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71.
Ritesh Agrawal Anup Das A. S. Rajawat 《Journal of the Indian Society of Remote Sensing》2018,46(10):1739-1747
Radargrammetry technique using the stereoscopic synthetic aperture radar (SAR) images is used for the generation of a digital elevation model (DEM) of a region requires only the amplitude images. SAR stereoscopic technique is analogous to the stereo-photogrammetric technique where the optical stereoscopic images are used for DEM generation. While the advantages of the SAR images are their indifference to atmospheric transparency and solar illumination conditions, the side-looking geometry of the SAR increases the complexity in the SAR stereo analysis. The availability of high spatial and temporal resolution SAR data in recent years has facilitated generation of high-resolution DEM with greater vertical accuracy using radargrammetric technique. In the present study, attempt has been made to generate the DEM of Dehra Dun region, India, from the COSMO-Skymed X-band SAR data-pair acquired at 8 days interval through the radargrammetry technique. Here, radargrammetric orientation approach has been adopted to generate the DEM and various issues and processing steps with the radargrammetry technique have been discussed. The DEM was validated with ground measured elevation values using a differential global positioning system and the root-mean-square error of the DEM was found as 7.3 m. The DEM was compared with the reference DEM of the study area generated from the Cartosat-1 stereo data with a model accuracy of 4 m. 相似文献
72.
Natural Hazards - Slope failures are recurrent phenomena during the Indian Summer Monsoon (ISM) season in the mountainous regions of Arunachal Himalaya, NE India, with a consequent damaging impact... 相似文献
73.
Probabilistic estimates of future changes in California temperature and precipitation using statistical and dynamical downscaling 总被引:1,自引:0,他引:1
David W. Pierce Tapash Das Daniel R. Cayan Edwin P. Maurer Norman L. Miller Yan Bao M. Kanamitsu Kei Yoshimura Mark A. Snyder Lisa C. Sloan Guido Franco Mary Tyree 《Climate Dynamics》2013,40(3-4):839-856
Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniques. Both monthly and daily timescale changes in T and P are addressed, the latter being important for a range of applications in energy use, water management, and agriculture. The T changes tend to agree more across downscaling techniques than the P changes. Year-to-year natural internal climate variability is roughly of similar magnitude to the projected T changes. In the monthly average, July temperatures shift enough that that the hottest July found in any simulation over the historical period becomes a modestly cool July in the future period. Januarys as cold as any found in the historical period are still found in the 2060s, but the median and maximum monthly average temperatures increase notably. Annual and seasonal P changes are small compared to interannual or intermodel variability. However, the annual change is composed of seasonally varying changes that are themselves much larger, but tend to cancel in the annual mean. Winters show modestly wetter conditions in the North of the state, while spring and autumn show less precipitation. The dynamical downscaling techniques project increasing precipitation in the Southeastern part of the state, which is influenced by the North American monsoon, a feature that is not captured by the statistical downscaling. 相似文献
74.
Trends and fluctuations of rainfall regime in the Brahmaputra and Barak basins of Assam, India 总被引:2,自引:1,他引:1
R. L. Deka C. Mahanta H. Pathak K. K. Nath S. Das 《Theoretical and Applied Climatology》2013,112(1-2):61-71
Severe weather conditions create negative impacts on humans. One of the severe weather conditions is storms. In the scope of this study, the storm effects on the Marmara Region were investigated using data for the period 2000 to 2010 giving the hourly averaged wind direction and speed in the Marmara Region, as provided by the Turkish Meteorological Service. The monthly distribution of storms has been estimated and their daily variability has been investigated. Additionally, air masses that cause storms have been determined by using NCEP/NCAR re-analysis data. Other than this, by studying the storms, extreme values have been ascertained and northerly values from these storm values (since in percentage terms they are larger) and hourly variability in a single day for 17 weather stations have been depicted graphically. The days that northerly storms reached extreme values are shown with the meteorological maps (surface chart, 850, 700, 500, and 300 hPa) and the temperature diagrams for Istanbul in the Marmara Region have been examined and analysed. 相似文献
75.
76.
The occurrences of 5772 microwave bursts recorded by the Sagamore Hill and Manilla Solar Radio Observatories over the period January 1968 to July 1970, covering the maximum phase of the current solar cycle at frequencies 2695, 4995 and 8800 MHz and their energy excesses have been examined in relation to the S-component of solar radio emission. The average slowly varying component has been determined by the superposed epoch method commonly known as the Chree analysis. Similar treatment of the bursts, data, mentioned above has been made to examine any probable 27-day variation and the results obtained have been compared with that of the S-component. Further, spectra of the microwave bursts under the so-called spectral type - inverted U, particularly those having a peak at 4995 MHz, have also been examined and compared with the average spectrum of the S-component. Some of the important results obtained from the present analysis are: (1) the nature of variation of both the average number of occurrences and energy excesses of the microwave bursts follow in general the average 27-day variation of the S-component, (2) the number of occurrences and energy excesses of the microwave bursts are comparatively greater in the ascending phase of the 27-day cycle than those in the descending phase, (3) bursts at progressively higher frequencies originate at lower levels in the solar atmosphere than those of the associated S-component, and (4) the average spectrum of the microwave bursts of inverted U spectral type having a peak at 4995 MHz is quite identical in nature to that of the S-component. 相似文献
77.
Rabindra Nath Das 《Astrophysics and Space Science》1978,58(2):419-425
The basic integro-differential equation is subjected to a one-sided finite Laplace transform to obtain linear integral equations of angular distribution of bounding faces. These linear integral equations have been transformed into linear singular integral equations which have been solved exactly to get the emergent distributions from the bounding faces by the theory of linear singular operators. Some solutions of linear singular integral equations have also been derived for future use in radiative transfer problems. 相似文献
78.
Equilibrium configuration of the upper Main-Sequence stars, with significant radiation pressure and having an interior magnetic field (matching with an external dipole field) has been cosidered. The structural parameters have been calculated for low and high magnetic fields by using a first-order perturbation method and a modified perturbation technique respectively. With the increase of radiation pressure, the star is seen to become more centrally condensed. 相似文献
79.
We have applied the method of Wiener-Hopf technique to obtain the Green's functions of one-group transport equations (with anisotropic unit plane source and with isotroic unit plane source) for a finite slab of passive and multiplying media. 相似文献
80.
The relative abundances of the nuclei from neon to iron in the energy interval 150–400 MeV/n have been estimated by using
a balloon borne cellulose-nitrate plastic detector. The source abundances are obtained by extrapolating the near-earth abundances
using leaky box model of cosmic ray propagation in the interstellar space. The results are compared with those of other investigators
and a general agreement is obtained. However, a discrepancy arises especially in the case of Al which is not detected in the
present investigation. 相似文献