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J.F. Shriver H.E. Hurlburt O.M. Smedstad A.J. Wallcraft R.C. Rhodes 《Journal of Marine Systems》2007,65(1-4):3
A 1/32° global ocean nowcast/forecast system has been developed by the Naval Research Laboratory at the Stennis Space Center. It started running at the Naval Oceanographic Office in near real-time on 1 Nov. 2003 and has been running daily in real-time since 1 Mar. 2005. It became an operational system on 6 March 2006, replacing the existing 1/16° system which ceased operation on 12 March 2006. Both systems use the NRL Layered Ocean Model (NLOM) with assimilation of sea surface height from satellite altimeters and sea surface temperature from multi-channel satellite infrared radiometers. Real-time and archived results are available online at http://www.ocean.nrlssc.navy.mil/global_nlom. The 1/32° system has improvements over the earlier system that can be grouped into two categories: (1) better resolution and representation of dynamical processes and (2) design modifications. The design modifications are the result of accrued knowledge since the development of the earlier 1/16° system. The improved horizontal resolution of the 1/32° system has significant dynamical benefits which increase the ability of the model to accurately nowcast and skillfully forecast. At the finer resolution, current pathways and their transports become more accurate, the sea surface height (SSH) variability increases and becomes more realistic and even the global ocean circulation experiences some changes (including inter-basin exchange). These improvements make the 1/32° system a better dynamical interpolator of assimilated satellite altimeter track data, using a one-day model forecast as the first guess. The result is quantitatively more accurate nowcasts, as is illustrated by several model-data comparisons. Based on comparisons with ocean color imagery in the northwestern Arabian Sea and the Gulf of Oman, the 1/32° system has even demonstrated the ability to map small eddies, 25–75 km in diameter, with 70% reliability and a median eddy center location error of 22.5 km, a surprising and unanticipated result from assimilation of altimeter track data. For all of the eddies (50% small eddies), the reliability was 80% and the median eddy center location error was 29 km. The 1/32° system also exhibits improved forecast skill in relation to the 1/16° system. This is due to (a) a more accurate initial condition for the forecast and (b) better resolution and representation of critical dynamical processes (such as upper ocean – topographic coupling via mesoscale flow instabilities) which allow the model to more accurately evolve these features in time while running in forecast mode (forecast atmospheric forcing for the first 5 days, then gradually reverting toward climatology for the remainder of the 30-day forecast period). At 1/32° resolution, forecast SSH generally compares better with unassimilated observations and the anomaly correlation of the forecast SSH exceeds that from persistence by a larger amount than found in the 1/16° system. 相似文献
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介绍目前国内外常见汽车转向盘多功能按键的外观结构及特点,分析产品常见的几种失效模式,总结汽车转向盘多功能按键在验证时应该关注的几个问题。 相似文献
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舰船电场的轴频信号分布在1~7 Hz,且存在明显的谐波成分,因此其在浅海环境中能传播较远距离,从而成为舰船的特征信号之一。本文基于时谐电偶极子模型,在海上测试了电场信号源的衰减规律。通过对试验数据的分析可知,水深为16 m时,1.06 Hz,1.94 Hz以及3.22 Hz交变电场纵向分量在海底平面沿纵向随距离分别呈1.91次方、1.91次方和1.88次方衰减,很好地验证了理论数值计算的正确性。 相似文献
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介绍了基于C/S结构的阅览室门控管理系统的设计、实现过程.系统基于C/S(Client/Server)模式运行.服务器端为阅览室管理模块.客户端为阅览室刷卡显示模块,每个客户端由一台PC机和一台读卡器构成.读卡器和PC机之间通过RS232口进行通信,使用CRC循环冗余校验码保证通信的准确性.数据库采用SQL Server2000系统,支持TCP/IP协议。 相似文献
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研究目的:鉴定旧桥承载力,可以评估桥梁运营的安全性,为加固设计提供依据。本文以钢筋混凝土简支T形梁桥为例,从桥梁整体工作状况、钢筋锈蚀程度、梁体开裂程度等因素入手,通过数值分析,对旧桥的承载力进行分析和鉴定。总结出旧桥承载力鉴定的基本程序。研究结论:旧桥承载力的鉴定,应该按照全桥检查、细部检测、主梁承载力检算、全桥承载力鉴定的程序进行。即首先根据桥梁的整体工作状况及病害情况确定折减系数,然后对病害最为严重和负荷最大的两类主梁进行检算,最后根据检算结果对桥梁承载力进行鉴定。对文中所列桥梁的承载力进行鉴定可见:该桥设计荷载低,加之病害的影响,承载力不能满足荷载的要求。必须对桥梁进行提高承载力加固,以保证桥梁运营的安全。 相似文献