Browsing by Author "Belehaki, Anna"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Restricted Modeling the IRI topside profile using scale heights from ground-based ionosonde measurements(Elsevier, 2004) Reinisch, Bodo W.; Huang, Xue-Qin; Belehaki, Anna; Shi, Jian-Kui; Zhang, Man-Lian; Ilma, RonaldIonograms present a new data resource for an effort to improve the IRI topside profiles. Ground-based ionograms measure the Chapman scale height at the P2 layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles and height-integrated profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC, the difference being attributed to the plasmasphere. It is suggested to use the scale height HT, routinely measured by a large number of digisondes around the globe, for the construction of a topside electron density profile that could become an option in the IRI model. To quickly establish a large database for HT, it would be useful to take advantage of the autoscaled HT values. A comparison of monthly medians using automatically and manually determined HT values is made. Direct calculation of HT from the bottomside IRI profile defined by B0, B1, D1, NmF2, and hmF2 using the same extrapolation technique suggests an alternate path to an estimate of the topside profile.Item Restricted Retrieval of thermospheric parameters from routinely observed F2-layer Ne(h) profiles at the geomagnetic equator(EDP Open, 2013-04-08) Mikhailov, Andrei; Belehaki, Anna; Perrone, Loredana; Zolesi, Bruno; Tsagouri, IoannaA principal possibility to retrieve basic thermospheric parameters (neutral temperature Tex, atomic [O] and molecular [O2] oxygen as well as molecular nitrogen [N2] concentrations) from the observed daytime electron density profiles Ne(h) in the equatorial F2-region is demonstrated for the first time. The reduction of a 2D continuity equation for electron concentration in the low-latitude F2-region at the geomagnetic equator (I = 0) results in a simple 1D equation which can be efficiently solved. The method was tested using Jicamarca Incoherent Scatter Radar (ISR) and Digisonde Ne(h) profiles for the periods when CHAMP and GRACE neutral gas density observations are available in the vicinity of the Jicamarca Observatory. The retrieved from ISR Ne(h) neutral gas densities were shown to be close to the observed ones (MRD < 10%) being within the announced absolute uncertainty (10–15%) of the neutral gas density observations and more successful than the predictions of the empirical models JB-2008 (MRD = 32%) and MSISE-00 (MRD = 27%) for the analyzed cases. The implementation of the method with Jicamarca Digisonde Ne(h) profiles has also shown acceptable results especially for solar minimum conditions (MRD ~ 12%) and higher prediction accuracy than modern empirical models provide. This finding seems to open a way for the practical exploitation of the method for thermospheric monitoring purposes.