlled by the IMF in both hemispheres.
For strongly northward IMF, we observed signatures
of two reverse cells, both in the Northern Hemisphere
(NH) and in the Southern Hemisphere (SH), due to lobe reconnection.
On one occasion, we also observed in the NH
two viscous cells at the sides of the reverse cell pair. For
duskward IMF, we observed in the NH a large dusk clockwise
cell, accompanied by a smaller dawn cell, and the signature
of a corresponding pattern in the SH. On two occasions,
a three cell pattern, composed of a large clockwise
cell and two viscous cells, was observed in the NH. As regards
the timings of the NH and SH convection reconfigurations,
we find that the convection reconfiguration from a
positive Bz dominated to a positive By dominated pattern
occurred almost simultaneously (i.e. within a few minutes)
in the two hemispheres. On the contrary, the reconfiguration
from a By dominated to a northward IMF pattern started
in the NH 8–13 min earlier than in the SH. We suggest that
part of such a delay can be due to the following mechanism:
as IMF Bx <0, the northward-tailward magnetosheath magnetic
field reconnects with the magnetospheric field first tailward
of the northern cusp and later on tailward of the southern
cusp, due to the IMF draping around the magnetopause.
Type
article
File(s)
Loading...
Name
Ambrosino_09.pdf
Size
8.38 MB
Format
Adobe PDF
Checksum (MD5)
ac3fbef71286c44819739297dab0378d