Indian Journal of Radio & Space Physics

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(CODEN: IJRSAK        ISSN: 0367-8393)

VOLUME 37

NUMBER 4

AUGUST 2008

 

CONTENTS

 

Heliographic distribution of bright solar flares and association of Forbush-decreases with flares and coronal mass ejections

 

237

        A P Mishra*, B N Mishra, Meera Gupta & V K Mishra

 

 

Relationship of interplanetary coronal mass ejections with geomagnetic activity

244

        Pankaj K Shrivastava* & Geeta Singh

 

 

Plasma drift motion in the F-region of the ionosphere using photometric nightglow measurements

249

G K Mukherjee* & D J Shetti

 

 

Geomagnetic-induced tropopause temperature and wind variation over low latitude

258

        Manohar Lal* & M V Subramanian

 

 

Temporal and vertical variations of atmospheric electrical conductivity related to radon and its progeny concentrations at Mysore

264

N Ragini, T S Shashikumar, M S Chandrashekara, J Sannappa & L Paramesh*

 

 

Modeling dry deposition of S and N compounds to vegetation

272

Ranjit Kumar, S S Srivastava & K Maharaj Kumari*

 

 

Study of MSMR retrieved data using map generation and representation methodology over Rajasthan, India

279

        O P N Calla*, Usha Rathore, Gitanjali Chakravorty, Naveen Dutt Joshi & Vikas Parihar

 

 

A method for calibration of space borne passive microwave sensors using a desert area

285

        O P N Calla*, Vikas Parihar, Naveen Dutt Joshi, Gitanjali Chakravorty & Usha Rathore

 

 

Design and development of wideband gap-coupled slot rectangular microstrip array antenna

291

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

 

__________

 

*Authors for correspondence

 

 


Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 237-243

 

Heliographic distribution of bright solar flares and association of
Forbush-decreases with flares and coronal mass ejections

A P Mishra*, B N Mishra, Meera Gupta & V K Mishra

Department of Physics, A P S University, Rewa (MP) 486 003, India

*E-mail: apm_apsu@yahoo.co.in

Received 17 April 2007; revised 29 January 2008; accepted 22 April 2008

Major solar flare events have been selected to study the heliographic distribution of solar flares during solar cycle 23. The occurrence of Forbush decreases (FDs), bright solar flares; solar flare index, coronal mass ejections (CMEs), average solar magnetic field and solar wind velocity have been studied for the period 1996-2006. It is found that the solar flare index in northern and southern hemisphere represents the cumulative activity of solar flare in both hemispheres. Though, the bright solar flares are equally distributed in the entire solar region, majority of the bright solar flares responsible for
FDs (≥ 4% magnitude) are located in the north-east region of the solar disk. Out of 41 FDs, 88% are found to be associated with halo (central position angle ≈ 360°) and partial halo (central position angles ≥ 120°) CMEs (coronal mass ejections) and 55% with bright solar flares of importance ≥ 1B. The abrupt increase in average solar magnetic field and solar wind velocity has also been found to be a necessary condition for producing FDs. The occurrence of non-recurrent type FDs are more frequent than recurrent type FDs. In latitudinal distribution, northern hemisphere is more dominant than the southern hemisphere in producing FDs. It is also found that eastern hemisphere is more effective as compared to western hemisphere to produce FDs in longitudinal distribution during the aforesaid period.

Keywords: Solar flares, Coronal mass ejections, Forbush decreases, Solar cycle

PACS No.: 96.60.Qe; 96.60.Ph

 

Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 244-248

 

 

Relationship of interplanetary coronal mass ejections with geomagnetic activity

Pankaj K Shrivastava

Department of Physics, Govt. Model Science College, Rewa 486 001(MP), India

E-mail: pankaj_in_2001@rediffmail.com

and

Geeta Singh

Department of Physics, A P S University, Rewa 486 003(MP), India

Received 25 September 2006; revised 7 June 2007; accepted 3 June 2008

The signatures of Coronal Mass Ejection (CME) associated interplanetary disturbances are called as Interplanetary Coronal Mass Ejections (ICMEs). In the present study, 69 events of ICMEs have been utilized to derive their relationship with the geomagnetic activity for the period of 1996-2002. A significant positive correlation between Ap-index and ICME speed has been observed. Results of present analysis suggest that ICMEs can produce geomagnetic activity with an increase in geomagnetic Ap-index and decrease in Dst-index.

Keywords: Interplanetary coronal mass ejection, Coronal mass ejection, Geomagnetic activity, Solar activity

PACS No.: 96.60

 

 

Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 249-257

 

Plasma drift motion in the F-region of the ionosphere using photometric
nightglow measurements

 

G K Mukherjee

Indian Institute of Geomagnetism, New Panvel(W), Navi Mumbai 410 218 (MS), India

e-mail: gkm@iigs.iigm.res.in

and

D J Shetti

Department of Physics, Shivaji University, Kolhapur 416 004 (MS), India

Received 12 February 2007; revised 26 July 2007, accepted 7 January 2008

The equatorial ionospheric plasma irregularities have been studied in the last few years by different ground based (radar, digisonde, GPS, optical instruments) techniques and in situ rocket and satellite measurements. The time evolution and propagation characteristics of these irregularities have been used to study the important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. In this study the plasma drift motion has been inferred in zonal and meridional directions at Kolhapur (16.8°E, 74.2°E, dip latitude 10.6°N) by measuring the OI 630.0 nm intensities at three directions in zenith using tilting filter photometers. Also, the observed zonal plasma drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-93 model to investigate the thermosphere-ionosphere coupling. In general there is good agreement between the model predictions and the observations. The HWM-93 model also reproduces well the altitudinal and latitudinal variations of the neutral wind velocity in the low latitude region. The dominant periodicities observed in OI 630.0 nm intensity fluctuations on a Spread-F night were typically varying between 30 and 50 min.

Keywords: Ionospheric irregularities, Plasma irregularities, F-region ionosphere, Nightglow, Photometric nightglow

PACS No.: 94.20.Ac

 

Indian Journal of Radio & Space Physics

Vol 37, August 2008, pp. 258-263

 

Geomagnetic-induced tropopause temperature and wind variation over low latitude

Manohar Lal1 & M V Subramanian2

1Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Maharajanagar,
Tirunelveli 627 011, India

e-mail: mlal@iigs.iigm.res.in

2A K G S Arts Collage, Srivaikuntam 627013, TamilNadu, India

Received 8 August 2007; revised 10 January 2008; accepted 10 April 2008

The present study reports the effect of geomagnetic storm on 200 mb altitude temperature and wind at a low latitude (8.7°N, 77.8°N) Indian region. The severe and strong geomagnetic storm (Dst < – 100 nT) between 2000 and 2005 has been studied. The impact of the geomagnetic activity on temperature and wind variation is affected by the QBO (Quasi-Biennial Oscillation) phase. The tropopause temperature increases by ~ 2.5 K during W-phase of QBO and decreases by ~ 1.5 K during E-phase of QBO. The time lag between the onset of the event and the maximum change in temperature becomes a minimum during the transition phase of QBO. The horizontal wind velocity shows a pronounced effect over the east coast of India. The effect has not been observed during the onset of the south-west monsoon. The vertical wind velocity at 200 mb shows increase (or decrease) during W- (or E-) phase of the event.

Keywords: Storms and substorms, Tropical meteorology, Wind variation, Tropopause temperature

PACS: 94.05.Sd

 

Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 264-271

 

Temporal and vertical variations of atmospheric electrical conductivity related to radon and its progeny concentrations at Mysore

N Ragini, T S Shashikumar, M S Chandrashekara, J Sannappa1 & L Paramesh

Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006, INDIA

1Department of Physics, Yuvaraja’s College, Mysore  570 005, INDIA

Email: lp@physics.uni–mysore.ac.in

Received 13 November 2006; revised 12 June 2007; accepted 16 January 2008

Atmospheric electrical conductivity, radon and its progeny concentrations are measured simultaneously at Mysore city (12° 18′′N, 76° 36′′E and 767 m above mean sea level), India. The concentrations of radon and its progeny are higher during nighttime compared to the daytime attaining maximum in the early morning (0400-0700 hrs IST). The electrical conductivity of the atmosphere also shows similar variations. The vertical variation shows a decrease of conductivity with increase in height. The weekly variations in conductivity show a higher value on Sundays compare to other weekdays. These results are discussed in terms of ionization rate due to radioactivity and meteorological parameters.

Keywords: Radioactive aerosol,  Ion production, Gerdien condenser

PACS No.: 92.60.Pw

 

Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 272-278

Modeling dry deposition of S and N compounds to vegetation

 

Ranjit Kumar1, S S Srivastava2 & K Maharaj Kumari2

1Applied Chemistry, D E I Technical College, Dayalbagh, Agra 282 005 (UP), India

2Department of Chemistry, Dayalbagh Educational Institute, Dayalbagh, Agra 282 005 (UP), India

E-mail: maharajkumari.k@rediffmail.com; rkschem@rediffmail.com

Received 19 February 2007; revised 15 January 2008; accepted 12 June 2008

This paper deals with parameterization method based on meteorological parameters for calculation of dry deposition
S and N compounds on natural surfaces (leaf of Cassia siamea) as direct measurement methods are cumbersome. A theoretical method for calculation of dry deposition of S and N compounds based on meteorological parameters has been outlined by which all the resistances responsible for deposition of gases and particles on vegetation could be determined. Since, numerous steps are involved in calculation; a computer program has been developed to make it fast, convenient and more useful. The deposition velocity of SO2, HNO3, SO42– and NO3 obtained by current parameterization method on vegetation (leaf of Cassia siamea) at Dayalbagh, Agra in a semi-arid region of India is 0.32, 0.74, 1.16 and 1.07 cm s–1. The obtained deposition velocities are in the reported range on vegetation.

Key words: Dry deposition, Parameterization, Sulphur, Nitrogen, Vegetation

PACS No.: 91.62.Rt


Indian  Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 279-284

 

Study of MSMR retrieved data using map generation and representation methodology over Rajasthan, India

O P N Calla, Usha Rathore, Gitanjali Chakravorty, Naveen Dutt Joshi & Vikas Parihar

International Center for Radio Science (ICRS), “OM NIWAS” A-23 Shastri Nagar, Jodhpur 342 003, Rajasthan, India

Received 16 May 2006; revised 18 September 2007; accepted 1 May 2008

The microwave radiometer MSMR (Multi-frequency Scanning Microwave Radiometer) data available in the months of June 1999-2001 have been studied. These data have been represented on the map of Rajasthan. The map has been generated using layered approach. The data available at 6.6 GHz for both horizontal and vertical polarization have been used for this study. The brightness temperature TB within 150 km diameter circle is displayed on the map of Rajasthan at the longitude and latitude obtained from the data set. The longitudes and latitudes are grouped in three zones A, B and C, depending on the geophysical parameters of the different sites.

Keywords: Microwave remote sensing, Brightness temperature, MSMR – IRS P4

PACS No.: 07.07.Df; 84.40.Xb

 

 

Indian Journal of Radio & Space Physics

Vol 37, August 2008, pp. 285-290

 

A method for calibration of space borne passive microwave sensors using a
desert area

O P N Calla, Vikas Parihar, Naveen Dutt Joshi, Gitanjali Chakravorty & Usha Rathore

International Centre for Radio Science (ICRS), “OM NIWAS” A-23 Shastri Nagar, Jodhpur 342 003, Rajasthan, India

Received 8 May 2006; revised 19 February 2007; accepted 5 June 2008

A new method is suggested in this paper, for on-flight calibration of passive sensors, using a desert area, from satellite data obtained over a uniform terrain. The satellite data of OCEANSAT I MSMR payload operating at 6.6 GHz in both horizontal and vertical polarization and having look angle of 49.7° have been used for the present study.

Keywords: Brightness temperature, Radiometer, MSMR, IRSP-4, Microwave remote sensing

PACS No.: 07.07.Df; 84.40.Xb

 

 

Indian Journal of Radio & Space Physics

Vol. 37, August 2008, pp. 291-295

Design and development of wideband gap-coupled slot rectangular
microstrip array antenna

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

Department of PG Studies and Research in Applied Electronics, Gulbarga University
Gulbarga 585106 (Karnataka), India

Received 19 March 2007; revised 20 June 2007; accepted 27 June 2008

A novel design of four-element gap-coupled slot rectangular microstrip array antenna (FGSRMSA) is presented for broadband operation. The elements of antenna are fed using aperture coupled technique. From the experimental results it is seen that the antenna operates at single band of frequencies and shows broadside radiation characteristics. The overall impedance bandwidth is found to be 26.72 %, which is 1.114 times more than that of four-element gap-coupled rectangular microstrip array antenna (FGRMSA). This shows the effect of slots in enhancing impedance bandwidth of FGSRMSA. The slots in FGSRMSA also improve the antenna input impedance and increase the gain by 20.8% when compared to FGRMSA. Details of antenna designs are described and experimental results are discussed.

Keywords: Slot antenna, Aperture coupling, Array antenna, Microstrip antenna, Wideband antenna, Rectangular antenna

PACS No.: 84.40.Ba