015092   Sharma A K;Thakur P K (Space Applicat Cent, (ISRO), Ahmedabad-380 015, Email: sharma_arun@sac.isro.gov.in) : Quantitative assessment of sustainability of proposed watershed development plans for kharod watershed, western India. J Indian Soc Remote Sens 2007, 35(3), 231-41.

Sustainability of watershed development plan is assessed through the quantification of the three major sub-components of Water Balance, namely Surface Runoff (SR), Ground Water Recharge (GWR) and Evapotranspiration (ET) for 71 micro-watersheds of Kharod watershed (1100 km² area) located in Western India. Annual estimates at micro-watershed level are carried out for two scenarios: A) The current water resources and land use/land cover scenario and B) Envisaged changed water resources and land use/land cover scenario after implementing all prescriptions for micro-watershed development. Finally water balance components level analysis and comparison was done to see the impact and assess the sustainability of envisaged watershed development scenario. It is estimated that there is a decrease of 40.2 mm in surface runoff component, increase of approx. 4 mm in groundwater recharge, increase of 102.3 mm in actual evapotranspiration for post-developmental scenario on annual basis. The computation of actual evapotranspiration (ET_a) showed that there is net increase in the ET after the post-development scenario. Also the surface water storage has increased from 21.2 mm to 65.3 mm. Overall there is 164.9 mm of available water balance after implementation of developmental activities which reflects the sustainability of the proposed development plans.

5 illus, 5 tables, 14 ref

015091   Sahai Y;Becker-Guedes F;Fagundes P R; Guarnieri F L;de Abreau A J;de Jesus R;Pillat V G;Lima W L C;J A Bittencourt (NO, Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP, Brazil) : Effect of recent space weather events in the equatorial and low latitude F-region in the Brazilian sector. Asian J Phys 2007, 16(2-3), 273-90.

The effects of space weather events in the ionosphere-thermosphere system evince growing interest of scientific community because of detrimental influence on ground-based and space-borne systems. During the recent, past, we have studied the effects of four space weather events, during the period March 2001 to November 2003, in the equatorial and low latitude F-region in the Brazilian sector. The investigations have used the ionospheric sounding observations carried out at Palmas (10.2 deg. S, 48.2 deg. W; dip latitude 5.5 deg. S) and Sao Jose dos Campos (23.2 deg. S, 45.9 deg. W; dip latitude 17.6 deg. S), Brazil. In this review, we present and discuss in a consolidated form the results obtained by us during the four events. The events investigated included intense and super geomagnetic storms. It should be mentioned that a variety of ionospheric effects have observed in the equatorial and low latitude F-region in the Brazilian sector during these events. The effects observed during these events include, prompt penetration of the storm-induced magrietospheric electric field, traveling ionospheric disturbances (TIDs), unusual formation of the equatorial ionospheric anomaly, onset and suppression of equatorial spread F (ESF), and negative ionospheric storm phase.

17 illus, 47 ref

015090   Nindos A (Astrogeophys Section, Physics Dep, Ioannina Univ, Ioannina GR-45110, Greece) : The magnetic origin of coronal mass ejections. Asian J Phys 2007, 16(2-3), 123-46.

Coronal mass ejections (CMEs) are large-scale expulsion of coronal plasma and magnetic field. In this article, Reviews the physics of CME initiation which resides in the magnetic field. Magnetic free energy and magnetic helicity are accumulated into the corona, and the magnetic structure is gradually driven away from possible minimum energy states. At some point the system becomes so stressed that the force balance breaks down by the development of either an ideal instability/loss of equilibrium or reconnection. Subsequent failure of magnetic field confinement gives rise to a CME. Diverse apprqaches about the details of the processes leading up to CMEs have been developed and presented.

10 illus, 113 ref

015089   Naidu N E;Govender M (Astrophysics and Cosmology Res Unit, School of Mathematics, Univ of Kwazulu Natal, Durban 4041, South Africa, , Email: 203507365@ukzn.ac.za) : Causal temperature profiles in horizon-free collapse. J Astrophys Astr 2007, 28(4), 167-74.

Investigates the causal temperature profiles in a recent model of a radiating star undergoing dissipative gravitational collapse without the formation of a horizon. It is shown that this simple exact model provides physically reasonable behaviour for the temperature profile within the framework of extended irreversible thermodynamics.

2 illus, 13 ref

015088   Karlicky M (Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-25165 Ondrejov, Czech Republic) : Solar flare reconnection, plasmoid ejection, loop-top X-ray sources and associated radio bursts. Asian J Phys 2007, 16(2-3), 165-88.

The 2-D Magneto-Hydrodynamic (MHD) model of the flare magnetic field reconnection shows that a reconnection activity, changes of the magnetic topology and generation of waves are closely related. It is found that after the phase of a quasi-stationary reconnection in the extended current sheet above the flare arcade, the tearing mode instability produces moving (ejected) plas-moids which can interact and generate additional MHD waves. Then a mechanism of acceleration of electrons in the collapsing trap formed in the flare arcade below the current sheet is studied using the MHD and test particle models. Computing the X-ray emission of the accelerated electrons, it is shown that the acceleration process in the collapsing trap easily explains the formation of observed loop-top X-ray sources. Furthermore, the acceleration of electrons during the tearing and coalescence processes in the current sheet is studied by the 2-5-D particle-in-cell simulation. Finally, all these processes are discussed from the point of view of possible radio emissions. While shocks can contribute to the type II radio bursts, the super-thermal electrons trapped in plasmoids can generate the so-called drifting pulsating structures. Furthermore, regions with the MHD turbulence, e.g., plasma reconnection outflows, may manifest themselves as the lace or dm-spike bursts. The radio emission transmitted or reflected from periodic density structures, e.g., in ion-sound shocks, can generate the zebra-like bursts.

18 illus, 42 ref

015087   Karami K;Mohebi R (Phys Dep, Univ of Kurdistan, Pasdaran St., Sanandaj, Iran, Email: karami@iasbs.ac.ir) : Velocity curve analysis of the spectroscopic binary stars PV Pup, HD 141929, EE Cet and V921 Her by Nonlinear regression. J Astrophys Astr 2007, 28(4), 217-30.

Mohebi (2007), and Karami & Teimoorinia (2007) which derive a the orbital parameters of the spectroscopic binary stars by the nonlinear least squares of observed vs. curve fitting (o-c). Using the measured experimental data for radial velocities of the four double-lined spectroscopic binary systems PV Pup, HD 141929, EE Cet and V921 Her, author found both the orbital and the combined spectroscopic elements of these systems. Numerical results are in good agreement with those obtained using the method of Lehmann-Filhes.

12 illus, 8 tables, 13 ref

015086   Kang M S;Im S J;Jang T I;Park S W;Kim S M (Biosystems Engng Dep, Auburn Univ, 200 Tom E. Corley Building, Auburn, AL36849, USA, Email: junie@snu.ac.kr) : Detecting areal changes in tidal flats after sea dike construction using landsat-TM images. J Earth Syst Sci 2007, 116(6), 561-73.

Estimate changes in the area of tidal flats that occurred after sea dike construction on the western coast of South Korea using Landsat- TM images. Applying the ISODATA method of unsupervised classification for Landsat- TM images, the tidal flats were identified, and the resulting areas were quantified for each image. The area of tidal flats from a topographic map published in one year differs significantly from that shown in another, which appears to be attributable to the tide levels at the time of aerial photography. During the study period, the area of tidal flats, as estimated from Landsat-TM images, increased by 4.57 km² per year in the study areas. The tidal flats in the inner sea of Chunsu Harbor area increased by 200 m² per zone, while the accumulation for a number of inner sea areas within Asan Harbor area occurred at over 50 m² per zone. The results of this research may serve as the basis of an environmentallyªfriendly development plan for tidal flats.

7 illus, 4 tables, 29 ref

015085   Janardhan P;Ananthakrishnan S;Balasubramanian V (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: jerry@prl.res.in) : Insights from ground and space based observations of long lasting low density anomalies at 1 AU. Asian J Phys 2007, 16(2-3), 209-32.

The magnetic field in the heliosphere evolves in response to the photospheric field at its base. This evolution, together with the rotation of the Sun, drives space weather through the continually changing conditions of the solar wind and the magnetic field embedded within it. Given this broad framework, it appears that the solar sources of interplanetary, disturbances that travel outwards from the Sun could be due to many causes. Although the majority of them could be due to CME's, there are many instances where they may have been caused by flare related events or transient coronal holes. It is apparent that all these phenomena are linked to the underlying disturbances in the magnetic field and that they manifest in different ways depending on the local conditions on the Sun. This paper will describe the efforts made with the Ooty Radio Telescope (ORT), since 1992, in making systematic interplanetary scintillation (IPS) observations of the solar wind with an aim to track traveling interplanetary disturbances and try and trace their solar sources. Describes the insights gained from studies of long lasting (≥ 24 hours) low density solar wind anomalies that have been observed at 1 AU.

17 illus, 39 ref

015084   Jain C;Paul B;Joshi K;Dutta A;Raichur H (Physics and Astrophys Dep, Univ of Delhi, Delhi-110 007, Email: chetanajain11@yahoo.co.in) : Search for orbital motion of the pulsar 4U 1626-67: candidate for a neutron star with a supernova fall-back accretion disk. J Astrophys Astr 2007, 28(4), 175-84.

Results from a new search for orbital motion of the accretion powered X -ray pulsar 4 U 1626-67 using two different analysis techniques. X-ray light curve obtained with the Proportional Counter Array of the Rossi X-ray Timing Explorer during a long observation carried out in February 1996, was used in this work. The spin period and the local period derivative were first determined from the broad 2-60 keV energy band light curve and these were used for all subsequent timing analysis. In the first technique, the orbital phase dependent pulse arrival times were determined for different trial orbital periods in the range of 500 to 10,000 s. Determined a 3a upper limit of 13lt-ms on the projected semiªmajor axis of the orbit of the neutron star for most of the orbital period range, while in some narrow orbital period ranges, covering about 10% of the total orbital period range, it is 20 It-ms. In the second method, pulse arrival times at intervals of 100 s over the entire duration of the observation have been measured. The pulse arrival time data were used to put an upper limit on any periodic arrival time delay using the Lomb-Scargle periodogram. Obtained a similar upper limit of 10 It-ms using the second method over the orbital period range of 500-10,000 s. This puts very stringent upper limits for the mass of the compact object except for the unlikely case of a complete face-on orientation of the binary system with respect to line-of-sight. In the light of this measurement and the earlier reports, possibility of this system have been discussed being a neutron star with a supernovae fall-back accretion disk.

6 illus, 20 ref

015083   Jain C;Dutta A;Paul B (Phys and Astrophys Dep, Univ of Delhi, Delhi-110 007, Email: chetanajain11@yahoo.co.in) : Pulse phase dependence of the magnetar bursts. J Astrophys Astr 2007, 28(4), 185-96.

Reports results from a study of X-ray bursts from 3 magªnetar candidates (SGR 1806-20, SGR 1900+14 and AXP IE 2259+586). Searched for a pulse phase dependence of the X-ray burst rate from these sources. X-ray light curves were obtained with the Proportional Counter Array on-board the Rossi X-ray Timing Explorer during the periªods of intense burst activity in these sources. On detailed analysis of the three sources, It was found a very significant burst rate for all pulsar phases. However, some locations appear to produce bursts slightly more often, renªdering the non-isotropic distribution. Only in the case of SGR 1900+ 14, there is a clear pulse phase dependence of burst rate.

6 illus, 2 tables, 48 ref

015082   Gao P X;Li Q X;Zhong S H (National Astronomical Observatories/Yunnan Observatory, , CAS, Yunnan, China, Email: gpx@yabao.ac.cn) : Distribution of latitudes and speeds of coronal mass ejections in the northern and sourthern hemispheres in cycle 23. J Astrophys Astr 2007, 28(4), 207-15.

Distribution of latitudes and speeds of Coronal Mass Ejections (CMEs) in the northern and southern hemispheres in cycle 23, from September 1996 to December 2006, have been analyzed. By calculating the actual probability of the hemispheric distribution of the activity of the CME, we find that a southern dominance of the activity of the CME is shown to occur in cycle 23 from September 1996 to December 2006. The CME activity occurs at all latitudes and is most common at low latitudes. This should furnish evidence to support that CMEs are associated with source magnetic structures on a large spatial scale, even with transequaªtorial source magnetic structures on a large spatial scale. The latitudinal distribution of CMEs in the northern and southern hemispheres are no different from a statistical point of view. The speed distribution in the northern and southern hemispheres are nearly identical and to a good approximaªtion they can be fitted with a single lognormal distribution. This finding implies that, statistically, there is no physical distinction between the CME events in the southern and northern hemispheres and the same mechanism of a nonlinear nature acting in both the CME events in the northern and southern hemispheres. Conclusions of the study seem to suggest that the northern-southern asymmetry of the CME events is related to the northern-southern asymmetry in solar dynamo theory (Jiang et al. 2007).

3 illus, 1 table, 31 ref

015081   Dryer M (NOAA Space environment Center, National Weather Service, Boulder, Colorado 80305, USA) : Space weather simulations in 3D MHD from the sun to earth and beyond to 100 AU: a modeler's perspective of the present state of the art. Asian J Phys 2007, 16(2-3), 97-121.

Significant strides have been made to simulate and to forecast the state of the solar wind at Earth and beyond under both "quiet" and "solar event-driven" conditions. A key physical condition, the solar wind speed, has been successfully predicted thus far under real time operational conditions. This property includes equal proton and electron speeds by assuming charge neutrality. Still beyond pur reach, however, are conditions such as the IMF (interplanetary magnetic field, B) components, especially By and Bz, despite the efforts of various three-dimensional, magnetohydro-dynamic (3D MHD) modeling efforts. Predicting these plasma and IMF conditions or, explicitly, the timing of interplanetary shock arrivals at Earth in real time and at other planetary locations (Mars, for example), ex post facto, and at distant spacecraft locations (Ulysses, Voyager 1 and Voyager 2) near the heliospheric boundary is presently being attacked with some success. This paper discusses a kinematic model and some 3D MHD follow-on models that represent the present state of the art for predicting solar wind plasma and IMF conditions. Emphasis is placed on the urgent need to continually monitor physical conditions at the Sun and at several locations, such as the LI libration point, as benchmarks for model comparisons. This need for continuous benchmarking includes the IMF topological paths for shock-energized, gradual enhancements of solar energetic particle (SEPs) fluxes from impending shock waves. Local enhancements of energetic storm particles (ESPs) upon shock arrival at an observing spacecraft at Mars are also briefly discussed. These objectives are essential for geospace predictions for societal reasons described elsewhere.

12 illus, 73 ref

015080   Choudhary D P (Physics and Astronomy Dep, California State Univ, Northridge 18111 Nordhoff Street, Northridge, CA, 91330, USA) : Magnetic field of the coronal mass ejection source regions. Asian J Phys 2007, 16(2-3), 147-64.

The magnetic field of the sun is responsible for most of its visible dynamic features, including the most energetic events that can affect the near earth space environment, producing space weather. The solar magnetic field is generated below the visible layer (the photosphere) and erupts in to the solar atmosphere. The cross-section of the erupting filed structure at the photosphere is observed as an active region, above which there exists a complex three-dimensional magnetic dome. Many fundamental physical processes take place in and above active regions that govern the dynamics of the hot, magnetized plasma manifesting in the observed features including large magnetic explosions leading to the alteration of near earth space weather. In order to understand these processes, a detailed understanding of the origin and dynamics of the magnetic field is essential. In the recent past, there have been spectacular advances in various topics related to this field such as: the importance of magnetic helicity and its conservation on large scales to the structure and evolution of the 'magnetic field: the temporal evolution of magnetic field creating large-scale structure; thermal and magnetic instabilities leading to fine-scale structure; wave dissipation and reconnection providing coronal heating; and instability and non-equilibrium states leading to eruptions. Discuses the observational studies and theoretical models that are useful to understand the magnetic field configuration of the source region and coronal mass ejections that affect the interplanetary space weather.

8 illus, 108 ref

014040   Yumoto K (Space Environment Research Centre, Kyushu Univ, Hakozaki 6-10-1, Higashi-ku, Fukuoka-812-8581, Email: yumoto@serc,kyushu-u.ac.jp) : Space weather activities at SERC for IHY: MAGDAS. Bull Astr Soc India 2007, 35(4), 511-22.

Introduces MAGDAS project of Space Environment Research Center (SERC), Kyushu University (KU) for space weather. The new MAGDAS data can be used to monitor global electromagnetic and plasma environment change in geospace, and then to bring about a better understanding of the complex and compound Sun-Earth system. The SERC also conducts daily space weather "now casting", to train and educate KU students, and to globally disseminate space weather information to the scientific community and the general public.

9 illus, 15 ref

014039   Ueno S;Shibata K;Kimura G;Nakatani Y;Kitai R; Nagata S (Hida Observatory, Kyoto Univ, Kurabashira, Kamitakara City, GIFU 506-1314, Japan, Email: ueno@kwasn.kyoto-u.ac.jp) : CHAIN-project and installation of the flare monitoring telescopes in developing countries. Bull Astr Soc India 2007, 35(4), 697-704.

The Flare Monitoring Telescope (FMT) was constructed in 1992 at the Hida Observatory in Japan to investigate the long-term variation of solar activity and explosive events, as a project of the international coordinated observations programme (STEP). The FMT consists of five solar imaging telescopes and one guide telescope. The five telescopes simultaneously observe the full-disk Sun at different wavelengths around H-alpha absorption line or in different modes. Therefore, the FMT can measure the three-dimensional velocity field of moving structures on the full solar disk without the atmospheric seeing effect. The science target of the FMT is to monitor solar flares and erupting filaments continuously all over the solar disk and as many events as possible and to investigate the relationship between such phenomena and space weather. Now we are planning to start a new worldwide project called as "Continuous H-alpha Imaging Network (CHAIN)-project". As part of this project, we are examining the possibility of installing telescopes similar to the FMT in developing countries with cooperative help by the United Nations. We have selected Peru as the candidate country where the first oversea FMT will be installed, and are beginning to study the natural environment, the seeing conditions, the proper design of the telescope for Peru and the training and education programme of operating staff, etc.

5 illus, 6 ref

014038   Srivastava A K;Jagdev Singh;Dwivedi B N; Muneer S;Sakurai T;Ichimoto K (Applied Physics Dep, Insitute of Technology, Banaras Hindu Univ, Varanasi-221 005) : Fe XIV green/Fe XIII infrared line ratio diagnostics. Bull Astr Soc India 2007, 35(4), 457-63.

Author consider the first 27-level atomic model of Fe XIII (5.9 K <60> electron as well as proton collisional excitations and de-excitations, radiative cascades, radiative excitations and de-excitations. Radiative cascade is important but the effect of dilution factor is negligible at higher electron densities. The 3P₁ -3P₀ and 3P₂ -3P₁ transitions in the ground configuration 3s² 3p² of Fe XIII result in two forbidden coronal emission lines in the infrared region, namely 10747 and 10798 A. While the 5303 A green line is formed in the 3s² 3p ground configuration of Fe XIV as a 2P_3/2 ^-2P_1/2 magnetic dipole transition. The line-widths of simultaneously observed Fe XIV green and Fe XIII infrared forbidden coronal emission lines can be a useful diagnostic tool to deduce temperature and nonthermal velocity in the largescale coronal structures using intensity ratios of the lines as the temperature signature, instead of assuming ion temperature to be equal to the electron temperature. Since the line intensity ratios IG5303/IIR10747 and IG5303/I/R.10798 have very weak density dependence, they are ideal monitors of temperature mapping in the solar corona. The computed ratios will be compared with the recently obtained observations.

2 illus, 15 ref

014037   Shylaja B S (NO, , Bangalore Association for education, Jawaharlal Nehru Planetarium, Bangalore 560 001, Email: taralaya@vsnl.com) : Solar observations as education tools. Bull Astr Soc India 2007, 35(4), 705-8.

Solar observations are very handy tools to expose the students to the joy of research. Discuss brieflythe various experiments already done here with a small 6" Coude refractor, like rotation estimates using spots and Doppler measurements, identification of elements from solar spectrum (from published high resolution spectrum), limb darkening measurements, deriving the curve of growth (from published data). Also describe future plans to develop this as a platform for motivating students towards a career in basic science research.

2 illus, 2 ref

014036   Sankarasubramanian K;Hagenaar H (NO, ISRO Satellite Centre, Bangalore-560 017, Email: sankark@isac.gov.in) : Fine scale magnetic fields in and around a decaying active region. Bull Astr Soc India 2007, 35(4), 427-35.

High spatial resolution spectro-polarimetric observation of a decaying spot was observed with the Diffraction Limited Spectro-Polarimeter. The spatial resolution achieved was close to the diffraction limit (0."18) of the Dunn Solar Telescope. The fine scales present inside the decaying active region as well as surrounding areas were studied. Two interesting phenomenon observed are: (i) Canopy like structures are likely to be present in the umbral dots as well as in the light bridges providing evidence for field-free intrusion, (ii) There are opposite polarity loops present outside of the spot and some of them connects to the main spot and the surrounding magnetic features.

6 illus, 21 ref

014035   Rawat R;Alex S;Lakhina G S (NO, Indian Insitute of Geomagnetism, Plot No 5, Sector-18, New Panvel(w), Navi Mumbai-410 206, Email: rashmir@iigs.iigm.res.in) : Geomagnetic storm characteristics under varied interplanetary conditions. Bull Astr Soc India 2007, 35(4), 499-509.

Solar cycle-23 witnessed many successive intense X-ray solar flares and coronal mass ejections (CME) during the peak activity period, as well as in the descending phase of the cycle. Some of these emissions had large solar energetic particle events associated with them. When such solar ejecta impact the Earth's magnetosphere, they cause large scale disturbances in the geomagnetic field known as geomagnetic storms. Large variability in the occurrence characteristics of geomagnetic storms is controlled ultimately by the solar activity. Thus the changes in the interplanetary conditions are distinctly seen in the low latitude geomagnetic records as each storm event differs from the other. Several intense storm events of solar cycle-23 are analyzed for assessing the role of interplanetary magnetic field components B_y (east-west) and B_z (north-south) in controlling the generation and development of various types of storms.

4 illus, 1 table, 21 ref

014034   Rathinavelu G C;Sivaraman M;Satya Narayanan A;Somasundaram K (Physics Dep, Gandhigram Rural Institute, Gandhigram-624 302, Email: david _physics@yahoo.com) : MHD surface waves along the interfaces of the magneto sheath, boundary layer and magnetosphere with the effect of solar wind. Bull Astr Soc India 2007, 35(4), 481-6.

The magnetospheric boundary layer, which is the interface between the magneto sheath and the magnetosphere, has been considered to be the plasma slab surrounded by moving and static plasma media on either side. The compressibility effect on surface waves propagating along the slab has been discussed. The effect of variation of the boundary layer thickness is studied as a special case, since the observed variation of the boundary layer thickness leads to unstable modes due to Kelvin-Helmholtz instability. The solar wind driven magneto sheath plasma is considered as the moving plasma medium and the effect of the velocity of the solar wind is also taken into account.

3 illus, 40 ref

014033   Rajaram G;Reddy A C;Alyana R;Rathod J;Misra D S;Patil C G;Prasad M Y S (CSRE, IIT-B, Mumbai 400 076, Email: girijarajaram@gmail.com) : Proton events at geostationary altitude during 2005, their relationship to solar wind and IMF parameters and their geoeffectiveness. Bull Astr Soc India 2007, 35(4), 487-98.

Solar wind and IMF parameters from the ACE satellite at the Earth's dayside Lagrangian point LI, are examined during solar proton events of 2005 for 'shock' structures. The GOES-10 satellite at geostationary orbit (G) sees proton events in the 10-30 MeV energy range only when the flux of these particles exceeds (5 x 10^-1) protons/cm² .sec.sr. (also known as pfu). Such events are invariably followed at G by REE (Relativistic Electron Events) which commence with an RED (Relative Electron Dropout). During REE, the enhanced flux of > 2 MeV electrons can exceed (> 5 x 10₄ ) pfu, and can cause operational anomalies on geostationary satellite instruments. Such large proton events also trigger off at Earth (E), ssc type of storms with typical signatures in the geomagnetic indices Dst and Kp, and large Forbush decreases in the Cosmic Ray Neutron Monitor (CRNM) Count. Relationships between the various Space Weather parameters recorded at L₁ , G and E during Proton events, assume special importance from the point of view of Satellite Anomaly predictions.

8 illus, 2 tables, 25 ref

014032   Rabiu A B;Nagarajan N (Physics Dep, Federal Univ Technol, Akure, Nigeria, Email: tunderabiu@yahoo.com) : Inter relationships between the thickness, width and intensity of the equatorial electrojet in Indian sector. Bull Astr Soc India 2007, 35(4), 645-54.

The temporal variations of the thickness, width and current intensity of equatorial electrojet over Indian sector have been evaluated from a thick current shell format of continuous current distribution model of equatorial electrojet on quiet condition. The thick current shell model takes into account the vertical ionospheric currents; permits both the width and the thickness of the jet to be determined simultaneously. The EEJ intensity increases from dawn reaches the peak at about local noon and thereafter decays towards sunset. The thickness and width of equatorial electrojet EEJ exhibit consistent diurnal variations. The thickness decreases from about 0.06642° at dawn to the minimum at about 1100 hr LT and then begins to increase towards the dusk. The width increases with the sunrise, reaches maximum at about 1100 hr LT and then begins to decrease towards the dusk. The mean annual half-thickness and half-width for the solar minimum year 1986 (Sunspot number R = 13.4) is 0.0625 ± 0.0037° and 2.68 ± 0.23° respectively. The dynamics of the variation of electrojet intensity and thickness shows that electrojet shrinks as its intensity increases. The thick current shell model is shown to give better hourly representation of jet behaviour than thin shell format hitherto being used. The thin current shell model best fits only the near local noon jet observation. The transient variation of the jet thickness is explained in terms of the wind shears in consistency with the electrodynamics of the dynamo region.

3 illus, 3 tables, 26 ref

014031   Rabiu A B;Mamukuyomi A I;Joshua E O (Physics Dep, Federal Univ Technol, Akure, Nigeria, Email: tunderabiu@yahoo.com) : Variability of equatorial ionosphere inferred from geomagnetic field measurements. Bull Astr Soc India 2007, 35(4), 607-18.

The variability of equatorial ionosphere has been examined by using ground based geomagnetic field data of horizontal and vertical field intensities obtained at the isolated terrestrial equatorial station of Ibadan (07.22°N 03.58°E). The values of Sq daily variation rises from the early morning period to maximum at about local noon and falls to lower values towards evening. The ionospheric current responsible for the magnetic field variations is inferred to build up at the early morning periods and attain maximum intensity at about local noon. The daytime variation in resultant solar quiet daily variations Sq in horizontal and vertical field intensities Sq(H) and Sq(Z) respectively were generally greater than night time. The rising rate of the ionospheric Sq current is generally greater than the decay rate. The vertical daytime ExB drift velocity in the ionospheric F region and the daytime strength of the equatorial electrojet are inferred to have seasonal variation. The scattering of variation is more on the disturbed condition than the quiet condition. This is obviously due to the ionospheric disturbances originating from external drives, such as. space weather effects, storms, etc. The seasonal variation is attributed to seasonal shift in the mean position of the Sq current system of the ionospheric electroject and the electrodynamics effects of local winds. Magnitude of the annual means is greater in element H than Z at, any given condition.

11 illus, 19 ref

014030   Patil P T;Gurubaran S;Rajaram R;Sharma A K; Bhonsle R V (NO, Indian Insitute of Geomagnetism, New Panvel, Navi Mumbai-410 218, Email: iigkop@unishivaji.ac.in) : Mesospheric winds from 70 to 98 km altitude over low latitude station Kolhapur by a partial reflection radar. Bull Astr Soc India 2007, 35(4), 561-8.

Temporal variations of daily winds in the altitude region 70 -98 km from the data collected during June 2000 to April 2003 using partial reflection radar at Kolhapur (16.40°N. 74.15°E), India, are presented in this study. Sequential wind profiles are obtained using partial reflections. The horizontal component of mesospheric mean winds and their monthly variations are presented in detail. The motions implied by mesospheric drifts closely resemble movements of the neutral air. Detailed study of the seasonal variations of the zonal and meridional winds is presented.

4 illus, 13 ref

014029   Patel R P;Singh S;Singh A K;Singh R P (Atmospheric Research Laboratory, Physics Dep, Banaras Hindu Univ, Varanasi 221 005, Email: rppatel12@yahoo.co.in) : VLF whistler wave activity and effects of geomagnetic disturbances at low latitudes. Bull Astr Soc India 2007, 35(4), 655-61.

The disturbances on the solar surface lead to the enhanced injection of energetic charged particles into the inner rnagnetosphere, which modifies the electrodynamic features of ionosphere and rnagnetosphere. The electrodynamic properties control the generation and propagation characteristics of VLF waves. At Varanasi station, which is one of the low latitude stations in India, Recorded VLF waves from 1990 onwards. The source of VLF wave is natural lightning discharges. Whistler activity varies with latitude having maximum around 50ø geomagnetic latitude. The occurrence rate is low at low latitudes and also depends on the solar and geomagnetic conditions. Reports the results derived from the statistical analysis of whistler waves recorded at Varanasi during the period January 1990 - December 1999. The monthly occurrence rate shows maximum during January to March. Seasonal variations of the occurrence rate are also studied. In order to study the role of geomagnetic disturbances on the occurrence rate, used Kp index and its variation. It is observed that the occurrence probability monotonically increases with EKp values. Detailed result of occurrence of whistler waves during the main phase and recovery phase of geomagnetic storms is also presented.

3 illus, 1 table, 16 ref

014028   Patel K;Singh A K;Patel R P;Singh R P (Atmospheric Research Laboratory, Physics Dep, Banaras Hindu Univ, Varanasi 221 005, Email: abhay_s@rediffmail.com) : Ionosphere scintillations by sporadic-E irregularities over low latitude. Bull Astr Soc India 2007, 35(4), 625-30.

The observations of daytime ionospheric scintillation are attributed to E-region irregularities at high and equatorial latitudes. VHP amplitude scintillations recorded during the daytime period from 1991 to 1999 at low latitude station Varanasi (geomag. lat. = 14° 55' N, long. = 154° E) are analyzed to study the behaviour of sporadic-E irregularities during the active solar and magnetic periods. The daytime digital scintillation data have been analyzed to study some important parameters of scintillation producing sporadic-E irregularities like auto-correlation function, power spectral densities, signal de-correlation time etc. Reports the behaviour of these parameters under weak and strong scintillation conditions. The results are also discussed in the light of recent works.

4 illus, 7 ref

014027   Nugroho J T (NO, National Institute of Aeronautics and Space (LAPAN), Indonesia, Email: jalu@bdg.lapan.go.id) : Appearance of solar activity signals in Indian ocean dipole (IOD)phenomena and monsoon climate pattern over Indonesia. Bull Astr Soc India 2007, 35(4), 575-9.

From previous studies, it is known that interaction between ocean-atmosphere causes climate variability in the tropical Indian Ocean region as well as in Indonesia. It has also been proposed that solar activity affects Earth's climate globally and regionally. In this study, we report association between Indian Ocean Dipole (IOD) phenomena and cloud cover over western Indonesia. The statistical correlation coefficient (r) is found to be 0.64, for the period April 1976 to January 1996. By using wavelet analysis, we also find that solar signal appears strongly on IOD during December-February.

2 illus, 6 ref

014026   Najat M R;Al Ubaidi (Astronomy & Space Dep, College of Science, Baghdad Univ, Iraq, Email: najatmr10@yahoo.Com) : Developed numerical mapping technique. Bull Astr Soc India 2007, 35(4), 663-8.

An automated mapping technique for representing the hourly behaviour of trie" ionosphere was presented by Rush in 1976. The technique is based on updating the predicted monthly median maps of ionospheric parameters with hourly observations. The procedure was accomplished by computing the differences between the predicted medians and the hourly values of ionospheric parameters that are observed at specific locations on the globe. This technique provides the basis for extending and extrapolating the influence of an observation from the observing location to the region surrounding the observing location, this method is very complicated, so in our research we have used another newly developed method. Our programme suggests a new mapping technique method to draw the maps based on updating the monthly median of ionospheric parameters predicted with geographic coordinates.

11 illus, 6 ref

014025   Najat M R;Al Ubaidi (Astronomy and space Dep, College of Science, Baghdad Univ, Baghdad, Iraq, Email: najatmr10@yahoo.com) : Daily mid latitude F2 region critical frequency foF2 variation with daily sunspot number R. Bull Astr Soc India 2007, 35(4), 639-43.

Ionosonde data recorded at Kokubunji, Japan (Latitude 35.7 N; Longitude 139.5 E) during a year of low solar activity (1994) and high solar activity (1990) were used in our research work to study the correlation between daily sunspot numbers (R) and the daily mid-latitude F2-region critical frequency (foF2) for four seasons. There is a diurnal variation of (foF2) with (R). Trends found over the year of solar maximum (1990) are more positive in March and December, but negative in June and September. The year of solar minimum (1994) shows positive trends in June and September, but negative trends in March and December.

9 illus, 5 ref

014024   Mukherjee S;Ma W (School Environmental Science, Jawaharlal Nehru Univ, New Delhi-110 067, Email: drsaumitramukherjee@usa.net) : Change in heliophysical parameter influence on environment of the earth. Bull Astr Soc India 2007, 35(4), 591-7.

Terrestrial as well as extraterrestrial satellite data and environmental parameter records were correlated. It has been observed that some relationship exists in between the changes in environment and extraterrestrial phenomenon. The star flare changes the cosmic parameters. The nearest star of earth, the Sun, is found to be under the influence of the star flare. It has been observed that there is some relationship in between the planetary indices (Kp) Electron flux (E flux) Proton flux (P-flux) of Sun-Earth environment with the changes in therrnosphere. ionosphere, atmosphere and geosphere. The tsunami of 26 December 2004, abnormal snowfall in 2004-2005, sudden hike in global temperature and erratic monsoon in India and irregular rainfall in other parts of the world in 2006-2007 followed by snowfall and torrential rain are the impact of the star-sun-earth relationship.

6 illus, 26 ref

014023   Monstein C;Ramesh R;Kathriravan C (Institue of Astronomy, ETH Zurich, Scheuchzerstrasse7, CH-8092 Zurich, Switzerland, Email: monstein@astro.phys.ethz.ch) : Radio spectrum measurments at the Gauribidanur observatory. Bull Astr Soc India 2007, 35(4), 473-80.

During a campaign in December 2006, radio spectrum measurements over the frequency range 45-870 MHz were carried out at the Gauribida-nur observatory, located about 100 km north of Bangalore. The spectrometer used for the above purpose was subsequently configured for radio spectral observations of the solar corona. Describes, (i) radio frequency interference over some of the frequency bands 'protected' for radio astronomy, and (ii) 'first' solar radio burst observation and the above instrument.

11 illus, 6 ref

014022   Manohar Lal (Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Maharajanagar, Tirunelveli-627 011, Email: mlal@iigs.iigm.res.in) : Ozone variability at equatorial latitude during severe geomagnetic storm. Bull Astr Soc India 2007, 35(4), 569-74.

Influence of geomagnetic storms on the total ozone variability over equatorial and polar latitude region has been studied. Total Ozone Mapping Spectrometer (TOMS) and METEOR- 3 satellite have provided the long duration ozone variability from polar to equatorial latitude region. It has been considered only severe and strong geomagnetic storm events between 2000 and 2005. The polar region shows an increase in the total ozone column abundance after the onset of geomagnetic storm. The equatorial region shows the increase in ozone abundance before as well as after the onset of severe magnetic storm. The increase in the total ozone column density is localized over the Pacific ocean. Solar flares could be the cause for the increase in ozone column density before the onset of geomagnetic storms.

3 illus, 1 table, 13 ref

014021   Kebede A;Nair J;Smith G (NO, NC A&T State Univ, 1601 East Market Street, Greensboro, North Carolina NC 27411, USA, Email: gutaye@ncat.edu) : Space science curriculum design and research at NC A&T state university. Bull Astr Soc India 2007, 35(4), 735-7.

Recently, North Carolina Agricultural and Technical State University (NCAT) won one of the largest awards from NASA to develop curriculum and research capability in space science in partnership with NASA centres. National Institute of Aerospace, the North Carolina Space Grant, the American Astronomical Society and a number of institutions affiliated with NASA. The plan is to develop curricula and research platforms that prepare science, technology, engineering and mathematics (STEM) students to be employed by NASA. The research programme initially focuses on the study of space and atmospheric physics, and the development of a general capability in atmospheric/space science.

1 table, 2 ref

014020   Joshi V;Srivastava N (Astronomy and Astrophysics Div, Physical Research Laboratory, Ahmedabad-380 009) : Kinematics of eruptive quiescent prominences observed in He 304 A. Bull Astr Soc India 2007, 35(4), 447-55.

The observations taken in He 304 A by the EIT telescope aboard SoHO reveals that these images are extremely useful in tracing prominences because of the relatively sharper spine which is better visible in 304 A than in H_α. We have developed a geometric technique of measuring the height of prominences. The technique was applied to six eruptive quiescent prominence images recorded by EIT in He 304 A during January 2000-July 2003 in an attempt to identify the precursors of geo-effective caronal mass ejections (CMEs) that are associated with eruptive prominences. Our analyses show that prominence eruptions evolve through a pre-eruptive phase and an eruptive phase, which are characterized by lower velocities of several km s^-1 and eruptive velocities of several tens to hundreds of km s^-1, respectively. The analyses also show that during the pre-eruptive phase, a prominence rises at a constant acceleration of several cm s^-2 and not at constant velocity as reported by previous workers. We suggest that this phase is indicative of the precursor of prominence eruption. This might be useful in predicting the occurrence of an associated coronal mass ejection.

4 illus, 11 ref

014019   Jagdev Singh;Muneer S;Sakurai T;Ichimoto K (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: jsingh@iiap.res.in) : Magnetic nature of coronal loops. Bull Astr Soc India 2007, 35(4), 437-45.

It is generally believed that the magnetic pressure is much higher than the gas pressure in the coronal loops and these loops are isothermal in nature. We made systematic observations of four strong coronal emission lines in the visible and near infrared part of the spectrum for about 8 years. Two emission lines were observed at a time, making raster scans of a steady coronal region. We studied the variation of line widths of these lines and intensity ratios as a function of height. The relationship between the widths of these lines and intensity ratios indicates that the steady coronal loops are not magnetically isolated. These findings put restrictions on coronal loop models and indicate that the magnetic pressure in coronal loops may be much less than assumed. These results strongly suggest that magnetic field strength in the corona needs to be measured accurately.

6 illus, 40 ref

014018   Iba J K I et al (Instituto Geofisico del Peru, Observatorio de Ancon, Panamericana Norte, Ancon, Peru, Email: pepe@geo.igp.gob.pe) : Solar observing station for education and research in Peru. Bull Astr Soc India 2007, 35(4), 709-12.

Since 1937 Carnegie Institution of Washington made observations of active regions of the Sun with a Hale type spectro-helioscope in Huancayo observatory of the Institute Geofisico del Peru (IGP). IGP has contributed significantly to geophysical and solar sciences in the last 69 years. Now IGP and the Faculty of Sciences of the Universidad Nacional San Luis Gonzaga de lea (UNICA) are planning to refurbish the coelostat at the observatory with the support of National Astronomical Observatory of Japan. It is also planned to install a solar Flare Monitor Telescope (FMT) at UNICA, from Hida observatory of Kyoto University. Along with the coelostat, the FMT will be useful to improve scientific research and education.

4 illus, ref

014017   Haubold H J;Mathai A M;Saxena R K (NO, , Offic for Outer Space Affairs, United Nations, Vienna International Centre, P.O. Box 500, A 1400, Vienna, Austria, Email: hans.haubold@unvienna.org) : Solution of fractional reaction-diffusion equations in terms of the H-function. Bull Astr Soc India 2007, 35(4), 681-9.

This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation associated with the Caputo derivative as the time-derivative and Riesz-Feller fractional derivative as the space-derivative. The solution is derived by the application of the Laplace and Fourier transforms in closed form in terms of the H-function. The results derived are of general nature and include the results investigated earlier by many authors, notably by Mainardi et al. (2001, 2005) for the fundamental solution of the space-time fractional diffusion equation, and Saxena et al. (2006a. b) for fractional reaction-diffusion equations. The advantage of using Riesz-Feller derivative lies in the fact that the solution of the fractional reaction-diffusion equation containing this derivative includes the fundamental solution for space-time fractional diffusion, which itself is a generalization of neutral fractional diffusion, space-fractional diffusion, and time-fractional diffusion. These specialized types of diffusion can be interpreted as spatial probability density functions evolving in time and are expressible in terms of the H-functions in compact form.

19 ref

014016   Hamid M K;Al Naimiy (College of Arts and Sciences, Sharjah Univ, P.O. Box 27272, UAE, Email: alnaimiy@sharjah.ac.ae) : International heliophysical year and basic space science in West Asia. Bull Astr Soc India 2007, 35(4), 727-33.

Summarizes the IHY and BSS activities in West Asia and their importance in many Arab countries, such as Algeria, Egypt, Iraq, Jordan, Kuwait, Qatar, Saudi Arabia, UAE, etc. BSS future plans for some of these countries are as follows: It is proposed by the astronomers from the Arabian Gulf Region to build the Gulf Observatory on top of Jabal Shams (2980 msl) which will have a 2-3 m optical telescope. Libya signed a contract with a French company for building an observatory which will have a 2-m optical robotic telescope. It is also proposed to rebuild the Iraqi National Astronomical Observatory (INAO) which was destroyed during the two wars. It is planned to build a 5-6 m optical telescope and a small solar telescope on the top of Korek mountain, which has excellent observing conditions.

2 illus, 11 ref

014015   Durga Prasad K;Somayaji T S N;Appala Naidu P; Arunamani T;Indira Devi M;Madhusudhana Rao D N (Post Graudate Courses, Maharajah's College, Vizianagaram-535 001) : Two-dimensional model study of latitudinal, seasonal and solar activity variation in transition height in the D-region. Indian J Phys 2007, 81(5-6), 521-30.

Height of transition above which the water cluster ions give way to molecular ions, is an important aspect of the D-region of the ionosphere. A recent and comprehensive two-dimensional neutral constituent model, SOCRATES, from NCAR has been used in conjunction with an appropriate ion chemical scheme to obtain ion composition and the transition height. The latitudinal and seasonal variation in the transition height for low and high solar activity conditions has been studied. It is found that the transition from water clusters to molecular ions generally occurs at higher altitudes in solar minimum than in maximum. At mid latitudes, an asymmetry about the equator is discernible. A perceptible seasonal variation exists at middle and high latitudes.

3 illus, 18 ref

014014   Dountio E G;Njomo D;Fouda E;Simo A (Physics Dep, Faculty Science, Yaounde Univ, LATEE, Cameroon, Email: eguemen@yahoo.com) : Radiative transfer model in the atmosphere and experimental solar data of Yaounde location. Bull Astr Soc India 2007, 35(4), 581-90.

In order to produce simulated data on solar irradiation on the earth's surface, we attempted to improve a tridimensional radiative transfer model which takes into account different inhomogeneities of the atmosphere. Those inhomogeneities have been shown to have a significant effect on solar radiation on the earth's surface. In this paper, the results of the model are compared with experimental solar data and improvements are made on the model to match the data. Two scales were used to compare numerical results with experimental data. A good correlation was found in the daily scale. For the hourly scale, a polynomial correlation was established between numerical data and experimental data.

5 illus, 1 table, 17 ref

014013   Damtie B;Lehtinen M;Orispaa M;Vierinen J (Physics Dep, Bahir Dar Univ, P O Box 79, Bahir Dar, Ethiopia, Email: bayliedamtie@yahoo.com) : Optimal long binary phase code mismatched filter pairs with applications to ionospheric radars. Bull Astr Soc India 2007, 35(4), 619-23.

Radars have been used extensively for ionospheric studies. In an ionospheric radar measurement one usually implements different types of codes and the choice largely depends on the geophysical phenomenon under investigation. As a result many kinds of coding and decoding methods have been used including binary phase codes. In ionospheric physics the performance of binary phase codes are usually investigated in terms of spatial and temporal resolution. This is done usually by employing a matched filter, which creates unwanted side lobes at the output of the receiver. These side lobes can be eliminated by using a mismatched filter. But there is an associated loss in signal-to-noise ratio (SNR). Presentes long optimal binary phase code-mismatched filter pairs that may be used in several applications including ionospheric radar measurements. This was done by investigating 1.04 x 10⁹ number of binary phase codes.

1 table, 11 ref

014012   Chakraborty S K;Hajra R (Physics Dep, Raja Peary College, Uttarpara, Hooghly-712 258, Email: skchak2003@yahoo.com) : Solar control of ambient ionization of the ionosphere near the crest of the equatorial anomaly in the Indian zone. Bull Astr Soc India 2007, 35(4), 599-605.

Long term (1979-90) total electron content (TEC) data have been analyzed to show its dependence on EUV radiation from the sun. TEC obser-vation-has been made from Calcutta (22.58° N, 88.38° E geographic, dip: 32ø N), situated virtually below the northern crest of equatorial ionization anomaly. Day to day changes in TEC at different local times do not show any significant correlation with F10.7 solar flux. A good correlation is, however, observed between F10.7 solar flux and monthly mean TEC when both are considered on long term basis, i.e., either in the ascending (1986-90) or in the descending (1979-85) phases. In the early morning hours correlation coefficient maximizes around 0800-1000 1ST interval. The flux independent nature of diurnal TEC is prominent around the noon time hours of few months with F10.7 values greater than 150. Variation of TEC for the whole time period (1979-90) also exhibits a prominent hysteresis effect. A remarkable feature of hysteresis effect is its local time dependent nature. Solar flux normalized TEC exhibit clear seasonal dependence with asymmetrical variations in the two equinoxes. A further normalization leads to prominent local time dependent feature. Based on solar flux, seasonal and local time dependent features of TEC an empirical formula has been developed to represent the TEC variation in the early morning hours. It yields a quantitative estimate of solar flux dependent nature of TEC variation.

6 illus, 20 ref

014011   Bhonsle R V;Sharma A K;Patil P T;Powar S A; Waichal P P;Vhatkar R S;Patil K J;Samant J S (Physics Dep, Shivaji Univ, Kolhapur, Email: rvbhonsle@yahoo.co.in) : Proposal for creating a centre for resarch in solar terrestrial physics as an interdepartmental activity during IHY at Shivaji university, Kolhapur (16.40°N, 74.15°E). Bull Astr Soc India 2007, 35(4), 713-16.

Describes teaching and R & D activities presently being carried out in the solar-terrestrial Physics at the Space Science laboratory. Department of Physics. Shivaji University, Kolhapur. A variety of solar and geophysical ground based experiments are available, which can be operated on a regular basis during IHY, with financial help from the government funding agencies in India. The main purpose is to briefly describe experimental research facilities of relevance to IHY.

7 illus, ref

014010   Ansari I A (Physics Dep, Aligarh Muslim Univ, Aligarh-202 002, Email: iaaamuphysics@gmail.com) : Relation between low latitude Pc3 magnetic micropulsations and solar wind. Bull Astr Soc India 2007, 35(4), 523-31.

Pc3 geomagnetic pulsations are quasi-sinusoidal variations in the earths magnetic field in the period range 10-45 seconds. These pulsations can be observed in a number of ways. However the application of ground based magnetometer arrays has proven to be one of the most successful methods of studying the spatial structure of hydromagnetic waves in the earth's magne-tosphere. The solar wind provides the energy for the earth's magnetospheric processes. Pc3-5 geomagnetic pulsations can be generated either externally or internally with respect to the magnetosphere. The spatial and temporal variations observed in Pc3 occurrence are of vital importance because they provide evidence which can be directly related to wave generation mechanisms both inside and external to the magnetosphere. At low latitudes (L < 3) wave energy predominates in the Pc3 band and the spatial characteristics of these pulsations have received little attention in the past. An array of four low latitude induction coil magnetometers was established in south-east Australia over a longitudinal range of 17 degrees at L=1.8 to 2.7 for carrying out the study of the effect of the solar wind velocity on these pulsations. Digital dynamic spectra showing Pc3 pulsation activity over a period of about six months have been used to evaluate Pc3 pulsation occurrence. Pc3 occurrence probability at low latitudes has been found to be dominant for the solar wind velocity in the range 320- 700 Km s^-1. The results suggest that solar wind controls Pc3 occurrence through a mechanism in which Pc3 wave energy is converted through the magnetosheath and coupled to the standing oscillations of magnetospheric field lines.

5 illus, 3 tables, 30 ref

014009   Ambastha A (Udaipur Solar Observatory, , Udaipur-313 001, Email: ambastha@prl.res.in) : Signatures of large flares on photospheric magnetic and velocity fields. Bull Astr Soc India 2007, 35(4), 419-26.

Analysed the spatial and temporal evolution of photospheric magnetic and doppler velocities in active regions, particularly in the superactive region NOAA 10486, to detect pre- and post-flare changes. These findings have been compared with recent reports by other workers, and significance of these results has been discussed. Helioseismic response of large flares, and the role of sub-photospheric flows in flare-productive as compared to that in less flare-productive active regions are presented.

3 illus, 65 ref

014008   Alyana R;Rajaram G;Rathod J;Reddy A C;Misra D S;Patil C G;Prasad M Y S (NO, , CSRE, IIT-B, Powai, Mumbai 400 076, Email: radha_alyana@rediffmail.com) : Differences between CME associated and CH associated red events during 2005. Bull Astr Soc India 2007, 35(4), 539-47.

12 illus, 2 tables, 16 ref

014007   Aggarwal M;Joshi H P;Iyer K N;Patra A K; Thampi S V (Physics Dep, Saurashtra Uinv, Rajkot, Email: asmalini@rediffmail.com) : Equatorial spread F using L-band and VHF radar. Bull Astr Soc India 2007, 35(4), 631-37.

An important component of ionospheric plasma irregularity studies at low latitudes involves the study of the plasma bubbles which produce intense scintillations of trans-ionospheric satellite signals. In order to investigate the dynamics of plasma density irregularities of different scale sizes, a campaign of multi-technique observations was conducted during 11 to 15 Sep.05 at Gadanki (geog.13.45°N, 79.17°E, dip latitude 6.4°N), an Indian station. A low latitude spread F event occurred during the campaign on the night of 15 Sep.05. The observations were made using dual frequency GPS receiver and VHP coherent backscatter radar from Gadanki and two ionosondes with some latitudinal separation, from Trivandrum and SHAR. Range type spread F on ionograms and radar plume signatures on range-time-intensity maps of the VHF radar were observed. Using the GPS receiver, the amplitude scintillation index (S₄ ) enhancements by 0.36 and 0.39 with two depletions in total electron content (5 and 12 TECU) are seen. The vertical plasma drift velocity is observed by ionosonde to be high (<126>35 m/s) which maximized around 1915 LT. which coincided with onset of range type spread F over the magnetic equator. Trivandrum. The irregularities are observed first at Trivandrum at 1915 hrs, thereafter by GPS receiver and later by VHF radar (off-equatorial station) indicating that the observed bubble is drifting eastward.

5 illus, 7 ref

010942   Saravanan T;Ponnudurai R (Library & Information Science Dep, Annamalai Univ, Tamil Nadu) : Report on the Potential aspects of research in astronomy in G7 countries : a bibliometric analysis. IASLIC Bull 2006, 51(3), 169-77.

Bibliometric analysis enables identification of potential areas of research in any discipline. An attempt has been made 10 identify research output areawise in the science of astronomy. This study relates to all publications from all G7 countries and India. This study encompasses papers relating to experimell1al studies on the practice and theory and the mathematical aspects of astronomy as well as application oriented research and those on the general nature of and new developments in the field and other areas of interest.

7 tables, 10 ref

010024   Vishwakarma R G;Narlikar J V (Unidad Academica de Matematicas, Universidad Autonoma de Zacatecas, C.P.98068, Zacatecas, ZAC, Mexico) : Modeling repulsive gravity with creation. J Astrophys Astr 2007, 28(1), 17-27.

There is a growing interest among cosmologists for theories with negative energy scalar fields and creation, in order to model a repulsive gravity. The classical steady state cosmology proposed by Bondi, Gold & Hoyle in 1948, was the first such theory which used a negative kinetic energy creation field to invoke creation of matter. It was emphasized that creªation plays a very crucial role in cosmology and provides a natural explaªnation to the various explosive phenomena occurring in local (z <60>0.1) and extra galactic universe. Author exemplify this point of view by considering the resurrected version of this theory - the quasi-steady state theory, which tries to relate creation events directly to the large scale dynamics of the universe and supplies more natural explanations of the observed phenomena. Although the theory predicts a decelerating universe at the present era, it explains successfully the recent SNe Ia observations (which require an accelerating universe in the standard cosmology), as we shownin this paper by performing a Bayesian analysis of the data.

2 illus, 44 ref

010023   Srivastava A K;Dwivedi B N (Applied Phys Dep, Inst of Technol, Banaras Hindu Univ, Varanasi-221 005) : Oblique propagation and dissipation of alfven wave in coronal holes. J Astrophys Astr 2007, 28(1), 1-7.

Investigates the effect of viscosity and magnetic diffusivity on the oblique propagation and dissipation of Alfven waves with respect to the normal outward direction, making use of MHD equations, density, temperature and magnetic field structure in coronal holes and underlying magnetic funnels. It was found that reduction in the damping length scale, group velocity and energy flux density as the propagation angle of Alfven waves increases inside the coronal holes. For any propagation angle, the energy flux density and damping length scale also show a decrement in the source region of the solar wind (<60> 1.05 R) where these may be one of the priªmary energy sources, which can convert the inflow of the solar wind into the outflow. In the outer region (<62> 1.21 R), for any propagation angle, the energy flux density peaks match with the peaks of MgX 609.78 Angstrom and 624.78 Angstrom linewidths observed from the Coronal Diagnostic Spectrometer (CDS) on SOHO and the non-thermal velocity derived from these observations, justify the observed spectroscopic signature of the Alfven wave dissipation.

4 illus, 14 ref