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使用Zebiak-Cane模式和条件非线性最优扰动(CNOP)方法,研究初始误差和参数误差共同作用对ENSO春季预报障碍现象的影响。选取模式中的8个El Ni?o事件,包括4次强事件和4次弱事件,每个El Ni?o事件又分别从8个不同的起始时间做1 a的预报,这样一共64个预报实验。对每个实验分别计算CNOP误差(初始误差和参数误差同时存在时的最优误差),通过分析误差增长,发现CNOP误差引起的1 a后的预报误差随着初始预报时间的不同有较大差异,并且不同强度的El Ni?o事件也会影响CNOP误差的发展,增长位相中强事件的预报误差要比弱事件的预报误差大一些;而衰减位相中恰恰相反,弱事件的预报误差要比强事件的预报误差要大一些;同时也发现高频El Ni?o事件对误差增长率的影响较大。本结论有助于提高Zebiak-Cane模式预报ENSO的技巧。 相似文献
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Brezinski等人给出了最小二乘问题近似解的一族误差估计。该误差估计含有1个实参数。本文的贡献有3个方面:其一是给出了1种参数选择策略;其二是对该族误差估计的性质做出进一步分析;其三是分析了应用于Tikhonov正则化时应注意的一些问题。 相似文献
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测高卫星径向轨道误差是影响测高数据精度的最主要因紊之一。为了充分利用测高数据中所含的地球物理信息,分析径向轨道误差对卫星测高数据处理结果的影响,更好地了解径向误差的空域分布模式,鉴别各种平差方法的有效性,对径向轨道误差在交叉点平差时的可观测性有一个较为清晰而明确的认识,本文据文献[1]、[2]中的理论推导,对测高卫星径向误差的频域及空域特征作了进一步的分析,并附以实例计算,得出了一些有益的结论。 相似文献
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GIS空间数据的质量是GIS可靠性、实用性、效益性的关键。本文从GIS数据的特征及误差类型出发,介绍了GIS数据采集方式及误差来源,并在各环节的误差改正方面提出了自己的一些观点。 相似文献
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研究线性矩阵方程的广对称解,对Bunch,Sun,Tisseur等人的一些已有结果进行推广,并把所得结果用于结构向后误差分析. 相似文献
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~(14)C断代的误差,是一个十分重要的问题。就手段本身来说,~(14)C断代法已是一种成熟的方法。但是,由一些因素造成的误差却影响着~(14)C断代成果的应用,甚至引起人们对方法本身的价值产生怀疑。因此,讨论有关~(14)C断代的误差问题,自然就成为~(14)C断代工作者与使用这些资料的人们最为关心的问题之 相似文献
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选取SMOS任务的2个海洋盐度专家中心(法国的CATDS-CECOS和西班牙的BEC)的5种经过再处理的新版SSS L3/4产品作为研究对象,以Argo浮标资料及WOA09资料作为参考标准,对其误差特征进行了细致的分析比较,为将其同化到海洋模式中以及用于其它海洋学的分析应用研究,提供必要的参考。主要结论如下:SMOS年平均海表盐度场与WOA09资料很接近,一些已知的重要的分布形势都有所体现;大洋中部误差较小,近陆误差大;热带误差较小,高纬地区误差较大;三大洋中太平洋均方根误差最小。随着时空分辨率的降低,SMOS SSS资料的均方根误差显著减小。检验的几种资料中,CATDS/CEC-OS处理制作的月平均海表盐度L3级产品误差最小,全球平均均方根误差(RMSE)为0.314;另外几种高分辨率产品中,除由BEC制作的简单加权平均产品均方根误差最大,全球平均0.543以外,其他3种资料的均方根误差量级相当,差异不太明显,全球平均的RMSE为0.3~0.4;BEC的两种分析产品总体上RMSE更小。 相似文献
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A sea floor magnetometer for the continental shelf 总被引:1,自引:0,他引:1
Antony White 《Marine Geophysical Researches》1979,4(1):105-114
Measurement of temporal magnetic variations on the sea floor is desirable in order to extend the technique of geomagnetic depth sounding into the oceans. This paper describes a recording three-component sea floor magnetometer and its use in continental shelf depths. The orientation and tilt of the instrument on the sea floor are recorded using gelatine solutions to freeze a compass card and a ball-bearing, respectively. A backing-off procedure initially nulls the magnetic field components along each of the three mutually orthogonal fluxgate sensors. Magnetic variations along each sensor axis are then recorded within a range of ± 300 nT of these nulled positions. The resolution is ± 1 nT, and with a power drain of 800 mW the magnetometer can record continuously for 30 days. The instrument capsule is moored to surface buoys for recovery in continental shelf applications. The buoys may have marker flags, radar reflectors or radio beacons attached to them to aid in relocation. 相似文献
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An instrument which measures the velocity and direction of benthic water currents at depths of up to 80 m is described. Characteristics of this meter include: (i) readings are not affected by water flow during sinking or retrieval; (ii) it is portable; (iii) it operates unattended; (iv) it is inexpensive; and (v) it requires only simple maintenance. A timing circuit which operates two time periods in succession is used to activate and de-activate a revolution counter and a fluidfilled compass which are mounted on a special frame and vane system. In the field, the instrument accurately measured average current velocities of up to 6 m s−1. Data are presented which illustrate the usefulness of this instrument in describing the velocity and direction of benthic currents along the east coast of Australia and demonstrate a positive correlation between benthic current velocity and catch rates of the commercially-exploited spanner crab Ranina ranina. 相似文献
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超短基线水声定位系统是海洋工程及水下无人系统中应用较广泛的精密仪器设备,为了提高对水下目标的定位精度,在使用前需对其进行校准。描述了一种基于最小二乘法迭代修正的超短基线水声定位系统校准方法,该方法以最小二乘法为基本原理,通过多次迭代修正的方式,修正基阵与GPS天线之间的平移偏差以及基阵与罗经之间的旋转偏差,从而提高系统的测量精度,最终通过湖上试验验证了该方法的有效性。 相似文献
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Yun X. Bachmann E.R. McGhee R.B. Whalen R.H. Roberts R.L. Knapp R.G. Healey A.J. Zyda M.J. 《Oceanic Engineering, IEEE Journal of》1999,24(3):396-404
A Small Autonomous Underwater Vehicle Navigation System (SANS) is being developed at the Naval Postgraduate School. The SANS is an integrated Global Positioning System/Inertial Navigation System (GPS/INS) navigation system composed of low-cost and small-size components. It is designed to demonstrate the feasibility of using a low-cost strap-down inertial measurement unit (IMU) to navigate between intermittent GPS fixes. The present hardware consists of a GPS/DGPS receiver, IMU, compass, water speed sensor, water depth sensor, and a data processing computer. The software is based on a 12-state complementary filter that combines measurement data from all sensors to derive a vehicle position/orientation estimate. This paper describes hardware and software design and testing results of the SANS. It is shown that results from tilt table testing and bench testing provide an effective means for tuning filter gains. Ground vehicle testing verifies the overall functioning of the SANS and exhibits an encouraging degree of accuracy 相似文献