共查询到20条相似文献，搜索用时 21 毫秒
1.
风通过影响海洋表面从而产生200 Hz以上的深海环境噪声，但有研究指出，通过风生表面波之间的非线性相互作用产生的驻波，能够与海床共振构成海底微震，从而产生10 Hz以下的噪声。针对这一新型风生噪声机制，本研究对威克岛海域10 Hz以下的极低频噪声进行了分析。比较了不同频率下海洋环境噪声功率谱级与风速的相关性，并讨论了风速和风向对设立在威克岛南北部二组水听器三联体信号的影响，结果表明2 Hz处的海洋环境噪声级与风速相关性最好，而风速和风向变化越剧烈海洋环境极低频噪声与风速风向的相关性越好。 相似文献
2.
为探索南海某区域海洋环境噪声谱级与风场的相关特性,结合潜标海洋环境噪声数据及对应海域的海面风场再分析数据,计算各频段噪声级与风速相关系数及线性拟合函数。分析结果表明:400～1 000 Hz频段,海洋环境噪声谱级与海面风速的相关系数在0.5～0.8之间,达到中等相关。1 000～5 000 Hz频段,两者互相关系数大于0.8,达到高度相关。对海洋环境噪声谱级与对数风速的回归分析结果显示,1000～5 000 Hz频段,两者的线性函数关系显著;并且在1 000 Hz附近的拟合斜率最大,海洋环境噪声谱级对海面风速变化的灵敏度最高。 相似文献
3.
4.
星载微波散射计海面风场与海洋环境噪声的相关特性分析 总被引：2，自引：1，他引：1
根据海洋环境噪声机理及风关噪声已有的研究成果,提出利用星载微波散射计反演的海面风场数据进行海洋环境噪声分析,并对HY-2A和ASCAT数据与噪声谱级的相关性进行了对比分析。选取南海海域作为研究区,利用潜标测量系统获取的噪声数据和多源散射计风场数据开展了相关实验,并采用NCEP海面风场数据进行对比分析。结果表明,ASCAT数据与噪声的相关性优于HY-2A,散射计数据优于NCEP数据,散射计风场更适合海洋环境噪声的分析研究。该研究内容拓展了微波散射计风场数据的应用领域,并为海洋环境噪声研究提供了更好的技术手段。 相似文献
5.
Microwave remote sensing is one of the most useful methods for observing the ocean parameters. The Doppler frequency or interferometric phase of the radar echoes can be used for an ocean surface current speed retrieval,which is widely used in spaceborne and airborne radars. While the effect of the ocean currents and waves is interactional. It is impossible to retrieve the ocean surface current speed from Doppler frequency shift directly. In order to study the relationship between the ocean surface current speed and the Doppler frequency shift, a numerical ocean surface Doppler spectrum model is established and validated with a reference. The input parameters of ocean Doppler spectrum include an ocean wave elevation model, a directional distribution function, and wind speed and direction. The suitable ocean wave elevation spectrum and the directional distribution function are selected by comparing the ocean Doppler spectrum in C band with an empirical geophysical model function(CDOP). What is more, the error sensitivities of ocean surface current speed to the wind speed and direction are analyzed. All these simulations are in Ku band. The simulation results show that the ocean surface current speed error is sensitive to the wind speed and direction errors. With VV polarization, the ocean surface current speed error is about 0.15 m/s when the wind speed error is 2 m/s, and the ocean surface current speed error is smaller than 0.3 m/s when the wind direction error is within 20° in the cross wind direction. 相似文献
6.
西沙北部海域海洋环境噪声频谱特性 总被引：2，自引：1，他引：1
Ambient noise is very important in the prediction system of a sonar performance, because it determines the detection ranges always in a passive sonar and usually in an active sonar. In the uncertainty issue for the so-nar performance, it is necessary to know this factor＇s statistical characteristics that are only obtained by data processing from the underwater ambient noise measurements. Broad-band ambient noise signals from 16 hydrophones were amplified and recorded for 2 min every 1 h. The results show that the ambient noise is essentially depth independent. The cross correlation of the ambient noise levels （1, 6 and 12 h average） with a wind speed is presented. It was found that the correlation is excellent on the upper frequency band and the noise levels correlate better with high wind speed than with low wind speed. 相似文献
7.
8.
A digital array of 120 acoustic channels 900 m in length has been constructed to study low-frequency (20-200 Hz) ambient noise in the ocean. The array may be deployed vertically or horizontally from the research platform FLIP and the array elements are localized with a high-frequency acoustic transponder network. The authors describe the instrumentation, telemetry, and navigation systems of the array during a vertical deployment in the northeast Pacific. Preliminary ambient noise spectra are presented for various array depths and local wind speeds. Ambient noise in the frequency band above 100 Hz or below 25 Hz increases with local wind speed. However, in the frequency band 25-100 Hz, ambient noise is independent of wind speed and may be dominated by shipping sources 相似文献
9.
为研究海洋环境信号在OBS(Ocean Bottom Seismograph)原始数据中的规律及应用,根据OBS原始数据的波形及频谱特征,将研究区划分为5个时间段,依次为旧涌浪阶段、风浪渐强阶段、风浪全盛阶段、风浪消退阶段和新涌浪阶段。结合海洋天气预报,认为上述现象是由偏南风风浪对海流的影响造成的。参考野外地震数据采集记录班报,得到各阶段的时长和距离,计算风浪渐强、全盛和消退阶段OBS附近海流的平均速度。结果表明:OBS原始资料中浅海海洋环境噪音增强的主要因素是风浪,且风浪引起的噪音信号的波形变化特征是渐进式的;OBS可用于接收某种特殊阶段(如台风、海啸等)的噪音信号,并根据噪音信号的波形特征、频谱变化规律和持续时间估算该阶段的海流速度变化。 相似文献
10.
Low-frequency ambient-noise measurements in the South Fiji basin 总被引：1，自引：0，他引：1
The effect of wind speed on ambient noise has been measured in an experiment carried out in the South Fiji basin. The noise data in the band 15-250 Hz are well correlated with the variations in the local wind speed. The relationship between noise level N and wind speed ν is expressed by N =B +20n log ν. The constants B and n have been estimated by fitting the data using this model. The analysis indicates that there are two types of behavior: for ν>15 kn, a value of n =1.5 is obtained for the entire band, whereas for ν<15 kn, there is no correlation with wind speed observed in the data. The results suggest that there is a delay of 40-120 min for the effect of wind on the hydrophone noise level 相似文献
11.
A buoy for measuring wind speed and the ambient noise sound pressure level from 10 to 1500 Hz with 1-Hz resolution is described. The measurement buoy was deployed in a remote fjord in southeastern Alaska from October to December, 1989. The results from the data collected show that, for a wind speed of 5 kn, the measured ambient noise level at 900 Hz lies well below the Knudsen curve for open-ocean, wind-generated noise. As the wind speed increases from 5 to 10 kn, the measured ambient noise level approaches the Knudsen curve, increasing at 4 dB/kn compared to 1 dB/kn for the Knudsen curve. Above 10 kn, the measured ambient noise level matches the Knudsen curve 相似文献
12.
在合成孔径雷达(Synthetic Aperture Radar,SAR)海面风场反演中,基于风条纹影像纹理特征的海面风向反演方法精度高,但是依赖于图像风条纹的存在,而外部风向信息与SAR资料时空分辨率不易匹配、精度较低,从而影响大面积、高分辨率海面风场反演的精度。针对此问题,提出一种将SAR图像风条纹线性纹理特征与外部风向信息相结合的星载SAR海面风向获取方法,在SAR影像线性纹理特征明显的区域采用二维连续小波变换得到高精度的海面风向,其余区域采用与之时空相匹配的数值预报模式风向填充;并利用地球物理模型函数进一步得到海面风速,进而实现高精度、大范围海面风场的反演。为验证本文方法的有效性,利用ENVISAT/ASAR数据进行风场反演试验,并将反演结果与浮标实测数据进行比对。结果表明:在线性纹理特征明显的区域,小波方法的反演精度优于快速傅里叶变换(FFT)法和数值预报模式风向;外部风向精度略低,但与SAR观测资料时空匹配性较好,弥补了风条纹风向的不足。二者的结合为星载SAR海面风场反演的业务化应用提供了支持。 相似文献
13.
The correlation of ambient noise with wind speed, and the depth dependence of ambient noise are both investigated, where the ocean noise data were recorded by a vertical line array in the northern South China Sea. It is shown that the correlation coefficients increase with increasing hydrophone depth during typhoon periods when the frequency ≥ 250 Hz, which opposes the generally accepted knowledge that the correlation coefficients of noise level and wind speed decrease with increasing depth during non-typhoon periods. Particularly at frequencies of 250 Hz, 315 Hz and 400 Hz, the correlation coefficients increase by more than 0.05 at depths ranging from 155 m to 875 m. At the three frequencies, the average noise levels also increase with increasing depth during typhoon periods. It is suggested that these differences are attributed to the wind-generated noise in shallow waters and the effect of "downslope enhancement" to sound propagation. During typhoon periods, the surf breaking and surf beat upon the shores and reefs are strengthened, and the source levels are increased. The wind-generated noise in shallow waters interacts with the downslope sea floor, with the noise-depth distribution changed by a "downslope enhancement" effect promoting noise propagation. 相似文献
14.
为实现对海面风速精确的短期预测,提出了一种基于长短期记忆(LSTM,long short-term memory)神经网络的短期风速预测模型,选取OceanSITES数据库中单个浮标站点采集的风速历史数据作为模型输入,经过训练设置最佳参数等步骤,实现了以LSTM方法,对该站点所在海区海面风速在各季节性代表月份海面风速的24h短期预测。同时通过不同预测时长的实验以及与BP(back propagation)神经网络神经网络和径向基函数神经网络(radial basis function neural network,RBF)的预测效果对比实验,证明了LSTM预测方法相比上述两种神经网络预测方法,在海表面风速预测应用中的优越性。最后通过多个海域对应的站点风速数据预测实验,证明了LSTM神经网络模型的普遍适用性,由相关系数和预测误差的分析可知该方法具备应对急剧变化数据的预测稳定性,可以作为海洋表面风速短期预测的一种可靠方法。 相似文献
15.
风速是重要的海洋状态参数之一，对海面风速的准确提取是实现海洋环境监测和沿海工程应用的重要保证。目前，作为新兴海洋环境监测设备，高频雷达在风速提取方面仍然存在挑战。本文提出了一种基于人工神经网络的风速提取方法，利用历史浮标测量海态数据训练风速提取网络，实现风速与有效波高、波周期、风向及时间因素之间的非线性映射。测试结果表明了这一网络在时间和空间上的稳定性；进而将已训练的网络应用到便携式高频地波雷达OSMAR-S的风速反演中，得到的风速与浮标测量风速间的相关系数达到0.849，均方根误差为2.11 m/s。这一结果明显优于常规由浪高反演风速的SMB方法，验证了该方法在高频雷达风速反演中的可行性。 相似文献
16.
17.
利用机载GNSS反射信号反演海面风速的研究 总被引：2，自引：0，他引：2
全球卫星导航定位系统的反射信号(GNSS-R)遥感技术作为一种新型的、低成本的、高机动性的海面微波遥感测风技术,与其他测风手段优势互补,可以增加测风手段的多样性,弥补局部测风手段不足的状况。研究了接收机在机载高度时,GPS反射信号功率理论模型四部分函数的性质,在此基础之上,数值模拟了机载高度下理论相关功率波形,基于海面风速对波形峰值与后沿的影响,提出了一种能够兼顾所有理论波形信息的二维插值风速反演方法。利用该方法,结合实测机载数据对海面风速进行反演,反演的风速均值与附近测站风速均值相差为1.4 m/s,与浮标数据相一致。 相似文献
18.
A study of a new retrieval algorithm for measurement of oceanic windvectors field using satellite microwave scatterometer 总被引：1，自引：1，他引：0
ＡｓｔｕｄｙｏｆａｎｅｗｒｅｔｒｉｅｖａｌａｌｇｏｒｉｔｈｍｆｏｒｍｅａｓｕｒｅｍｅｎｔｏｆｏｃｅａｎｉｃｗｉｎｄｖｅｃｔｏｒｓｆｉｅｌｄｕｓｉｎｇｓａｔｅｌｌｉｔｅｍｉｃｒｏｗａｖｅｓｃａｔｔｅｒｏｍｅｔｅｒＬｉｎＭｉｎｇｓｅｎ,ＳｕｎＹｉｎｇ,Ｚ... 相似文献
19.
We propose a new analytical algorithm for the estimation of wind speeds from altimeter data using the mean square slope of
the ocean surface, which is obtained by integration of a widely accepted wind-wave spectrum including the gravity-capillary
wave range. It indicates that the normalized radar cross section depends not only on the wind speed but also on the wave age.
The wave state effect on the altimeter radar return becomes remarkable with increasing wind speed and cannot be neglected
at high wind speeds. A relationship between wave age and nondimensional wave height based on buoy observational data is applied
to compute the wave age using the significant wave height of ocean waves, which could be simultaneously obtained from altimeter
data. Comparison with actual data shows that this new algorithm produces more reliable wind speeds than do empirical algorithms.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
为了解各向异性随机粗糙海面的微波双站散射机制及其特性，本文利用解析近似的积分方程模型以及一种改进的半经验海浪谱模型实现了对各向异性随机粗糙海面的全极化微波散射仿真模拟，并与卫星观测数据、经验的地球物理模式函数及已有的解析近似散射模型仿真结果进行了对比，验证了仿真结果的可行性和准确性。利用该模型分析了入射波频率、入射角、极化方式、海面风速及风向等参数对各向异性海面双站散射的影响。模拟结果表明，在不同的入射角、散射角及方位角等观测几何条件下，海面不同波段的双站散射表现出不同的空间散射特性，且对风速、风向等海面动力学参数表现出不同的敏感性，以L波段为例，海面向后半球双站散射在各个极化方式下都对风速较为敏感，而在同极化方式下，其对风向的响应在中低风速和高风速条件下相反，整体而言，低风速下海面双站散射对风向更为敏感。这表明对于海面动力参数的反演，双站散射可以提供比传统单站雷达后向散射更丰富的物理信息。本文探讨了各向异性海面微波双站散射特性，为基于主动式及分布式微波传感器的海洋动力参数遥感反演提供了理论分析基础。 相似文献