NOPR Collection:

Statistical distribution of IEC at midlatitude and its application to earth-ionosphere communication systems

2016-10-24T07:38:07Z

Title: Statistical distribution of IEC at midlatitude and its application to earth-ionosphere communication systems Authors: Bhuyan, P K; Bhattacharyya, M; Tyagi, T R Abstract: The IEC data obtained from three midlatitude stations Tokyo (33.5°N, I38.7°E)and Osan (34.0°N, 127.0°E)in the Pacific and Athens (34.5°N, 18.4°E)in the Mediterranean region, during solar maximum period January-December 1980(_Z = 154.6)have been statistically analysed so as to prepare a ready-to-use reference for earth-ionosphere communication system predictions A good correlation of ΔlEC with IEC_max shows that the latter could be used as an indicator of depolarization of communication signals. Page(s): 205-206

All sky imaging Fabry-Perot spectrometer for optical investigation of the upper atmosphere

2016-10-24T07:08:28Z

Title: All sky imaging Fabry-Perot spectrometer for optical investigation of the upper atmosphere Authors: Sekar, R; Gurubaran, S; Sridharan, R Abstract: A simple optical design, keeping in view of the available components, has been worked out to develop the 'all sky imaging Fabry-Perot spectrometer' to study the spatial structures in thermospheric winds and temperature. This system comprises three subsystems, namely, (i) field widening front-end optics, (ii) high resolution Fabry-Perot spectrometer and (iii) a two-dimensional detector. The design details of the above imaging spectrometer that has been commissioned for routine observations from Mt. Abu along with the first results on 0I 6300 A airglow emission are presented and discussed. Page(s): 197-204

Study of scintillations observed at Delhi during high solar activity period

2016-10-24T07:06:51Z

Title: Study of scintillations observed at Delhi during high solar activity period Authors: Gupta, J K; Singh, Lakha; Tyagi, T R Abstract: Diurnal and seasonal variations in the occurrence of both daytime and nighttime scintillations observed at Delhi during high solar activity period of 1979-80 are described. The occurrence of daytime scintillations is maximum in summer and minimum in winter months. They peak around midday and show negative correlation with solar activity. The nighttime scintillations are of two types, viz, class I (with fading rate more than 6 per min) and class II (with fading rate less than 6 per min). Class I type scintillations show maximum occurrence in equinox and class II in summer. The nighttime class I type scintillations show positive correlation with solar activity, while class II type show negative correlation. Page(s): 193-196

A study on the response of tropical stratosphere to the solar activity in 11-year cycle

2016-10-24T07:05:17Z

Title: A study on the response of tropical stratosphere to the solar activity in 11-year cycle Authors: Mohanakumar, K; Kumar, K Praveen Abstract: An investigation on the influence of solar activity in the 11-year cycle on temperature changes in the tropical stratosphere, based on M-100 and M-100 B rocket observations over Thumba for a period of two decades, has been made. It has been noted that the temperature in the tropical stratosphere show an out-of-phase variation with the changes in solar activity. The stratosphere cools during the period of high solar activity and warms during the period of low solar activity. The negative response of solar activity in the 11-year cycle on temperature is found to be higher in the upper part of the stratosphere, and it decreases as the height decreases. The role of QBO on solar activity induced changes in the tropical stratosphere seems to be comparatively lower than that observed from the middle and high latitudes. In tropics, the upper stratosphere shows a better out-of-phase relation with solar activity during summer, and the middle stratosphere exhibits higher inverse association during winter. Page(s): 186-192