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141.
The purpose of this paper is the canonical connection of classical global gravity field determination following the concept of Stokes (Trans Camb Philos Soc 8:672–712, 1849), Bruns (Die Figur der Erde, Publikation Königl. Preussisch. Geodätisches Institut, P. Stankiewicz Buchdruckerei, Berlin, 1878), and Neumann (Vorlesungen über die Theorie des Potentials und der Kugelfunktionen. Teubner, Leipzig, pp 135–154, 1887) on the one hand and modern locally oriented multiscale computation by use of adaptive locally supported wavelets on the other hand. The essential tools are regularization methods of the Green, Neumann, and Stokes integral representations. The multiscale approximation is guaranteed simply as linear difference scheme by use of Green, Neumann, and Stokes wavelets. As an application, gravity anomalies caused by plumes are investigated for the Hawaiian and Iceland areas. 相似文献
142.
P. Jayaprasad B. Narender S. K. Pathan Ajai 《Journal of the Indian Society of Remote Sensing》2008,36(4):313-322
Digital elevation model (DEM) and the derived terrain parameters e.g. contour, slope, aspect, drainage pattern, etc are required
for natural resources management, infrastructure planning and disaster management. The present paper aims at generating DEM
from ERS tandem pair using interferometric technique supported by differential GPS measurements (DGPS) and multispectral optical
data. Validation of DEM has been carried out by DGPS measurements. Ground Control Points (GCP) established by DGPS measurements
have been used to georeference the IRS-1D optical data that has finally been co-registered with SAR amplitude image. Optical
data, co-registered with ERS - I SAR data has helped in locating the GCP’s and check points, precisely, for refinement of
DEM and its validation. 相似文献
143.
A. K. Singh P. K. Singh B. Lal A. N. Singh A. Mathur 《Journal of the Indian Society of Remote Sensing》2008,36(2):183-188
A World Bank-aided project on sodic land reclamation in Uttar Pradesh is being executed by U.P. Bhumi Sudhar Nigam, Lucknow,
and Remote Sensing Applications Centre, U.P., Lucknow has the responsibility of sodic land mapping for the execution of land
reclamation programme at the cadastral level. Sodic lands are mainly concentrated in the Gangetic alluvial plains but the
problem of sodicity is particularly acute in the canal-irrigated areas. A study of the distribution pattern of sodic lands
in canal and noncanal command areas in a reclamation site (covering 60 villages out of which sodic lands were mapped in 51
villages) of Etah district in Uttar Pradesh, indicates that 18.39 per cent area of the canal command villages was barren sodic
which was 13.41 per cent of the total geographical area of the site (15417 ha), however, 11.69 per cent area was recorded
to be barren sodic in the non-canal command villages which was only 3.16 per cent of the geographical area of the site. The
results of soil chemical analysis indicate that barren sodic lands of canal command area are saline-sodic with higher concentration
of soluble salts (pH2 >8.5, EC2 >4 dSm−1), however, those of non-canal command area are sodic (pH2 >8.5, EC2 <4 dSm−1). The post-monsoon ground level in the canal-irrigated areas was in the critical and semicritical zone (< 3.0 mbgl) whereas
it was well below the semi-critical zone in the non-canal command area, which indicates that the high ground water level is
a major factor to higher the area under sodicity. 相似文献
144.
An evaluation of some systematic error sources affecting terrestrial gravity anomalies 总被引:1,自引:2,他引:1
B. Heck 《Journal of Geodesy》1990,64(1):88-108
Terrestrial free-air gravity anomalies form a most essential data source in the framework of gravity field determination.
Gravity anomalies depend on the datums of the gravity, vertical, and horizontal networks as well as on the definition of a
normal gravity field; thus gravity anomaly data are affected in a systematic way by inconsistencies of the local datums with
respect to a global datum, by the use of a simplified free-air reduction procedure and of different kinds of height system.
These systematic errors in free-air gravity anomaly data cause systematic effects in gravity field related quantities like
e.g. absolute and relative geoidal heights or height anomalies calculated from gravity anomaly data.
In detail it is shown that the effects of horizontal datum inconsistencies have been underestimated in the past. The corresponding
systematic errors in gravity anomalies are maximum in mid-latitudes and can be as large as the errors induced by gravity and
vertical datum and height system inconsistencies. As an example the situation in Australia is evaluated in more detail: The
deviations between the national Australian horizontal datum and a global datum produce a systematic error in the free-air
gravity anomalies of about −0.10 mgal which value is nearly constant over the continent 相似文献
145.
M. B. Potdar 《Journal of the Indian Society of Remote Sensing》1990,18(1-2):1-7
Growth profiles of 1987-88 rabi sorghum crop cultivated in spatially extensive sites in six tehsils of Solapur and Ahmadnagar districts in Maharashtra have been generated using multidate NOAA AVHRR data based on crop growth equation suggested by Badhwar (1980). The sensitive parameters for sorghum yield modelling have been identified. The correlation of final grain yield with growth parameters shows that yield relationship is stronger when logarithmic senescence rate and timeintegrated logarithmic senescence rate are considered as the parameters instead of its value on any day during 30 days senescence period after attaining maximum vegetative cover. 相似文献
146.
B. K. Sinha Ashok Kumar Deepak Shrivastava Sanjay Srivastava 《Journal of the Indian Society of Remote Sensing》1990,18(3):1-8
In recent years satellite remote sensing techniques have greatly aided identification of fractures/joints/faults in connection with groundwater exploration. However, due to some constraints in filtering out the type of fracture i.e. shear fracture, tensional fracture, mineralised fracture etc. as to their “open or closed” nature from groundwater aspects, there is need of adding geophysical survey, particularly resistivity survey to further enhance the accuracy, and hence minimise drilling failures. The area under study is a part of Ranchi plateau and lithologically comprising of granite-gneiss. The present paper lays stress on an integrated approach for localising well sites through satellite data analysis and resistivity profiling along with vertical electrical sounding which is based on fracture patterns. With this combined effort i.e. firstly considering the surfacial features like drainage, geomorpho-logy, lithology and lineaments, and secondly taking into account geophysical survey aspects, i.e. depth and thickness of fracture zone, lateral extent, different layer parameter, etc., fairly accurate results are achieved. In the presnt study this type of an integrated survey has been carried out in Lohardaga and Gumla districts in Bihar, the results of which are highlighted in the paper. 相似文献
147.
Dhruvesh P Patel Mrugen B Dholakia N. Naresh Prashant K. Srivastava 《Journal of the Indian Society of Remote Sensing》2012,40(2):299-312
Geo-visualization concept has been used for positioning water harvesting structures in Varekhadi watershed consisting of 26
mini watersheds, falling in Lower Tapi Basin (LTB), Surat district, Gujarat state. For prioritization of the mini watersheds,
morphometric analysis was utilized by using the linear parameters such as bifurcation ratio (Rb), drainage density (Dd), stream frequency (Fu), texture ratio (T), length of overland flow (Lo) and the shape parameter such as form factor (Rf), shape factor (Bs), elongation ratio (Re), compactness constant (Cc) and circularity ratio (Rc). The different prioritization ranks were assigned after evaluation of the compound factor. 3 Dimensional (3D) Elevation
Model (DEM) from Shuttle Radar Topography Mission (SRTM) and DEM from topo contour were analyzed in ArcScene 9.1 and the fly
tool was utilized for the Geo-visualization of Varekhadi mini watersheds as per the priority ranks. Combining this with soil
map and slope map, the best feasibility of positioning check dams in mini-watershed no. 1, 5 and 24 has been proposed, after
validation of the sites. 相似文献
148.
Simulation study of a follow-on gravity mission to GRACE 总被引:6,自引:3,他引:6
The gravity recovery and climate experiment (GRACE) has been providing monthly estimates of the Earth’s time-variable gravity
field since its launch in March 2002. The GRACE gravity estimates are used to study temporal mass variations on global and
regional scales, which are largely caused by a redistribution of water mass in the Earth system. The accuracy of the GRACE
gravity fields are primarily limited by the satellite-to-satellite range-rate measurement noise, accelerometer errors, attitude
errors, orbit errors, and temporal aliasing caused by un-modeled high-frequency variations in the gravity signal. Recent work
by Ball Aerospace & Technologies Corp., Boulder, CO has resulted in the successful development of an interferometric laser
ranging system to specifically address the limitations of the K-band microwave ranging system that provides the satellite-to-satellite
measurements for the GRACE mission. Full numerical simulations are performed for several possible configurations of a GRACE
Follow-On (GFO) mission to determine if a future satellite gravity recovery mission equipped with a laser ranging system will
provide better estimates of time-variable gravity, thus benefiting many areas of Earth systems research. The laser ranging
system improves the range-rate measurement precision to ~0.6 nm/s as compared to ~0.2 μm/s for the GRACE K-band microwave
ranging instrument. Four different mission scenarios are simulated to investigate the effect of the better instrument at two
different altitudes. The first pair of simulated missions is flown at GRACE altitude (~480 km) assuming on-board accelerometers
with the same noise characteristics as those currently used for GRACE. The second pair of missions is flown at an altitude
of ~250 km which requires a drag-free system to prevent satellite re-entry. In addition to allowing a lower satellite altitude,
the drag-free system also reduces the errors associated with the accelerometer. All simulated mission scenarios assume a two
satellite co-orbiting pair similar to GRACE in a near-polar, near-circular orbit. A method for local time variable gravity
recovery through mass concentration blocks (mascons) is used to form simulated gravity estimates for Greenland and the Amazon
region for three GFO configurations and GRACE. Simulation results show that the increased precision of the laser does not
improve gravity estimation when flown with on-board accelerometers at the same altitude and spacecraft separation as GRACE,
even when time-varying background models are not included. This study also shows that only modest improvement is realized
for the best-case scenario (laser, low-altitude, drag-free) as compared to GRACE due to temporal aliasing errors. These errors
are caused by high-frequency variations in the hydrology signal and imperfections in the atmospheric, oceanographic, and tidal
models which are used to remove unwanted signal. This work concludes that applying the updated technologies alone will not
immediately advance the accuracy of the gravity estimates. If the scientific objectives of a GFO mission require more accurate
gravity estimates, then future work should focus on improvements in the geophysical models, and ways in which the mission
design or data processing could reduce the effects of temporal aliasing. 相似文献
149.
Mehmet ?ahin B. Yi?it Y?ld?z Ozan ?enkal Vedat Pe?temalc? 《Journal of the Indian Society of Remote Sensing》2012,40(3):399-409
This study introduces artificial neural networks (ANNs) for the estimation of land surface temperature (LST) using meteorological and geographical data in Turkey (26?C45°E and 36?C42°N). A generalized regression neural network (GRNN) was used in the network. In order to train the neural network, meteorological and geographical data for the period from January 2002 to December 2002 for 10 stations (Adana, Afyon, Ankara, Eski?ehir, ?stanbul, ?zmir, Konya, Malatya, Rize, Sivas) spread over Turkey were used as training (six stations) and testing (four stations) data. Latitude, longitude, elevation and mean air temperature are used in the input layer of the network. Land surface temperature is the output. However, land surface temperature has been estimated as monthly mean by using NOAA-AVHRR satellite data in the thermal range over 10 stations in Turkey. The RMSE between the estimated and ground values for monthly mean with ANN temperature(LSTANN) and Becker and Li temperature(LSTB-L) method values have been found as 0.077?K and 0.091?K (training stations), 0.045?K and 0.003?K (testing stations), respectively. 相似文献
150.