The spatial distribution of hydrogen ions at topside ionosphere in local daytime

Abstract

Using DEMETER and DMSP satellite data, the spatial distribution of hydrogen ion (H + ) in local daytime has been compared and analyzed. At 840 km of DMSP height, the seasonal variations of H + density is basically symmetric, with similar density values near to the magnetic equator at northern hemisphere in December and at southern hemisphere in June. But at DEMETER satellite height, the peak H + density shows obvious enhancement at northern hemisphere in December solstice, while with approximate small values at both hemispheres in June. This spatial distribution feature is totally different with other ions such as O + and He + at the topside ionosphere. And also it influences the transition height in topside ionosphere, with lower transition height over northern hemisphere in December season at 10 -20°N than those at equator and over southern hemisphere in June season. The solstitial asymmetry index (AI) of H + at 670 km altitude gives the significant December season enhancement over northern hemisphere, which is typically reversed with electron density (Ne) and ion density (Ni) with large numbers over southern hemisphere in December season. Finally combining with the distribution of H atoms and neutral wind velocity in upper atmosphere, the forming mechanism and asymmetry feature of peak H + density is discussed. It is illustrated that the upwelling movement at equatorial area and northward neutral wind play important roles in H + peak drift in December season at DEMETER satellite altitude below the transition height where H + is not the main composition in the local daytime in solar minimum years. Keywords:Hydrogen ion, Topside ionosphere, Seasonal asymmetry, DEMETER satellite Citation:Shen, X. and X. Zhang, 2017: The spatial distribution of hydrogen ions at topside ionosphere in local daytime.

Topside Ionospheric Structures Determined via Automatically Detected DEMETER Ion Perturbations during a Geomagnetically Quiet Period

“…Ionospheric irregularity has always been a main topic of investigations of ionospheric dynamics systems, and various data from ground-based sensors and in situ measurement onboard satellites have been utilized to establish ionospheric models and main large-scale ionospheric structures [2][3][4][5][6][7][9][10][11][12][13][16][17][18][19][20][21][22][23][24], as well as their inner structure and property [58]. Unlike previous works using continuous data, during this time, automatically searched ion PERs were investigated for properties such as varied amplitude, space scale, location, and occurrence time.…”

“…[11,[16][17][18][19][20][21]. Other parameters such as O + , H +, and He + densities and total electron densities are also used to research the ionospheric characteristics of background, seasonal, and day-to-day variations, as well as the large-scale depletion of oxygen ions [22][23][24].…”

Chinese ionospheric investigations in 2016–2017

“…Shen XH and Zhang XM (2017) investigated the spatial distribution of hydrogen ions with the data from the DEMETER and DMSP satellites. At the 840 km altitude of the DMSP satellite, the seasonal variations of H + density are basically symmetric at the two winter hemispheres; but at the 660 km altitude of DEMETER, the peak H + is enhanced in the northern hemisphere in the December season and quite weak at both hemispheres in June.…”

Topside Ionospheric Structures Determined by Automatically Detected DEMETER Ion Perturbations

“…2 occultation measurements has been employed to investigate the properties of ionospheric irregularities such as EIA, MIT, middle latitudinal band structures, Wedell Sea Anomaly, and so on [11,[17][18][19][20][21][22]. Other parameters like O+, H+ and He+ densities and total electron density are also used to research ionospheric characteristics of background, seasonal and day-to-day variations and largescale depletion of oxygen ion [23][24][25].…”