NOPR Collection:

Effect of IMF Sector Boundary Passage on the Equatorial Anomaly in the Indian Zone

2016-11-09T07:17:37Z

Title: Effect of IMF Sector Boundary Passage on the Equatorial Anomaly in the Indian Zone Authors: Murthy, B S; Ahmed, Md Iqhbal; Rao, M S Abstract: The effect of IMP sector boundary passage on the equatorial anomaly in the Indian Zone has been investigated. It is noticed that the anomaly index parameter R decreases following the passage of sector boundary. Page(s): 158-160

Solar Latitudinal Distribution of Solar Flares of Different Importances around the Sun

2016-11-09T07:16:00Z

Title: Solar Latitudinal Distribution of Solar Flares of Different Importances around the Sun Authors: Yadav, R S; Badruddin; Kumar, Santosh Abstract: Solar flare events (853) have been utilized to study the solar. latitudinal frequency distribution pattern of the solar flares of different importances in northern and southern hemispheres of the sun. It has been found that the peaks are located in the interval 10-20° in both the hemispheres. The frequency distribution indicates that out of 853 flares about 64% occur in the northern hemisphere and 36% in the southern hemisphere. The north-south asymmetry has been observed for the period 1957-78. The asymmetry in favour of the northern hemisphere increases with the importance of the flares. It is noted that during the entire period (1957-78) the number of flares occurred in the northern hemisphere is significantly large as compared to that in the southern hemisphere except during 1971-74, when the frequency distribution pattern .is reversed and the number is more in the southern hemisphere than that in the northern hemisphere. The relation between the occurrence of flares and the polarity of the solar magnetic field has also been discussed. Page(s): 155-157

Mean Energy Expended per Ion Pair by Charged Particles in Atmospheric Gases

2016-11-09T07:14:49Z

Title: Mean Energy Expended per Ion Pair by Charged Particles in Atmospheric Gases Authors: Kaushik, Y D; Khare, S P; Kumar, A Abstract: Following the semi-empirical approach of S P Khare and A Kumar [Physica, 100C (1980), 135] for ionization cross-section per unit energy range, the mean energy expended per ion pair due to proton impact on molecular nitrogen and oxygen of uniform density has been calculated by the continuous slowing down· approximation (CSDA.) The values so obtained are practically constant for the energy of the proton greater than 1 MeV and are in agreement with the available data. Page(s): 151-154

Study of Nighttime Vertical Drifts in F-region over Waltair Using Phase-path Technique

2016-11-09T07:13:12Z

Title: Study of Nighttime Vertical Drifts in F-region over Waltair Using Phase-path Technique Authors: Rai, P Ernest; Rao, M Srirama; Jogulu, C; Rao, B Madhusudhana Abstract: Nighttime F-region phase-path records taken at Waltair (dip 20°N; 83° 18'E), a low latitude station, are used to calculate vertical drifts. Vertical speed is upward around 1800 hrs LT, undergoing a post-sunset reversal around 1900 hrs LT; the layer then moves downwards till 2050 hrs LT. Vertical speed is positive again between 2050 and 2330 hrs LT and later the F-layer moves downwards ti1sunrise hours. These observations are consistent at this station and are different from the nighttime vertical speeds noticed at equatorial and midlatitude stations. Upward and downward movements at Waltair seem to closely fol1ow the F-region height variations at Ahmedabad (dip 34°N; 72°36'E). The post-sunset reversal at Waltair is very similar to the E x B drift reversal at post-sunset times reported for the equatorial F-region. The upward motion of the F-region for about two and half hours prior to midnight is noticed to be a regular feature at this station and the dominance of neutral wind effect on the motion of the F-layer at that time appears to be a possible explanation. Vertical drifts on all spread-F days, observed before the post-sunset reversal, are noticed to be large when compared to those on no spread-F days. Page(s): 147-150