Seasonal trends of nighttime plasma density enhancements in the topside ionosphere

Abstract
<p>In situ registrations of electron density from the Langmuir probe on board Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions satellite are used to study spatial and temporal evolution of nighttime plasma density enhancements (NPDEs). The study introduces the normalized density difference index <em>I</em><sub>NDD</sub> in order to provide global estimates of the phenomenon. In the validation test, in situ data are compared with synthetic data set generated with the International Reference Ionosphere model. We find signatures of two most common examples of NPDEs, the Weddell Sea Anomaly (WSA) and midlatitude nighttime summer anomaly (MSNA) with proposed index, in the topside ionosphere. The study provides evidence that the occurrence of the WSA and MSNA is not limited to the local summer conditions. Analyzed annual trend of <em>I</em><sub>NDD</sub> and in particular spatial pattern obtained during equinoxes suggest that mechanisms governing the behavior of the equatorial ionosphere cannot be neglected in the explanation of the development of NPDEs.</p>
Year of Publication
2014
Journal
Journal of Geophysical Research: Space Physics
Volume
119
Number of Pages
6902-6912
Date Published
08/2014
URL
http://doi.wiley.com/10.1002/2014JA020181
DOI
10.1002/2014JA020181