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81.
Encounter of Voyager with Saturn’s environment revealed the presence of electromagnetic ion-cyclotron waves (EMIC) in Saturnian magnetosphere. Cassini provided the evidence of dynamic particle injections in inner magnetosphere of Saturn. Also inner magnetosphere of Saturn has highest rotational flow shear as compared to any other planet in our solar system. Hence during these injections, electrons and ions are transported to regions of stronger magnetic field, thus gaining energy. The dynamics of the inner magnetosphere of Saturn are governed by wave-particle interaction. In present paper we have investigated those EMIC waves pertaining in background plasma which propagates obliquely with respect to the magnetic field of Saturn. Applying kinetic approach, the expression for dispersion relation and growth rate has been derived. Magnetic field model has been used to incorporate magnetic field strength at different latitudes for radial distance of \(6.18~R_{{s}}\) (\(1~R_{{s}}= 60{,}268~\mbox{km}\)). Various parameters affecting the growth of EMIC waves in cold bi-Maxwellian background and after the hot injections has been studied. Parametric analysis inferred that after hot injections, growth rate of EMIC waves increases till \(10^{\circ}\) and decreases eventually with increase in latitude due to ion density distribution in near-equatorial region. Also, growth rate of EMIC waves increases with increasing value of temperature anisotropy and AC frequency, but the growth rate decreases as the angle of propagation with respect to \(B_{0}\) (Magnetic field at equator) increases. The injection events which assume the Loss-cone distribution of particles, affect the lower wave numbers of the spectra. 相似文献
82.
Ankur Srivastava Patricia M. Saco Jose F. Rodriguez Nikul Kumari Kwok Pan Chun Omer Yetemen 《水文研究》2021,35(1):e13990
Previous studies on semi-arid ecosystems have shown high values of soil moisture variability (SMV) primarily induced by the combined effects of non-uniform precipitation, incoming solar radiation, and soil and vegetation properties. However, the relative impact of these various factors on SMV has been difficult to evaluate due to limited availability of field data. In addition, only a limited number of studies have analysed the role of landscape morphology on SMV. Here we use numerical simulations of a simple hydrological model, the Bucket Grassland Model, to systematically analyse the effect of each contributing factor on SMV on two different landscape morphologies. The two different landform morphologies represent landscapes dominated respectively by either diffusive erosion or fluvial erosion processes. We conducted various simulations driven by a stochastically generated 100-year climate time series, which is long enough to capture climatic fluctuations, in order to understand the effect of various soil moisture controlling factors on the spatiotemporal SMV. Our modelling results show that the fluvial dominated landscapes promote higher spatial SMV than the diffusive dominated ones. Further, the role of landform morphology on SMV is more pronounced in regions where the spatial variability of incoming solar radiation and precipitation is high. 相似文献
83.
Surface ozone concentrations in Agra: links with the prevailing meteorological parameters 总被引:1,自引:0,他引:1
Vyoma Singla Tripti Pachauri Aparna Satsangi K. Maharaj Kumari Anita Lakhani 《Theoretical and Applied Climatology》2012,110(3):409-421
Measurements of surface ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx=NO+NO2) and meteorological parameters have been made at Agra (North Central India, 27°10??N, 78°05??E) in post monsoon and winter season. The diurnal variation in O3 concentration shows daytime in situ photochemical production with diurnal maximum in noon hours ranging from 51 to 54 ppb in post monsoon and from 76 to 82 ppb in winter, while minimum (16?C24 ppb) during nighttime and early morning hours. Average 8-h O3 concentration varied from 12.4 to 83.9 ppb. The relationship between meteorological parameters (solar radiation intensity, temperature, relative humidity, wind speed and wind direction) and surface O3 variability was studied using principal component analysis (PCA), multiple linear regression (MLR) and correlation analysis (CA). PCA and MLR of daily mean O3 concentrations on meteorological parameters explain up to 80 % of day to day ozone variability. Correlation with meteorology is strongly emphasized on days having strong solar radiation intensity and longer sunshine time. 相似文献
84.
Himanshu K. Sachan Anubhooti Saxena Preeti Verma Santosh K. Rai Aditya Kharya 《Journal of the Geological Society of India》2013,82(5):509-518
Quartzitic pelites forms a part of Higher Himalayan Crystalline of higher geotectonic zone in Garhwal Himalaya. Quartzitic pelites (locally known as Pandukeshwar Quartzite) in Garhwal Himalaya is sandwiched between high grade metamorphic rocks of Central Crystallines and Badrinath Formation. Fluid inclusion studies are carried out on the detrital, and recrystallized quartz grains of quartzitic pelites to know about the fluid phases present during recrystallization processes at the time of maximum depth of burial. The quartzitic pelite (Pandukeshwar Quartzite) essentially consists of recrystallised quartz with accessory minerals like mica and feldspar. Fluid microthermometry study reveals the presence of three types of fluids: (i) high-salinity brine, (ii) CO2-H2O and (iii) H2O-NaCl. These fluids were trapped during the development of grain and recrystallization processes. The high saline brine inclusions and CO2-H2O fluid with the density of 0.90 to 0.97 gm/cm3 are remnants of provenance area. CO2 density in detrital quartz grains characterise the protolith of the sandstone as granite or metamorphic rock. The H2O-NaCl fluids involved in the recrystallization processes at temperature-pressure of 430-350°C; 4.8 to 0.5 Kbars as constrained by fluid isochores of CO2-H2O and H2O-NaCl inclusions and bulging and subgrain development during recrystallization processes. The re-equilibration of the primary fluid due to elevated internal and confining pressure is evident from features like ‘C’ shaped cavities, stretching of the inclusions, their migration and decrepitation clusters. The observed inclusion morphology revealed that the rocks were exhumed along an isothermal decompression path. 相似文献
85.
AbstractRiver basin assessment is crucial for water management and to address the watershed issues. So, an integrated river basin management and assessment model using morphometric assessment, remote sensing, GIS and SWAT model was envisaged and applied to Kaddam river basin, Telangana state, India. Morphometric results showed high drainage density ranging from 2.19 to 5.5?km2/km, with elongated fan shape having elongation ratio of 0.60–0.75 with sparse vegetation and high relief. Land use change assessment showed that 265.26?km2 of forest land is converted into irrigated land and has increased sediment yields in watersheds. The calibration (r 2?=?0.74, NSE?=?0.84) and validation (r 2?=?0.72, NSE?=?0.84) of SWAT model showed that simulated and observed results were in agreement and in recommended ranges. The SWAT simulations were used to compute mean annual water and sediment yield from 1997 to 2012, along with morphometric results to categorize critical watersheds and conservation structures were proposed accordingly. 相似文献
86.
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88.
Natural Hazards - The present research aims to co-relate the plasticity and liquefaction response of soil as well as its significance in defining liquefaction probability. To accomplish this,... 相似文献
89.
The exposure of Puntius sophore to different concentrations of crude oil (200… 4000 ppm) revealed that 4000 ppm was acutely lethal to the fish and mortality did not occur at <500 ppm at 21±1 °C for up to 15 days. The increase in the opercular frequency during exposure to crude oil has been recorded almost parallel to toxicant concentrations. The objectionable odour of the crude oil and the formation of coagulated mucous film over the body and gills were the main factors causing mortality among the experimental fish. The 24, 48, 78 and 96-h TL 50 values have been 3275, 1750, 1650 and 1450 ppm. The corresponding regression coefficients b were –1.8056, –1.5849, –1.6037 and –1.6497. 相似文献
90.
Miss Santosh Kumari Wadhwa 《Pure and Applied Geophysics》1971,89(1):84-97
Summary The problem of a transiton layer lying between two homogeneous liquid media has been discussed in a previous paper. There, some of the terms in the integrands in the expressions for the displacement potentials due to a periodic point source, lying in the upper layer, have been evaluated along the Sommerfeld loops. Both first order and second order discontinuities in density and bulk modulus at the boundaries of the transition layer have been considered. In the present paper, the integrals for the displacement potentials have been evaluated by the method of stationary phase and the results obtained are compared with those obtained previously. Also the first order discontinuities in density and velocity at the two ends of the transition layer are removed and the work is extended to an explosion type pulse. It is found that for a pulse source, the decrease with distance is the same as for a periodic point source. Also the frequency dependence for the refraction arrivals, when frequency is extremely high, is 1/3 as compared to –1 in the case when there are discontinuities at the boundaries of the transition layer. 相似文献