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Indian Journal of Radio & Space Physics

 

 

 

ISSN : 0367-8393

 

    CODEN : IJRSAK   

VOLUME 33

NUMBER 1

FEBRUARY 2004

 

 

CONTENTS

 

Effect of solar flares on electron and ion temperatures as measured by SROSS-C2 satellite

7

D K Sharma*, Jagdish Rai, M Israil, P Subrahmanyam, P Chopra & S C Garg

 

 

Kinetic Alfven waves in inhomogeneous anisotropic dusty magnetoplasma with inhomogeneous electric field Particle aspect analysis

13

R P Shandilya, P Varma & M S Tiwari*

 

 

Alfven waves in dusty magnetosphere

25

J Shrivastava & M S Tiwari*

 

 

Measurement of ELF emission in the upper atmosphere over Kolkata due to Schumann Schumann resonances

32

S S De*, A K Saha & M De

 

 

Orissa super cyclone of October 1999 as revealed by IRS-P4 satellite data

35

S G Narkhedkar*, P N Mahajan, R M Khaladkar, Sathy Nair, P C Joshi &
P K Pal

 

 

Polarizability affecting nucleation of water vapour condensation and ice glaciation in presence of external electric field

43

N Singh* & Devendra Singh

 

 

Lidar observations of middle atmosphere temperature variability over low latitude

50

M Krishnaiah*, U Jaya Prakash Raju, Y Bhavani Kumar, K Raghunath,
V Siva Kumar, P B Rao, B V Krishna Murthy, M N Sasi, K Parameswaran,
K Krishna Murthy & Prabha Nair

 

 

 

Effects of ultraviolet-C radiation on isolated fish scale melanophores

58

Sharique A Ali, Ayesha S Ali, S Nasir Ali & Ravi Jain*

 

 

Sensitivity of brightness temperatures to the oceanic surface roughness and rainfall for TRMM and IRS-P4-MSMR radiometric channels over the Indian Ocean

61

R M Gairola*, A K Varma, Samir Pokhrel, B S Gohil & V K Agarwal

 

 

 

Study on compact meandered microstrip antenna with a shorting pin

71

R M Vani, S F Farida & P V Hunagund*

 

 

 

_________

 

*Corresponding authors

 

 

Indian Journal of Radio & Space Physics

Vol. No. 33, February 2004, pp 7-12

 

Effect of solar flares on electron and ion temperatures as measured by SROSS-C2 satellite

D K Sharma & Jagdish RaiM Israil, P Subrahmanyam, P Chopra & S C Garg

 

The ionospheric electron and ion temperatures (Te and Ti) measured by RPA payload aboard SROSS-C2 satellite are found to be enhanced during the solar flares. The electron temperature (Te) is enhanced by ~32.05-45.31% and the ion temperature (Ti) enhanced by ~4.12-21.95% over quiet days. This enhancement has been obtained in the daytime ionosphere. The solar flare does not have any significant effect on the nightside ionosphere.

 

Keywords:   Solar flares, Electron temperature, Ion temperature, SROSS-C2

 

PACS No.: 94.20 Yx; 94.20 Rr

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 13-24

 

 

Kinetic Alfven waves in inhomogeneous anisotropic dusty magnetoplasma with inhomogeneous electric field Particle aspect analysis

R P Shandilya, P Varma & M S Tiwari

 

Kinetic Alfven waves in the presence of an inhomogeneous electric field perpendicular to the ambient magnetic field in inhomogeneous dusty magnetoplasma are investigated. Expression for the field-aligned current, perpendicular current (to the B0), dispersion relation, particle energy and growth-rate are derived and the effect of inhomogeneous electric field is discussed. The particle aspect approach is adopted to investigate the trajectories of charged particles in the electromagnetic field of kinetic Alfven wave in dusty magnetosphere. It is found that electric field enhances the frequency of kinetic Alfven wave for both the waves travelling towards the ionosphere and reflected by the ionosphere. Enhancement of growth rate at the particular wave number is predicted. Reduction in wave frequency and enhancement of growth rate by electric field inhomogeneity is observed. Minor effects of inhomogeneous electric field on perpendicular and parallel currents are noted. The applicability of the finding is discussed for auroral acceleration phenomena.

 

Keywords:   Alfven waves, Magnetoplasma, Auroral acceleration, Inhomogeneous electric field.

 

PACS No.: 94, 20.Yx

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 25-31

 

 

Alfven wave in dusty magnetosphere

 

J Shrivastava & M S Tiwari

 

Dispersion relation and associated field-aligned currents are evaluated for Alfven wave with bi-Maxwellian distribution function using particle aspect approach in a warm, magnetized dusty plasma, consisting of electrons, ions and charged dust particles. Effects of different charge concentrations, dust particle density and the ratio of the temperature of the dust particle to that of electron have been examined on the propagation of Alfven wave. It is found that the dust grain concentration and charge on dust grains reduce the wave frequency of the Alfven wave. However, the temperature of dust particles increases the wave frequency. Positively charged dust grain enhances the downward field-aligned current and negatively charged dust grain increases the upward current of the lower auroral ionosphere. Similar effects are also noted for the dust grain number density, whereas the temperature of the dust grain reduces the field-aligned current. Applications of the findings are indicated for the magnetosphere-ionosphere coupling.

 

Keywords: Alfven wave, Magnetosphere, Field-aligned current, Magnetized plasma, Auroral ionosphere

 

PACS No.: 52.35.Bj ; 94.10.Rk

 

 

 

Indian Journal of Radio Space Physics

Vol. 33, February, 2004, pp. 32-34

 

 

Measurement of ELF emission in the upper atmosphere
over Kolkata due to Schumann resonances*

S S De, A K SahaV & M De

 

The discrete spectra of the transmission frequencies at 8, 14, 20, Hz, due to Schumann resonances are generated by electromagnetic emission from the lightning strokes and can be regarded as excitation of an AC global circuit. In this paper, the results of an attempt to detect experimentally these discrete signals at Kolkata (lat. 2234N) are presented. Some frequency changes of 10% - 20% about the peak values are found to be present in the observed data which may be attributed by the uncertainties arising from spatial distribution of lightning sources exciting the Schumann resonance modes.

 

Keywords: ELF emission, Schumann resonances, Upper atmosphere, Lightning

 

PACS No: 92.70.-j; 92.60.Ta; 94.20. Ss

 

 

 

Indian Journal of Radio Space Physics

Vol. 33, February, 2004, pp. 35-42

 

Orissa super cyclone of October 1999 as revealed by
IRS-P4 satellite data

S G Narkhedkar, P N Mahajan, R M Khaladkar & Sathy Nair, P C Joshi & P K Pal

 

A super cyclone hit Orissa coast during 24-31 Oct. 1999 causing vast damage to property and life. Life cycle of this super cyclonic storm from its genesis to landfall is studied using IRS-P4 satellite derived parameters over the oceanic region. The parameters, viz. sea surface temperature, sea surface wind, integrated water vapour, cloud liquid water content are studied over the region 5 -25 N and 70-100E. Synoptic surface pressure charts were compared with INSAT imagery. The IRS-P4 satellite data supplemented the data from INSAT in studying various characteristics associated with the super cyclone.

 

Keywords:   Orissa super cyclone, Sea surface temperature, Winds, Clouds, IRS-P4, Satellite imagery

 

PACS No.:   92.60.Qx

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 43-49

 

Polarizability affecting nucleation of
water vapour condensation and ice glaciation
in presence of external electric field

N Singh & Devendra Singh

 

Using the modified value of polarizability based on the present calculations, it is found that the critical nuclei have much less radii in the presence of electric field. The nucleation rate in presence of electric field is greater than in its absence. The enhancement factor to the nucleation rate in presence of electric field is several orders higher than in the absence of an electric field. The polarizability of water vapour molecules in presence of external electric field plays an important role in the nucleation rate of water vapour condensation and ice glaciation. The increase in polarizability results in the increase in Gibbs free energy, and hence the increase in nucleation rate, but at the same time there is a decrease in relaxation time. The polarizability enhances the nucleation rate and equilibrium concentration, e.g. for a given relaxation time 510-15 s, the radius of critical nucleus is found to increase from 27.7210-9 cm to 81.0710-9 cm when electric field increases from 10 esu to 50 esu, whereas Gibbs free energy increases from 3.2210-15 erg to 27.5410-15 erg for same increase in electric field.

 

Keywords: Polarizability; Nucleation; Water vapour nucleation; Condensation; Ice glaciation; Gibbs free energy

 

PACS No.: 92.60.Jq; 92.60.Nv

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 50-57

 

Lidar observations of middle atmosphere temperature variability over low latitude

 M Krishnaiah & U Jaya Prakash Raju, Y Bhavani Kumar, K Raghunath, V Siva Kumar & P B Rao

and B V Krishna Murthy, M N Sasi, K Parameswaran, K Krishna Murthy & Prabha Nair

 

In this paper, 246 Rayleigh lidar observations covering the altitude range of stratosphere and mesosphere collected during the period March 1998 - December 2001 (37 months) using Indo-Japanese Lidar at National MST Radar Faculty (NMRF), Gadanki (13.8N, 79.2E), India. are presented. The atmospheric density profiles were derived. Using the limited database, a climatological structure of temperature over a tropical site giving seasonal variations of upper stratosphere and mesospheric region is also presented. It has been observed over Gadanki, that the stratopause is quite broad and occurred in the range of 43-58 km with the temperature maximum observed in winter and equinox periods. A semi-annual variation is seen clearly around 70 km with maxima at May/June and Dec/Jan. Mesospheric temperature shows strong inversion very often. The average climatology over 37 months period is found to compare well with a reference atmosphere model (MSISE 90). The observed temperature is, in general, colder throughout the year in the 30-45 km range and warmer in summer at 70-80 km as compared to the model derived values. The present study suggests that the 45-55 km region is less affected by temperature variability, which is well suited for the detection of possible temperature trends.

 

Keywords: Lidar, Middle atmosphere, Temperature variability, MST radar.

 

PACS No: 94.10.Dy

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 58-60

 

Effects of ultraviolet-C radiation on isolated fish scale melanophores

Sharique A Ali & Ayesha S Ali, S Nasir Ali, and Ravi Jain

 

The effects of ultraviolet-C radiation on isolated fish scale melanophores are studied. The responses of melanophores were measured by mean melanophores size index (MMSI). At a temperature range of 27-29C, the melanophores were exposed for varying durations ranging from one min to 60 min, to a direct source of ultraviolet-C radiation of wavelength 254 nm. It was found that the exposure of 30 min of UV-C radiation produced the highest effects on the melanophores of C. punctatus, where the MMSI reached a peak value of 8.351 0.3798. The melanophores had become highly dispersed, with their cellular processes extending maximally.

 

Keywords : UV-C, Melanophores, Fish scale

 

PACS No.: 95.85 Mt

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 61-70

 

Sensitivity of brightness temperatures to the oceanic surface roughness and rainfall for TRMM and IRS-P4-MSMR radiometric channels over the Indian Ocean

R M Gairola, A K Varma, Samir Pokhrel, B S Gohil & V K Agarwal

 

Upwelling microwave radiances at the top of the atmosphere originate partly from the oceanic/land surfaces and partly from atmospheric constituents. Radiative transfer simulations have been carried out for the Tropical Rainfall Measuring Mission (TRMM)-Microwave Imager (TMI) and Indian OCEANSAT-Multichannel Scanning Microwave Radiometer (MSMR) radiometric frequencies for varying winds, under clear sky (non-raining) and raining conditions. Both emission and scattering based radiative transfer simulations are carried out for typical atmospheric profiles over the North Indian Ocean during the monsoon season. The simulation results match reasonably well with the real observations from TRMM-TMI and MSMR channels that represent a variety of oceanic and atmospheric conditions during the south-west monsoon season. The main purpose of simulations is to delineate the frequencies that are most sensitive (as far as brightness temperatures are concerned) to the ocean surface and rainfall characteristics. This effort will contribute for the combined use of different sensors to retrieve geophysical parameters with better accuracy.

 

Keywords:   Remote sensing, Radiative transfer, Radiometers, Rainfall, Brightness temperature, Hydrometeors.

 

PACS No.: 92.60.Jq

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, February 2004, pp. 71-73

 

Study on compact meandered microstrip antenna
with a shorting pin

R M Vani, S F Farida, and P V Hunagund

 

Realization of a  compact configuration by combining the techniques of patch meandering and shorting pin loading for rectangular microstrip antenna is reported in this paper. The patch meandering is made by inserting number of slits at the radiating edges of microstrip patch. Typical experimental results of the proposed antenna are presented. Through the experimental results it is clear that the meandered microstrip patch with shorting pin will resonate at much lower frequency compared to the conventional microstrip patch of same size.

 

Keywords: Microstrip patch antenna, Antenna, Rectangular antenna.

 

PACS No: 84.40.Ua