Indian Journal of Radio & Space Physics

(CODEN: IJRSAK ISSN: 0367-8393)

http://nopr.niscair.res.in

VOLUME 38

NUMBER 3

JUNE 2009

CONTENTS

 

Properties of SEPs effective CMEs during solar cycle 23

129

Santosh Kumar*, Janki Pal & Amita Raizada

 

 

Features of long term evolution of solar wind and IMF and their signature on geomagnetic activity

134

V Sanalkumaran Nair* & S R Prabhakaran Nayar

 

 

Anomalous behavior of D-layer formation time of the ionosphere due to earthquake

138

Achintya K Chatterjee*, Washimul Bari & Asit K Choudhury

 

 

Studies on sferics over Kolkata in relation to rainy and winter seasons

143

S S De*, B K De, S K Adhikari, B Bandyopadhyay, Suman Paul, D K Haldar & A Guha

 

 

Imaging observations of upper mesospheric nightglow emissions from Tirunelveli (8.7oN)

150

V Lakshmi Narayanan, S Gurubaran* & K Emperumal

 

 

Study of Z-R relationship over Gadanki for different rainfall rates

159

R Sen Jaiswal*, S Uma & A Santhakumaran

 

 

Multi dimensional scaling of geomagnetic Sq (H) variations

165

M Sridharan* & R Samuel Selvaraj

 

 

Broadband aperture-coupled equilateral triangular microstrip array antenna

174

S N Mulgi*, G M Pushpanjali, R B Konda, S K Satnoor & P V Hunagund

 

 

*Authors for correspondence

 

 

 

 

 

 

 


Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 129-133

 

Properties of SEPs effective CMEs during solar cycle 23

 

Santosh Kumar$,*, Janki Pal & Amita Raizada

Department of Physics & Electronics, R. D. University, Jabalpur (M.P.)

$E mail: s_ kumar123@rediffmail.com

Received 13 November 2007; revised received and accepted 12 February 2009

Seventy five large solar energetic particle (LSEP) events of different groups of proton intensity have been investigated during 1997-2005. It is observed that proton intensity increases linearly with increase in velocity of SEPs effective coronal mass ejections (CMEs). Further, for proton intensity I > 350 pfu, most of the SEPs effective CMEs are associated with X class of X-ray flares; whereas, for proton intensity I< 350 pfu, the SEPs effective CMEs are associated mainly with M and C class of X-ray flares. Furthermore, most of the CMEs are of halo type and occur mostly in western hemisphere for proton intensity I>350 pfu; whereas, for proton intensity I<350 pfu, CMEs observed in the eastern hemisphere are equally important. The association of SEPs effective CMEs has been observed better for longer wavelength, i.e. Decameter Hectometer (DH) Type II radio bursts than shorter wavelength, i.e. metric (m) Type II radio bursts.

Keywords: Coronal mass ejection, Solar energetic particles, Solar flares, Radio bursts

PACS Nos.: 96.50.Vg; 96.60.ph; 96.60.qe

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 134-137

 

Features of long term evolution of solar wind and IMF and their signature on geomagnetic activity

 

V Sanalkumaran Nair1,$,* & S R Prabhakaran Nayar2

1Department of Physics, V.T.M. N.S.S. College, Dhanuvachapuram, Thiruvananthapuram 695 122, Kerala

2Department of Physics, University of Kerala, Kariavattom, Thiruvananthapuram 695 581, Kerala

$E-mail: sanalkumar.nair@yahoo.co.in

Received 10 October 2006; revised 1 September 2008; accepted 16 December 2008

The geomagnetic activity is mainly controlled by variations in the solar wind and interplanetary magnetic field (IMF) features. The solar wind data available during 1965-2004 has been utilized to study large scale features in interplanetary medium and their signature on geomagnetic activity. The solar wind plasma, IMF and geomagnetic activity are found to evolve with the phase of solar cycle. The evolution and role of solar wind streams and IMF field strength (B) in shaping long term features of planetary magnetic activity index (Ap) index have been studied. The high speed streams are caused mainly by the increase in coronal hole activity around the declining phase of solar cycle and by the presence of large number of coronal transients around solar maximum. Association between coronal holes and geomagnetic activity is clear from the simultaneous presence of high negative correlation between solar wind velocity (Vsw) and density (n) and the enhancement in geomagnetic activity during declining phase of solar cycle. During this period, Vsw and Ap index also exhibit good correlation. Around solar maximum periods, good correlation is found between B and Ap index. These results suggest that Vsw has a major role in deciding the geomagnetic activity around declining phase and IMF magnitude has a major role in deciding geomagnetic activity around solar maximum.

Key words: Geomagnetic activity, Coronal holes, Solar maximum, Solar minimum, Solar wind velocity, Interplanetary magnetic field

PACS Nos.: 96.50.Bh; 96.60.pc; 96.60.Vg

 

 


Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 138-142

 

Anomalous behavior of D-layer formation time of the ionosphere due to earthquake

Achintya K Chatterjee$,*, Washimul Bari# & Asit K Choudhury+

Indian Centre for Space Physics (Malda Branch), Malda 732 101 (West Bengal), India

E-mail: $akc_malda@fastmail.fm; #w_bari@rediffmail.com; +asit_mda@hotmail.com

Received 3 September 2008; revised received and accepted 30 December 2008

The very low frequency (VLF) data for over three months (May to July 2008) using Gyrator II loop antenna has been analyzed in the present study. The significant anomalies of D-layer formation time of the ionosphere are observed during sunrise. These anomalies are observed only before, during and after the earthquakes, which took place in the neighboring region. The anomalies were also observed in sunrise terminator time during seismically active days. These abnormal behavior may be due to the lithosphere - ionosphere coupling. These anomalies may be a precursor of earthquake.

Keywords: Radio wave propagation, D-layer, Ionospheric disturbances, Earthquake

PACS Nos.: 94.20.-y; 95.85.Bh; 94.20.de; 94.20.Vv; 91.30.Px

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 143-149

 

Studies on sferics over Kolkata in relation to rainy and winter seasons

S S De1, $,*, B K De2, S K Adhikari1, B Bandyopadhyay1, Suman Paul1, D K Haldar1 & A Guha1

1Centre of Advanced Study in Radio Physics and Electronics, University of Calcutta, Kolkata 700 009, India

2Department of Physics, Tripura University, Suryamaninagar 799 130, Tripura (West), India

$Email: de_syam_sundar@yahoo.co.in

Received 02 July 2007; revised 3 October 2008; re-revised received and accepted 5 January 2009

The VLF spectral characteristics of the sferics over Kolkata (22.56N, 88.5E) are studied in relation to the rainy and winter seasons. The nature of sferics during rainy and winter seasons is determined for different times of the day. The recorded data of sferics from Kolkata exhibit many interesting monitoring possibilities due to the involvement of the characteristics of atmospheric and ionospheric parameters. The recorded sferics exhibit diurnal variation of electron density of the lower ionosphere. Many interesting features are observed including sunrise and sunset effects.

Keywords: VLF sferics, Ionospheric propagation

PACS No.: 92.60.Ta; 92.60 Pw

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 150-158

 

Imaging observations of upper mesospheric nightglow emissions from
Tirunelveli (8.7oN)

V Lakshmi Narayanan, S Gurubaran* & K Emperumal

Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli 627 011, India

Received 31 December 2007; revised 18 August 2008; re-revised received and accepted 16 December 2008

An all-sky airglow imager was installed at the equatorial site Tirunelveli (8.7oN, 77.8oE geographic; 1.34oN magnetic dip) during January 2007 to study the small-scale dynamics occurring in the mesosphere-lower thermosphere (MLT) region. The instrument details are presented in the paper along with methods of information retrieval from the recorded data. The presence of a variety of small-scale mesospheric dynamical events, observed with the instrument, is demonstrated. Preliminary results on the observed features, viz. the quasi-monochromatic gravity waves and instability features, such as ripples and mesospheric bores, are presented in the paper.

Keywords: Airglow imagers, Mesosphere-lower thermosphere region, Gravity waves, Nightglow emissions

PACS No.: 92.60.hw; 92.60.hh; 92.60.hc

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 159-164

 

Study of Z-R relationship over Gadanki for different rainfall rates

 

R Sen Jaiswal1,$,*, S Uma1 & A Santhakumaran2

1Department of Physics, Sona College of Technology, Salem 636 005, Tamilnadu

2Department of Statistics, Sowdeswari College, Salem 636 010, Tamil Nadu

$E-mail: senoritta_in@yahoo.co.in, research_sona@yahoo.co.in

Received 13 November 2007; revised 14 November 2008; re-revised received and accepted 12 February 2009

In this paper, Z-R relationship for different rain fall rates over Gadanki has been studied over a period of four years 1998-2001. The basic data set consists of rainfall rates and reflectivities derived from disdrometer during this period. The study has been carried out for rainfall rates R≤ 0.5 mmh-1, 0.5<R≤ 4.0 mmh-1, 4<R≤10 mmh-1, 10<R≤ 50 mmh-1 and
R>50 mmh-1. The study shows that Z-R relationship varies for different rainfall rates. The various functional relations between reflectivity and rainfall rate are obtained.

Keywords: Rainfall rate, Reflectivity, Drop size distribution

PACS No.: 92.40.eg

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 165-173

 

Multi dimensional scaling of geomagnetic Sq (H) variations

M Sridharan1,$,* & R Samuel Selvaraj2

1Magnetic Observatory, Indian Institute of Geomagnetism, Pondicherry University Campus, Pondicherry 605 014, India

2Department of Physics, Presidency College, Chennai 600 005, India

$E-mail: mopondy@bsnl.in

Received 11 October 2007; revised 27 January 2009; accepted 20 February 2009

The dominant relationship in respect of geomagnetic solar quiet day variations (Sq) among the six Indian geomagnetic observatories is analysed by employing multidimensional scaling. This is a powerful technique for data analysis to identify the proximity and dominance relationship between data points of different classes.

Keywords: Multidimensional scaling, Proximity relationship, Geomagnetic solar quiet day (Sq) variation

PACS No.: 91.25.Rt

 

 

 

Indian Journal of Radio & Space Physics

Vol. 38, June 2009, pp. 174-179

 

Broadband aperture-coupled equilateral triangular microstrip array antenna

 

S N Mulgi$,*, G M Pushpanjali, R B Konda, S K Satnoor & P V Hunagund

Department of PG Studies and Research in Applied Electronics, Gulbarga University, Gulbarga 585 106, Karnataka, India

$E-mail: s.mulgi@rediffmail.com

Received 15 March 2007; revised 30 July 2007; re-revised received 17 December 2008; accepted 26 December 2008

The aperture-coupled equilateral triangular microstrip array antenna comprising parasitic element and slot for broadband operation is designed and presented. An experimental study is carried out to see the effect of slot placed in the parasitic and radiating elements for enhancing the impedance bandwidth. The four-element aperture-coupled equilateral triangular microstrip array antenna (FAEMA) using a common parasitic element in the form of gap-coupled between the two radiating element gives an impedance bandwidth of 18.46%. If the slot is placed at the center of all elements of FAEMA, the impedance bandwidth is found to be 18.57%. However, this bandwidth is enhanced to 19.04% by placing the slot at the center of radiating elements of FAEMA. Further, the bandwidth is increased from 19.04 to 19.07% by placing a slot at the center of parasitic element of FAEMA. This bandwidth is 38% more when compared to four-element array antenna without using parasitic elements. The gain, azimuthal radiation patterns and input impedance of proposed antennas are studied and reported. Details of the antenna design are given and experimental results are discussed.

Keywords: Equilateral triangular array antenna, Aperture coupled antenna, Microstrip array antenna

PACS No.: 84.40.Ba