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1.
Satellite altimetry can be used to infer subsurface geological structures analogous to gravity anomaly maps generated through
ship-borne survey. The Eastern offshore was taken up for analysis using Geosat Exact Repeat Mission (ERM) altimeter data.
A methodology is developed to use altimeter data as an aid to offshore hydrocarbon exploration. Processing of altimeter data
involves corrections for various atmospheric and oceanographic effects, stacking and averaging of repeat passes, cross-over
correction, removal of deeper earth and bathymetric effects, spectral analysis and conversion into free-air gravity anomaly.
The final processed results were derived for Eastern offshore in the form of prospecting geoid and gravity anomaly maps and
their spectral components. The highs and lows observed in those maps were derived in terms of a number of prominent megastructures
e.g., gravity linears, 85°E and 90°E ridges, the Andaman trench complex etc. Satellite-derived gravity profiles along 12°N
latitude match well with the existing structures. 相似文献
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3.
Ute C. Herzfeld Craig S. Lingle Cecily Freeman Chris A. Higginson Michael P. Lambert Li-Her Lee Vera A. Voronina 《Mathematical Geology》1997,29(6):859-890
The Antarctic Ice Sheet plays a major role in the global system, and the large ice streams discharging into the circumpolar
sea represent its gateways to the world’s oceans. Satellite radar altimeter data provide an opportunity for mapping surface
elevation at kilometerresolution with meteraccuracy. Geostaristical methods have been developed for the analysis of these
data. Applications to Seasat data and data from the Geosat Exact Repeat Mission indicate that the grounding line of Lambert
Glacier/Amery Ice Shelf, the largest ice stream in East Antarctica, has advanced 10–12 km between 1978 and 1987–89. The objectives
of this paper are to explore possibilities and limitations of satellite-altimetry-based mapping to capture changes for shorter
time windows and for smaller areas, and to investigate some methodological aspects of the data analysis. We establish that
one season of radar altimeter data is sufficient for constructing a map. This allows study of interannual variation and is
the key for a limeseries analysis approach to study changes in ice streams. Maps of the lower Lambert Glacier and the entire
Amery Ice Shelf are presented for austral winters 1978, 1987, 1988, and 1989. As a first step toward understanding the dynamics
of the ice-stream/iceshelf system, elevation changes are calculated for grounded ice, the grounding zone, and floating ice.
In the absence of (sufficient) surface gravity control for the Lambert Glacier/Amery Ice Shelf area, altimetry-based maps
may facilitate improvement of geoid models as they provide constraints on the terrain correction in the inverse gravimetric
problem. 相似文献
4.
Coastal Gravity Anomalies from Retracked Geosat/GM Altimetry: Improvement, Limitation and the Role of Airborne Gravity Data 总被引:6,自引:0,他引:6
Cheinway Hwang Jinyun Guo Xiaoli Deng Hsin-Ying Hsu Yuting Liu 《Journal of Geodesy》2006,80(4):204-216
We process geophysical and waveform data records of the Geosat/GM (geodetic mission) satellite altimeter mission for waveform retracking and applications. An improved threshold retracker is developed. The performances of the Beta-5, threshold and improved threshold retrackers are assessed over waters around Taiwan. The improved threshold retracker outperforms the other two. The improvement in the accuracy of sea surface height (SSH) is investigated according to marine zone and the distance of waters to the shore. The improvement rate increases closer to the land, with the largest improvement rate of about 20% in waters within 10 km of the shore. Over waters around islands and coasts, there are still retracked SSHs with large errors. Least-squares collocation is used to compute gravity anomalies from the Geosat/GM altimeter data. Use of retracked SSHs improves the accuracy of gravity anomalies by about 11%. Adding airborne gravity data further improves the accuracy, especially in the immediate vicinity of the coasts. Tide model errors over coastal waters remain a problem in altimetry applications, even if the waveforms are properly retracked. 相似文献
5.
Geosat/GM波形重跟踪反演中国沿海区域重力异常 总被引:1,自引:1,他引:0
利用Geosat/GM测高波形数据,在中国海域内(117°E~129°E,21°N~41°N)比较了阈值法、Beta5和改进阈值法三种重跟踪算法.分析表明,改进阚值法优于其他两种重跟踪方法.由改进阈值法的测高数据.分别采用最小二乘法(least sqlilare collocation,LSC)和逆Vening-Meinesz(IVM)计算了卫星测高重力异常,并与船测重力数据进行了比较.结果显示,LSC的精度优于IVM.与KMS02和Sandwell & Smith V15两个重力场模型相比较,本文结果在东海优于这两个模型,在台湾海域结果稍差,需要融合ERS-1等其他数据进一步提高精度. 相似文献
6.
Ute C. Herzfeld Craig S. Lingle Cecily Freeman Chris A. Higginson Michael P. Lambert Li-Her Lee Vera A. Voronina 《Mathematical Geology》1997,29(7):859-890
The Antarctic Ice Sheet plays a major role in the global system, and the large ice streams discharging into the circumpolar sea represent its gateways to the world's oceans. Satellite radar altimeter data provide an opportunity for mapping surface elevation at kilometer-resolution with meter-accuracy. Geostatistical methods have been developed for the analysis of these data. Applications to Seasat data and data from the Geosat Exact Repeat Mission indicate that the grounding line of Lambert Glacier/Amery Ice Shelf, the largest ice stream in East Antarctica, has advanced 10–12 km between 1978 and 1987–89. The objectives of this paper are to explore possibilities and limitations of satellite-altimetry-based mapping to capture changes for shorter time windows and for smaller areas, and to investigate some methodological aspects of the data analysis. We establish that one season of radar altimeter data is sufficient for constructing a map. This allows study of interannual variation and is the key for a time-series analysis approach to study changes in ice streams. Maps of the lower Lambert Glacier and the entire Amery Ice Shelf are presented for austral winters 1978, 1987, 1988, and 1989. As a first step toward understanding the dynamics of the ice-stream/ice-shelf system, elevation changes are calculated for grounded ice, the grounding zone, and floating ice. In the absence of (sufficient) surface gravity control for the Lambert Glacier/Amery Ice Shelf area, altimetry-based maps may facilitate improvement of geoid models as they provide constraints on the terrain correction in the inverse gravimetric problem. 相似文献
7.
Steve Sramek 《Marine Geodesy》2013,36(2-3):151-163
Local changes in the marine geoid (<100 nm in size) correspond well with bathymetric features such as seamounts. Thus the marine geoid height may be used to verify existing features, predict the bathymetry of unsurveyed areas, and fill gaps in existing data. The application of matching high‐pass filters to both the geoid and bathymetry data of an area allows the regional trends to be removed so that only the features remain. Filter values that begin to pass data with wavelengths less than 125 miles and all data with wave lengths less than 70 miles were selected. The high‐frequency variations of the geoid can then be correlated to the bathymetry and a scaling factor between the two calculated. The highest correlations (.81) were achieved using a cut‐off value for the filtered geoid data. A gridded synthetic bathymetry file was created by scaling the filtered geoid to the filtered bathymetry and adding the low pass background bathymetry. The gridded historical bathymetry could then be subtracted from the synthetic bathymetry in an automated method to display probable new features. A final selection of 458 previously unreported major features was then made. 相似文献
8.
INTRODUCTIONBeing a current of high temperature and high salinity, the Kuroshio carries a large amount ofheat from low latitude tropical ocean to high latitude ocean, and plays an imPOrtant role in theheat balance in East Asia. The variability of the Kurosl,io can affect the climate of East Asia, aswell as the ocean environment and the fishery resources. A lot of studies showed that the variabilitiies of the Kuroshio were related to the global changes especially to the onset of ENSO.… 相似文献
9.
Pan Jiayi Wang Junqin Wang Yanfeng Zhang Xinmei Yuan Yeli Zheng Quan''an 《海洋学报(英文版)》1999,18(4):523-533
INTRODUCTIONThegeoidistheiargeopotentials~econfidingmostlywiththemeanseasurfaceandisdenotedastheheightrelativetotheidealelliPSes~eoftheearth.Thegeoidundulationsinglobalaceareupto100m.TheunevenstructureOftheearthgivesrisetotheunevenfeatureofthecitysot... 相似文献
10.
A multi-subwaveform parametric retracker of the radar satellite altimetric waveform and recovery of gravity anomalies over coastal oceans 总被引:3,自引:0,他引:3
HWANG CheinWay 《中国科学:地球科学(英文版)》2010,(4)
The quality of satellite radar altimetric data is very important in studies of geodesy,geophysics,and oceanography.Over coastal oceans,altimeter waveforms are contaminated by the terrain and physical environments so that the accuracy of altimeter data is lower than that over open oceans.Here we develop a new multi-subwaveform parametric retracker(MSPR) to improve the quality of altimeter data for the recovery of gravity anomaly in coastal oceans.The least squares collocation method is used to recover the residual gravity anomaly over the coastal water from altimetric data.The waveform data records from Geosat/GM around Taiwan Island are practically retracked with MSPR.When compared with the Taiwan geoid height,the results retracked by MSPR are more accurate than those retracked by the well-known β-5-parmeter method and from the geophysical data records(GDRs).The gravity anomalies over Taiwan coastal waters are calculated from the retracked altimeter data with the least squares collocation.When we compared gravity anomalies computed using altimeter GDRs with the ship-borne gravity data over Taiwan coastal ocean,we found that the results from retracked data are more accurate than those from GDRs. 相似文献