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71.
时空Kriging法通过将变异函数向时空域进行扩展得到时空变异函数,有效地利用时空邻近的采样点综合进行插值,由于时空稀疏散布数据集具有单一时刻下样本点数量少以及时空分布不规律的特点,难以满足使用时空Kriging插值法的基本条件,导致插值精度不高,据此本文提出了优化方法:通过多时段叠置拟合空间变异函数的方法,综合利用时空邻域内的采样点以解决单一时刻下空间邻域内数量不足情况;控制时间变异对空间变异函数拟合的误差影响;采用积合式模型构建时空变异函数进行插值。最后使用Argo海温数据进行插值实验,在相同条件下与时空Kriging法以及时空权重法的交叉验证结果对比得出,该方法在保证拟合所需采样点数量要求的同时,有效削减了一般时空Kriging法中时间变异对空间变异函数拟合结果的干扰,插值结果的绝对误差均值从0.5降低至0.2以内,稳定性进一步增强,改善了时空Kriging法在稀疏散布数据条件下精度上的不足。 相似文献
72.
Reconstruction of eddies by assimilating satellite altimeter data into Princeton Ocean Model 总被引:2,自引:1,他引:1
An optimal interpolation assimilation model for satellite altimetry data is developed based on
Princeton Ocean Model (POM), which is applied in a quasi-global domain, by the method of
isotropic correlation between sea level anomaly (SLA) and sea temperature anomaly. The perfor-
mance of this assimilation model is validated by the modeled results of SLA and the current patterns.
Comparisons between modeling and satellite data show that both the magnitudes and distribution
patterns of the simulated SLA are improved by assimilation. The most signiˉcant improvement is
that meso-scale systems, e.g., eddies, are well reconstructed. The evolution of an eddy located in
the northwest Paciˉc Ocean is traced by using the assimilation model. Model results show that
during three months the eddy migrated southwestward for about 6 degrees before merging into the
Kuroshio. The three dimensional structure of this eddy on 12 August 2001 is further analyzed.
The strength of this warm, cyclonic eddy decreases with the increase of depth. The eddy shows
di?erent horizontal patterns at di?erent layers, and the SLA and temperature ˉelds agree with each
other well. This study suggests that this kind of data assimilation is economic and reliable for eddy
reconstruction, and can be used as a promising technique in further studies of ocean eddies as well
as other ˉne circulation structures. 相似文献
73.
为了探寻发达省份内城市间相互作用的时空特征,该文以浙江省为样本单元,选取2005、2010年和2015年3个时间截面,采用反距离权重法和空间插值手段,从城市流强度视角展开了实证分析。结果表明:(1) 城市间的联系在不断加强,期间城市流强度值随时间的推移而整体得到提升,空间上由初始的“中心点”通过发展扩散向“中心域”转变,中心城市的辐射带动作用开始发挥成效。(2)结构上呈现出相对稳定的北高南低的分布格局,以杭州市为龙头,宁波为副核心,温州、绍兴、舟山为重要节点的多中心城市网络结构雏形初步形成。(3) 城市流强度的空间分异特征分析明显,但分异程度有了些许的改善,侧面说明空间上由初始的“中心点”通过发展扩散向“中心域”转变的基本观点。最后就浙江省如何加强省内城市间“流”的规模性、区域协调性和可持续性展开了讨论。 相似文献
74.
???й?????????????????????????????????5?????壬????????????????С???????÷?????С?????????????????????3????????????????о??й?????????????????????????????????????????????????????С???????÷????????壨??????????????????壩????????????????????|?????????????????????????????????????????????????С???????÷?????й????1°×1°?????????????????????????????????С?? 相似文献
75.
为防止三维激光扫描数据中的噪声对实景重构造成扭曲,基于消噪的相关理论,提出了3种具有先验信息的去噪算法,利用高程注记点所提供的先验信息作为去噪依据,分别对比高程插值、最小二乘拟合平面及趋势面,选取适当阈值消去噪声。利用Timble GX200地面三维激光扫描系统获取的地形测量数据进行实验分析,结果表明:高程注记点可以作为先验信息为点云去噪提供依据,并确保去噪后基本符合实体特征。 相似文献
76.
“一带一路”倡议是新时期中国为加强对外开放提出的全球化合作倡议,资源环境的优化配置对全球化发展意义重大。气温作为重要的基础数据和输入要素,对其进行空间化处理是实现大尺度区域资源环境优化配置的前提。本文基于地理信息技术(GIS),运用距离平方反比法(IDS)、协同克里格法(CK)、回归距离平方反比法(RIDS)和回归协同克里格法(RCK),对“一带一路”地区1980—2017年的2679个气象站点的月平均气温和年平均气温数据进行插值,获得了“一带一路”地区10 km分辨率的气温空间分布数据。交叉验证结果表明:① IDS、CK、RIDS和RCK插值法在整体上均较好地展示了“一带一路”地区气温的地理空间分布规律,4种插值方法的月均气温的均方根误差分别在1.93~2.43、1.78~2.14、1.31~2.23和1.23~1.92 ℃之间;年均气温的均方根误差分别为1.94、1.83、1.37和1.27 ℃;② 在“一带一路”地区,加入协变量分析的CK插值精度整体优于IDS,并且削弱了IDS的极值现象;③ RIDS和RCK对年均气温的插值精度分别较IDS和CK提高了29.4%和30.6%,表明加入地理要素并进行残差修正的插值精度得到了进一步提高。总体来看,RCK插值法对气温数据的插值精度最高,可以考虑将此方法作为“一带一路”地区温度等气象要素的插值方法。 相似文献
77.
78.
We present an alternate mathematical technique than contemporary spherical harmonics to approximate the geopotential based
on triangulated spherical spline functions, which are smooth piecewise spherical harmonic polynomials over spherical triangulations.
The new method is capable of multi-spatial resolution modeling and could thus enhance spatial resolutions for regional gravity
field inversion using data from space gravimetry missions such as CHAMP, GRACE or GOCE. First, we propose to use the minimal
energy spherical spline interpolation to find a good approximation of the geopotential at the orbital altitude of the satellite.
Then we explain how to solve Laplace’s equation on the Earth’s exterior to compute a spherical spline to approximate the geopotential
at the Earth’s surface. We propose a domain decomposition technique, which can compute an approximation of the minimal energy
spherical spline interpolation on the orbital altitude and a multiple star technique to compute the spherical spline approximation
by the collocation method. We prove that the spherical spline constructed by means of the domain decomposition technique converges
to the minimal energy spline interpolation. We also prove that the modeled spline geopotential is continuous from the satellite
altitude down to the Earth’s surface. We have implemented the two computational algorithms and applied them in a numerical
experiment using simulated CHAMP geopotential observations computed at satellite altitude (450 km) assuming EGM96 (n
max = 90) is the truth model. We then validate our approach by comparing the computed geopotential values using the resulting
spherical spline model down to the Earth’s surface, with the truth EGM96 values over several study regions. Our numerical
evidence demonstrates that the algorithms produce a viable alternative of regional gravity field solution potentially exploiting
the full accuracy of data from space gravimetry missions. The major advantage of our method is that it allows us to compute
the geopotential over the regions of interest as well as enhancing the spatial resolution commensurable with the characteristics
of satellite coverage, which could not be done using a global spherical harmonic representation.
The results in this paper are based on the research supported by the National Science Foundation under the grant no. 0327577. 相似文献
79.
Standard least-squares collocation (LSC) assumes 2D stationarity and 3D isotropy, and relies on a covariance function to account
for spatial dependence in the observed data. However, the assumption that the spatial dependence is constant throughout the
region of interest may sometimes be violated. Assuming a stationary covariance structure can result in over-smoothing of,
e.g., the gravity field in mountains and under-smoothing in great plains. We introduce the kernel convolution method from
spatial statistics for non-stationary covariance structures, and demonstrate its advantage for dealing with non-stationarity
in geodetic data. We then compared stationary and non- stationary covariance functions in 2D LSC to the empirical example
of gravity anomaly interpolation near the Darling Fault, Western Australia, where the field is anisotropic and non-stationary.
The results with non-stationary covariance functions are better than standard LSC in terms of formal errors and cross-validation
against data not used in the interpolation, demonstrating that the use of non-stationary covariance functions can improve
upon standard (stationary) LSC. 相似文献
80.
简要介绍双方向性插值方法的原理,并以线性插值和三次插值过程中的误差传播为基础,利用误差传播定律,推导出双方向性插值方法生成的DEM曲面平均高程误差值,并对线性插值和三次插值公式本身的精度进行分析。 相似文献