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21.
A multifold crustal-scale deep seismic near-vertical reflection profile generates a large number of single-ended shot gathers, which provide redundant data sets because of overlapping coverage of the shallow refractors. We present an approach for deriving the shallow velocity structure by modelling and inversion of single-ended seismic refraction first arrival traveltime data. We apply this method to a data set acquired with a 12-km long spread with 100 m spacing of shots and receivers, of the Neoproterozoic Marwar basin in the NW Indian shield. The approach is shown to be quite successful for delineating the shallow refractor depths, steep dips and velocities, even in the absence of regular reverse refraction profiles. The study reveals two-layered sedimentary formations, Malani volcanics and a complicated basement configuration of the Marwar basin, and provides a measure of resolution and uncertainty of the estimated model parameters. A seismic section of the near-trace gather is found to be qualitatively consistent with the derived structural features of the basin. The relative highs and lows, observed in the Bouguer gravity profile, further corroborate the derived velocity model. The present approach can be especially useful in offshore areas and elsewhere, where the single-ended multifold seismic profiles are the only available data sets. 相似文献
22.
An Experiment Using the High Resolution Eta and WRF Models to Forecast Heavy Precipitation over India 总被引:1,自引:0,他引:1
Y. V. Rama Rao H. R. Hatwar Ahmad Kamal Salah Y. Sudhakar 《Pure and Applied Geophysics》2007,164(8-9):1593-1615
In the present study using the Weather Research and Forecasting (WRF) and Eta models, recent heavy rainfall events that occurred
(i) over parts of Maharastra during 26 to 27 July, 2005, (ii) over coastal Tamilnadu and south coastal Andhra Pradesh during
24 to 28 October, 2005, and (iii) the tropical cyclone of 30 September to 3 October, 2004/Monsoon Depression of 2 to 5 October
2004, that developed during the withdrawal phase of the southwest monsoon season of 2004 have been investigated. Also sensitivity
experiments have been conducted with the WRF model to test the impact of microphysical and cumulus parameterization schemes
in capturing the extreme weather events. The results show that the WRF model with the microphysical process and cumulus parameterization
schemes of Ferrier et al. and Betts-Miller-Janjic was able to capture the heavy rainfall events better than the other schemes. It is also observed
that the WRF model was able to predict mesoscale rainfall more realistically in comparison to the Eta model of the same resolution. 相似文献
23.
The diurnal structure of the boundary layer during Indian summer monsoon period is studied using a one-dimensional meteorological
boundary layer model and the observations collected from the Monsoon Trough Boundary Layer Experiment conducted in 1990 at
Jodhpur, India. The model was initialized with the observed temperature profiles at 0530 LST on 17 July, 1990 at Jodhpur and
was run for 26 hours. The study is carried out with a geostrophic wind speed of 9.5 m s−1 corresponding to the strong wind simulation. The mean thermodynamic and wind structure simulated by the model are in good
agreement with those observed from 30 m tower. The computed surface layer characteristics such as the surface fluxes, TKE
and standard deviations of velocity components are found to be reasonably in good agreement with those based on turbulence
measurements. The shear and buoyancy budget computed from the model are also compared with the turbulence measurements. The
integrated cooling budget in the nocturnal boundary layer is examined. 相似文献
24.
Ndr Krishna A K Maji YVN Krishna Murthy BSP Rao 《Journal of the Indian Society of Remote Sensing》2001,29(3):107-113
Availability of remote sensing data from earth observation satellites has made it convenient to map and monitor land use/land cover at regional to local scales. A land cover map is very critical for a various planning activities including watershed planning. The spectral and spatial resolutions are major constraints for mapping the crop resources at microlevel. The cropping pattern zones have been mapped using the false color composite, physiography, irrigation and toposheets. The IRS LISS-III data is classified into various categories depending on spectral reflectance from crop canopy and are overlaid on cropping zones map. The re-classified resultant map provides land use/land cover information including dominant cropping systems. The canopy cover is estimated monthly considering the crop calendar for the area. 相似文献
25.
Integrated and environmentally sustainable development strategies have become inevitable for micro-level planning these days. The usefulness of remotely sensed data from earth resource satellites for watershed management is discussed for an eastern Himalayan watershed covering 39.09 km2 area. The biophysical conditions were assessed based on field experience. The SPOT HRV-I MLA and PLA scenes were interpreted for land use/cover categories and associated characteristics. These parameters were found to be significant towards evolving the management priorities for development of agriculture, soil conservation, afforestation and rain water harvesting structures in ecologically fragile Himalayan region. The remote sensing inputs were important in deriving the relevant details faster and precisely. 相似文献
26.
A. Suryachandra Rao Y. Sadhuram V. V. Gopala Krishna 《Journal of Earth System Science》1995,104(4):607-611
We estimate, from the moisture budget the bulk aerodynamic coefficient for latent heat flux (C
e) during the monsoon season over the central Arabian Sea. The average value ofC
eunder active monsoon conditions was found to be 2.25 × 10−3 which is nearly 60% higher than those previously used. 相似文献
27.
Krishna De 《Pure and Applied Geophysics》1970,80(1):114-123
Summary The propagation of Love waves is discussed on the basis of finite strain theory. The primary Love wave is found to be associated with a secondary Rayleigh wave and a tertiary Love wave. Numerical calculations are presented for two values of the wave-velocity; the results show that the theory of Love waves based on infinitesimal strain, is not applicable to short period waves. 相似文献
28.
The effects of E-region electric fields on F-region parameters like height of constant electron density contours (hN) and semi-thickness, at an equatorial station, Trivandrum, are investigated. The E-region east-west electric field (Ey) has been deduced using the horizontal magnetic field values from the ground magnetograms. It is found that the semi-thickness parameter and hN follow closely the E-region electric field (Ey) variations in the forenoon and noon periods. In the afternoon, it is shown that there is close association between hN and Ey, when the electric field variations are large. On a day-to-day basis also, hN and the E-region electric field show very good correlation in the forenoon and noon hours. It is also shown that higher levels are affected more than the lower levels in the F-region by Ey. 相似文献
29.
30.
N. Rama Rao P. K. Garg S. K. Ghosh 《Journal of the Indian Society of Remote Sensing》2006,34(1):69-78
Motivated by the increasingly availability and importance of hyperspectral remote sensing data, this study aims to determine
whether current generation narrowband hyperspectral remote sensing data could be used to estimate vegetation Leaf Area Index
(LAI) accurately than the traditional broadband multispectral data. A comparative study has been carried out to evaluate the
performance of the narrowband Normalized Difference Vegetation Index (NDV1) derived from Hyperion hyperspectral sensor with
that of derived from IRS LISS-III for the estimation of LAI of some major agricultural crops (e.g. cotton, sugarcane and rice)
in part of Guntur district, India. It has been found that the narrowband NDVI derived from Hyperion has shown better results
over its counterpart derived from broadband LISS-III. Linear regression models have been used which with selected subsets
of individual Hyperion bands performed better to predict LAI than those based on the broadband datasets, although the potential
to overfit models using the large number of available Hyperion bands is a concern for further research. 相似文献