天绘一号卫星三线阵影像RPC模型定位精度验证与分析   总被引：1，自引：0，他引：1  

刘建辉  姜挺  李延杰  李厚朴 《测绘工程》2014,23(11):25-29

天绘一号卫星以RPC参数作为主要的影像辅助数据提供给用户,对传感器的技术参数进行隐藏.文中简要介绍RPC模型的立体定位方法,并针对定位结果中存在的明显的系统误差,采用像方补偿方案进行补偿,最后利用两景天绘一号卫星三线阵影像RPC模型对测区进行实验验证和分析.结果表明,采用少量地面控制点进行系统误差补偿后,定位精度提升效果明显,验证了模型的正确性和有效性.  相似文献   

浅海区域Topex/Poseidon测高卫星数据波形重构方法   总被引：6，自引：2，他引：4       下载免费PDF全文

鲍李峰  陆洋  许厚泽 《地球物理学报》2004,47(2):216-221

根据测高卫星返回波形的特征,给出了由Topex/Poseidon卫星波形数据进行波形重构的方法,并采用函数逼近算法确定波形重构改正量,进而改善测高卫星近海岸海面高观测值的精度.在中国南海区域计算了四圈T/P测高卫星经过波形重构后的海面高数据.近海岸海面高数据与相近时刻验潮站数据相比,精度比波形重构前有了很大提高,证明该方法的有效性.  相似文献   

A global satellite view of the seasonal distribution of mineral dust and its correlation with atmospheric circulation     

《Dynamics of Atmospheres and Oceans》2014

Aerosols make a considerable contribution to the climate system through their radiative and cloud condensation nuclei effects, which underlines the need for understanding the origin of aerosols and their transport pathways. Seasonal distribution of mineral dust around the globe and its correlation with atmospheric circulation is investigated using satellite data, and meteorological data from ECMWF. The most important sources of dust are located in North Africa, the Middle East and Southwest Asia with an observed summer maximum, and East Asia with a spring peak. Maximum dust activity over North Africa and the Middle East in summer is attributed to dry convection associated with the summertime low-pressure system, while unstable weather and dry conditions are responsible for the spring peak in dust emission in East Asia. Intercontinental transport of mineral dust by atmospheric circulation has been observed, including trans-Atlantic transport of North African dust, trans-Pacific transport of Asian dust, and transport of dust from the Middle East across the Indian Ocean. The extent of African dust over the Atlantic Ocean and its latitudinal variation with season is related to the large-scale atmospheric circulation, including seasonal changes in the position of the intertropical convergence zone (ITCZ) and variation of wind patterns. North African aerosols extend over longer distances across the North Atlantic in summer because of greater dust emission, an intensified easterly low level jet (LLJ) and strengthening of the Azores-Bermuda anticyclonic circulation. Transport of East Asian aerosol is facilitated by the existence of a LLJ that extends from East Asia to the west coast of North America.  相似文献   

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李黎  龙四春  沈军  李浩军  张立亚 《大地测量与地球动力学》2014,34(2):74-78

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Seasonality of oceanic primary production and its interannual variability from 1998 to 2007     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

The seasonality of primary productivity plays an important role in nutrient and carbon cycling. We quantify the seasonality of satellite-derived, oceanic net primary production (NPP) and its interannual variability during the first decade of the SeaWiFS mission (1998 to 2007) using a normalized seasonality index (NSI). The NSI, which is based upon production half-time, t(1/2), generally becomes progressively more episodic with increasing latitude in open ocean waters, spanning from a relatively constant rate of primary productivity throughout the year (mean t(1/2) ~5 months) in subtropical waters to more pulsed events (mean t(1/2) ~3 months) in subpolar waters. This relatively gradual, poleward pattern in NSI differs from recent estimates of phytoplankton bloom duration, another measure of seasonality, at lower latitudes (~40°S–40°N). These differences likely reflect the temporal component of production assessed by each metric, with NSI able to more fully capture the irregular nature of production characteristic of waters in this zonal band. The interannual variability in NSI was generally low, with higher variability observed primarily in frontal and seasonal upwelling zones. The influence of the El Niño–Southern Oscillation on this variability was clearly evident, particularly in the equatorial Pacific, where primary productivity was anomalously episodic from the date line east to the coast of South America in 1998. Yearly seasonality and the magnitude of annual production were generally positively correlated at mid-latitudes and negatively correlated at tropical latitudes, particularly in a region bordering the Pacific equatorial divergence. This implies that increases of annual production in the former region are attained over the course of a year by shorter duration but higher magnitude NPP events, while in the latter areas it results from an increased frequency or duration of similar magnitude events. Statistically significant trends in the seasonality, both positive and negative, were detected in various patches. We suggest that NSI be used together with other phenomenological characteristics of phytoplankton biomass and productivity, such as the timing of bloom initiation and duration, as a means to remotely quantify phytoplankton seasonality and monitor the response of the oceanic ecosystem to environmental variability and climate change.  相似文献   

Andean earthquakes triggered by the 2010 Maule,Chile (Mw 8.8) earthquake: Comparisons of geodetic,seismic and geologic constraints     

《Journal of South American Earth Sciences》2014

The Maule, Chile, (M_w 8.8) earthquake on 27 February 2010 triggered deformation events over a broad area, allowing investigation of stress redistribution within the upper crust following a mega-thrust subduction event. We explore the role that the Maule earthquake may have played in triggering shallow earthquakes in northwestern Argentina and Chile. We investigate observed ground deformation associated with the M_w 6.2 (GCMT) Salta (1450 km from the Maule hypocenter, 9 h after the Maule earthquake), M_w 5.8 Catamarca (1400 km; nine days), M_w 5.1 Mendoza (350 km; between one to five days) earthquakes, as well as eight additional earthquakes without an observed geodetic signal. We use seismic and Interferometric Synthetic Aperture Radar (InSAR) observations to characterize earthquake location, magnitude and focal mechanism, and characterize how the non-stationary, spatially correlated noise present in the geodetic imagery affects the accuracy of our parameter estimates. The focal mechanisms for the far-field Salta and Catamarca earthquakes are broadly consistent with regional late Cenozoic fault kinematics. We infer that dynamic stresses due to the passage of seismic waves associated with the Maule earthquake likely brought the Salta and Catamarca regions closer to failure but that the involved faults may have already been at a relatively advanced stage of their seismic cycle. The near-field Mendoza earthquake geometry is consistent with triggering related to positive static Coulomb stress changes due to the Maule earthquake but is also aligned with the South America-Nazca shortening direction. None of the earthquakes considered in this study require that the Maule earthquake reactivated faults in a sense that is inconsistent with their long-term behavior.  相似文献   

Effects of Crustal Structure for Estimation of Vertical Load Deformation on the Solid Earth Using GRACE in China Mainland     

Jia Lulu  Xiang Longwei  Wang Hansheng 《地球科学进展》2014,29(7):828-834

When the inversion of vertical load deformation on Earth’s surface using GRACE (Gravity Recovery and Climate Experiment) data, the load Love numbers based on PREM (Preliminary Reference Earth Model) are commonly used. But the crustal structure under China mainland especially under Tibet Plateau is quite different from that given by PREM Earth model. New load Love numbers were calculated based on a modified Earth model which accounted for regional crustal structure in China mainland. And the effect of regional crustal structure in China mainland for estimation of vertical load deformation on Earth’s surface using GRACE RL05 data was investigated in this paper. It is found that the effect of crustal difference is very prominent. The relative difference of load Love numbers for vertical deformation can reach about 11% at degree 90. The extreme value of difference in vertical load deformation below 90 degree of spherical harmonic coefficients located at the southeastern Tibet Plateau and the maximum relative difference reaches 10%. The relative difference of the root mean square is about 4%. It is suggesting that an Earth model with a more realistic crustal structue instead of PREM should be used for the estimation of vertical load deformation in China mainland espacially in Tibet Plateau.  相似文献   

Interpolation of wave heights   总被引：1，自引：0，他引：1  

M. C. Deo  N. Kiran Kumar 《Ocean Engineering》2000,27(9)

Remote sensing of waves often necessitates presentation of data in the form of wave height values grouped over large time intervals. This restricts their use to long-term applications only. This paper describes how such data can be made suitable for short-term usage in the field. Weekly mean significant wave heights were derived from their monthly mean observations with the help of different alternative techniques. These include model-free neural network schemes as well as model-based statistical and numerical methods. Superiority of neural networks was noted when the estimations were compared with corresponding observations. The network was trained using three different training algorithms, viz., error back propagation, conjugate gradient and cascade correlation. The technique of cascade correlation took minimum training time and showed better coefficient of correlation between observations and network output.  相似文献   

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刘根友  郝晓光  陈晓峰  孙保琪  彭碧波  周旭华  柳林涛  胡小刚 《大地测量与地球动力学》2007,27(5):115-118

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Nature of the iogenic plasma source in Jupiter's magnetosphere: II. Near-Io distribution     

William H. Smyth  M.L. Marconi 《Icarus》2005,176(1):138-154

Three-dimensional calculations are presented for the distribution of the iogenic plasma source that is created near Io (i.e., within ∼24 satellite radii about Io) by O and S gases located in the volume above Io's exobase (i.e., corona and escaping extended neutral clouds, designated as the “Outer Region”) and are complementary to a preceding paper for calculations on a circumplanetary scale. The instantaneous pickup ion production rates for both electron impact and charge exchange have significant radial, north-south, and orbital-plane asymmetries beginning just inside and/or beyond Io's Lagrange sphere (5.81 Io radii) and, within the Lagrange sphere, are distributed nearly symmetrically about Io and are highly peaked about Io's exobase. The spatial natures of the corresponding pickup ion density, mass loading rates, and the pickup ion conductivity, current, and magnetic field are investigated. Spatially integrated rates are calculated for the corona volume and compared to larger Outer Region circumplanetary volumes and are also compared to estimates drawn from the scientific literature (but not modeled here) of the spatially integrated rates for pickup processes in the strongly perturbed “Inner Region” below the exobase. Within the corona volume, the spatially-integrated net-mass loading rate and total (electron impact and charge exchange) mass loading rate are only a factor of ∼3 and ∼5, respectively, smaller than those estimated for the Inner Region, whereas for the whole plasma torus, the Outer Region rates are larger or comparable to those estimated for the Inner Region. The total pickup ion gyration power supplied to the whole plasma torus is estimated to be significantly less than the power radiated by the plasma torus, indicating that an additional power source, likely a circumplanetary distribution of nonthermal electrons, is present.  相似文献