中国HY-2卫星雷达高度计有效波高真实性检验

Chinese Haiyang-2(HY-2) satellite is the first Chinese marine dynamic environment satellite. The dual-frequency(Ku and C band) radar altimeter onboard HY-2 has been working effective to provide operational significant wave height(SWH) for more than three years(October 1, 2011 to present).We validated along-track Ku-band SWH data of HY-2 satellite against National Data Buoy Center(NDBC) in-situ measurements over a time period of three years from October 1, 2011 to September 30, 2014, the root mean square error(RMSE) and mean bias of HY-2SWH is 0.38 m and(–0.13±0.35) m, respectively. We also did cross validation against Jason-2 altimeter SWH data,the RMSE and the mean bias is 0.36 m and(–0.22±0.28) m, respectively. In order to compare the statistical results between HY-2 and Jason-2 satellite SWH data, we validated the Jason-2 satellite radar altimeter along-track Ku-band SWH data against NDBC measurements using the same method. The results demonstrate the validation method in this study is scientific and the RMSE and mean bias of Jason-2 SWH data is 0.26 m and(0.00±0.26) m,respectively. We also validated both HY-2 and Jason-2 SWH data every month, the mean bias of Jason-2 SWH data almost equaled to zero all the time, while the mean bias of HY-2 SWH data was no less than –0.31 m before April2013 and dropped to zero after that time. These results indicate that the statistical results for HY-2 altimeter SWH are reliable and HY-2 altimeter along-track SWH data were steady and of high quality in the last three years. The results also indicate that HY-2 SWH data have greatly been improved and have the same accuracy with Jason-2SWH data after April, 2013. SWH data provided by HY-2 satellite radar altimeter are useful and acceptable for ocean operational applications.     

基于漂流浮标的南大洋卫星高度计有效波高研究

随着技术的进步和数据处理方法的完善,经过修正的卫星高度计数据已获得普遍认可.但在南大洋缺少波浪现场数据,卫星高度计在极端恶劣气候条件下获得数据的准确度仍受到一定程度的质疑.中国于2020年第36次南极考察中,在南大洋布放了一套感应耦合漂流浮标,可提供可靠的南大洋现场波浪数据.本文利用该漂流浮标2020年1月27日至9月...     

有效波高的非线性统计及在南海卫星高度计中的应用

在已获得的海浪非线性波面概率模式的基础上通过Ochi关系，导出了一种有效波高的非线性统计分布。分布表明，本研究结果既推广了有效波高的双参数对数－正态分布，又能够以波陡作为有效波高的非线性控制参量来体现概率分布形式的变化。此研究应用于南海卫星高度计的资料分析，获得了理论与现场数据较为吻合的结果。     

TOPEX卫星高度计有效波高数据分析与极值统计预报

利用TOPEX卫生高度计测量的有效波高资料，对中国近海9个海域进行了卫星主度计的C，Ku两波段测量值的比较分析与处理,出合理的有效波高数值。利用三参数Weibull分布，以渤海海域、上海附近海域和南海东部海域的作为特定区进行有效波高的极值统计预报，并进行了统计分析。     

HY-2A卫星高度计有效波高信息提取业务化算法

2011年8月16日我国成功发射了第一颗自主海洋动力环境卫星HY-2A,有效波高是其搭载的雷达高度计可获取的重要海洋动力环境参数之一。本文详细介绍了应用于HY-2A雷达高度计的有效波高信息提取业务化算法,该算法通过迭代最小二乘拟合方法提取有效波高信息。同时,基于HY-2A雷达高度计业务化运行获取的有效波高数据,分别与Jason-2卫星高度计有效波高和NDBC浮标海浪波高数据进行了比对分析。比较结果表明,HY-2A雷达高度计与Jason-2有效波高的标准偏差为-0.26m,RMS为0.58m;HY-2A高度计与NDBC浮标数据间的标准偏差为-0.22m,RMS为0.37m。结果证明了目前应用于HY-2A雷达高度计业务化运行中的有效波高信息提取算法的可行性。     

北部湾海区有效波高与最大波高的关系及最大设计波高

目前,各种海洋工程规范采用的有效波高H_(1/3)与最大波高H_(max)的关系各不相同,它们采用窄谱条件下的理论关系或经验关系。本文针对北部湾海区的实际波浪状况,利用测波资料计算了谱宽参数的分布规律,然后在宽谱的条件下分析并确定了最大波高H_(max)与有效波高H_(1/3)的关系随谱宽度参量ε与波个数N的变化规律,最后结合北部湾有效波高的长期分布计算出不同重现期约设计波高。     

TOPEX卫星高度计有效波高数据分析与极值统计预报

利用 TOPEX卫星高度计测量的有效波高资料 ,对中国近海 9个海域进行卫星高度计的 C,Ku两波段测量值的比较分析与处理 ,得出合理的有效波高数值。利用三参数 Weibull分布 ,以渤海海域、上海附近海域和南海东部海域作为特定区进行有效波高的极值统计预报 ,并进行了统计分析     

太平洋波高熵的分布变化规律研究

使用1992年IO月到1998年12月连续共75个月、230个重复周期的Topex／Poseidon卫星高度计有效波高资料，对南、北太平洋波高熵的空间分布特征和时间变化规律进行了研究。统计分析了太平洋波高熵的多年的空间分布特征和多年各月的时间变化规律。结果表明，太平洋波高熵呈现出中间低、南北高的马鞍形空间分布特征和明显季节变化的规律，与太平洋的平均有效波高和气候分布特征和变化规律相一致。给出了南北太平洋模拟波高熵的计算公式及计算稳定性检验。     

基于HY-2卫星高度计机载校飞数据的有效波高信息提取及初步分析

利用HY-2卫星雷达高度计校飞数据,开展了有效波高信息提取及精度比对研究。首先对其进行波形筛选、1s平均和去噪,然后基于Hayne海面回波模型进行波形拟合,提取出波高均方根并得到有效波高,并与浮标和同轨迹的Jason-1卫星高度计有效波高进行了比较。结果表明,本次校飞其高度计测波精度存在系统偏差,初步分析可能是其数据未经仪器校正等原因导致。     

多源卫星高度计有效波高数据融合方法研究

有效波高数据融合可以弥补单颗卫星高度计数据存在的时间和空间分辨率不足的问题,为有效波高的海洋学应用提供更精确的分析资料.对反距离加权法、克里金插值法和逐步订正法等数据融合方法进行了研究,得到了适合于有效波高数据融合的模型和参数,并利用GFO,Jason-1和Envisat高度计获取的我国海域及其邻近海域有效波高数据,对不同融合方法、滤波器窗口和卫星个数等影响融合结果的因素进行了分析,结果表明:(1)融合后的有效波高分布特征与前人多年统计分析结果基本一致;(2)数据较密集时,不同融合方法的结果差别不大;(3)选择的滤波器窗口大小与时间分辨率有关,对于时间分辨率为10d的融合而言,采用2.5°×2.5°~3°×3°大小的滤波器窗口所得到的融合结果最合适;(4)参加融合的卫星个数至少为3颗.     

Assessment of SARAL/AltiKa Wave Height Measurements Relative to Buoy,Jason-2, and Cryosat-2 Data

SARAL/AltiKa GDR-T are analyzed to assess the quality of the significant wave height (SWH) measurements. SARAL along-track SWH plots reveal cases of erroneous data, more or less isolated, not detected by the quality flags. The anomalies are often correlated with strong attenuation of the Ka-band backscatter coefficient, sensitive to clouds and rain. A quality test based on the 1 Hz standard deviation is proposed to detect such anomalies. From buoy comparison, it is shown that SARAL SWH is more accurate than Jason-2, particularly at low SWH, and globally does not require any correction. Results are better with open ocean than with coastal buoys. The scatter and the number of outliers are much larger for coastal buoys. SARAL is then compared with Jason-2 and Cryosat-2. The altimeter data are extracted from the global altimeter SWH Ifremer data base, including specific corrections to calibrate the various altimeters. The comparison confirms the high quality of SARAL SWH. The 1 Hz standard deviation is much less than for Jason-2 and Cryosat-2, particularly at low SWH. Furthermore, results show that the corrections applied to Jason-2 and to Cryosat-2, in the data base, are efficient, improving the global agreement between the three altimeters.     

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.     

时空窗口对HY-2有效波高产品检验影响模拟研究

时空窗口的选择是卫星高度计有效波高产品检验的主要影响因素。采用Monte Carlo(MC)数学模拟的方法 ,研究了时空窗口对HY-2高度计有效波高检验的影响,并采用现场浮标测量数据验证了MC模拟的可靠性。MC模拟结果表明,采用浮标测量数据对HY-2高度计有效波高检验时,必须分海况选取对应的最优空间窗口进行,并给出不同海况下的最优的时空窗口。对于高海况需采用小的空间窗口,在1 m,2 m,3 m,4 m有效波高的海况下,其理想的时空窗口为0 min,117 km,30 km,18 km和13 km。     

有效波高的对数-Beta分布

基于非线性Beta波面分布，采用变换ξ=lnH／γ，导出了一种仅用随机波面偏度λ3和尖度λ4两个参数表示的非线性有效波高概率分布——对数-Beta分布，发展了线性海浪有效波高的双参数对数-正态分布。对比结果表明，对数-Beta分布理论曲线与其对应的实测资料符合良好。推导出的对数-Beta分布的优点是，基本参数较少且便于确定，并可由随机波面高度资料直接推导出对应的有效波高概率密度函数。     

大西洋波高熵的分布变化规律研究

使用1992年10月-1998年12月连续75个月、230个重复周期的Topex／Poseidon卫星高度计有效波高资料，对南北大西洋波高熵的空间分布特征和时间变化规律进行了研究，统计分析了大西洋波高熵的多年的空间分布特征和多年各月的时间变化规律。结果表明，大西洋波高熵呈现出中间低、南北高的马鞍形空间分布特征和明显季节变化的规律，与大西洋的平均有效波高、气候的地理分布以及大气活动分布特征和变化规律相一致。     

Long-Term Validation of Wave Height Measurements from Altimeters

Since July 1991, six altimeter missions have been launched successfully, and they have provided almost continuous wave height measurements for more than 12 years. Long-term series of wave height measurements are of major interest for climatology and oceanic wave modeling. Before using such data, the measurements have to be validated, and the homogeneity of the data from various satellites has to be checked. Significant wave height measurements from ERS, TOPEX/Poseidon, GEOSAT Follow-on, Jason-1 and ENVISAT altimeters are validated using cross-altimeter and buoy comparisons. Emphasis is put on the two recent missions Jason-1 and ENVISAT. Corrections for biases and trends are proposed for the six altimeters, allowing the generation of consistent and homogeneous data. Tests of these corrections are performed over global ocean simple statistics.     

Long-Term Validation of Wave Height Measurements from Altimeters

Since July 1991, six altimeter missions have been launched successfully, and they have provided almost continuous wave height measurements for more than 12 years. Long-term series of wave height measurements are of major interest for climatology and oceanic wave modeling. Before using such data, the measurements have to be validated, and the homogeneity of the data from various satellites has to be checked. Significant wave height measurements from ERS, TOPEX/Poseidon, GEOSAT Follow-on, Jason-1 and ENVISAT altimeters are validated using cross-altimeter and buoy comparisons. Emphasis is put on the two recent missions Jason-1 and ENVISAT. Corrections for biases and trends are proposed for the six altimeters, allowing the generation of consistent and homogeneous data. Tests of these corrections are performed over global ocean simple statistics.     

基于SVR和LSTM算法反演散射计下有效波高研究

有效波高反演对于海洋工程及海洋环境安全具有重要意义.我国海洋二号(HY-2A)卫星载有散射计和高度计等获取海洋要素的仪器.散射计可获取海洋风场数据但无法直接获取有效波高数据,高度计可获取海洋有效波高数据但覆盖区域狭小.本文将散射计与高度计各自优势结合,利用支持向量回归(SVR)和长短期记忆(LSTM)智能算法反演散射计...