共查询到17条相似文献，搜索用时 171 毫秒
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利用GOCE重力场模型确定全球稳态海面地形及表层地转流 总被引：1，自引：0，他引：1
稳态海面地形(MDT)是大地测量学家和海洋学家共同关心的一个重要物理量.该文基于WHU2009全球平均海面高模型和GO_CONS_GCF_2_TIM_R3纯GOCE重力场模型,采用几何法经高斯滤波处理后确定了全球稳态海面地形,与CLS09及DTU10 MDTs相比,其差值均方根RMS均小于8 cm,表明该文结果具有较高的精度;根据地转流方程计算了相应的表层地转流,与GRACE重力场模型GGM03S结果相比,GOCE重力场模型所确定的表层地转流在墨西哥湾流、黑潮及厄加勒斯海流等海域均体现了更强的流速和更多的细部特征,验证了GOCE在洋流探测中的优势. 相似文献
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利用卫星测高、GRACE和GOCE资料估计全球海洋表面地转流 总被引：1，自引：1，他引：0
重力恢复和气候试验GRACE(gravity recovery and climate experiment)卫星极大地提高了地球重力场的精度和分辨率,特别是中长波分量,联合卫星测高数据可获得全球海洋表面大尺度洋流循环。另外,新一代地球重力和海洋环流探测卫星GOCE(gravity field and steady-state ocean circulation explorer)于2009年3月成功发射,采用卫星重力梯度测量原理,对重力场的高频部分非常敏感,使其高分辨率监测全球海洋循环成为可能。本文利用1~7年GRACE观测数据确定的重力场模型和18个月GOCE观测数据确定的地球重力场模型GO_CONS_GCF_2_TIM_R3,联合卫星测高确定的平均海面高模型MSS_CNES_CLS_11,分别估计全球海洋表面地转流,并且与实测浮标数据结果进行比较。分析表明GOCE重力卫星确定的重力场模型具有更高的空间分辨率,能够确定高精度和高空间分辨率的全球海洋地转流,如墨西哥湾暖流的细节和特征,并且与实测浮标结果基本一致。而基于1~4年GRACE观测资料的模型不能很好估计全球地转流特征,基于7年GRACE观测资料的重力场模型ITG-Grace2010s确定的全球地转流的精度仍低于18个月GOCE观测数据确定的地球重力场模型GO_CONS_GCF_2_TIM_R3的结果,估计的全球地转流仍含有较大的噪声,不能很好地反应中小尺度地转流细节特征。并计算ITG_Grace2010s和GOCE_TIM3的稳态海面地形和全球平均地转流的内符合精度,结果显示,在全球范围内,GOCE_TIM3的稳态海面地形和全球平均地转流的精度都比ITG_Grace2010s结果的精度有着很大的改善,其中ITG_Grace2010s的稳态海面地形的精度为21.6cm,而GOCE_TIM3的结果则为7.45cm,ITG_Grace2010s的全球平均地转流的精度为40.7cm/s,而GOCE_TIM3的结果则为19.6cm/s。 相似文献
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基于106个月的Grace（gravity recovery and climate experiment）月重力场模型（120阶次）,消除了月重力场的月、季度及年度变化,得到了稳态的地球重力场模型（Grace_sta）。在2～120阶次之间,Grace_sta与已有高阶重力场EGM2008及EGM96三个模型的阶方差是一致的。在2～100阶次之间,Grace_sta模型误差阶方差要小于EGM2008与EGM96误差阶方差。在全球范围内,Grace_sta重力场的大地水准面与EGM2008相应阶次的大地水准面标准差约为3cm,与EGM96模型大地水准面差异则高达52cm。结果表明,Grace_sta足可以取代EGM2008重力场模型2～100阶次的低阶部分,新得到的稳态重力场模型可为海面地形分析提供了可靠的参考场。 相似文献
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为得到中国近海及邻域精度较高的海面地形,同时尽可能减少滤波对海面地形精度的影响,提出了联合卫星测高潮汐分析与XGM2019e地球重力场模型确定海面地形的方法,首先通过T/P系列(包括Jason-1、Jason-2、Jason-3)卫星测高数据潮汐分析得到沿迹点平均海面高,从中扣除根据XGM2019e重力场模型计算相应沿迹点上的大地水准面高得到沿迹点海面地形,最后通过Kriging插值和Gauss滤波得到研究区域内30′×30′海面地形模型。与DTU22同区域海面地形对比整体差异为±4.49 cm,与沿岸长期验潮站实测海面地形对比整体精度为±4.56 cm,高精度的海面地形为研究海流的变化提供了现实依据。 相似文献
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海面风不仅是驱动上层海洋运动的主要动力, 其能量也是维持海洋表层流动的主要机械能来源。为了分析南海表层流风能输入的变化, 用SODA(Simple Ocean Data Assimilation)(1901—2010)资料估算了风向南海表层流(表层地转流+表层非地转流)的能量输入。结果表明, 风向南海表层流、表层地转流和表层非地转流输入的能量总体均呈减少趋势, 110年间分别减小了约56%、65%和49%。导致风能输入减小的最主要因素是风应力的减弱(减小了35%)。由于南海受季风系统的控制, 风向表层流及其各成分输入的能量呈现出显著的季节性变化。冬季风能输入最强, 高值区位于南海西部及北部区域, 呈一个显著的“回力镖”状结构。这些结果对深入认识南海环流具有理论意义。 相似文献
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由于卫星高度计数据分辨率高、观测范围广的特点,我们使用该数据开展了黑潮流的研究。在之前的研究中,卫星绝对地转流都被用于对黑潮流域的表层流场的时空变化特征进行研究,并采用了一些探测方法提取了黑潮流轴和流路。然而,海面绝对地转流是由绝对动力地形估计得到,应该被当做实际流场的地转分量,在实际应用中并不能代表真实流场。在本研究中,建立了气候态绝对地转流与网格平均的漂流浮标流场间的数学校验关系,以此对卫星绝对地转流场进行修正,即便这两种数据的性质存在些许偏差。因此,基于主成分探测法,修正后的卫星绝对地转流被用于探测黑潮流轴和流路。对比结果表明,由修正后的卫星地转流场探测得到的黑潮流轴和流路均要好于地转流和表层流估计结果。修正后的地转流有助于开展更加准确的黑潮流轴和流路的逐日探测。 相似文献
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《海洋预报》2021,38(4)
分别利用地转流、风海流和ROMS模式表层海流中的一项或者多项作为自变量,建立了关于表层漂流浮标漂移速度的回归模型,模拟了2017年12月—2018年2月和2019年12月—2020年2月的南海海域表层漂流浮标轨迹。根据回归模型结果对浮标进行72 h的漂移轨迹模拟,对比结果显示:基于地转流、风海流和ROMS模式表层海流3项作为自变量的回归模型(M_EGR)效果最好,其浮标模拟轨迹的72 h平均距离误差为38 km,平均角度误差为35°,平均综合技术得分为0.34。将风海流和地转流作为自变量加入到以ROMS模式表层海流结果为自变量的回归模型中,浮标模拟轨迹的72 h平均距离误差减少10 km,平均角度误差减少5°,平均技术得分提高0.09,特别是在涡旋附近区域的模拟效果得到显著提升。该方法对利用ROMS模式结果进行漂移浮标轨迹预测具有较好的校正效果。此外,风海流叠加地转流数据和ROMS模式数据在南海漂流浮标轨迹的预测方面具有较好的互补性;在南海流速相对稳定的区域,利用M_EGR模型得到的拟合流速可以较为准确地模拟漂移浮标轨迹,在南海涡旋活跃的区域,该模型效果有待进一步提升。 相似文献
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Wenyan Sui Junru Guo Jun Song Zhiliang Liu Meng Wang Xibin Li Yanzhao Fu Yongquan Li Yu Cai Linhui Wang Lingli Li Xiaofang Guo Wenting Zuo 《海洋学报(英文版)》2021,40(3):142-152
The new gravity field models of gravity field and steady-state ocean circulation explorer(GOCE), TIM_R6 and DIR_R6, were released by the European Space Agency(ESA) in June 2019. The sixth generation of gravity models have the highest possible signal and lowest error levels compared with other GOCE-only gravity models, and the accuracy is significantly improved. This is an opportunity to build high precision geostrophic currents. The mean dynamic topography and geostrophic currents have been calculated by the 5 th(TIM_R5 and DIR_R5), 6 th(TIM_R6 and DIR_R6) release of GOCE gravity field models and ITSG-Grace2018 of GRACE gravity field model in this study. By comparison with the drifter results, the optimal filtering lengths of them have been obtained(for DIR_R5, DIR_R6, TIM_R5 and TIM_R6 models are 1° and for ITSG-Grace2018 model is 1.1°). The filtered results show that the geostrophic currents obtained by the GOCE gravity field models can better reflect detailed characteristics of ocean currents. The total geostrophic speed based on the TIM_R6 model is similar to the result of the DIR_R6 model with standard deviation(STD) of 0.320 m/s and 0.321 m/s, respectively. The STD of the total velocities are 0.333 m/s and 0.325 m/s for DIR_R5 and TIM_R5. When compared with ITSG-Grace2018 results, the STD(0.344 m/s) of total geostrophic speeds is larger than GOCE results, and the accuracy of geostrophic currents obtained by ITSG-Grace2018 is lower. And the absolute errors are mainly distributed in the areas with faster speeds, such as the Antarctic circumpolar circulation, equatorial region, Kuroshio and Gulf Stream areas. After the remove-restore technique was applied to TIM_R6 MDT, the STD of total geostrophic speeds dropped to 0.162 m/s. 相似文献
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D. I. Lysaker∗ 《Marine Geodesy》2013,36(1):42-63
Two mean dynamic topography (MDT) fields are determined in the Fram Strait between Svalbard and Greenland. New airborne gravity anomalies, older data, and two different mean sea surface (MSS) fields are combined using the least squares collocation (LSC) technique. The results are compared to an oceanographic MDT model and two synthetic MDT fields. The same main currents are seen in all fields. Additionally, smaller scale features are revealed in the new MDT fields. Geostrophic surface currents derived from the MDT models are compared to moorings and Lagrangian drifters. The agreement is desultory. The oceanographic data are an inadequate basis of comparison due to data gaps. Nevertheless, it is the only one available. 相似文献
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Combined measurements of satellite altimeters make it possible to determine anomalies of the sea level of the Black Sea on a regular grid with a high spatial resolution 1/8°. In this work arrays of total geostrophic velocities of currents in the Black Sea basin are retrieved and compared with drifter measurements of current velocities for 1999–2007. The comparison is performed both for the whole array of drifter measurements (～110000 measurements) and individually for each drifter. To retrieve the velocities, two different arrays of mean dynamic topography (MDT) are used: synthetic and climatic mean dynamic topography. The comparison results demonstrate that using synthetic MDT is preferable for calculating geostrophic velocities. Velocities calculated by from satellite altimetry data agree with velocities obtained by in-situ data. 相似文献
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Altimeter measurements of sea‐level variability have errors due to the altimeter not repeatedly sampling the same point on the ocean surface. The errors are proportional to the local slope of the mean sea surface. Accurate removal of geoid error is essential if altimeter data are to be used to study the relationship between geostrophic turbulence and bathymetry. The error can be reduced by using an accurate model of the mean surface. We use the multiyear TOPEX altimeter data set to develop a model for the mean sea surface along the TOPEX/POSEIDON ground track by estimating the coefficients of a local plane centered on every 2 km x 7 km bin sampled by the altimeter. We have evaluated the ability of this model. compared against two global mean sea‐surface models, to reduce the error associated with steep gradients. The two global models are the Center for Space Research 1995 model and the Ohio State University 1995 model. The three models show similar variability over the oceans, and none shows the large residual errors that can be seen in collinear analysis near some seamounts and trenches. The standard deviation of the variability using the plane model, however, is consistently smaller in low‐variability, high‐geoid‐gradient areas, indicating a slightly better performance than the two global models. 相似文献
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The sea surface height anomaly (SSHA) and geostrophic circulation in the South ChinaSea (SCS) are studied using TOPEX/POSE1DON (T/P) altimetry data. The SSHA, which is obtained after tidal correction based on the tidal results from T/P data, is predominated by seasonal alternating monsoons. The results reveal that the SSHA in the central part of the SCS is positive in spring and summer, but negative in autumn and winter. It is also found that the SSHA in the SCS can be approached with the sum of tidal constituents SA and SSA. The geostrophic circulations in the SCS are calculated according to sea surface dynamic topography, which is the sum of SSHA and mean sea surface height. It is suggested that the circulation in the upper layer of the SCS is generally cyclonic and notably western intensified during autumn and winter, while the western intensification is weak during spring and summer. It is also indicated that the Kuroshio intrudes into the northeastern SCS throuth the Luzon Strait in winter. But ther 相似文献
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Variability of Sea Surface Circulation in the Japan Sea 总被引：3，自引：0，他引：3
Composite sea surface dynamic heights (CSSDH) are calculated from both sea surface dynamic heights that are derived from altimetric data of ERS-2 and mean sea surface that is calculated by a numerical model. The CSSDH are consistent with sea surface temperature obtained by satellite and observed water temperature. Assuming the geostrophic balance, sea surface current velocities are calculated. It is found that temporal and spatial variations of sea surface circulation are considerably strong. In order to examine the characteristics of temporal and spatial variation of current pattern, EOF analysis is carried out with use of the CSSDH for 3.5 years. The spatial and temporal variations of mode 1 indicate the strength or weakness of sea surface circulation over the entire Japan Sea associated with seasonal variation of volume transport through the Tsushima Strait. The spatial and temporal variations of mode 2 mostly indicate the temporal variation of the second branch of the Tsushima Warm Current and the East Korean Warm Current. It is suggested that this variation is possibly associated with the seasonal variation of volume transport through the west channel of the Tsushima Strait. Variations of mode 3 indicate the interannual variability in the Yamato Basin. 相似文献