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Ann. Geophys., 26, 1071-1081, 2008
www.ann-geophys.net/26/1071/2008/
© European Geosciences Union 2008
A case study of a sporadic sodium layer observed by the ALOMAR Weber Na lidar
H. Nesse1,2, D. Heinrich1, B. Williams3, U.-P. Hoppe1, J. Stadsnes2, M. Rietveld4, W. Singer5, U. Blum1,6, M. I. Sandanger2, and E. Trondsen7
1Norwegian Defence Research Establishment, Kjeller, Norway
2University of Bergen, Department of Physics and Technology, Bergen, Norway
3NorthWest Research Associates/Colorado Research Associates Division, Boulder, USA
4EISCAT Scientific Association, Tromsø, Norway
5Leibniz Institute for Atmospheric Physics, Kühlungsborn, Germany
6Fraunhofer Institute for Technological Trend Analysis, Euskirchen, Germany
7University of Oslo, Department of Physics, Oslo, Norway
Abstract. Several possible mechanisms for the production of sporadic sodium layers
have been discussed in the literature, but none of them seem to explain all
the accumulated observations. The hypotheses range from direct meteoric
input, to energetic electron bombardment on meteoric smoke particles, to ion
neutralization, to temperature dependent chemistry. The varied
instrumentation located on Andøya and near Tromsø in Norway gives us
an opportunity to test the different theories applied to high latitude
sporadic sodium layers. We use the ALOMAR Weber sodium lidar to monitor the
appearance and characteristics of a sporadic sodium layer that was observed
on 5 November 2005. We also monitor the temperature to test the hypotheses
regarding a temperature dependent mechanism. The EISCAT Tromsø Dynasonde,
the ALOMAR/UiO All-sky camera and the SKiYMET meteor radar on Andøya are
used to test the suggested relationships of sporadic sodium layers and
sporadic E-layers, electron precipitation, and meteor deposition during this
event. We find that more than one candidate is eligible to explain our
observation of the sporadic sodium layer.
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