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联合基于GRACE重力卫星观测资料恢复的重力场模型(EIGEN-GL04S1)和卫星测高推求的平均海面高模型(KMSS04)来构造南极绕极流区域的平均海面动力地形,并利用小波滤波方法去掉短波及噪声信号,进而推算大、中尺度的绕极流。与非卫星重力场模型、同化资料及海洋水文资料确定相应结果的验证分析表明:基于新的卫星重力场模型推算的南极绕极流区域的海面动力地形、PF、SAF和表层流场等都与海洋学结果相吻合,且局部特征更加清晰。表明卫-卫跟踪重力卫星计划确定的地球重力场模型较之以前存在的重力场模型在中长波部分精度有较大提高,从大地测量(从空间)角度来探测南极绕极流已达到较高的精度。 相似文献
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南极冰盖物质平衡最新的研究进展表明,西南极洲表现出两种变化模式,西部在增厚,而北面在更快地减薄。西南极冰盖总体可能正在减薄,其物质损失的速率可能足以使海平面每年上升近0.2mm。东南极冰盖物质不平衡可能很小,甚至其符号还不能被确定。南极半岛正在经历着快速变化。目前还不能可靠地估算南极冰盖的物质平衡状态。同时,大型冰川的停滞,一些冰川流速加快,冰盖大范围加速减薄,冰架大面积的快速崩解和支流冰川的加速,以及着地线强烈的底部融化等显示出南极冰盖存在快速变化。南极冰盖物质平衡未来的重点研究领域是开展冰盖表面高程变化的监测与模拟,确定表面物质平衡及其在各冰流盆地的分布,着地线的冰流通量,冰架底部的融化,了解冰后期冰盖退缩的动力过程,以及开发、对比和改进与冰盖物质平衡模拟和预测相关的各种模型。 相似文献
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利用GRACE重力卫星监测祁连山水储量时空变化 总被引：1，自引：0，他引：1
利用经过高斯平滑滤波处理的2003年1月～2010年12月逐月的GRACE卫星时变重力场数据反演得到祁连山山区水储量变化,其空间分辨率为1°×1°,结合同时间段该区域35个国家气象台站逐月降水资料,采用趋势分析方法研究了祁连山山区近8 a来的水储量时空变化特征。结果表明:祁连山山区水储量变化从空间分布上来看具有明显的空间差异性,总体表现为东少西多,南多北少的空间分布格局。在时间上,水储量变化与降水一样具有明显的季节变化规律,两者变化过程基本一致。祁连山山区平均水储量变化趋势的年内分布总体上为1～12月水储量趋势呈由高到低的递减变化。1～11月份,变化趋势为正增长,最大正增长为47.8 mm/a,出现在6月份。12月变化趋势呈负增长,负增长趋势为-2.5 mm/a。2003-2010年祁连山山区水储量总体上呈逐年上升趋势,平均上升速度为0.72 mm/mon,8 a间水储量增加约13.6×108m3,其主要原因一方面是由于气候转暖使该区冻土退化,活动层加厚,导致蓄水增加,另一方面是由于近些年该地区加大山区水源涵养林建设,增加了山区蓄水功能。 相似文献
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区域海面变化研究受到验潮站数据时段不一致、空间分布不均匀及影响要素复杂性和不确定性等因素制约。本文基于西北太平洋海域22 个站位的验潮数据,应用RegEM及MTM方法探讨其多尺度波动过程的时空差异,基于空间邻近性及有序聚类方法,将区域海面变化划分为5个区段(渤海-黄海北部沿岸、黄-东海中国沿岸、东海海域日本沿岸、东海南部沿岸以及南海西北部沿岸),进而利用MGF方法对各站位进行中长期的统计预测,并结合主成分方法进行区域综合。结果显示各区2001-2030 年的海面变化平均速率分别为：1.23~1.27 mm/a,3.30~3.34 mm/a,2.72~2.76 mm/a,1.43~1.47 mm/a和1.13~1.15 mm/a,而区域海面上升速率为2.01~2.11 mm/a。 相似文献
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2002-2010年长江流域GRACE水储量时空变化特征 总被引：2，自引：0，他引：2
利用高斯平滑滤波对2002年4月-2010年12月逐月GRACE卫星的时变重力场数据反演得到长江流域大尺度陆地水储量变化,对其时空变化进行研究,并将结果与全球陆面同化数据(GLDAS)模拟结果进行比较。其结论为:根据GRACE数据反演与GGLDAS模拟得到的水储量结果在大多数区域变化趋势相同,两者具有一致性,相关性达到0.89(P<0.05)。GRACE水储量研究结果表明:①2002-2010年长江流域水储量呈增加趋势,平均增长速率为0.43mm/月,相当于约95.04亿m3/年。长江上游增长速率为0.53mm/月,相当于约67.13亿m3/年;中游增长速率为0.51mm/月,相当于25.73亿m3/年;下游增长速率为0.36mm/月,相当于9.14亿m3/年。近9年长江流域水储量共增加约855.33亿m3。②从多年平均水储量空间分布来看,长江流域冬季月份(12、1、2、3月)水储量处于亏损状态,7-9月水储量处于盈余状态,4-6月下游至上游地区由亏损向盈余状态过渡,而10-11月则从上游至下游地区由盈余向亏损状态过渡。③全流域、上游及中游水储量逐月增长速率最大值出现在9月,分别为1.01cm/a、1.37cm/a、1.05cm/a;而下游地区则出现在7月,增长速率为1.62cm/a。 相似文献
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利用南极大陆12个累积观测数据超过3年的GNSS跟踪站的监测序列,比较分析了其径向的形变趋势与GIA(Glacial Isostatic Adjustment)模型预测形变,并且与GRACE(Gravity Recovery and Climate Experiment)估计的径向位移结果进行相关性分析。GNSS结果显示跟踪站的径向形变多呈现上升趋势,少量出现下降的跟踪站多分布在东南极沿海区域,下降速度较小。与GRACE计算结果相比,两者的相关系数在0.241—0.663之间,表明两种观测手段得到的结果总体呈现较强的相关性。GNSS形变趋势与最新的GIA模型(W12a)预测形变趋势有一定的偏差,但总体吻合。 相似文献
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1986―2008年广东沿海海平面变化趋势 总被引：3，自引：0，他引：3
根据1993-2008年TOPEX和Jason-1观测的南海海面高度资料和1986-2008年广东省沿海验潮站潮位资料,分析南海绝对海平面及广东沿海相对海平面变化趋势,结果显示:近16年南海(绝对)海平面平均上升率为4.5 mm/a,近23年广东沿海相对海平面上升率为2～3 mm/a,较南海绝对海平面上升率低1～2 mm/a:月平均海平面及年平均海平面变化均存在极强的同步性,在年平均海平面变化中,验潮站的最高值一致出现于2001年.预估未来30年南海海平面比常年升高9～17 cm.海平面上升将加剧珠江口感潮河段的咸潮灾害. 相似文献
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自第4个国际极地年2007/2008开始至2013年,中国南极内陆冰盖科考队相继在自南极大陆边缘的中山站至东南极地形最高点昆仑站(Dome A)一线进行了低温甚宽频地震观测。本文对7个天然地震台站数据进行了分析,提取了这些台站的S波接收函数,据此反演获得了这些台站下的地壳厚度分布。结果显示:随着纬度的升高,地壳厚度由大陆边缘的中山站下的约38 km逐渐增加至CHNB台下的58 km,随后又于CHNA台站下方减薄至47 km,然后快速增大到南极地形最高点昆仑站(Dome A)下的62 km。昆仑站或Dome A是南极大陆地壳最厚的地方。从中山站至昆仑站之间地壳厚度的变化与冰下地貌变化存在明显的相关性,它们都说明了从中山站至CHNB之间地壳构造相对均匀。在距昆仑站约200 km的CHNA台下的地壳厚度(约47 km)明显比临近台站地壳偏薄,这可能说明了甘伯采夫山脉地壳侧向变化较大,即其形成时所遭受的构造作用较复杂。 相似文献
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Monthly gravity solutions of the Gravity Recovery and Climate Experiment (GRACE) reveal three areas in Antarctica with striking interannual mass trends. The positive mass trend in Enderby Land, East Antarctica, is poorly understood because of uncertainties in the surface ice-sheet mass balance, post-glacial rebound (PGR), and processing of GRACE data. In this study, we compare the GRACE mass trends with values estimated from in situ snow-stake measurements, and Ice Cloud and land Elevation Satellite (ICESat) data. The mass trends estimated from ICESat data show a strong correlation with GRACE mass trends. In contrast, the snow-stake data show discrepancies with temporal variations in GRACE mass, especially in 2006. The discrepancies are probably associated with basal ice-sheet outflow, which is difficult to observe using snow stakes. We conclude that the bulk of the GRACE mass trend can be explained by snow accumulation and basal ice-sheet outflow. 相似文献
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Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity 总被引：2，自引：0，他引：2
Isabelle Panet Valentin Mikhailov Michel Diament Fred Pollitz Geoffrey King Olivier de Viron Matthias Holschneider Richard Biancale Jean-Michel Lemoine 《Geophysical Journal International》2007,171(1):177-190
The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December ( M w = 9.2) and 2005 March ( M w = 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin. 相似文献
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Retrieving earthquake signature in grace gravity solutions 总被引：2，自引：0，他引：2
O. de Viron I. Panet V. Mikhailov M. Van Camp M. Diament 《Geophysical Journal International》2008,174(1):14-20
The GRACE satellites have been orbiting the Earth since 2002, monitoring the time variable gravity field. Some of the observed fluctuations are due to geodynamic causes, but they are often hidden in the complex signal, composed of hydrology, ocean, atmosphere, and geodynamics, the signal of geodynamic origin being usually the smallest. In addition, dealiasing residuals and noise make the separation of the signal from the different causes more difficult. We proposed a method based on the Empirical Orthogonal Function decomposition to extract the signal of physical origin, under the hypothesis that the physical signal is spatially more consistent than the noise and aliasing incomplete correction. We used synthetic geoid variations associated with earthquakes located at nearly 2000 positions at the Earth surface, based on several examples of large actual subduction events. We show that, with the present day accuracy, we can retrieve the geoid variations associated with more than 98 per cent of the earthquakes of magnitude 9 or above, around 60 per cent for magnitude 8.8, 40 per cent for magnitude 8.6 and 33 per cent for magnitude 8.3. Some events, with the right properties and location, can be detected with magnitude as low as 8. We then applied the method to the GRACE solutions, and retrieved the Hokkaido event (2003) and the Sumatra event (2004), which is in agreement with the retrieval rates mentioned here above. 相似文献
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There are only limited surface water resources available in the Heihe River Basin （HRB）, a typical inland river basin in the arid region of northwestern China, where groundwater overexploitation is a serious problem. Groundwater has become one of main resources of fresh water in the HRB. In this paper, temporal and spatial variations of groundwater in the HRB are estimated by the Gravity Recovery and Climate Experiment （GRACE） satellites. Our analysis shows that groundwater storage in the HRB reaches its highest in the summer of 2005, and then begins to decline in the following years and reaches steady status in 2008. Spatially, groundwater shows a decline in the upper HRB in the first two years and a slight increase in the following years, while this phenomenon is reversed in the middle HRB where groundwater slightly increases in 2005 and then declines in the following three years. In the lower HRB, GRACE detects a continual increase in the full six-year period. This approach is proven successful when employed in the HRB and thus offers a new insight into monitoring groundwater variations in a river basin with limited or even without any observed data. 相似文献
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Inference of mantle viscosity from GRACE and relative sea level data 总被引：12，自引：0，他引：12
Gravity Recovery And Climate Experiment (GRACE) satellite observations of secular changes in gravity near Hudson Bay, and geological measurements of relative sea level (RSL) changes over the last 10 000 yr in the same region, are used in a Monte Carlo inversion to infer-mantle viscosity structure. The GRACE secular change in gravity shows a significant positive anomaly over a broad region (>3000 km) near Hudson Bay with a maximum of ∼2.5 μGal yr−1 slightly west of Hudson Bay. The pattern of this anomaly is remarkably consistent with that predicted for postglacial rebound using the ICE-5G deglaciation history, strongly suggesting a postglacial rebound origin for the gravity change. We find that the GRACE and RSL data are insensitive to mantle viscosity below 1800 km depth, a conclusion similar to that from previous studies that used only RSL data. For a mantle with homogeneous viscosity, the GRACE and RSL data require a viscosity between 1.4 × 1021 and 2.3 × 1021 Pa s. An inversion for two mantle viscosity layers separated at a depth of 670 km, shows an ensemble of viscosity structures compatible with the data. While the lowest misfit occurs for upper- and lower-mantle viscosities of 5.3 × 1020 and 2.3 × 1021 Pa s, respectively, a weaker upper mantle may be compensated by a stronger lower mantle, such that there exist other models that also provide a reasonable fit to the data. We find that the GRACE and RSL data used in this study cannot resolve more than two layers in the upper 1800 km of the mantle. 相似文献
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Increased accuracy in measuring temporal variations in the Earth's gravity field allow inprinciple the use of gravity observations to deduce subsurface water-mass changes. This canbe with respect to a small area, or as a larger spatial average of water mass change usinggravity observations from low-altitude satellites, such as the forthcoming GRACE mission.At both scales, there is a need to validate gravity-based estimates against field recordings ofactual subsurface water-mass variations. In practice, this could prove difficult because thespatial integral of all water-storage change components can be subject to considerable fieldmeasurement error. An alternative approach to the validation process is proposed by whichsuitable geological formations are utilized as giant weighing devices to directly measure area-integratedwater-mass changes. The existence of such natural geological weighing lysimetersis demonstrated using observations from a replicated experimental site in New Zealand. Sitesof this type could be used to verify water-storage change estimates derived from sensitiveground surface gravity instrumentation. In addition, geological lysimeters could be used tomake local checks on the accuracy of any estimated regional water-mass time series, whichis proposed for satellite calibration. The land area weighed by a geological lysimeter increaseswith formation depth and it is speculated that recordings made at oil well depth may allowdirect monitoring of subsurface water mass changes at the regional scale. 相似文献
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Gobashy Mohamed Abdelazeem Maha Abdrabou Mohamed Khalil Mohamed H. 《Natural Resources Research》2020,29(1):499-519
The use of spontaneous potential (SP) anomalies is well known in the geophysical literatures because of its effectiveness and significance in solving many complex problems in mineral exploration. The inverse problem of self-potential data interpretation is generally ill-posed and nonlinear. Methods based on derivative analysis usually fail to reach the optimal solution (global minimum) and trapped in a local minimum. A new simple heuristic solution to SP anomalies due to 2D inclined sheet of infinite horizontal length is investigated in this study to solve these problems. This method is based on utilizing whale optimization algorithm (WOA) as an effective heuristic solution to the inverse problem of self-potential field due to a 2D inclined sheet. In this context, the WOA was applied first to synthetic example, where the effect of the random noise was examined and the method revealed good results using proper MATLAB code. The technique was then applied on several real field profiles from different localities aiming to determine the parameters of mineralized zones or the associated shear zones. The inversion parameters revealed that WOA detected accurately the unknown parameters and showed a good validation when compared with the published inversion methods.
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