NOPR Collection:

Ozone Concentrations at Indian Stations during High Sunspot Years

2016-11-08T05:59:16Z

Title: Ozone Concentrations at Indian Stations during High Sunspot Years Authors: Indira, K; Jyothi, K K; Ramanarao, B V Abstract: The influence of the solar activity on ozone concentrations at several Indian stations [Delhi. Banaras. Srinagar. Kodaikanal. Ahmedabad and Dum Dum (Calcutta)] during high sunspot years is studied. Correlation coefficients between the smoothed monthly mean ozone concentrations and sunspot numbers showed both positive and negative values at most of the stations studied, the negative value being less significant. Page(s): 167-170

Changes in the Low Latitude E-region Drifts Associated with Counter Electrojet

2016-11-08T05:45:32Z

Title: Changes in the Low Latitude E-region Drifts Associated with Counter Electrojet Authors: Chandra, H; Vyas, G D; Patel, V P Abstract: Changes in the horizontal drifts measured by spaced receiver technique at a low latitude station Ahmedabad at times of counter electrojet events are examined. Counter electrojet events have been identified from the geomagnetic H variations and confirmed from the drift measurements at an equatorial station Tiruchirapalli. Investigations show that during the winter months there is a marked change in the wind system as measured at Ahmedabad. The zonal winds which are predominantly westward during winter change to eastward during counter electrojet events. It is concluded that counter electrojets are probably caused by the changes in the atmospheric circulation pattern rather than the localized changes near magnetic equator. Page(s): 164-166

Variation of Electron Collision Frequency in the Ionosphere

2016-11-08T05:43:18Z

Title: Variation of Electron Collision Frequency in the Ionosphere Authors: Datta, Savita M; Aggarwal, Kanti M; Setty, C S G K Abstract: The effective collision frequency of electrons in the height range 100-460 km has been computed using the incoherent backscatter radar data of electron density and temperature and the neutral composition model given by L G Jacchia [Special rep. No. 375 (Smithsonian Astrophysical Observatory, Massachusetts, USA), 1977]. It is found that the collision frequency varies with height and time of the day. The variations are similar to the experimental observations although the latter are an order of magnitude higher. Page(s): 160-163

Ionospheric Scintillation Modelling

2016-11-08T05:39:30Z

Title: Ionospheric Scintillation Modelling Authors: Pasricha, P K; Reddy, B M Abstract: The phenomenon of ionospheric scintillations has long been observed by radio astronomers and physicists. The observations have provided valuable information towards the (qualitative) morphology of the phenomenon. The (quantitative) information about scintillation effects for today's satellite system design is rather meagre. Thus, it is not possible to know (and predict) as to how much of the time a given level of scintillation activity will remain in different parts of the world. It is shown that a more organized approach towards the collection and dissemination of data, in time and geographic location, is needed for a realistic worldwide model of ionospheric scintillations. Page(s): 153-159