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1.
K. K. Singh R. P. Patel J. Singh B. Kumar A. K. Singh R. P. Singh B. L. Koul Lalmani 《Journal of Earth System Science》2008,117(3):219-225
In this paper, we report observations of unusual whistlers recorded at Jammu (geomag. lat. = 22°26′N; L = 1.17), India on March 8, 1999 during the daytime. They are interpreted as one-hop ducted whistlers having propagated along
higher L-values in closely spaced narrow ducts from the opposite hemispheres. After leakage from the duct, the waves might have propagated
in the earth-ionosphere waveguide towards the equator in surface mode. Tentative explanation of the dynamic spectra of these
events is briefly presented. 相似文献
2.
The aim of the present study is to investigate the lineaments of Kolli hills of Tamil Nadu State for which CARTOSAT-1 satellite’s DEM output has been made use of. The extracted lineaments were analysed using ArcGIS and Rockworks software. The total number and length of lineaments are 523 and 943.81 km, respectively. Shorter lineaments constitute about 3/4th of the total number of lineaments. The density of the lineaments varies from 0 to 7.41 km/km2, and areas of very high to high density are restricted to the south central, central and north eastern parts, and these areas reflect the high degree of rock fracturing and shearing which makes these areas unsuitable for the construction of dams and reservoirs. However, these areas could be targeted for groundwater exploitation as they possess higher groundwater potential. The lineaments are oriented in diverse directions. However, those orienting in ENEWSW, NE-SW and NW-SE are predominating followed by those oriented in sub E-W and sub N-S directions. These orientations corroborate with results of previous regional studies and with orientations of prominent geological structures and features of the study area. Distinct variation in the predominant orientations of lineaments of varied sizes is observed, while the shorter ones are oriented in either NW-SE or NNW-SSE directions, the longer ones are oriented in either NE-SW or ENE-WSW. A comparative analysis of lineament datasets of the eight azimuth angles and the final lineament map underlines the need to extract lineaments from various azimuth angles to get a reliable picture about the lineaments. 相似文献
3.
Glaciers in Himalaya have been studied with respect to their mass balance to assess their response, if any, to global warming. Naradu glacier in the Baspa Valley of Himachal Pradesh is one such glacier that has been studied in the backdrop of the impact of inter- and intra-annual variation in weather parameters on the health of glaciers. The trends in seasonal and monthly mean temperatures from 1994 to 2003 show an interesting shift of peak summer (late August–September) and winter seasons (February–March). The data also suggest night warming during summer (June, August, and September) and winter (November, January, April), and cooling during peak summer seasons (July) and very cold during winter (December, February, March). The fluctuation in ELA, snout position and surface ablation of Naradu glacier is attributed to variation in albedo of rock debris and valley walls from season to season and year to year. 相似文献
4.
Mapping salt-affected soils in Sangrur district (Punjab) using aerial photo-interpretation technique
P. K. Sharma Jawahar L. Sehgal K. R. Sharma 《Journal of the Indian Society of Remote Sensing》1976,4(1-2):43-54
A detailed-reconnaissance soil survey of the Sangrur district was undertaken through systematic aerial photo-interpretation technique and a soil map on 1: 50,000 scale showing the association of soil series prepared. The salt-affected soils have been grouped into 4 soil associations and 8 soil series based on the diffrences in texture, drainge, profile development and degree of deterioration. The salt-affected soils are found both in plains and Channels. The piain unit without distinct parcelling (barren) white and fine textured tones represented the association of salic Natraqualfs (Ghabdan series) and Aquic Natruststalfs (Kaheru series). The piain units partly cultivated whitish-gray, fine to medium textured tones consisted of a association of Natraquic Calciorthids (Langrian and Narikc series) and Natraquic Camborthids (Isri Series). Lastly, the piain units with pattern of dark-tone and light mottles (mottled-iones,) distinct parceiling, cultivated consists of Typic Ustochrepts (Balewal series), Aquic Camborthids (Phaguwala series) and Natraquic Calciorthids (Marike series). The filled up Channels whitish-gray tones, concave relief, cultivated comprise wet soils (Jatwan series) which have been classified as Aeric Halaquepts. It is found that about 17% of the mapped area in Sangrur district is salt-affected, out of which 12% consisiing Ghabdan, Kaheru, Langrian and Isri series is severely salt-affected and rest 5% consisting, Phaguwala, Narike and Jatwan series is moderately to slightly affected. 相似文献
5.
Sangla valley is situated at an altitude of ~ 3500 m above mean sea level and lies in the Kinnaur district of Himachal Pradesh.
It is fed by river Baspa, a tributary of river Sutlej, that entrenches through the Quaternary glaciogenic deposits before
emerging out of the valley and joining the river Sutlej at Karcham. The unstratified to stratified glaciogenic deposits consist
of large boulders to fine silt and are classified into four major depositional facies on the basis of sedimentary texture
and depositional environment. The facies — basal conglomerates, debris flow, water/sheet flow and laminites — represents the
change in the environment of deposition from glaciofluvial to lacustrine and also the extent of the glacier to the valley
floor during late Quaternary. 相似文献
6.
Ranjna Bakaya R. R. Rausaria P. K. Koul P. N. Khosa 《Astrophysics and Space Science》1989,151(1):103-113
Evolution of electron energy distributions have been studied by combining small-angle scattering with analytical treatment of large-angle collision using the Monte-Carlo technique. By use of these, the distributions and energy loss have been calculated as functions of column density, the heating functions have been calculated at different depths of the solar atmosphere. From the heating functions, an increase in temperature produced by the electrons at different column densities has been computed. It is found that rise in temperature increases with an increase in incident electron energy. 相似文献
7.
A feasibility study has been carried out to assess the potentialof an Artificial Neural Network (ANN) for determiningthe direction of incidence of an Atmospheric Cerenkov Event(ACE) from the arrival-time information registered by aspaced-array of wide-angle Cerenkov detectors. Theresults obtained so far, using both, simulated and experimental data, indicate that a properly-trained net can yield a degree of accuracy which is comparable with what is achieved through the conventional 2-minimization, wavefront-fitting procedure. 相似文献
8.
Fine time variation of hard X-rays has been explained in terms of a spread in the angle of incidence of the source electrons in non-thermal thick-target model for bremsstrahlung generation. The electron energy and angular distributions have been calculated by combining small angle scatterings using analytical treatment with a large angle collision using Monte Carlo calculations as a function of column density. The incidence angles of electrons are taken as 0, 30, and 60°. Using the Bethe-Heitler cross section and the above calculated electron distributions, the bremsstrahlung flux for different photon energies as a function of column density has been studied. The computed X-ray pulse as a function of column density has been converted into time profile. It corresponds well with the observed fine time structure. The calculated spectra of X-rays at the peak and valley are also consistent with the observations. The variation of photon flux with time has also been computed for photon energies 20, 50, and 100 keV for 90 and 180° observation angles together with the changes in spectral shapes of photon energy spectrum at different times for 90 and 180° observation angles. 相似文献
9.
H. S. Rawat V. K. Senecha R. C. Rannot M. L. Sapru A. K. Tickoo C. L. Bhat R. K. Koul H. Razdan S. C. Tonwar 《Astrophysics and Space Science》1989,151(1):149-156
The Gulmarg gamma-ray telescope (threshold energy 6 TeV) was tracking Cygnus X-3 on four days in October 1985, around the time the source produced one of its most outstanding radio flares. Examined here is the behaviour of the event rates recorded during this period with a time-resolution of 216 s. Two episodes of higher event rates, each several minutes in duration and having a Poissonian significance of 4, were recorded on 10 and 12 October, suggesting possible activity at TeV energies during the radio flare period of Cygnus X-3. 相似文献
10.
Development of pan coefficients for estimating evapotranspiration from riparian woody vegetation
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Tanya M. Doody Richard G. Benyon S. Theiveyanathan Vijay Koul Leroy Stewart 《水文研究》2014,28(4):2129-2149
The long‐term ‘Millennium Drought’ has put significant pressure on water resources across Australia. In southeastern Australia and in particular the Murray‐Darling Basin, removal of exotic, high‐water‐use Salix trees may provide a means to return water to the environment. This paper describes a simple model to estimate evapotranspiration of two introduced Salix species under non‐water‐limited conditions across seven biogeoclimatic zones in Australia. In this study, Salix evapotranspiration was calculated using the Penman–Monteith model. Field measurements of leaf area index and stomatal conductance for Salix babylonica and Salix fragilis were used to parameterize the models. Each model was validated using extensive field estimates of evapotranspiration from a semi‐arid (S. babylonica, r2 = 0.88) and cool temperate (S. fragilis, r2 = 0.99) region. Modelled mean annual evapotranspiration showed strong agreement with field measurements, being within 32 and 2 mm year?1 for S. babylonica and S. fragilis, respectively. Monthly pan coefficients (the ratio of mean evapotranspiration to mean pan evaporation) were developed from 30 years of meteorological data, for 30 key reference sites across Australia for both species using the validated Penman–Monteith models. Open‐water evaporation was estimated from field measurements and was used to develop a simple linear regression model for open‐water evaporation across the 30 reference sites. Differences between modelled evapotranspiration and open‐water evaporation at each site provide an indication of the amount of water that might be returned to the environment from removal of in‐stream Salix species. The monthly pan coefficient method reported has application across riparian environments worldwide where measured evapotranspiration is available for model validation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献