Indian Journal of Radio & Space Physics


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(CODEN : IJRSAK ISSN : 0367-8393)

VOLUME 35

NUMBER 6

DECEMBER 2006

 

CONTENTS

 

Guest Editorial: Seismo-electromagnetics: A prospective tool for earthquake prediction

Birbal Singh*

 

385

Correlation of the long-term cosmic ray intensity variations with sunspot numbers and tilt angle

Meera Gupta*, V K Mishra & A P Mishra

 

 

387

 

Detection of 2004 Leonid meteor shower by observing its effects on VLF transmission

S S De*, B K De, A Guha & P K Mandal

 

 

396

Depletion of ozone and its effect on night airglow intensity of Na 5893 at Srinagar and Halley Bay

P K Jana*, S C Nandi & D Sarkar

 

 

401

Verification of NCMRWF temperature output with observed data over
West Bengal region during 2000-2002 monsoon period

V Mandal, U K De* & B K Basu

 

 

407

Vertical structure of the lower atmosphere over the Arabian Sea and West Coast Station during weak phase of the Indian summer monsoon

T Dharmaraj*, B S Murthy & S Sivaramakrishnan

 

 

418

Studies on crop growing period and NDVI in relation to water balance components

A A L N Sarma* & T V Lakshmi Kumar

 

424

Analysis of notch-loaded patch for dual-band operation

Shivnarayan & Babau R Vishvakarma*

 

435

Design of wideband equilateral triangular microstrip antennas

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

 

443

Annual Index

 

448

Referees of the year

 

453

___________________

*Authors for correspondence

 

 


Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 387-395

 

Correlation of the long-term cosmic ray intensity variations with
sunspot numbers and tilt angle

Meera Gupta*, V K Mishra & A P Mishra

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

*E-mail: soumya_rishi@rediffmail.com

Received 6 February 2006; revised 16 June 2006; accepted 26 October 2006

Based on the monthly data of sunspot numbers (SSN), tilt angle (TA) and cosmic ray intensity (CRI), a detailed correlative analysis has been performed to study the relationship of CRI (observed by the neutron monitor stations having different cut-off rigidity) with SSN and TA for the period 1976-2005, covering solar cycles 21, 22 and 23. It is an observed fact that SSN and TA are highly correlated with each other and cosmic ray intensity shows anti-correlation with them. The present analysis is found to support the earlier findings and holds good for solar cycles 21, 22 and current cycle 23. Further, the cross-correlation coefficients between CRI-SSN and between CRI-TA have been obtained considering the time-lag factor and it is found that time-lag is larger for odd solar cycles in comparison to even cycles. The odd-even behaviour in relation to time-lag is also evident from the hysteresis curve between CRI-SSN and between CRI-TA, where wider loops for odd solar cycles have been observed. Moreover, we find that correlation between CRI and SSN as well as between CRI and TA is better during negative polarity than the positive polarity of solar magnetic cycle. From the tilt angle observations, it has been noticed that the behaviour of cycle 23 in declining phase is different from that of cycle 21 and 22.

Keywords: Cosmic ray intensity, sunspot numbers, tilt angle

PACS No: 96.40.-Z; 96.60.Qc

 

 

 

Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 396-400

 

 

Detection of 2004 Leonid meteor shower by observing its effects on
VLF transmission

S S De,1 B K De,2 A Guha,1 & P K Mandal1

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

2 Department of Physics, Tripura University, Tripura 799 130, India

E-mail: de_syam_sundar@yahoo.co.in

Received 3 March 2006; revised 29 May 2006; accepted 26 October 2006

Results of the detection of 2004 Leonid meteor shower over Kolkata (2234 N, 8830 E), India is presented in this paper, by using a VLF amplifier tuned at one of the transmission frequencies of Indian Navy Traffic stations at Vijayananarayanam (82559.88 N, 7748 E) at 16.3 kHz. The shower was predicted to exhibit a peak activity on 19 Nov. 2004. In spite of low ZHR predicted, the peak activity had been observed earlier than the predicted times, which confirms the nongravitational A2 effect on meteoroid trails. The observation also suggests that electromagnetic detection of meteor shower is better than the visual observation, as any time of the day and night its effect on VLF transmission can be recorded.

Keywords: Meteor shower, VLF radio wave, ionospheric disturbances.

PACS No: 47.20.Ft, 96.50.Kr, 94.20.Vu, 95.85.Bh


Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 401-406

 

 

Depletion of ozone and its effect on night airglow intensity of Na 5893 at Srinagar and Halley Bay

P K Jana, S C Nandi & D Sarkar

Department of Chemistry, Institute of Education (PG) for Women, Chandernagore, Hooghly (West Bengal), 712 138, India.

Received 11 August 2005; revised received 23 December 005; accepted 22 February 2006

The paper presents the effect of O3 depletion on night airglow emission of Na 5893 line at Srinagar (34oN, 74.8oE), India and Halley Bay (76oS, 27oW), a British Antarctic survey station. Calculations based on chemical kinetics reveal that the airglow intensity of Na 5893 line is also affected due to ozone decline. The nature of yearly and seasonal variation of intensity of Na 5893 line for the above two stations are shown and compared. It is shown that the rate of decrease of yearly intensity of Na 5893 line is comparatively more at Halley Bay due to dramatic decrease of Antarctic O3 concentration. During Antarctic spring time, stratospheric ozone is depleted dramatically at Antarctic region because of very low temperature (80C), elevated concentration of atomic chlorine and chlorine oxides, low abundances of nitrogen oxides and large appearance of polar stratospheric clouds (PSCs).

Keywords: Ozone depletion, Airglow emissions, Excitation mechanism, Intensity.

PACS No.: 94.10. Fa, 94.10. Rk

 

Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 407-417

 

 

Verification of NCMRWF temperature output with observed data over West Bengal region during 2000-2002 monsoon period

V Mandal & U K De

School of Environmental Studies, Jadavpur University, Kolkata 700 032

E-mail: deutpal2003@yahoo.com

and

B K Basu

NCMRWF, A-50, Sector-62, Noida (UP) 201 307

Received 17 May 2005; revised 18 August 2006; accepted 5 October 2006

The temperature forecasts of the National Centre for Medium Range Weather Forecasting (NCMRWF) global model are validated over West Bengal (WB) region against the observations from 39 or more agricultural field stations of the Government of West Bengal and 11 observatories of India Meteorological Department (IMD), Government of India. The validation was done at 0700 hrs IST and 1400 hrs IST for 2000-2002 and at 0830 hrs IST in addition for 2000 only. The agreement between forecast and observed surface temperatures is within the reasonable limit for forecast up to 5 days, though it deteriorates gradually with the length of forecast time. Weekly performance of the model for the whole region is remarkably good throughout the season in each of the years under study. It is noted that from the north to south, both root mean square error and correlation coefficient decrease.

Keywords: Objective analysis, Weighing function, Cressman function, Grid-point output, Mean correction

PACS No.: 92.60Wc
        IPC Code: G 01W1/ 02


Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 418-423

 

Vertical structure of the lower atmosphere over the Arabian Sea and West Coast Station during weak phase of the Indian summer monsoon

T Dharmaraj, B S Murthy & S Sivaramakrishnan

Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pune 411 008

Received 14 July 2005; revised 24 May 2006; accepted 9 November 2006

The height of the day time mixed layer, vertical structure of the atmospheric boundary layer (ABL) and its variation over the Arabian Sea (hereafter Sea) and the West Coast Station (Goa: 15o21' N, 73o51' E) during the weak phase of south-west monsoon (20-24 July 2002) have been calculated using Radiosonde, the surface meteorological data collected at 12 m above mean sea level onboard ORV Sagarkanya and at Goa during ARMEX-I. It is observed that the depth of mixed layer over Goa and offshore was about 1 km during the period, while the first 200 m was showing super adiabatic lapse rate over Goa but not over the Sea. The marine atmospheric boundary layer is found to be well-mixed with its height, progressively increasing from 750 m to 1000 m during 21-24 July 2002. The vertical profiles of virtual potential temperature show an inversion above 1 km, which was very steep over both the Sea and Goa. The relative humidity (RH) in the mixed layer (0-1 km AGL) was varying from 70 to 100% over the sea, whereas over Goa it was from 70 to 90 % during 20-24 July 2002. Above 2-3 km, RH decreases from 70% to 30% over the Arabian Sea and Goa on 24 July, indicating the presence of subsiding warm and relatively dry layer.

Keywords: Mixed layer, Virtual potential temperature, Relative humidity

PACS No.: 92.60.Hp

 

 

Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 424-434

 

 

Studies on crop growing period and NDVI in relation to
water balance components

A A L N Sarma & T V Lakshmi Kumar

Dept of Meteorology & Oceanography, Andhra University, Visakhapatnam, Andhra Pradesh-530 003, India

e-mail : aalnsarma_met@rediffmail.com; lkumar@ausi.com

Received 12 January 2006; revised 10 July 2006; accepted 14 August 2006

The primary water balance components such as rainfall, water need, actual evapotranspiration, water deficit and water surplus, are studied for All Andhra Pradesh for the south-west monsoon months of 1999 to 2002 on daily basis. Crop growing periods for the selected stations over Andhra Pradesh (AP) are reported to understand the climatic potentialities of the region for crop and irrigation schedule under consideration. The investigation also addresses the spatiotemporal variability of the integrated normalized difference vegetation index (INDVI) in relation to the pattern of soil moisture adequacy. Using mean daily water deficit and water need, aridity index is obtained and studied to understand drought monitoring over Andhra Pradesh in relation to INDVI. The present study shows that the crop growing periods are high to the north of 15 latitude compared to south. The relation of the rainfall with NDVI is found to be weak when the rainfall is taken for the 10-day periods compared to soil moisture adequacy. But in the case of cumulative rainfall, the results revealed better positive correlation with NDVI.

Keywords: Water balance concept, Soil moisture adequacy, Crop growing period, INDVI

PACS No.: 92.40.Ea; 92.40.Lg

IPC Code: G02B13/14


Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 435-442

 

 

Analysis of notch-loaded patch for dual-band operation

Shivnarayan & Babau R Vishvakarma*

Department of Electronics Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India

E-mail: * brvish@bhu.ac.in

Received 27 May 2005; revised 4 May 2006; accepted June 2006

Analysis of notch loaded rectangular patch antenna for dual-band operation has been proposed, in which dual frequency behaviour is obtained by notch loading. The theoretical analysis is based on modal expansion cavity model. The resonance frequency changes with the variation in the length and width of the notch. Thus the input impedance, VSWR, return loss and bandwidth are calculated. The obtained resonance frequency ratio is variable from 1.17 to 1.77 with the length and width of the notch.

Keywords: Notched patch antenna, Dual-band patch antenna, Rectangular patch

PACS NO.: 84.40. Ba

IPC Code: H01Q9/00; H01Q21/00; H01Q23/00

 

 

 

Indian Journal of Radio & Space Physics

Vol. 35, December 2006, pp. 443-447

 

 

Design of wideband equilateral triangular microstrip antennas

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

Department of Applied Electronics, Gulbarga University, Gulbarga (Karnataka) 585 106, India

Received 11 November 2005; revised 2 February 2006; accepted 3 April 2006

A novel design of corporate fed two-element slotted equilateral triangular microstrip array antenna (SETMSA) for enhancing the impedance bandwidth and gain is presented. The experimental results show improvement in both impedance bandwidth and gain compared to the conventional two-element equilateral triangular microstrip array antenna (ETMSA) without changing much the radiation characteristics. A study is also made by using a common rectangular parasitic element in the form of gap coupled between the two slotted equilateral triangular microstrip elements, and the antenna is fed by aperture-coupled feeding technique. This modified antenna further enhances the impedance bandwidth and it operates for three bands of frequencies. If a slot is inserted in the parasitic element, the antenna operates at two nearly equal widebands of frequencies. This type of wideband and multiband operation of antenna may find application in wireless communication.

Keywords: Slot antenna, Stacked antenna, Gap-coupled antenna

PACS No.: 84.40.Ba

IPC Code: H01 Q9/00; H01 Q21/00; H01 Q23/00