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991.
B. P. Rathore S. K. Singh Purnesh Jani I. M. Bahuguna Rupal Brahmbhatt A. S. Rajawat S. S. Randhawa Anjana Vyas 《Journal of the Indian Society of Remote Sensing》2018,46(9):1497-1506
Monitoring of seasonal snow cover is important for many applications such as melt runoff estimation, climate change studies and strategic requirements. Contribution of seasonal snow melt runoff of Chenab River is significant and important to meet hydrological requirement at foothills. Seasonal snow cover of Chandra, Bhaga, Miyar, Bhut, Warwan and Ravi, six major tributaries of Chenab River, becomes crucial to assess the water availability. In addition, altitudinal distribution of snow cover significantly influences the melt runoff which is highly sensitive to minor variations in atmospheric temperature. In this investigation, remote sensing based Normalized Difference Snow Index technique has been used to generate 10 daily snow cover product. Snow cover monitoring of all the sub-basins were carried out for 10 years from 2004–2005 to 2013–2014 during hydrological year (October to June) using Advanced Wide Field Sensor (AWiFS) of Indian remote sensing satellite (IRS). Accumulation and ablation patterns of snow cover have also been analyzed for the six sub-basins. Accumulation and ablation pattern of snow cover, from 2004 to 2014 which shows slightly increasing trend for all the sub-basins. Meteorological data of Kelong at Bhaga sub-basin was also analysed. Average monthly snow line altitude was estimated for all the sub-basins using hypsographic curve. Chandra and Bhaga sub-basins are at higher altitude and Ravi sub-basin is at lower altitude. It was also observed that areal extent of snow reaches to lower altitude during last 5 years, particularly in Ravi sub-basin. 相似文献
992.
K. N. Prudhvi Raju Sarvajeet Kumar Kshitij Mohan Manish Kumar Pandey 《Journal of the Indian Society of Remote Sensing》2008,36(3):283-288
With growing urban expanses, one of the pre-requisites for effective governance is Urban Information Systems (UIS) with content
down to individual properties (and individuals). The basic input i.e., a map, in UIS should show individual property boundaries
showing the plan outline of all structures existing within, at a scale of 1:1000 and larger with sub-metre to centimeters
planimetric and geometric accuracy. With very high resolution remote sensing data of the order of 1m available in hand, it
is possible to prepare maps with high resolution spatial content. The present exercise demonstrates a method of preparing
a geometrically and planimetrically accurate urban cadastral map on very large scale for a small area of about 5 sq km. IKONOS
merged data with 1m resolution is used for the purpose. Mapping was done in conjunction with on-site measurements and sketches.
Guides are used to maintain shape symmetry and accuracy of buildings and other features. Working out cost of mapping per unit
area is another objective in the present exercise. For want of fully or semi-automatic methods of information extraction from
very high resolution remote sensing data, it is imperative that mapping should be carried out in conjunction with some on-site
measurements wherever necessary. 相似文献
993.
Three-dimensional frequency dependent S-wave quality factor (Qβ(f)) value for the central Honshu region of Japan has been determined in this paper using an algorithm based on inversion of strong motion data. The method of inversion for determination of three-dimensional attenuation coefficients is proposed by Hashida and Shimazaki (J Phys Earth. 32, 299–316, 1984) and has been used and modified by Joshi (Curr Sci. 90, 581–585, 2006; Nat Hazards. 43, 129–146, 2007) and Joshi et al. (J. Seismol. 14, 247–272, 2010). Twenty-one earthquakes digitally recorded on strong motion stations of Kik-net network have been used in this work. The magnitude of these earthquake ranges from 3.1 to 4.2 and depth ranging from 5 to 20 km, respectively. The borehole data having high signal to noise ratio and minimum site effect is used in the present work. The attenuation structure is determined by dividing the entire area into twenty-five three-dimensional blocks of uniform thickness having different frequency-dependent shear wave quality factor. Shear wave quality factor values have been determined at frequencies of 2.5, 7.0 and 10 Hz from record in a rectangular grid defined by 35.4°N to 36.4°N and 137.2°E to 138.2°E. The obtained attenuation structure is compared with the available geological features in the region and comparison shows that the obtained structure is capable of resolving important tectonic features present in the area. The proposed attenuation structure is compared with the probabilistic seismic hazard map of the region and shows that it bears some remarkable similarity in the patterns seen in seismic hazard map. 相似文献
994.
The Chow-Kulandaiswamy general hydrologic system (GHS) model is revisited. Based on a mathematical study by Singh and McCann the GHS model is simplified. Explicit solutions are obtained for special cases which can satisfactorily determine watershed surface runoff response due to given rainfall excess. A rational criterion is developed to determine the number of derivative terms to be retained in the model. In order to determine the coefficients in the GHS model the method of moments is proposed. Criteria are developed to determine complex roots and oscillations for these coefficients. By analysing Chow-Kulandaiswamy's results it is found that in a majority of cases which they studied roots are complex. Moreover, for the cases which have complex roots, a majority of the solutions oscillate. A brief sensitivity analysis of the GHS model is performed with regard to: (a) its leading coefficient, and (b) the order of the differential equation. Finally, the peak characteristics are specified for the second order case and their qualitative properties are shown for the third order case. 相似文献
995.
B. Praveen Kumar J. Vialard M. Lengaigne V. S. N. Murty M. J. McPhaden M. F. Cronin F. Pinsard K. Gopala Reddy 《Climate Dynamics》2013,40(7-8):2049-2071
In this paper, we present TropFlux wind stresses and evaluate them against observations along with other widely used daily air-sea momentum flux products (NCEP, NCEP2, ERA-I and QuikSCAT). TropFlux wind stresses are computed from the COARE v3.0 algorithm, using bias and amplitude corrected ERA-I input data and an additional climatological gustiness correction. The wind stress products are evaluated against dependent data from the TAO/TRITON, PIRATA and RAMA arrays and independent data from the OceanSITES mooring networks. Wind stress products are more consistent amongst each other than surface heat fluxes, suggesting that 10 m-winds are better constrained than near-surface thermodynamical parameters (2 m-humidity and temperature) and surface downward radiative fluxes. QuikSCAT overestimates wind stresses away from the equator, while NCEP and NCEP2 underestimate wind stresses, especially in the equatorial Pacific. QuikSCAT wind stress quality is strongly affected by rain under the Inter Tropical Convergence Zones. ERA-I and TropFlux display the best agreement with in situ data, with correlations >0.93 and rms-differences <0.012 Nm?2. TropFlux wind stresses exhibit a small, but consistent improvement (at all timescales and most locations) over ERA-I, with an overall 17 % reduction in root mean square error. ERA-I and TropFlux agree best with long-term mean zonal wind stress observations at equatorial latitudes. All products tend to underestimate the zonal wind stress seasonal cycle by ~20 % in the western and central equatorial Pacific. TropFlux and ERA-I equatorial zonal wind stresses have clearly the best phase agreement with mooring data at intraseasonal and interannual timescales (correlation of ~0.9 versus ~0.8 at best for any other product), with TropFlux correcting the ~13 % underestimation of ERA-I variance at both timescales. For example, TropFlux was the best at reproducing westerly wind bursts that played a key role in the 1997–1998 El Niño onset. Hence, we recommend the use of TropFlux for studies of equatorial ocean dynamics. 相似文献
996.
Petrochemical studies on acid plutonic (granite, microgranite) and volcanic (rhyolite, trachyte) rocks occurring in the Siner area of the Siwana Ring Complex, Malani Igneous Suite have been carried out. These rocks are characterized by high concentrations of SiO2, Na2O, K2O, Zr, Nb, Y and REE (except Eu) but low in MgO, Fe2O3(t), CaO, Cr, Ni, Sr; indicating their A-type affinity. Field studies in conjunction with the geochemical characteristic indicate that the magmatism in the Siner area is generally represented by peralkaline suite of rocks which are formed due to rift tectonics. It is also suggested that these acidic rocks could have been derived by low degree partial melting of crustal material. Characteristics of certain pathfinder elements such as Rb, Ba, Sr, K, Zr, Nb, REE and the ratios of K/Rb, Zr/Rb, Ba/Rb along with the multi elemental primitive mantle normalized spidergrams suggest that the Siner peralkaline granites and microgranites have the potential for rare metal and rare earth mineralizations. 相似文献
997.
The Abor volcanics outcroping in the core of the Siang window in the Eastern Himalaya comprise voluminous mafic volcanics (47%-56% w(SiO2)),with subordinate felsic volcanics (67%-75% w(SiO2)).The felsi... 相似文献
998.
Fluxes have been computed for Fex (6374 Å) and Fe xiv (5303 Å) lines as a function of solar radii and at various coronal tempratures. The electron density derived from the white light corona during the total solar eclipse of 1980 were used in the computations. Fluxes in adjacent continua have also been computed. The computed ratios of line flux to the square of continuum flux at a coronal temperature of 1.6 × 106 K show a good fit with the observed values for Fex line. Further, radiative excitation seems to dominate over collisional excitation beyond 1.3 solar radius. 相似文献
999.
Mritunjay Kumar Singh R.D. Gupta Snehmani Anshuman Bhardwaj Ashwagosha Ganju 《国际地球制图》2016,31(5):506-526
The orbital and the rational polynomial coefficients (RPC) models are the two most commonly used models to compute a three-dimensional coordinates from an image stereo-pair. But it is still confusing that with the identical user provided inputs, which one of these two models provides more accurate digital elevation model (DEM), especially for mountainous terrain. This study aimed to find out the answer by evaluating the impact of used models on the vertical accuracy of DEM extracted from Cartosat-1 stereo data. We used high-accuracy photogrammetric DEM as the reference DEM. Apart from general variations in statistics, surprisingly in a few instances, both the DEMs provided contrasting results, thus proving the significance of this study. The computed root mean square errors and linear error at 90% (LE90) were lower in case of RPC DEM for various classes of slope, aspect and land cover, thus suggesting its better relative accuracy. 相似文献
1000.
Journal of Geographical Sciences - Rapid economic development and human activities have severely affected ecosystem function. Analysis of the spatial distribution of areas of rapid urbanization is... 相似文献