NmF2 enhancement during ionospheric F2 region nighttime: A statistical analysis based on COSMIC observations during the 2007–2009 solar minimum. Issue 11 (21st November 2015)

• Record Type: Journal Article
• Authors: Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing; Zhang, Hui
• Is Part Of: Journal of geophysical research. Volume 120:Issue 11(2015:Nov.)
• Page Start: 10083
• Page End: 10095
• Publication Date: 2015-11-21
• Subjects: nighttime enhancement -- ionospheric peak electron density -- COSMIC; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA021652
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: In this paper the global features of Nm F2 enhancement occurring during ionospheric F 2 region nighttime (the period when the sunlight is occulted by the Earth in the altitudinal range of ionospheric F 2 region) and lasting for more than 2 h were investigated based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurements during the 2007–2009 solar minimum. This nighttime enhancement of Nm F2 mainly appears at the latitudes with dips larger than 45° in the winter hemisphere in solstice seasons. The magnitude of Nm F2 enhancement reaches latitudinal maxima (minima) at the geomagnetic latitudes of about 40°–50° (60°–70°), with larger magnitudes in the northern winter hemisphere than in the southern winter hemisphere. The longitudinal variation of nighttime enhancement is also evident; especially the magnitude of Nm F2 enhancement shows a significant longitudinal modulation in the southern winter hemisphere. The controlling factors of the spatial variations of Nm F2 nighttime enhancement were analyzed. The longitudinal variation of Nm F2 nighttime enhancement is suggested to be related to the longitudinal differences in background Nm F2, thermospheric density, and interhemispheric plasma transport, and the latitudinal variation of Nm F2 nighttime enhancement is possibly related to the latitudinal variations of geomagnetic inclination and the plasma storage in the topside ionosphere and the plasmasphere. The configuration of the geomagnetic field plays an important role in the longitudinal and latitudinal variations of Nm F2 nighttime enhancement. Key Points: Global features of Nm F2 nighttime enhancements at solar minima are presented Nm F2 nighttime enhancement significantly depends on geomagnetic filed configuration Physical interpretations of longitudinal variations of Nm F2 nighttime enhancement