http://nopr.niscpr.res.in/handle/123456789/58949 2026-10-10T01:13:28Z 2026-10-10T01:13:28Z Patil, Dnyandev Bhausaheb Kale, Vijay Sadashiv Shaligram, Arvind Digamber http://nopr.niscpr.res.in/handle/123456789/58956 2022-02-18T11:12:40Z 2021-09-01T00:00:00Z

Title: Implementation of e-CALLISTO Network for study of solar activities Authors: Patil, Dnyandev Bhausaheb; Kale, Vijay Sadashiv; Shaligram, Arvind Digamber Abstract: The Earth is influenced by the effects of the continuously varying solar wind, the flow of plasma and the embedded magnetic field from the Sun. Life on the earth is driven by the sunlight incident from the Sun. Therefore, the climate is critically sensitive to solar activities. The variation in the Sun’s atmosphere has an important role in changing life on the earth and therefore it becomes necessary to monitor, observe and study solar activities. Many instruments and observatories have been keeping watch on Sun’s activities. The Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (CALLISTO) is one of them. It is popular, portable and low-cost instrument. All CALLISTO station spectrometers together form an e-CALLISTO network. The e-CALLISTO network is spread worldwide and has been providing observations from different countries. This paper reports the antenna and receiver of e-CALLISTO network. It represents the information about antenna especially Log-periodic Dipole Antenna (LPDA) which is low cost and easy to design which can help antenna designer to identify the benefits of LPDA. The e-CALLISTO network is still growing, therefore this may help the people who are going to work on solar activity or working on the e-CALLISTO network. Page(s): 109-114

2021-09-01T00:00:00Z Battula, Prem Kumar D V, Phani Kumar K, Chenna Reddy K, Kishore Kumar G, Yellaiah http://nopr.niscpr.res.in/handle/123456789/58955 2022-01-25T07:11:58Z 2021-09-01T00:00:00Z

Title: Latitudinal variation in vertical distribution of meteor decay time and its relation with mesospheric Ozone in the altitude range of 80-90 km Authors: Battula, Prem Kumar; D V, Phani Kumar; K, Chenna Reddy; K, Kishore Kumar; G, Yellaiah Abstract: Investigations on meteor trail decay time and its evolution in the mesosphere and lower thermosphere are very important to estimate the temperature in this region. The present study focuses on the vertical distribution of meteor decay times at three different latitudes to understand the mechanism responsible for the deviation of meteor decay time from the theoretical estimations below 90 km of altitude. The present study is based on measurements from three identical meteor radars located at equatorial (Kototabang: 0.2° S, 100.3° E), low (Thumba: 8.5° N, 76.9° E) and polar latitudes (Eureka: 80.0° N, 85.8° W). The results reveal a pronounced seasonal variation of vertical distribution of meteor decay time turning altitude (inflection point) over polar latitudes as compared to that over equatorial and low latitudes. Apart from direct estimations from meteor radar observations, the meteor decay time is estimated using temperature and pressure measurements from the SABER/TIMED. Above 90 km of altitude, decay times estimated from both methods are in good agreement. However, below 90 km of altitude, these estimations start deviating and it has been noted that the deviation increases with decreasing altitude. Further, observed meteor decay times correlated with ozone concentration at three representative altitude bins. The correlation analysis reveals a significant negative correlation at 80 - 90 km of altitude over the three latitudes indicating that an increase in ozone concentration results in decrease in meteor decay time. The significance of the present results lies in analyzing the vertical distribution of meteor decay time simultaneously from three radar locations representing equatorial, low and polar latitudes and evaluating the relation between ozone concentration and meteor decay time, quantitatively. Page(s): 115-124

2021-09-01T00:00:00Z Bello, Saeed Abioye Hamid, Nurul Shazana Abdul Abdullah, Mardina Yoshikawa, Akimasa Hozumi, Kornyanat Tsugawa, Takuya http://nopr.niscpr.res.in/handle/123456789/58954 2022-02-03T09:48:07Z 2021-09-01T00:00:00Z

Title: Equatorial Electrojet and electron density over Southeast Asian Region during moderate solar activity condition Authors: Bello, Saeed Abioye; Hamid, Nurul Shazana Abdul; Abdullah, Mardina; Yoshikawa, Akimasa; Hozumi, Kornyanat; Tsugawa, Takuya Abstract: The study presents a simultaneous variation of equatorial electrojet (EEJ) current and the ionospheric F2-layer maximum electron density (NmF2) during geomagnetic quiet days and moderate solar conditions (solar radio flux, 𝐹10.7 􀵎 120 sfu). The geomagnetic measurements at Kotatobang (KTB) and Langkawi (LKW) stations have been used to estimate the magnetic daily variation in H-component and in deriving EEJ. The NmF2 data set is from Frequency Modulation Continuous Wave (FM-CW), an analogue ionosonde located at the KTB station. The study examines both the diurnal and seasonal variation in EEJ and the corresponding effect on the measured NmF2. The results obtained show that the derived EEJ at LKW shows a daytime peak which coincides with the period NmF2 measurement at KTB station depleted to a daytime low value. The role of EEJ at the LKW station correlates poorly with the NmF2 at KTB in which their correlation coefficient (r) is in the range of 0.02 to 0.04 for equinox, summer and winter, respectively. However, an r-value of 0.33 was observed when the whole data set for the year 2012 was considered. The poor correlation coefficient between derived EEJ and NmF2 measured at KTB during the moderate solar condition suggest that EEJ has little or no influence on the prevailing ionospheric condition at a low latitude station located outside the EEJ strip. Page(s): 125-131

2021-09-01T00:00:00Z Chatterjee, Purbita http://nopr.niscpr.res.in/handle/123456789/58953 2022-01-25T07:03:27Z 2021-09-01T00:00:00Z

Title: Study of functional Ionospheric Models Authors: Chatterjee, Purbita Abstract: The ionosphere has played an important role for propagation of electromagnetic waves. They contribute to a major portion of the propagation delay, especially for the low frequency navigation signals, as they pass through earth’s atmosphere. The amount of delay of these signals depends on ionospheric total electron content, which has a spatio-temporal variation. While the dual frequency users can remove the delay errors in signals, these delays pose a major threat mostly for single frequency users, who has to resort to the ionospheric models for the removal these delay errors in the signals, and hence for improving the positioning accuracy. This work has reviewed various Ionospheric Models, both theoretical and Empirical, which have been designed for a better determination of variation of TEC values. These models, still useful for both the navigation and other scientific purposes are important for understanding the characteristics of the ionosphere and gaining insight about its temporal and spatial variations. Page(s): 132-141

2021-09-01T00:00:00Z