Abstract
Abstract. A 30-day incoherent scatter radar (ISR) experiment was conducted at Millstone Hill (288.5° E, 42.6° N) from 4 October to 4 November 2002. The altitude profiles of electron density Ne, ion and electron temperature (Ti and Te), and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height Hp, vertical scale height VSH, Chapman scale height Hm, ion velocity, and the relative altitude gradient of plasma temperature (dTp/dh)/Tp, as well as the F2 layer electron density (NmF2) and height (hmF2). These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed conditions. Results show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions, while the main feature of the scale heights, as well as other parameters, deviated significantly from their median behaviors under disturbed conditions. The enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights, as well as the shape of the topside electron density profiles. Over Millstone Hill, the diurnal behaviors of the median VSH and Hm are very similar to each other and are not so tightly correlated with that of the plasma scale height Hp or the plasma temperature. The present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and dynamics. The values of VSH/Hp tend to decrease as (dTp/dh)/Tp becomes larger or the dynamic processes become enhanced.
Highlights
The ionospheric scale height, as a measure of the shape of electron density (Ne) profiles or the altitude dependence of electron density, is one of the key ionospheric parameters, due to its intrinsic connection to the ionospheric dynamics, plasma temperature and compositions (Luan et al, 2006; Stankov and Jakowski, 2006b)
We will focus on the median behavior of the topside scale heights and their behaviors under geomagnetically quiet and disturbed conditions. Another objective is to investigate the correlations between vertical scale height (VSH)/Hp and the thermal structure and diffusion processes in the ionosphere over Millstone Hill
Our results suggest, over Millstone Hill, that the diurnal behaviors of median VSH and Hm are much different from that of Hp
Summary
The ionospheric scale height, as a measure of the shape of electron density (Ne) profiles or the altitude dependence of electron density, is one of the key ionospheric parameters, due to its intrinsic connection to the ionospheric dynamics, plasma temperature and compositions (Luan et al, 2006; Stankov and Jakowski, 2006b). The seasonal and solar activity features of Hm over Millstone Hill (288.5◦ E, 42.6◦ N) have been investigated with ISR observations (Lei et al, 2005) and over Wuhan (114.4◦ E, 30.6◦ N) with digisonde measurements (Liu et al, 2006). Liu et al (2007) conducted a statistical analysis on the diurnal, seasonal, and solar cycle variations of ionospheric scale heights from the 1966–2002 ISR measurements at Arecibo (293.2◦ E, 18.3◦ N; geomagnetic latitude 30◦), Puerto Rico Their statistical analysis identified a clear solar activity pattern of VSH, Hm, and Hp over Arecibo. We will focus on the median behavior of the topside scale heights and their behaviors under geomagnetically quiet and disturbed conditions Another objective is to investigate the correlations between VSH/Hp and the thermal structure and diffusion processes in the ionosphere over Millstone Hill
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
