Bibliography

Retrieval of thermospheric parameters from routine ionospheric observations: assessment of method\textquoterights performance at mid-latitudes daytime hours

A new method has been developed to retrieve neutral temperature T_n and composition [O], [N₂], [O₂] from electron density profiles in the daytime mid-latitude F₂-region under both quiet and disturbed conditions. A comparison with CHAMP neutral gas density observations in the vicinity of Millstone Hill Incoherent Scatter Radar (ISR) has shown that the retrieved neutral gas densities coincide with the observed ones within the announced accuracy of CHAMP observations, provided that accurate N_e(h) ISR profiles are used for the retrieval. The performance of the method has also been tested ingesting Digisonde N_e(h) profiles. In this case the agreement with CHAMP neutral gas density observations is less successful. Possible factors that can influence the performance accuracy are investigated. These are mostly related to limitations due to the ionogram scaling and inversion methods, including performance limitations of the sounding technique itself, like for instance during G-conditions. Several tests presented here demonstrate that discrepancies in the hmF2 values provided by the Digisondes could have an important impact on the performance of the method. It should be noted that in all tests performed here using Digisonde N_e(h) profiles, the topside part is approximated with the NeQuick model and any assessment concerning the impact of the topside profiler on the accuracy of the method is beyond the scope of this investigation. Despite the limitations related to the use of Digisonde profiles, the proposed method has the potential to monitor the thermosphere at least with ISR N_e(h) profiles. Digisonde electron density profiles can also be used if quality improvements are made concerning the ionogram inversion methods.

Mikhailov, A.V.; Belehaki, A.; Perrone, L.; Zolesi, B.; Tsagouri, I.;

Published by: Journal of Space Weather and Space Climate      Published on: 06/2012

YEAR: 2012     DOI: 10.1051/swsc/2012002

ionosphere/atmosphere interactions; ionosphere: instruments; Ionospheric storms; techniques; thermospheric dynamics; topside ionosphere

Neutral density depletions associated with equatorial plasma bubbles as observed by the CHAMP satellite

Using CHAMP observations from 2002 to 2005 we investigate neutral density depletions (NDDs) associated with equatorial plasma bubbles (EPBs). The seasonal–longitudinal distribution of NDDs generally follows that of EPBs. However, there are several important differences between them. The maximum NDD occurrence rate is much smaller than the maximum EPB occurrence. NDDs occur at latitudes north and south of the dip equator with an offset of about 15∘, which is collocated with the Appleton anomaly peaks and slightly poleward of EPB occurrence maxima. The NDD occurrence maximizes around 21 LT, and has nearly died out after 23 LT. Meanwhile, the EPB occurrence shows a broad maximum between 20 and 24 LT. NDD distribution deviates slightly from that of EPBs shifted toward the region of high ion–neutral interaction. Based on our statistical results, as well as on some physics-based calculations, we suggest that an enhanced friction between ions and neutrals is needed for the NDD generation.

Park, Jaeheung; Lühr, Hermann; Min, Kyoung;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on:

YEAR: 2010     DOI: https://doi.org/10.1016/j.jastp.2009.11.003

ionospheric irregularities; Equatorial ionosphere; thermospheric dynamics; ionosphere/atmosphere interactions