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Three satellite-tracked drifting buoys released in the south equatorial current in the Indian Ocean followed the path of the
current moving westward approximately zonally in the vicinity of 10 S latitude. On nearing the east coast of Africa two buoys
moved north and the third moved south. Over the open sea regime the buoys moved with a speed of approximately 30 cm/s at an
angle of about 35° to the left of the wind. The overall tendencies seen in the buoy drift are similar to those observed elsewhere
in the world oceans. 相似文献
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F. Frappart N. Roussel R. Biancale J.J. Martinez Benjamin F. Mercier F. Perosanz 《Marine Geodesy》2015,38(3):219-232
This study presents the results of the 2013 Ibiza (Western Mediterranean) calibration campaign of Jason-2 and SARAL altimeters. It took place from 14 to 16 September 2013 and comprised two phases: the calibration of the GNSS (Global Navigation Satellite System) buoys to estimate the antenna height of each of them and the absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was performed at ~ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and SARAL nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and SARAL, respectively. The GNSS data were processed using precise point positioning technique. The biases found are of (?0.1 ± 0.9) and (?3.1 ± 1.5) cm for Jason-2 and SARAL, respectively. 相似文献
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利用2014—2017年华南沿海及南海的浮标站、海岛站、石油平台站、沿海自动站等277个自动站风场数据,与ASCAT反演风场进行了对比分析。结果表明,当观测风速小于5 m/s(大于15 m/s)时,ASCAT反演风速的平均绝对误差在3 m/s左右(存在2级左右的高(低)估);当风速介于5~10 m/s时,平均绝对误差在2 m/s左右(多数ASCAT有1~2级的高估);介于10~15 m/s时,ASCAT反演结果相对最好,风速、风向准确率能够达到60%以上。ASCAT对风速的反演结果受陆地影响较大,与观测风速的相关系数从高到低可分为三类:(1)浮标、平台站;(2)西沙、南沙自动站;(3)广东沿海自动站及海岛站、海南海岛站。ASCAT反演风场在风向的应用较风速更优,其中,东北风样本数最多,其次分别为西南风、东南风和西北风。浮标站、平台站、西沙自动站的风向反演质量相对较好;所有测站风向偏差主要由5 m/s以下的弱风贡献。单站多年月平均风速变化显示,ASCAT反演风速相对测站主要为正偏差,且秋冬季比春夏季偏差更大,这可能与大气稳定度有关。 相似文献
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Comparison of Grid Averaged Altimeter and Buoy Significant Wave Heights in the Northern Indian Ocean
A quantitative comparison of the collocated inter-annual significant wave height (SWH) data collected between 2006 and 2009 from buoys and altimeters at nine buoy locations (total n = 2241) in the Northern Indian Ocean is attempted for assessing the validity of daily averaged gridded altimeter significant wave height (ASWH) provided by AVISO for operational use. ASWH is underestimated by 0.20 m, the root-mean-square error (RMSE) is less than 0.30 m, the Scatter Index is less than 20%, and the correlation coefficient is greater than 0.90. Further, at three locations, the examination of the above statistics showed that the bias and RMSE is high during the southwest monsoon season compared with the Northeast monsoon. Scatter Index showed only slight variation (14–18%) for different ranges of SWH. The response of the daily average gridded ASWH data during extreme conditions (cyclones) in the vicinity of the buoy locations is poor at all compared buoy locations. The gridded ASWH from different satellite missions provided by AVISO can be used for basin scale validation experiments of the wave model and for climatological studies in the Indian Ocean, except during cyclone conditions. 相似文献
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Abstract Using GPS phase observations in the kinematic mode, we are able to achieve centimeter accuracy in relative three‐dimensional coordinates. This could be verified even for fast‐moving sensors in aircraft, such as airborne photogrammetric cameras, at the time of exposure. Sophisticated kinematic software has been developed resolving cycle slips and carrier‐phase ambiguities during motion. To determine the instantaneous sea surface, the GPS receiver is placed in a free‐drifting buoy with the antenna on top. Differencing the 1‐Hz observations, wave heights can be determined as well as velocity and direction of ocean (tidal) currents. This article deals with the experiences from a test for the practical realization of this proposal. Hardware installation, software, and data analysis are described. Plans to use such an observational scenario of a GPS buoy array in the North Sea for the calibration of the radar altimeter of the European satellite ERS‐1 are presented. 相似文献
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J.P. Manning D.J. McGillicuddy Jr. N.R Pettigrew J.H. Churchill L.S. Incze 《Continental Shelf Research》2009
Two-hundred and twenty seven satellite-tracked drifters were deployed in the Gulf of Maine (GoM) from 1988 to 2007, primarily during spring and summer. The archive of tracks includes over 100,000 km logged thus far. Statistics such as transit times, mean velocities, response to wind events, and preferred pathways are compiled for various areas of the coastal GoM. We compare Lagrangian flow with Eulerian estimates from nearby moorings and evaluate drifter trajectories using Ekman theory and 3-D ocean circulation models. 相似文献
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2015年9月16日22时54分(当地时间)智利中部近岸发生Mw8.3级地震,震源深度25 km。同时,强震的破裂区长200 km,宽100 km,随之产生了中等强度的越洋海啸。海啸影响了智利沿岸近700 km的区域,局部地区监测到近5 m的海啸波幅和超过13 m的海啸爬坡高度。太平洋区域的40多个海啸浮标及200多个近岸潮位观测站详细记录了此次海啸的越洋传播过程,为详细研究此次海啸近场及远场传播及演化规律提供了珍贵的数据。本文选择有限断层模型和自适应网格海啸数值模型建立了既可以兼顾越洋海啸的计算效率又可以实现近场海啸精细化模拟的高分辨率海啸模型。模拟对比分析了海啸的越洋传播特征,结果表明采用所建立的模型可以较好地再现远场及近场海啸特征,特别是对近场海啸的模拟结果非常理想。表明有限断层可以较好地约束近场、特别是局部区域的破裂特征,可为海啸预警提供更加精确的震源信息,结合高分辨率的海啸数值预报模式实现海啸传播特征的精细化预报。本文结合观测数据与数值模拟结果初步分析了海啸波的频散特征及其对模型结果的影响。同时对观测中典型的海啸波特征进行的简要的总结。谱分析结果表明海啸波的能量主要分布在10~50 min周期域内。这些波特征提取是现行海啸预警信息中未涉及,但又十分重要的预警参数。进一步对这些波动特征的详细研究将为海啸预警信息及预警产品的完善提供技术支撑。 相似文献