 |
| Titel |
Worldwide impacts of sudden stratospheric warmings on the ionosphere and thermosphere |
| VerfasserIn |
Larisa Goncharenko, Anthea Coster, Shun-Rong Zhang, Phillip Erickson, Nestor Aponte, V. Lynn Harvey, Nicholas Pedatella, Astrid Maute |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122053
|
| Publikation (Nr.) |
 EGU/EGU2016-982.pdf |
|
|
|
|
|
| Zusammenfassung |
| Recent studies have demonstrated large variations in the low-latitude ionosphere during
strong, persistent meteorological disturbances known as sudden stratospheric warmings.
Several possible lower/upper atmosphere coupling mechanisms were identified, including
changes in the dynamics of the background neutral atmosphere, modification of solar and
lunar tides, and subsequent variations in electric field. We extend these studies using
observations by GNSS TEC receivers, by several ionosondes located at low, middle, and high
latitudes, and by Jicamarca, Arecibo and Millstone Hill incoherent scatter radars to
investigate large-scale ionospheric disturbances for several SSW events. To separate
ionospheric anomalies associated with SSW from regular ionospheric behavior, we develop
an empirical model of ionospheric parameters (TEC, NmF2) using available long-term data
records (10-40 years of data depending on the instrument). The models describe variations in
parameters for each longitude/latitude bin (or ionosonde location) as a function
of solar activity, geomagnetic activity, day of year, and local time. Ionospheric
anomalies are obtained as the difference between the observations and the empirical
model.
Ionospheric anomalies are observed for both major and minor SSW events, reaching
50-100% variation from expected seasonal behavior for major SSW events and 30-60%
variation for minor SSW events. The largest variations in the daytime TEC and NmF2 are
observed both in the crests of equatorial ionization anomaly and at 40-60S (geodetic). Recent
expansion of GNSS TEC receiver network to high latitudes in the southern hemisphere
indicates that SSW anomalies are communicated across the globe and associated with
ionospheric disturbances even over Antarctica.
Observational studies focused on SSW events present an important opportunity to better
understand processes governing the behavior of the Earth’s ionosphere and thermosphere. We
use examples of observations from different latitudes and longitudes to illustrate how
additional information helps to constrain global circulation models and to characterize the
relative importance of different coupling mechanisms. |
|
|
|
|
|
|