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Indian Journal of Radio & Space Physics

 

 

ISSN : 0367-8393

VOLUME 33

 

NUMBER 6

CODEN:IJRSAK

DECEMBER 2004

 

 

CONTENTS

 

First experience with SONG-M measurements on board CORONAS-F satellite

353

S N Kuznetsov, K Kudela*, I N Myagkova, A N Podorolsky, S P Ryumin & B Yu Yushkov

 

 

Variations of solar indices during the sunspot maximum years (1999-2002) of cycle 23

358

R P Kane*

 

 

Meridional wind derived from HF Doppler radar and ionosonde over the magnetic equator

367

S R Prabhakaran Nayar*, C Bhuvanendran, N Jyoti, C V Devasia & K S V Subbarao

 

 

Atmospheric electrical field in relation to severe meteorological disturbances

373

T Datta & A B Bhattacharya*

 

 

Turbulent eddy characteristics in temperature and wind field of surface layer during MONTBLEX’90 over Jodhpur, India

380

N Das & U K De*

 

 

Surface ozone measurements over Himalayan region and Delhi, North India

391

Kaushar Ali*, G A Momin, P D Safai, D M Chate & P S P Rao

 

 

Mositure dependent Ku band microwave characteristics of red soil

399

Vijaya Puri*, S Darshane & S Shaikh

 

 

Estimation of scattering coefficient of saline soil for slightly rough surface and undulating surface at microwave frequencies

405

O P N Calla* & Himadri Sekhar Kalita

 

 

Annual Index

411

 

 

Referees of the year

415

 

 

*Corresponding authors

 

 

 

 

Indian Journal of Radio & Space Physics

 Vol. 33, December 2004, pp. 353-357

 

First experience with SONG-M measurements on board CORONAS-F satellite

 S N Kuznetsov1, K Kudela2, I N Myagkova1, A N Podorolsky1, S P Ryumin1 & B Yu Yushkov1

 

One of the experiments on CORONAS-F satellite is SONG-M devoted to the study of hard electromagnetic and neutron emissions from the sun. This paper presents the first results of the observations of g-ray emissions obtained by the instrument SONG-M during the period August 2001-May 2002.

 

Key words: CORONAS-F satellite, SONG-M experiment, Solar g-rays, Solar cosmic rays, Solar flares

PACS No.: 95.85 Ry; 96.60.Vg; 96.40.-z; 96.60.Rd

 

 

 

Indian Journal of Radio & Space Physics

 Vol. 33, December 2004, pp. 358-366

 

Variations of solar indices during the sunspot maximum years (1999-2002) of cycle 23

R P Kane

 

Comparison of the evolutions of daily and monthly values of several solar indices during 1999-2002 indicated that the daily values had large day-to-day fluctuations with peak spacings differing considerably from the 27-day solar rotation period. Plots of the percentage increases (trough-to-peak) versus temperature of the source regions of the various indices indicated a double-humped structure. The monthly values showed many peaks. The average spacing was ~3.5 months (~100 days). The 12-month moving averages showed considerable differences. Some indices reached a maximum near March 2000. Some of these decreased since then and continue to decrease at present; but some reached a minimum near January 2001 and remained steady there, or started increasing again to reach a probable maximum near June 2002. Some indices did not have a maximum in March 2000 and continued to increase till June 2002. Thus, the evolutions of the various solar indices during the sunspot maximum of cycle 23 (1999-2002) are substantially different from each other. Obviously, the dynamical upheavals in the photosphere reach upper levels of the solar atmosphere with varying intensities.

 

Key words: Solar indices, Sunspot maximum, Solar cycle 23.

PACS No.: 96.60 Qc; 96.60 Tf; 94.20 Vv

 


 

Indian Journal of Radio & Space Physics

Vol 33, December 2004, pp. 367-372

 

Meridional wind derived from HF doppler radar and ionosonde over the magnetic equator

S R Prabhakaran Nayar & C Bhuvanendran and N Jyoti, C V Devasia & K S V Subbarao

 

The nature of plasma motion in the F-region at the magnetic equator is such that they are driven by the neutral air wind along the geomagnetic field. The meridional wind at the equatorial F-region is evaluated using HF Doppler radar of the Kerala University, Trivandrum (8.6° N, 77° E, dip 0.5° N) operated in spaced receiver configuration and ionosonde at equatorial station Trivandrum and an off-equatorial station Sriharikota (SHAR, 13.7° N, 80.2 °E, dip 10° N) for a few days during 1994-1995. The meridional component of the plasma drift at the magnetic equator is determined from the HF Doppler radar data by finding the time delay between the signals received at the central and north antennae by cross-correlation method. The thermospheric meridional wind is also determined by using h¢F values obtained from the ionograms of both Trivandrum and Sriharikota. The temporal variation of meridional wind at the magnetic equator as determined by using both the HF Doppler and ionosonde methods show similar pattern. These results are compared with that obtained using HWM93. It was found that the magnitude of the poleward wind and its time of reversal depend on the altitude of the ionospheric layer.

 

Key words: HF doppler radar, Doppler radar, Radar, Ionosonde, F-region, Magnetic equator

PACS No: 94.20. Ji: 84.40 Xb

IPC Code: G 01 S 1/38

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, December 2004, pp. 373-379

 

Atmospheric electrical field in relation to severe meteorological disturbances

T Datta* & A B Bhattacharya

 

Techniques and instrumentation for studying atmospheric electric field including the working principle of the field mill employed for the present investigation are outlined. The variations of the electric field as observed over Kolkata during unusual meteorological disturbances are reported. During local precipitation, a significant reduction of electric field is noticed in the records, while in the occasions of local thunderstorms there is a pronounced increase of the electric field, sometimes, even showing a very intense value of more than 600 Vm-1. The results have been discussed in the light of the source activity and further problems are focused.

 

Key words: Atmospheric electric field, Meteorological disturbance, Field mill, Thunderstorm.

PACS No: 92.60 Pw

IPC Code: G 01 W 1/02 ; G 01 W 1/16

 

 

 

Indian Journal of Radio & Space Physics

Vol. 33, December 2004, pp. 380-390

 

Turbulent eddy characteristics in temperature and wind field of surface layer during MONTBLEX’90 over Jodhpur, India

N Das & U K De

 

Study of turbulent eddies is a very challenging topic, as it plays a dominant role in controlling the transport of atmospheric constituents in the tropical boundary layer. Tower data of temperature and horizontal wind speed collected by fast response sensors during MONTBLEX’90 (MONsoon trough Boundary Layer Experiment, 1990) field experiment, are considered here, to study the characteristics of the eddies. For this purpose autocorrelation has been performed, by applying a series of lags to different data set. Studying the value of autocorrelation, an attempt is made to determine the type and nature of turbulence eddies, which dominates in the surface boundary layer during the period concerned. The observation shows that turbulent plumes have a specific temporal scale during the period of study. At the same time the approximate spatial extension of the plumes in both horizontal and vertical directions is suggested for some general days as well as for some synoptically significant days. Lastly, comparative studies about the sensitivity of the sensors have been performed.

 

Key words: Turbulence, Time lag, Autocorrelation, Eddy

PACS No.: 92.60.Fm, 92.10.Lq, 94.10.Lf

 

 

 

Indian Journal of Radio & Space Physics

 Vol. 33, December 2004, pp. 391-398

 

Surface ozone measurements over Himalayan region and  Delhi, North India

Kaushar Ali, G A Momin, P D Safai, D M Chate & P S P Rao

 

Measurement of surface ozone concentration has been made at two Himalayan stations, Mohal (during 19-26 May 1999 and 20-25 May 2000) and Kothi (during 27 May - 1 June 1999 and during 27-31 May 2000) and at Delhi (during 2-5 June 2000). The study reveals that the average concentration of ozone at Mohal was 19.1 ppb during May 1999 and 26.1 ppb during May 2000. At Kothi, the average concentrations were 42.7 ppb and 23.0 ppb, respectively, and it was 38.3 ppb at Delhi. Diurnal variation of ozone at Mohal indicated the dominance of photochemical production mechanisms in both the years. Lack of diurnal signal was seen at Kothi over the period of observation in 1999 which suggests that there may be transport of ozone in the region from upper level of the atmosphere. During observational period in 2000, a weak diurnal variation of O3 was observed. It suggests that apart from photochemical production of ozone, some other mechanisms also contribute considerably to the observed O3 concentration. At Delhi also, the diurnal variation showed the influence of temperature on O3 production. Variation of O3 concentration with O3 concentration at previous hour, temperature, relative humidity at previous hour and wind speed at individual locations and years showed a good degree of association of O3 with these parameters.

 

Key words: Photochemical production, Industrial activity, Thunderstorm, Deposition mechanism

PACS No.: 82.33.Tb; 94.10.Fa


 

 

Indian Journal of Radio & Space Physics

Vol. 33, December 2004, pp. 399-404

 

Moisture dependent Ku band microwave characteristics of red soil

Vijaya Puri, S Darshane & S Shaikh

 

In this paper a study of the Ku band (12-18 GHz) properties of red soil obtained from Shivaji University, Kolhapur, due to moisture has been reported. The attenuation in the transmitted and reflected mode of the wetted soil has been measured using standard gain horn antenna. The effect of the angle of incidence (0° and 45°) is also reported. For very low moisture content, angle of incidence and angle of reflection dependent effects are observed. The results indicate that for very low moisture content detection in red soil, angle of incidence of 45° is more suitable and angle of reflection of 60° is most sensitive.

 

Key words: Ku-band, Microwave, Red soil, Soil characteristics

PACS No: 92.40.Lg; 95.75. Rs; 84.40. –x

IPC Code: G 01 N 33/24

 

 

 

Indian Journal of Radio & Space Physics

 Vol. 33, December 2004, pp. 405-410

 

 Estimation of scattering coefficient of saline soil for slightly rough surface and undulating surface at microwave frequencies

O P N Calla and Himadri Sekhar Kalita

 

Microwave remote sensing of soil requires the study of electrical parameters of the soil like (permittivity, emissivity and scattering coefficient) along with its physical parameters like surface roughness and undulation. Out of these the dielectric constant can be used for estimating emissivity and scattering coefficient. Microwave backscattering from soil depends on its dielectric constant. In this paper the scattering coefficient has been estimated for a slightly rough surface and undulating surface for saline soil, using the Perturbation Model and Geometric Optics Model. The database of the estimated scattering coefficient at X-band (8-10 GHz) for saline soil with different moisture content for both horizontal and vertical polarization and different look angles and two types of surfaces has been generated. The result shows that as the salinity increases, the scattering coefficient decreases. Also scattering coefficient increases with the increase in the moisture content. For active microwave remote sensing the scattering coefficient data for saline soil for different moisture content and for different types of surfaces are useful for image analysis and its applications. By using this database it is possible to design an active microwave sensor used for remote sensing of soil, which is largely useful in the field of agriculture.

 

Key words: Scattering coefficient, Saline soil, Dielectric constant, Remote sensing

PACS No.: 95.75 Rs; 84.40 Xb; 92.40.Lg

IPC Code: Gc 01 N 33/24