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| Titel |
A global picture of the temporal response of surface atmospheric pressure to the passage of the heliospheric current sheet |
| VerfasserIn |
Mai Mai Lam, Gareth Chisham, Mervyn P. Freeman, Kathryn A. McWilliams, Devin R. Huyghebaert |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075892
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| Zusammenfassung |
| The meteorological response (e.g., of surface pressure) in the polar regions to fluctuations in
the interplanetary magnetic field (IMF) By component (the ‘Mansurov effect’) has been
proposed to occur via superimposed changes of the ionospheric potential on the global
atmospheric electric field. Previously we have shown, in a time-averaged study, that the
Mansurov effect also results in mid-latitude (40°-70°) changes to the latitudinal pressure
gradient (and the zonal wind field), and thereby the atmospheric Rossby wave field. Since the
evolution of storm tracks can be highly sensitive to Rossby wave dynamics, the IMF can in
principle also significantly influence the evolution and distribution of atmospheric vorticity.
Over the last 40 years, convincing evidence has accumulated for the ‘Wilcox effect’ - the
correlation between the time of reversals in polarity of the IMF (crossings of the
heliospheric current sheet) and decreases in the winter tropospheric low-pressure
vorticity at mid to high latitudes. It has been suggested that such changes to storm
vorticity are due to the occurrence of reductions in the relativistic electron flux during
HCS crossings, and associated changes in the ionosphere-Earth current density. To
investigate further possible mechanisms for the Wilcox effect, we conduct a superposed
epoch analysis (SEA) of the global atmospheric pressure at the Earth’s surface using
NCAR/NCEP reanalysis data ordered according to HCS crossings. We use a similar SEA
of solar wind data (including both IMF By and Bx) to investigate the role of the
high-latitude Mansurov effect (and other mechanisms) in the mid-high latitude Wilcox
effect. We discuss our results in the context of our previous time-averaged global
study. |
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