Indian Journal of Radio & Space Physics

(CODEN : IJRSAK    ISSN : 0367-8393)

 

ISSN : 0367-8393  

CODEN : IJRSAK

VOLUME 31

NUMBER 6

DECEMBER 2002

CONTENTS

Foreward

305                            

K K Mahajan

 

 

Equatorial geomagnetic and ionospheric effects of substorms

309 

J Hanumath Sastri

 

 

In situ measurements of electron density and electric field fluctuations over low latitudes during eqatorial spread-F

 

321

H S S Sinha & P K Rajesh

 

 

Space weather research in India: An overview

337

G S Lakhina & S Alex

 

 

Ionospheres and atmospheres of non-magnetic planets and solar wind interaction: Part I–Venus

 

349

K K Mahajan & A K Dwivedi

 

 

Applications of facilities at NMRF, Gadanki, in the area of meteorology and coupling processes in the atmosphere ― A brief review and future prospects

 

 

357

A R Jain & V K Anandan

 

 

Considerations for methane mitigation from Indian paddy fields

369

D C Parashar & Sumana Bhattacharya

 

 

 Simulation of marine boundary layer characteristics over the Indian Ocean during INDOEX-IFP’99

 

376

       U C Mohanty, N V Sam, A N V Satyanarayana & Swati Basu

 

Developments in tropospheric aerosols studies in India

391

        D R Sikka

 

 

Free air carbon dioxide enrichment facility development for crop experiment

404

H K Maini, M K Tiwari, Madhu Bahl, Thomas John, P Chopra, Dhan Singh, V S Yadav, J R Anand, H N Poddar, A P Mitra, S C Garg, D C Uprety, G C Shrivastava, D C Saxena, Neeta Dwivedi, Rajat Mohan, Franco Miglietta & Alessandro Zaldei

 

 

ANNUAL INDEX

410

 

 

 

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 309-320

 

 

 

Equatorial geomagnetic and ionospheric effects of substorms

J Hanumath Sastri

Changes in the magnetosphere-ionosphere coupling during substorms produce geomagnetic and ionospheric effects not only in high latitudes but also in the sub-auroral region. In this paper the current understanding of the coupling processes during substorms is briefly reviewed with a focus on recent results concerning substorm effects in ground level measurements of equatorial geomagnetic field and ionospheric electric fields. Significant issues and concerns regarding the high latitude-low latitude coupling during substorms are highlighted and suggestions for further work are advanced.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 321-336

 

In situ measurements of electron density and electric field fluctuations over low latitudes during equatorial spread-F

 

H S S Sinha & P K Rajesh

A review of in situ measurements of electron density and electric field fluctuations over low latitudes has been presented. The paper deals only with F-region measurements conducted during equatorial spread-F epochs, mainly using rocket-borne Langmuir probe and electric field probes. At long wavelengths (l ³ 20 km), spectra of electron density irregularities are best represented by a spectral index of –1.5±0.4. Some of the mechanisms, which are considered to be potential, include a two-fluid mechanism, strong shears in horizontal velocity of plasma and gravity wave organization of plasma. The spectral index of intermediate scales (100 m < l < 20 km) lies in the range of –2.4±0.2. Regarding the mechanism of generation of intermediate scales, there is a general consensus that the generalized Rayleigh Taylor instability is the main mechanism. There are some minor problems with this mechanism, such as flattening of spectra (n » –1.5) in some regions and an insufficient growth rate, which puts a condition of minimum seed amplitude (» 5%) for the initial perturbations. Irregularities in transitional scale (10 m < l < 100 m) have much steeper spectra with spectral index ranging between –4 and –5, and are believed to be generated by low frequency electrostatic waves with finite wavelength parallel to the magnetic field. Low frequency drift waves appear to be the most plausible mechanism at transitional scales. For short scales (l £ 10 m), the two most probable mechanisms are: (i) lower hybrid drift mode and (ii) a resonant wave-particle interaction.

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 337-348

 

 

Space weather research in India: An overview

G S Lakhina & S Alex

The regime of space weather includes the sun, solar wind, interplanetary space, magnetosphere, ionosphere and the thermosphere. The immediate manifestations of space weather events are the result of solar flares and coronal mass ejections (CMEs) leading to the occurrence of geomagnetic storms and substorms, appearance of auroral forms, ionospheric disturbances, etc. The solar-terrestrial environment has a wide range of effects on many aspects of our everyday life. This paper discusses various aspects of space weather and presents an overview of the space weather research activities in India. There is a need for a comprehensive space weather prediction programme for India in view of the fact that the space-based systems are already being exploited for a variety of applications such as remote sensing and meteorology, radio communications, broadcasting, earth resources survey, etc.

 

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 349-356

 

Ionospheres and atmospheres of non-magnetic planets and
solar wind interaction: Part I — Venus

K K Mahajan & A K Dwivedi

The solar-planetary interaction is unique for non-magnetic planets, since the solar wind interacts directly with the atmospheres and ionospheres of these planets. Venus and Mars are now known to be non-magnetic planets and in this paper a brief description of the ionosphere and atmosphere of Venus as evolved through several planetary missions, particularly the Pioneer Venus Orbiter which had onboard several aeronomy experiments, has been given. The results on the response of the Venus ionosphere and its upper atmosphere to changes in solar wind, especially on (i) disappearing atmospheres, (ii) orbit-to-orbit variability of electron and ion concentration and (iii) location of nightside ionopause are presented. These results in relation to features like plasma holes and disappearing ionospheres are also discussed.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 357-368

 

 

Applications of facilities at NMRF, Gadanki, in the area of meteorology and coupling processes in the atmosphere—A brief review and future prospects

 

A R Jain & V K Anandan

The National MST Radar Facility (NMRF) was set up as an off-shoot of Indian Middle Atmosphere Programme (IMAP). It became fully operational in MST mode in 1994. Recently many new experimental facilities have been collocated at radar site. These systems are, basically, complementary to the main MST radar facility. Addition of these facilities has enhanced the scientific applications of NMRF. In this paper, the significance of the recent technical developments on Indian MST radar are discussed and possible scientific applications in the area of meteorology and for the studies of various coupling processes in the atmosphere in which dynamics plays an important role are highlighted. Some typical results are also presented.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 369-375

 

Considerations for methane mitigation from Indian paddy fields

 

D C Parashar and Sumana Bhattacharya

Methane emission from paddy cultivation is one of the major anthropogenic activities releasing methane into the atmosphere. Various parameters like water management, cultivars, nature of fertilizer, soil temperature and texture have been investigated and found to change the emission by a few times to orders of magnitude. Studies of irrigation practices in India have shown that submergence is not necessary for high yields and controlled irrigation can be very effective in mitigation of methane emission without affecting the yield. The use of cultivars having high yields associated with low methane emission and use of appropriate fertilizer can reduce methane emission by more than an order of magnitude. Measurements carried out in the National Physical Laboratory, New Delhi have also shown an excellent correlation of methane emission with soil temperature and suggest the increase in paddy cultivation in the Rabi season to be another important measure to mitigate methane emission. Possibilities of implementing the aforesaid mitigation measures to reduce methane emission are discussed along with the options available through the Clean Development Mechanism in the agriculture sector and their importance for India. Comparative cost estimates of methane mitigation measures for rice cultivation and the least cost mitigation option that might be used for the country are also discussed in this paper.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 376-390

 

Simulation of marine boundary layer characteristics over the
Indian Ocean during INDOEX-IFP’99

 

U C Mohanty, N V Sam & A N V Satyanarayana

The characteristic features of the marine boundary layer (MBL) over the Indian Ocean during the north-east monsoon and the factors influencing it have been investigated. The Indian Ocean Experiment (INDOEX) Intensive Field Phase-1999 (IFP’99) has provided the atmospheric sounding data for this study. This is for the first time that such high-resolution upper air data are obtained over the Indian Ocean. Different synoptic scenarios corresponding to convectively active and convectively suppressed situations over the Indian Ocean are considered to study the variability in MBL characteristics using one-dimensional (1-D) multi-level PBL model with a TKE-e closure scheme. The NCMRWF-GCM was also used to simulate surface layer parameters such as sensible heat and latent heat fluxes, the marine boundary layer height, etc. The simulations also include the vertical profiles of potential temperature, specific humidity and zonal and meridional wind components. It is noticed that, in general, the non-local closure and the scheme due to turbulent kinetic energy (TKE) can simulate vertical profiles closer to the observations. The 1-D PBL model simulates the temporal evolution of TKE, marine boundary layer height (MBLH) and sensible and latent heat fluxes. The model also generates the vertical profiles of potential temperature, specific humidity, and zonal and meridional wind. These simulated values are comparable with the observations available from INDOEX experiment. The 1-D model could not simulate the dynamical features associated with advection and winds satisfactorily. However, the convective regimes are well simulated.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 391-403

 

Developments in tropospheric aerosols studies in India

D R Sikka

The paper traces the development of aerosol studies in India in the last 5 decades. Measurements on atmospheric transparency, rain water chemistry and air sampling were the techniques employed up to 1990. From mid 1980s other systems like radiometers and lidar have been introduced. Aerosol research got a boost in India under the IMAP in 1980s, which enabled Indian research community to participate actively in INDOEX (1996-1999) phases. Large number of studies undertaken in India in pre-INDOEX and INDOEX phases reveal that aerosol concentrations are increasing and so is the component due to anthropogenic sources, in all seasons. There could be implications of these trends on regional climate system. The need for enhanced monitoring on a regular network mode, archival of data and modelling is emphasized under a well coordinated multi-agency programme.

 

Indian Journal of Radio & Space Physics

Vol. 31, December 2002, pp. 404-409

 

 

Free air carbon dioxide enrichment facility development for crop experiments

 

H K Maini, M K Tiwari, Madhu Bahl, Thomas John, P Chopra, Dhan Singh, V S Yadav, J R Anand,
H N Poddar, A P Mitra & S C Garg

The level of carbon dioxide (CO2) gas in earth’s atmosphere is increasing exponentially due to global industrialization and is likely to reach double its pre-industrial value by the middle of present century. Free air CO2 enrichment (FACE) facilities, in which the simulation of elevated level of CO2 is done in the open fields by artificially injecting CO2 gas in a controlled manner, are being used to study the the impact of rising concentration of CO2 on environment. The FACE facilities exist only in few places in the world as they are quite expensive, complex to develop and involve state-of-the-art technology. This paper describes the details of a medium size FACE facility (Mid-FACE) designed, developed and fabricated indigenously for conducting CO2 enrichment experiments on crop plants. With this development, India becomes the second after Japan to have such a facility in whole of Asia for carrying out CO2 enrichment research.