联合多种测高数据确定中国边缘海及全球海域的垂线偏差

On the basis of gravity field model （EIGEN_CG01C）, together with multi-altimeter data, the improved deflection of the vertical gridded in 2＇×2＇ in China marginal sea and gridded in 5＇×5＇ in the global sea was determined by using the weighted method of along-track least squares, and the accuracy is better than 1.2^# in China marginal sea. As for the quality of the deflection of the vertical, it meets the challenge for the gravity field of high resolution and accuracy, it shows that, compared with the shipboard gravimetry in the sea, the accuracy of the gravity anomalies computed with the marine deflection of the vertical by inverse Vening-Meinesz formula is 7.75 m.s ^-2.     

High precision vertical deflection over China marginal sea and global sea derived from multi-satellite altimeter

On the basis of gravity field model (EIGEN_CG01C), together with multi-altimeter data, the improved deflection of the vertical gridded in 2′×2′ in China marginal sea and gridded in 5′×5′ in the global sea was determined by using the weighted method of along-track least squares, and the accuracy is better than 1.2″ in China marginal sea. As for the quality of the deflection of the vertical, it meets the challenge for the gravity field of high resolution and accuracy. It shows that, compared with the shipboard gravimetry in the sea, the accuracy of the gravity anomalies computed with the marine deflection of the vertical by inverse Vening-Meinesz formula is 7.75 m·s?2.     

On the absolute deflection of the vertical at Potsdam

Summary After a numerical comparison of geoidal surfaces, the author finds confirmed the values of the deflection of the vertical at Potsdam, as given by ProfessorLedersteger. These values should, however, not be considered as definitive before the value determined by means of the profile of the gravimetrically obtained geoid, will be in sufficient agreement with the amount computed by means of theVening Meinesz-Integral. According to the present state, a discrepancy in the north-south direction of more than 2″ seems to exist between both. Definitive statements might not be possible before the supply of the gravity material by means of additional observations.

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Zusammenfassung Die von Professor Dr.Ledersteger ermittetten Werte für die Lotabweichung in Potsdam findet der Verfasser auf Grund einer numerischen Vergleichung von Geoidfl?chen best?tigt. Jedoch dürften die Werte der Lotabweichungskomponenten für Potsdam erst dann als endgültig anzusehen sein, wenn der aus dem Profil des gravimetrisch ermittellen Geoides bestimmte Wert mit dem nach dem Integral vonVening Meinesz berechneten Betrag hinreichend übereinstimmt. Nach dem augenblicklichen Stand scheint zwischen beiden in Nordsüdrichtung noch eine Differenz von über 2′ zu bestehen. Endgültige Aussagen wird man erst nach Vervollst?ndigung des Schwerematerials durch neue Beobachtungen treffen k?nnen.

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Resumen Según una comparación numérica de superficies sobre el geoide, confirma el autor los valores de la desviación de la vertical en Potsdam, dados por el professorLedersteger. Dichos valores no pueden, sin embargo, ser considerados como definitivos sino después de su comparación con los datos gravimétricos que parecen dar una discordancia del órden de 2″ para la componente Norte-Sur.

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Résumé D'après une comparaison numérique de surfaces sur le géo?de, l'auteur confirme les valeurs de la déviation de la verticale à Potsdam données par le ProfesseurLedersteger. Elles ne pourront toutefois être considérées comme définitives qu'après comparaison avec les dennées gravimétriques qui semblent donner une discordance de l'ordre de 2″ pour la composante Nord-Sud.

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Sommario Fondandosi su di un confronto numerico, l'Autore conferma i valori della deviazione della verticalè a Potsdam dati dal prof.Ledersteger. Questi valori si potranno considerare tuttavia come definitivi soltanto dopo confronto con i risultati gravimetrici, che sembrano mostrare una discordanza dell'ordine di 2″ per la componente meridiana.

     

Integral formulas for computing the disturbing potential, gravity anomaly and the deflection of the vertical from the second-order radial gradient of the disturbing potential

Integral formulas are derived which can be used to convert the second-order radial gradient of the disturbing potential, as boundary values, into the disturbing potential, gravity anomaly and the deflection of the vertical. The derivations are based on the fundamental differential equation as the boundary condition in Stokes’s boundary-value problem and the modified Poisson integral formula in which the zero and first-degree spherical harmonics are excluded. The rigorous kernel functions, corresponding to the integral operators, are developed by the methods of integration.     

ENVISAT测高卫星沿轨大地水准面梯度的海洋垂线偏差法研究

研究了利用沿轨大地水准面梯度数据计算海洋垂线偏差的最小二乘法,首先对ENVISAT测高数据进行各项地球物理改正得到近似测高大地水准面,然后计算沿轨大地水准面的梯度,接着用最小二乘法计算格网垂线偏差东西分量和南北分量的平均值。最后,用该方法计算了南中国海区域及其邻近海域(4°N～25°N,104°E～120°E)的5′×5′垂线偏差南北分量和东西分量,其精度优于7″,并与EGM96模型计算的垂线偏差值进行了比较,证明了该方法的有效性。     

局部区域模型垂线偏差快速算法

针对利用地球重力场模型计算大范围、高分辨率局部区域模型垂线偏差速度慢这一问题,该文在对位系数模型泰勒级数展开的基础上,提出了采用向量运算、混合编程、预先计算缔合勒让德函数Belikov递推方法中与经纬度无关量的方法;最后与严密公式计算结果作对比。实验结果表明,该方法不仅可以满足精度要求,而且可以有效提高计算速度。     

基于Laplace方程的垂线偏差法反演全球海域重力异常

海洋重力场模型反演的质量主要依赖于采用测高数据的精度、空间分辨率和数据分布密集程度。本文联合Geosat GM/ERM、ERS-1 GM/ERM、TOPEX/Poseidon、Envisat、Cryosat-2、Jason-1 ERM/GM和SARAL/AltiKa等多种测高观测数据集,深入比较了多种波形重跟踪算法的效果,回波数据重跟踪处理后的沿轨海面高标准差。统计表明,Sandwell算法优于MLE-4算法、Davis阈值法、改进阈值法和β参数拟合法;基于不同测高数据波形重采样的结果给出了沿轨海面梯度计算中低通滤波的参数选择方法,并采用Sandwell提出的垂线偏差法,反演了全球海域1′×1′的重力场模型。检核表明,反演结果与DTU13和SIO V23.1模型检核的差值均方根分别为3.4、1.8 mGal,与NGDC船测数据的检核精度为4～8 mGal,且本文模型在部分典型海区内精度更优。     

滇东南地区垂直负荷形变特征研究

针对传统的全球水文同化模型计算陆地垂直负荷形变的不确定度问题,该文采用GPS、GRACE以及GLDAS3种数据对滇东南13个GPS连续站的垂直负荷形变进行了综合的分析。结果表明:GPS垂向形变时间序列中,陆地水负荷形变显著,高值达12 mm,其中GRACE的贡献值为32.1%,GLDAS的贡献值为26.9%;对于初相位而言,GPS、GRACE、GLDAS三者符合得很好;对于振幅而言,GPS与GRACE的振幅较为接近,GLDAS的振幅最小;通过主成分分析方法所获取的GPS共模误差与GRACE的相关性高达0.90。虽然GRACE的空间分辨率较低,但GRACE为连续监测地表垂直负荷形变提供了一种有效和可靠的手段。     

An analysis of vertical deflections derived from high-degree spherical harmonic models

The theoretical differences between the Helmert deflection of the vertical and that computed from a truncated spherical harmonic series of the gravity field, aside from the limited spectral content in the latter, include the curvature of the normal plumb line, the permanent tidal effect, and datum origin and orientation offsets. A numerical comparison between deflections derived from spherical harmonic model EGM96 and astronomic deflections in the conterminous United States (CONUS) shows that correcting these systematic effects reduces the mean differences in some areas. Overall, the mean difference in CONUS is reduced from −0.219 arcsec to −0.058 arcsec for the south–north deflection, and from +0.016 arcsec to +0.004 arcsec for the west–east deflection. Further analysis of the root-mean-square differences indicates that the high-degree spectrum of the EGM96 model has significantly less power than implied by the deflection data. Received: 9 December 1997 / Accepted: 21 August 1998     

The deflection of the vertical in the Western and Central Mediterranean area

The deflection of the vertical at 23 stations was determined by gravimetrical methods and compared to the difference of astronomic observations and geodetic values of the European adjustment. The results show a fair agreement between the two independent sets of values, indicating that doubts about the relative reliability of submarine gravity observations are not justified. A systematic discrepancy in the meridian components of the deflection may reflect on theHayford ellipsoid as used in the European adjustment.

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Zusammenfassung Auf 23 Stationen wurde die Lotabweichung gravimetrisch bestimmt und den astro-geod?tischen Werten der europ?ischen Ausgleichung gegenübergestellt. Die beiden Ergebnisse stimmen sehr gut überein. Damit werden die Bedenken hinf?llig, die sich gegen den Wert von Messungen in Unterseebooten richteten. Systematische Abweichungen in den meridionalen Komponenten beruhen m?glicherweise auf der art der Anwendung des Hayfordschen Ellipsoids in der Ausgleichung des Zentraleurop?ischen Netzes.

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Resumen La desviación de la vertical en 23 estaciones ha sido determinada por el método gravimétrico y compara con los resultados astrogeodéticos de la compensación europea. Existe muy buen acuerdo entre los dos conjuntos de datos, que demuestra que las dudas emitidas en cuanto al valor de las observaciones en submarino son injustificadas. Una discordancia sistemática en las componentes meridianas podria ser debida al empleo del elipsoide deHayford en la compensación de la red europea.

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Résumé La déviation de la verticale en 23 stations a été déterminée par la méthode gravimétrique et comparée aux résultats astrogéodésiques de la compensation européenne. Il y a très bon accord entre les 2 ensembles de données, ce qui montre que les doutes émis quant à la valeur des observations en sous-marins sont injustifiés. Une discordance systématique dans les composantes méridiennes pourrait être due à la fa?on dont on a employé l'ellipso?de deHayford dans la compensation du réseau central européen.

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Sommario E'stata determinata col metodo gravimetrico la deviazione della verticale in 23 stazioni e comparata ai risultati astro-geodetici della compensazione europea. Vi é molto buon accordo tra i due insiemi di dati, ciò che dimostra che i dubbi emessi circa il valore delle osservazioni in sottomarino sono ingiustificati. Una discordanza sistematica tra le componenti maridiane potrebbe essere dovuta all'impiego nella compensazione della rete central europea dell'ellisoide diHayford.

     

我国GPS基准站地壳垂直位移周年变化的气象激发

利用全球大气、海洋、积雪和土壤水的地表质量负荷资料 ,计算了中国GPS基准网 2 4个台站垂向位移周年变化的气象激发 ,得到振幅 5mm10mm的高程变化。通过与GPS观测资料解算的垂向位移结果比较 ,大部分台站的结果与GPS结果在振幅上符合比较好 ,但相位普遍超前一到二个月     

基于通量均衡基准的地壳垂直形变场逼近的Fourier分析法

本文根据地壳运动的全球通量均衡假说建立了地壳垂直形变场的分析模型,分析了以往作者所研究的球谐函数和球冠谐函数模型的优缺点,着重推导了在密切平面坐标系下该模型的Fourier级数解,该模型一方面可以简单地应用于地壳垂直形变场的逼近,另一方面为采用谱分析法提取地壳垂直形变场信息提供了理论依据。     

Determination of Geopotential of Local Vertical Datum Surface

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珠峰高程测量大气垂直折光系数的研究

大气垂直折光是影响珠峰高程测量成果和精度的重要因素之一。本文根据2005年珠峰高程测量实际数据详细分析研究了大气温度垂直梯度与大气垂直折光系数的计算原则、方法及其变化特征与变化趋势,结合同以往(1975、1992年)珠峰高程测量中大气温度垂直梯度与大气垂直折光系数变化趋势的比较,得出气温垂直梯度与大气垂直折光系数均存在周日变化并给出了它们的变化趋势,提高了珠峰高程的计算精度。     

小波分解AR-BP网络模型在大坝垂直位移预测中的应用

针对大坝内部垂直位移数据序列不仅具有周期性、平稳性,且在频域上存在高、低频,显著的多尺度等特性,本实验利用多尺度小波分析的原理与方法对数据序列进行分解,对低频序列和高频序列分别建立AR模型和BP神经网络模型并进行预测,最后叠加各个序列的预测值,得到数据序列的预测结果。该方法适用于大坝垂直位移的预测,结果与自回归模型及单BP神经网络模型相比,该模型具有更高预测精度。     

横断山区地表真实面积与垂直投影面积差异分析 ——以雅江县为例

横断山脉地形起伏复杂,以垂直投影面积作为地表真实面积进行定量计算会产生较大误差.本文以横断山脉中部雅江县为例,基于DEM数据和地表覆盖产品数据集,利用地表粗糙度的地学意义,计算了雅江县不同土地利用类型地表真实面积,并分析了地表真实面积与垂直投影面积之间的差异.结果表明:雅江县地表面积与投影面积的差异与DEM分辨率呈正相...     

Detection of small hydrological variations in gravity by repeated observations with relative gravimeters

Recently, a new application of time-dependent gravity observations is emerging: the study of natural hydrological mass changes and their underlying processes. Complementary to GRACE data and continuous recordings with superconducting gravimeters, repeated observations with relative instruments on a local network may contribute to gain additional information on spatial changes in hydrology. The questions that need to be addressed are whether the results of these repeated measurements will be of sufficiently high resolution and accuracy, as well as how unique the information obtained will be. To examine this, a local gravity network with maximum point distances of 65 m was established in a hilly area around the Geodynamic Observatory Moxa, Germany. Using three to five LaCoste & Romberg relative gravimeters repeated measurements were carried out in a seasonal rhythm as well as at particular events like snowmelt or dryness in 17 campaigns between November 2004 and April 2007. The standard deviations obtained by least squares adjustment range from ±9 to ±14 nm/s² for a gravity difference of one campaign, thus for gravity changes between two campaigns from ±13 to ±20 nm/s². Between the points of the network, spatial gravity changes of up to 171 nm/s² (139 nm/s² between two successive campaigns) could be proven significantly. They correlate with changes in the local hydrological situation. Particularly, a steep slope next to the observatory is identified as a gravimetrically significant hydrological compartment. The results obtained contribute to an improved reduction of the local hydrological signal in continuous gravity recordings and provide constraints to hydrological models.     

鄂尔多斯块体东北缘近期地壳垂直形变监测

为深入分析并研究鄂尔多斯块体东北缘近期的地壳垂直形变趋势,基于区域中10条国家一等水准测量路线的共用水准点,通过分段平差计算其相应的高程平差值及垂直形变量,进而利用三角网法提取该地区的垂直形变速率等值线。通过效果图对比可知,近期鄂尔多斯块体东北缘呈现下沉的趋势,两个V型漏斗区分布于整个研究区域中部的南北两侧,南侧漏斗区的下沉速率较北侧偏大,这在一定程度上与该地区北高南低的地形走向大体一致。但对于V型漏斗区形成的具体原因还有待进一步研究并确认。     

高原山区局部大地水准面精化方法研究

局部大地水准面精化的实质是精确计算出大地水准面的起伏变化情况。一般情况下,需要密度足够的重力数据,依重力异常密集计算大地水准面差距或高程异常。但是在大陆西部高原山区重力点密度是不够的,无法达到大地水准面精化的目的。本文从理论上证实了用地形和岩石密度数据进行局部大地水准面精化的可行性。     

COVID-19疫情初期美国城市夜间灯光时空变化分析

为应对COVID-19疫情而采取的非药物干预措施显著改变了城市社会经济活动,但其变化特征和时空模式仍不明确。本研究以美国20个大城市为例,获取NPP-VIIRS月度合成数据分析2020年2—4月COVID-19疫情初期城市夜光亮度变化的空间格局、衰减特征和用地类型差异。结果表明,疫情防控措施导致美国城市夜光亮度普遍变暗,平均降低5%—8%。夜光变化呈现明显“中心—边缘”空间结构特征,夜光降低幅度随到城市中心距离增加而减小。不同用地类型夜光变化幅度存在差异,纽约居住用地和航空设施用地夜光亮度降低幅度最明显,分别下降12%和11%。芝加哥各类用地夜光亮度普遍下降20%左右,除体育设施用地外,其他各类用地夜光亮度一个月后有所恢复。夜光遥感有效反映了城市社会经济活动变化,在监测评估突发事件社会影响方面具有重要应用。