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Gurubaran, S.
- Schumann Resonances Observed at Maitri, Antarctica:Diurnal Variation and its Interpretation in Terms of Global Thunderstorm Activity
Abstract Views :227 |
PDF Views:87
Authors
Affiliations
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN
Source
Current Science, Vol 109, No 4 (2015), Pagination: 784-790Abstract
Schumann resonances (SRs) are the AC components of the global electric circuit and are excited by the lightning activity within the Earth-ionosphere waveguide. An induction magnetometer, which was operated from the Indian Antarctic station, Maitri (70.8°S, 11.7°E), served to examine the SR parameters, namely the amplitude and frequency, in the north-south (HNS) and east-west (HEW) magnetic components. The analysis for the first resonant mode presented in this work reveals a strong UT variation in its amplitude in seasonal as well as yearly timescales. The NS amplitude reveals a semi-diurnal variation with peaks at ~1000 and ~2100 UT, whereas the EW amplitude exhibits a strong diurnal variation with a pronounced peak at 1600 UT. The diurnal curves for the frequency for both components are similar in nature to those for the amplitude, but for a time shift. The diurnal trend in the amplitude is retained irrespective of seasons, whereas significant difference are noticed in the frequency behaviour between the summer and winter seasons, especially in the EW component. The observed diurnal variation in the SR intensity is explained in terms of the dominant thunderstorm activity centred over the three convectively active regions: Asia/Maritime Continent (Indonesia), South America and Africa. The diurnal variation in frequency depends not only on the location of the thunderstorm region with respect to the observer, but also on the ionospheric day/night conditions and the Earth-ionosphere cavity thickness.Keywords
Diurnal Variations, Global Electric Circuit, Lightning, Schumann Resonances.- Development of Fast Image Analysis Technique for All-Sky Images
Abstract Views :248 |
PDF Views:94
Authors
A. K. Sharma
1,
D. P. Nade
1,
S. S. Nikte
1,
R. N. Ghodpage
2,
P. T. Patil
2,
M. V. Rokade
1,
R. S. Vhatkar
1,
S. Gurubaran
3
Affiliations
1 Earth and Space Science Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, IN
2 Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur 416 004, IN
3 Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410 218, IN
1 Earth and Space Science Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, IN
2 Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur 416 004, IN
3 Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410 218, IN
Source
Current Science, Vol 106, No 8 (2014), Pagination: 1085-1093Abstract
This article describes the possibility of using the fast image analysis technique for qualitative and quantitative analysis of equatorial plasma bubble obtained using All-Sky imager (ASI) data. Automated image processing (generally) is useful for identification of equatorial plasma bubbles (EPBs) and its parameters. We have developed a fast (and efficient) analysis technique essential to study the data of images. The present work reports the results of a statistical study of the zonal plasma bubble velocities using nightglow OI 630.0 nm emission data, acquired by ASI (FOV 140°) at the low-latitude station Kolhapur (16.42°N, 74.2°E and 10.6°N dip lat.). Based on the observations of 15 nights made in January 2012, we have determined the velocity of EPB using our new method. The daily mean values of the EPB velocity match well with those of the earlier studies made at Kolhapur. We have found that, generally, the mean zonal drift velocities of the plasma bubbles tend to decrease with local time (after midnight). The most significant finding from this work is that the calculated velocities of plasma bubble using fast and scanning methods are nearly equal.Keywords
All-Sky Imager, Equatorial Plasma Bubble, Nightglow Emissions, Zonal Drift Velocity.- On the Vertical Wavelength Estimates Using the Krassovsky Parameters of OH Airglow Monitoring
Abstract Views :236 |
PDF Views:82
Authors
Affiliations
1 Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur 416 004, IN
2 Atmospheric Research Laboratory, Gadanki 517 112, IN
3 Indian Institute of Tropical Meteorology, Pune 411 008, IN
4 Indian Institute of Geomagnetism, Navi Mumbai 410 218, IN
5 Department of Physics, Shivaji University, Kolhapur 416 004, IN
1 Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur 416 004, IN
2 Atmospheric Research Laboratory, Gadanki 517 112, IN
3 Indian Institute of Tropical Meteorology, Pune 411 008, IN
4 Indian Institute of Geomagnetism, Navi Mumbai 410 218, IN
5 Department of Physics, Shivaji University, Kolhapur 416 004, IN
Source
Current Science, Vol 108, No 7 (2015), Pagination: 1362-1369Abstract
The photometric measurements of mesospheric OH and O(1S) emission, carried out from Kolhapur (16.8°N, 74.2°E), Maharashtra during January-April 2005 are used to study the wave characteristics. The nocturnal variability reveals the dominant long-period wave signatures with significant amplitudes of embedded short-period waves. We carry out a sensitivity study on the vertical wavelength (VW) derived with the help of Krassovsky parameters (η = |η|eiΦ) of the OH data, which reveals VW to vary from 38.9 to 110.2 km. This was compared with the VW estimates using the phase difference of the simultaneously observed waves in both OH and O(1S) emission intensities. Results reveal that in the absence of attitudinally resolved measurements, the VW estimated using Krassovsky method can be used.Keywords
Airglow, Atmospheric Gravity Waves, Lower Thermosphere, Mesosphere, Vertical Wavelength.- A Differential Electrometer for Vector Electric Field Measurements on a Balloon Platform
Abstract Views :286 |
PDF Views:91
Authors
Affiliations
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN
1 Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, IN
2 Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai 410 218, IN