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| Titel |
Solar-wind-driven changes to the ionospheric electric potential lead to changes in tropospheric temperature and geopotential height |
| VerfasserIn |
Mai Mai Lam, Gareth Chisham, Mervyn P. Freeman |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104065
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| Publikation (Nr.) |
 EGU/EGU2015-3486.pdf |
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| Zusammenfassung |
| There are a large number of responses, on the day-to-day timescale, of the dynamics of the
troposphere to regional changes in the downward current of the global atmospheric electric
circuit (GEC). They provide compelling evidence that, via the GEC, the solar wind plays a
role in influencing surface weather and climate. We use reanalysis data to estimate the
altitude and time lag dependence of one such response – the Mansurov effect. This effect
was first observed as a correlation between the duskward component By of the
interplanetary magnetic field (IMF) and surface pressure anomalies in Antarctica.
Additionally, we have more recently shown that the polar Mansurov effect can
affect mid-latitude atmospheric planetary waves, the amplitude of the effect being
comparable to typical initial analysis uncertainties in ensemble numerical weather
prediction. Here we shed light on the origins of the polar surface effect by examining the
correlation between IMF By and geopotential height anomalies throughout the
Antarctic troposphere and lower stratosphere. We find that the correlation is highly
statistically significant within the troposphere, and not so in the stratosphere. The peak in
the correlation occurs at greater time lags at the tropopause (~ 6 – 8 days) and
in the mid troposphere (~ 4 days) than in the lower troposphere (~ 1 day). This
supports a mechanism involving the action on lower tropospheric clouds of the
GEC, modified by variations in the solar wind (through modulations of the spatial
variation in ionospheric potential). The increase in time lag with increasing altitude is
consistent with the upward propagation by conventional atmospheric processes of the
solar wind-induced variability in the lower troposphere. This is in contrast to the
downward propagation of atmospheric effects to the lower troposphere from the
stratosphere due to solar variability-driven mechanisms involving ultraviolet radiation or
energetic particle precipitation. We also find a correlation between IMF By and the
tropospheric air temperature anomaly, which is of lower statistical significance than the
geopotential height effect described above. Up to altitudes of 3 km, the anomalies in air
temperature are related to the geopotential height by the environmental lapse rate, and
therefore considered to be real and to be part of the Mansurov effect. The mean air
temperature anomaly across Antarctica associated with the Mansurov effect is up to 0.8 K. |
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