Ionospheric effects of transient celestial X-ray and gamma-ray events     

K. Kasturirangan  U. R. Rao  D. P. Sharma  R. G. Rastogi  S. C. Chakravarty 《Astrophysics and Space Science》1976,42(1):57-62

The paper presents the results on investigations of the ionospheric effects arising out of the transient celestial events at X-ray and gamma-ray energies such as that from X-ray novae and cosmic gamma-ray bursts. The VLF data recorded at Ahmedabad corresponding to the 164 kHz transmission from Tashkent are examined to see whether there are any observable effects time coincident with the transit of the X-ray novae Cen X-4 and Cet X-2 around their intensity maxima. Besides, the VLF data have also been examined in relation to the cosmic gamma-ray bursts detected by Vela, IMP-6 and OSO-7 satellites.Theoretical computations are carried out for estimating electron density enhancements using the available data on intensities and energy spectra for these events. Further, the observational resutls are explained in terms of these theoretical calculations.Presently at Indian Space Research Organization, Bangalore, India.Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.  相似文献   

RARE GASES IN BANSUR,UDAIPUR AND MADHIPURA CHONDRITES     

K. Gopalan  M.N. Rao 《Meteoritics & planetary science》1976,11(2):131-136

We have analysed three Indian meteorites — Bansur, Udaipur and Madhipura — for the elemental and isotopic composition of Ne, Ar, Kr and Xe and determined their radiation and gas-retention ages. It is found that Udaipur belongs to the group of unequilibrated ordinary chondrites and Madhipura probably belongs to the group of shocked hypersthene chondrites.  相似文献   

Solar Activity and the Semidiurnal Component of Lunar Daily Variation in H at Alibag     

N. S. Sastri  D. R. K. Rao 《Geophysical Journal International》1974,38(2):417-421

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Landscape analysis for pedo-geomorphological characterization in part of basaltic terrain,central India using remote sensing and GIS     

M. G. Raghavendra Reddy  G. P. Obi Reddy  A. K. Maji  K. Nageshwara Rao 《Journal of the Indian Society of Remote Sensing》2003,31(4):271-282

In the present study, an attempt has been made to analyse IRS-ID LISS-III satellite data in conjunction with field observations for geomorphological mapping and pedo-geomorphological characterisation in Mohgaon area of Nagpur district, Maharashtra. Analysis of satellite data reveals distint geomorphological units viz., plateau top, isolated mounds, linear ridges, escarpments, plateau spurs, subdued plateau, rolling plains, pediments, narrow valleys and main valley floor. Soil profiles, studied on different identified landforms, showed variation in site and morphological charactaristics. Moderate soil erosion occurs on plateau top, isolated mouds, plateau spurs, rollinmg plains and pediments. Severe erosion was identified on escarpments and subdued plateau and narrow valleys suffer very slight erosional hazards. Moderately well drained soils were found on rolling plains, pediments, narrow valleys and main valley floor. Well drained soils were noticed on plateau top and plateau spurs. Very shallow soils were found on the plateau top and isolated mounds. Shallow soils are found in linear ridges, escarpments, plateau spurs and rolling plains. Moderately deep and deep soils are found on subdued plateau, pediments and main valley floor. The landform-soil relatioinship reveals that the soils on the plateau top and isolated mounds are very shallow, well drained, clay textured. The soils on the narrow valleys and main valley floor are deep, moderatly well drained, and clayey in texture. It also indicates that landform-soil processes are governed by physiographic position, drainage, slope and erosion conditions of the area. The present study reveals that the analysis of remotely sensed data in conjunction with field observations in GIS will be of immense help in geomorphology mapping, analysis of landform-soil relationships and generation of their geo-spatial database.  相似文献   

Behaviour of masonry structures during the Bhuj earthquake of january 2001     

K. S. Jagadish  S. Raghunath  K. S. Nanjunda Rao 《Journal of Earth System Science》2003,112(3):431-440

A variety of masonry structures suffered damage during the recent Bhuj earthquake. Some of the traditional masonry structures had no earthquake resistant features and suffered considerable damage. This paper attempts to evaluate the behaviour of masonry structures based on the type of masonry used in places like Bhuj, Anjar, Bhachau, Morbi, Samakhyali and several other places. Quite a few masonry buildings had used earthquake resistant features like lintel bands and corner reinforcements. The cracking and failure patterns of such buildings have also been examined. The paper concludes with a discussion on the relevance of the current codal provisions for earthquake resistance of masonry structures and the direction of further research in the area.  相似文献   

Groundwater prospecting and management in an agro-based rural environment of crystalline terrain of India     

N. Subba Rao 《Environmental Geology》2003,43(4):419-431

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The Indian summer monsoon as revealed by the NCMRWF system     

P. L. S. Rao  U. C. Mohanty  P. V. S. Raju  Gopal Iyengar 《Journal of Earth System Science》2003,112(1):95-111

In this study, we present the mean seasonal features of the Indian summer monsoon circulation in the National Centre for Medium Range Weather Forecasting (NCMRWF) global data assimilation and forecast system. The large-scale budgets of heat and moisture are examined in the analyzed and model atmosphere. The daily operational analyses and forecasts (day 1 through day 5) produced for the summer seasons comprising June, July and August of 1995 and 1993 have been considered for the purpose. The principal aim of the study is two-fold. Primarily, to comprehend the influence of the systematic errors over the Indian summer monsoon, secondarily, to analyze the performance of the model in capturing the interseasonal variability. The heat and moisture balances show reduction in the influx of heat and moisture in the model forecasts compared to the analyzed atmosphere over the monsoon domain. Consequently, the diabatic heating also indicates reducing trend with increase in the forecast period. In effect, the strength of Indian summer monsoon, which essentially depends on these parameters, weakens considerably in the model forecasts. Despite producing feeble monsoon circulation, the model captures interseasonal variability realistically. Although, 1995 and 1993 are fairly normal monsoon seasons, the former received more rainfall compared to the latter in certain pockets of the monsoon domain. This is clearly indicated by the analyzed and model atmosphere in terms of energetics.  相似文献   

Preface     

G.V. Rao  S. Raman  M.P. Singh 《Pure and Applied Geophysics》2003,160(1-2):1-2

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Cyclone track prediction by a quasi-Lagrangian limited area model     

K. Prasad  Y. V. Rama Rao 《Meteorology and Atmospheric Physics》2003,83(3-4):173-185

Summary. ?Cyclone track predictions in the Indian seas (Bay of Bengal and Arabian Sea) with a quasi-Lagrangian model (QLM) have been attempted. QLM has a horizontal resolution of 40 km and 16 sigma levels in the vertical. It is integrated in a domain of about 4400 × 4400 km². A new initialization procedure to provide initial fields for running the model has been designed. The initialization procedure consists of updating the global model forecasts, used as first guess, provided by the National Center for Medium Range Weather Forecasting (NCMRWF), New Delhi. A new version of IMD’s operational optimum interpolation scheme has been created to suit the QLM grid structure. Lateral boundary conditions are computed from the extended forecasts of NCMRWF. The track forecasts in each case show a reasonable skill of the forecast model in predicting the direction of movement within acceptable limits of forecast errors, which are comparable to some of the best models operated by advanced NWP centers of the world. Even the recurving storms are well predicted. Evolution of the vertical motion fields are also studied which reveal some interesting features, which are described in detail in the text. The composited vertical motion fields are projected against observed rainfall distribution, which show a good spatial correspondence. Received August 9, 2001; revised March 12, 2002; accepted June 17, 2002 Published online: May 8, 2003  相似文献   

Circulation characteristics over the Himalayas during winter season     

P. L. S. Rao 《Meteorology and Atmospheric Physics》2003,83(1-2):19-33

Summary ?During winter season, atmospheric systems, which traverse from west to east interact with the Himalayan massif and produce widespread rainfall over North India. In this study, we made an endeavor to examine the mean circulation features and large-scale budgets of kinetic energy, heat and moisture over Himalayas and the adjoining domain for winter season. The time-mean circulation is bifurcated into stable mean and transient eddy parts and examined the mean component of the circulation. The uninitialized daily analyses of European Centre for Medium range Weather Forecasts (ECMWF) for five winter seasons (1986–90) comprising December, January and February (DJF) have been used for the purpose. We noticed certain zones of strong activity over Iran, Afghanistan, and West China regions during winter season. These are characterized by intense vertical motions, cyclonic vorticity and adiabatic generation of kinetic energy. The features noticed over these zones include strong horizontal convergence of heat and moisture. These zones are further characterized by massive adiabatic conversion of available potential energy to kinetic energy. These features are conducive for the growth of atmospheric systems, which traverse over the zones and produce precipitation subsequently. Received November 16, 2000; revised February 5, 2002  相似文献