Indian Journal of Radio & Space Physics

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(CODEN : IJRSAK        ISSN : 0367-8393)

VOLUME 37

NUMBER 3

JUNE 2008

 

CONTENTS

 

Parallel architecture and algorithms for space weather prediction – A review

157

        M De, S De & A B Bhattacharya*

 

 

ELF hiss generation at lower edge of inner radiation belt

174

        Ram Prakash*, D D Gupta, B M Agrawal, Manoj Kumar Singh & Pawan Chauhan

 

 

Monitoring tropical cyclone evolution with NOAA satellites microwave observations

179

        Devendra Singh*

 

 

Retrieval of raindrop size distributions from the L-band and VHF wind profilers during convective and stratiform rain

 

185

        Sanjay Sharma*, Diganta Kumar Sarma, Mahen Konwar, J Das & A R Jain

 

 

Investigation of propagation characteristics of UHF waves in Akwa Ibom State, Nigeria

197

        Michael U Onuu* & Adekunle Adeosin

 

 

Resonant frequency of circular microstrip antenna using artificial neural networks

204

        Som Pal Gangwar, R P S Gangwar, B K Kanaujia* & Paras

 

 

Surface ozone measurements at Anantapur (AP), India

209

        R R Reddy*, K Rama Gopal, L Siva Sankara Reddy, K Narasimhulu, Y Nazeer Ahammed &
T V R Rao

 

Measurement of CO and SO2 trace gases in the southern India during ISRO-GBP Land Campaign–I

216

        R R Reddy*, K Rama Gopal, K Narasimhulu, L Siva Sankara Reddy, K Raghavendra Kumar,
Y Nazeer Ahammed, V Vinoj & S K Satheesh

 

 

Measurement of complex dielectric constant of soils of Gujarat at X- and C-band microwave frequencies

 

221

        D H Gadani & A D Vyas*

 

 

 

*Authors for correspondence

 

 


Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 157-173

 

Parallel architecture and algorithms for space weather prediction – A review

M De1, S De2 & A B Bhattacharya2

1University Science Instrumentation Centre, University of Kalyani, Kalyani 741 235 (WB), India

2Department of Physics, University of Kalyani, Kalyani 741 235 (WB), India

Received 6 September 2006; revised 17 April 2007; accepted 27 February 2008

A critical review is presented in this paper on parallel computing, including parallel algorithms and parallel architectures. Emphasis is laid on different interconnection networks, including recent efficient multi-mesh network. The role of parallel computing for design and analysis of adaptive sampling are pointed out. Different parallel computing platforms and their basic characteristics, along with some computing paradigms that are used in conjunction with adaptive designs are discussed. Some fundamental physical and numerical issues related to constructing modern numerical MHD codes for space weather prediction are outlined. Efficient execution of scientific simulations on high-performance parallel computers is focused. Scope for future development is also suggested.

Keywords: Parallel architecture, Parallel algorithms, Magneto hydrodynamics, Space weather prediction

PACS No: 92.60.Wc; 89.20.Ff

 

 

Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 174-178

 

ELF hiss generation at lower edge of inner radiation belt

Ram Prakash, D D Gupta, B M Agrawal & Manoj Kumar Singh

Department of Physics, Bipin Bihari PG College, Jhansi 284 001 (UP), India

and

Pawan Chauhan

Department of Physics, Maharana Pratap Government PG College, Hardoi 241 001 (UP), India

Received 6 September 2006; revised 22 February 2007; accepted 22 April 2008

An attempt has been made to investigate the possibility of generation of ELF hiss emissions (a few hundred Hz < f < 3 kHz) at the lower edge of inner radiation belt (L = 1.2) by calculating their equatorial magnetic field intensities in terms of incoherent and coherent Cerenkov radiation mechanisms. The results indicate that ELF hiss emissions can not be generated by incoherent Cerenkov radiation mechanism at this location, because the intensities calculated in terms of this mechanism are found to be much lower than the observed intensities. The intensities calculated in terms of coherent Cerenkov radiation mechanism, being several orders of magnitude higher than the observed ones, indicate that the conditions are propitious for the generation of ELF hiss emissions (other than the plasmaspheric hiss) having large wave normal angles at the lower edge of inner radiation belt (L = 1.2) through partially coherent Cerenkov radiation mechanism. This is not, however, true in the case of plasmaspheric hiss (f < 1 kHz), which is thought to be originated in the vicinity of the plasmapause through electron-cyclotron resonance instability mechanism and reaching the lower L-shells after several magnetospheric reflections from there.

Keywords: Extremely low frequency (ELF); ELF hiss; Inner radiation belt; Cerenkov radiation

PACS No.: 94.30. Hn

 

 

Indian Journal of Radio Space Physics

Vol. 37, June, 2008, pp. 179-184

 

Monitoring tropical cyclone evolution with NOAA satellites microwave observations

Devendra Singh

Department of Science and Technology, Technology Bhavan, New Mehrauli Road, New Delhi 110 016, India

Received 22 August 2006; revised 20 March 2007; accepted 8 May 2008

An attempt has been made in this paper to demonstrate the potential use of observations from Advanced Microwave Sounding Unit (AMSU) onboard NOAA 15, 16, 17 and 18 satellites series for the monitoring of tropical cyclones. Geophysical parameters derived from AMSU measurements like surface pressure, upper tropospheric warm core, gradient winds and cloud liquid water are demonstrated for the monitoring of the intensity of recently formed tropical cyclone in the Bay of Bengal on 28 Nov. 2005. The AMSU soundings, which penetrate high clouds, delineate the development and dissipation of the upper tropospheric warm core associated with a tropical cyclone. Vertical cross-sections reveal the intensification of the upper tropospheric warm core as the storm develops, and the downward propagation of the warm core as the storm dissipates.

Key words; Tropical cyclone, Warm core, Microwave sounding, NOAA satellite

PACS No.: 92.60.Hp

 

 

Indian Journal of Radio Space Physics

Vol. 37, June, 2008, pp. 185-196

 

Retrieval of raindrop size distributions from the L-band and VHF wind profilers during convective and stratiform rain

Sanjay Sharma, Diganta Kumar Sarma, Mahen Konwar

Department of Physics, Kohima Science College, Jotsoma, Nagaland 797 002, India

and

J Das

Electronics and Communication Science Unit, Indian Statistical Institute, Kolkata 700 108, India

and

A R Jain

Radio and Atmospheric Science Division, National Physical Laboratory, New Delhi 110 012, India

Received 4 August 2006; revised 2 July 2007; accepted 6 May 2008

A new approach is proposed to retrieve the rain drop size distribution (RDSD) by the combined use of velocity spectra of L–band and VHF wind profilers by taking into account of updrafts/downdrafts. The corrected velocity spectra during rain are fitted with the lognormal functional form by using the Marquerdt-Levenberg algorithm. The corrected velocity spectrum of the L-band profiler is converted to RDSD spectrum. On 22-23 June 2000, for convective and stratiform rain, the retrieved rain integral parameters from the wind profilers are compared with Joss-Waldovegel Disdrometer (JWD) measurements. Reasonably good agreement is found between the observations from these two systems, when the updrafts/downdrafts corrections are applied. During the convective rain, for rain rate, the root mean square (rmse) and correlation coefficients are found to be 5.0 mm/h and 0.74, respectively and for mean rain drop diameter (Dm) the rmse and correlation coefficient are 0.66 mm and 0.58. Similarly during stratiform rain, rmse and correlation coefficients for rain rate are found to be 1.01 mm/h and 0.71. For Dm, the rmse and correlation coefficient are 0.67 mm and 0.65, respectively. An inverse relationship is observed between profiler derived total number of drops (Nt) and Dm.

Keywords:   Rain drop size distribution, Lognormal model, Rainfall intensity, L-band wind profiler, VHF wind profiler, Joss-Waldvogel Disdrometer

PACS No.:

 

 

Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 197-203

 

Investigation of propagation characteristics of UHF waves in
Akwa Ibom State, Nigeria

Michael U Onuu & Adekunle Adeosin

Department of Physics, University of Calabar, P.M.B. 1115, Calabar,  Cross River State, Nigeria

E-mail: monuu@justice.com,  michaelonuu@yahoo.com

Received 13 December 2005; revised 19 June 2007; accepted 18 February 2008

Propagation characteristics of 2.0 GHz ultra high frequency (UHF) waves in Akwa Ibom State (lat. 4.50°N 5.50°N, long. 7.50°E 8.30°E), Nigeria, have been investigated along their line-of-sight  (LOS) links. The LOS was obtained in all the cities in the state where the investigation was conducted. There is good agreement between measured and calculated values of Fresnel zone clearance deducted from path profile. The difference between measured and calculated values varies from 0.92 m to 1.68 m for 0.6 zone number and from 2.56 m to 4.68 m for 2.0 zone number. Also calculated and measured values of path loss (isotropic radiator) vary in the range 109.09-132.00 dB for 0.6 zone number to 110.66-132.72 dB for 2.0 zone number. Results further show that signal strength and signal-to-noise ratio (SNR) are in the range of from – 87 to – 80 dm and 11-18 dB, respectively. Receiving antennae heights fall within 0.6-1.0 Fresnel zone numbers for good reception of UHF signals in Akwa Ibom State. City or degree of urbanization influences UHF propagation in a characteristic manner.

Keywords: Propagation characteristics, UHF waves, Line-of-sight (LOS), Fresnel zone clearance

PACS No.: 41.20.Jb

 

 

Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 204-208

 

Resonant frequency of circular microstrip antenna using
artificial neural networks

 

Som Pal Gangwar1, R P S Gangwar2, B K Kanaujia3 & Paras2

Department of Electronics and Communication Engineering

1S R M S College of Engineering & Technology, Bareilly 243 202 (UP), India

2G B Pant University of Agriculture & Technology, Pantnagar 263 145 (Uttaranchal), India

3M J P Rohilkhand University, Bareilly 243 006 (UP), India

E-mail: bkkanaujia@yahoo.co.in

Received 6 September 2006; revised 8 January 2007; accepted 9 May 2008

A novel method of using artificial neural networks (ANNs) for the calculation of the resonant frequency of electrically thick and thin circular microstrip patch antenna has been adopted in this paper. It is useful for the computer-aided design (CAD) of microstrip antennas. The results obtained using ANNs are compared with the measured and calculated values reported by other authors. The theoretical resonant frequency values obtained using ANNs are in very good agreement with measured and calculated values reported by other researchers.

KeywordsResonant frequency; Circular microstrip antenna; Microstrip antenna, Genetic algorithms; Artificial neural networks

PACS No.: 84.40.Ba

 

 

Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 209-215

 

Surface ozone measurements at Anantapur (AP), India

R R Reddy1, K Rama Gopal1, L Siva Sankara Reddy1, K Narasimhulu1, Y Nazeer Ahammed2, T V R Rao3

1Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003 (AP), India

2Radio and Atmospheric Science Division, National Physical Laboratory, New Delhi 110 012, India

3Nova Education Society of Engineering & Technology, Ibrahim Patnam, Vijayawada 520 008 (AP), India

Received 10 January 2007; revised 20 June 2007; accepted 25 April 2008

The ozone-mixing ratio in ambient air is being measured for every 15 min at Anantapur, a semi-arid zone since April 2001 and analysed. The results show diurnal, day-to-day and seasonal variability. A typical diurnal variation shows an increase during the day, reaching maximum around local noon. However, the diurnal minimum is reached about an hour after sunrise but not during night. The other important feature observed is that the magnitude of the diurnal variation as well as the absolute concentrations of ozone are much higher in winter and summer than in autumn. While the average ozone during noon hours in autumn months is about 25 ppbv, it becomes as high as 50 ppbv during winter and summer months.

Keywords: Surface ozone; Semi-arid zone; Ozone mixing ratio

PACS No: 92.60.Sz; 92.70.Cp

 

 

Indian Journal of Radio & Space Physics

Vol 37, June 2008, pp. 216-220

 

Measurement of CO and SO2 trace gases in southern India during
ISRO-GBP Land Campaign – I

R R Reddy1, K Rama Gopal1, K Narasimhulu1, L Siva Sankara Reddy1

K Raghavendra Kumar1, Y Nazeer Ahammed2, V Vinoj3 & S K Satheesh3

1Aerosol & Atmospheric Research Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, India

2Radio and Atmospheric Sciences Division, National Physical Laboratory, New Delhi 110 012, India

3Centre for Atmospheric and Oceanic Sciences, Indian Institute of Sciences, Bangalore 560 012, India

Received 29 January 2007; revised 10 August 2007; accepted 29 April 2008

Under ISRO-GBP land campaign-I, the concentrations of CO and SO2 gases were simultaneously measured during
1-29 Feb. 2004 over southern India. These measurements were made onboard instrument vehicle along the road network during the dry, winter season of 2004. The study region covered coastal, industrial, urban, rural, remote, semi-arid and vegetated forest lands in the central part of the southern India. Average CO concentration at Nellore, an urban and coastal site is comparatively high (1300 ppbv) and the same is low (620 ppbv) at Sri Perumbuthur, a semi-urban site. These maximum levels of CO at Nellore may be due to traffic emissions and shallow surface layer. Average SO2 concentrations at Sri Perumbuthur and Shadnagar (5 ppbv) are significantly higher than those at other locations. Fairly good correlation has been established between CO, SO2 and meteorological parameters over the study region.

Keywords: Emission inventory, Pollution-urban, Pollution-rural, CO trace gas, SO2 trace gas

PACS No.: 92.60.Sz

 

 

Indian Journal of Radio & Space Physics

Vol. 37, June 2008, pp. 221-229

 

Measurement of complex dielectric constant of soils of Gujarat at X- and
C-band microwave frequencies

D H Gadani1 & A D Vyas2

1Physics Department, C U Shah Science College, Ashram Road, Ahmedabad 380 014, Gujarat, India

2Department of Physics, University School of Sciences, Gujarat University, Ahmedabad 380 009, India

E-mail: dhgadani@yahoo.com

Received 16 February 2006; revised 6 June 2007; accepted 05 May 2008

Dielectric constant and dielectric loss of soils collected from different districts of Gujarat state for various moisture contents have been measured at X- and C-band microwave frequencies. It has been observed that the dielectric constant of soils depend on the moisture content in the soils and frequency of measurement. Dielectric constant of soils increases slowly with increase in the moisture content in the soil up to the transition moisture, after which it increases rapidly with moisture content. The measured values of complex permittivity of dry and wet soils are compared with the values calculated from the empirical models and are found to be in agreement. The observed complex permittivity is used to calculate emissivity of soils for various moisture contents. It has been found that emissivity of soils decreases with increase in moisture content in the soil.

Keywords: Dielectric constant, Microwave frequency, Soil moisture content, Emissivity

PACS No.: 77.22.Gm