共查询到17条相似文献，搜索用时 359 毫秒
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海面发生大面积溢油事故时,由于太阳耀斑区的存在,海面的油膜在遥感影像上会发生明暗的变化。这对溢油的检测会产生严重的干扰。如何在海面太阳耀斑区准确地检测出溢油是目前溢油检测的难题。针对这一问题,本文利用Landsat7 ETM+多光谱影像数据,开展了基于卷积神经网络(CNN)的海面太阳耀斑区溢油检测方法研究。通过设置对照实验,对比支持向量机、最大似然、随机森林等分类方法,我们发现在相同实验条件下CNN模型的分类精度为95%～99%, Kappa系数为0.92～1,均高于其他三种分类方法,表明了CNN模型在海面太阳耀斑区溢油的检测具有更高的精度与一致性。 相似文献
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本文简要介绍了M99、R06、G01、L10四种典型水上法估算遥感反射率方法的原理,利用现场观测数据,对四种方法的应用效果进行了评估分析。利用高光谱SAS实测的76个站位数据,对比分析了四种方法结果的差异性以及不同太阳天顶角和云况条件的差异分布,结果表明,四种方法估算的遥感反射率总体差异性不大,有80%站位的差异在10%以内,L10方法的结果更接近四种方法的平均值,R06方法的结果与L10大体相当,当太阳天顶角过大时,四种方法估算遥感反射率的差异较大,在阴天条件下,差异性有小幅度增大。利用高光谱SAS和剖面仪MicroPro同步观测的73个站位数据,分析了四种水上法与水中法计算遥感反射率的差异性,以及不同水体和太阳天顶角条件的差异分布,结果显示,四种水上法与水中法计算的遥感反射率结果差异分布趋势大体一致,约75%站位的差异在15%以内,在较好的比对环境下(去掉近岸站位和太阳天顶角较大的站位),四种方法与水中法差异明显减小,其中,R06和L10方法在处理粗糙海面的天空和太阳耀斑修正方面略优。 相似文献
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利用2006-2007年东海海区(120°E～128°E,26°N～31°N)的太阳辐射、常规气象和皮温等观测资料,分析太阳辐射季节变化特征,并讨论其与相关因子的关系;分析大气透过率与太阳高度角、总云量和相对湿度的关系,并进一步讨论海而反照率与太阳高度角、大气透过率和风的相关性.结果表明:东海海区辐射分量除向上短波辐射外,都表现出夏季最大,冬季最小的季节变化特征;大气透过率秋季最大,夏季最小;海面反照率秋季最大,春季最小.向下(上)短波辐射主要受太阳高度角和云量影响,向下长波辐射与气温、相对湿度的相关性较好,向上长波辐射与皮温的关系非常密切;大气透过率在少云时主要受太阳高度角影响,多云时主要受总云量影响,空气湿度的影响较弱;大气透过率变大时海面反照率减小;太阳高度角是影响海面反照率最主要的因素,且影响作用随着大气透过率的变大而增强,太阳高度角越大,海面反照率越小;风引起的海而粗糙度影响最弱,在太阳高度角较高、大气透过率较大时,风增大海面反照,卒的作用增强. 相似文献
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探测距海面几米高以下的温、湿和风等气象要素的梯度变化,以获取梯度廓线及贴水层大气的动量、热量和乱流等通量传递系数,是研究小尺度海气相互作用的必要手段。由于海上工作条件不同于陆地,进行海上大气梯度探测是比较困难的。为了适应我国海气相互作用研究的需要,我们研制成功了一种采用小型浮标系统,通过电缆遥测海面温度、湿度和风速的仪器—《海面温湿风梯度仪》(以下简称《梯度仪》)。由该仪器可得到距海面以上5米内不同高度的温、湿和风速的梯度资料。 相似文献
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应用海面矢量和标量廓线，以及贴海层厚度的相似分析，提出并论证了海面矢量与标量粗糙度近似相等的结论。 相似文献
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准确的海面风速预报是舰艇航行安全和防台工作的重要保证。目前在舰艇上估测海面风速方法主要是利用传真天气图手工绘算单站地转风,并对理论风速值进行适当摩擦系数订正。这种方法的估测精度比较差,很难满足舰艇指挥人员在复杂天气中的预报需求。为了深入探讨海面风估算方法,给出了传真地面天气图上地转风、梯度风的近似计算公式,介绍了用传真图实时计算地转风与梯度风的实现方法,提出了通过建立风速订正值库由风速理论值实时估测平均海面风速的一种新方法,并深入探讨了梯度风测风方法在强天气测风中的应用特点和优势。经实际应用和分析表明,计算精度得到很大提高,有一定应用和推广价值。 相似文献
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太阳耀光是来自粗糙海面的直接太阳反射光,其强度与海面粗糙度密切相关,而海面粗糙度主要受海面风场影响。因此,包含太阳耀光信息的光学遥感影像在海洋动力过程和海面风速探测中具有积极意义。本文利用2016年2月到2017年3月期间成像的25幅Terra卫星MISR(Multi-angle Imaging Spectro Radiometer)传感器的多角度遥感影像,分别提取了太阳的高度角和方位角、正视和后视影像的卫星观测角、方位角等信息,校正获得正视和后视影像的太阳耀光辐射强度,进一步反演海表面粗糙度信息,进而计算海面风速。最后利用ECMWF(European Centre for Medium-Range Weather Forecasts)的模式风速数据与反演获得的风速结果进行对比验证。结果表明,两者的相关系数较高(R=0.745),均方根误差和平均绝对偏差值分别为1.514 m·s-1和1.319 m·s-1。初步实验结果表明,利用MISR多角度光学遥感影像估算海表面风速是可行性的。 相似文献
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星载微波辐射计外定标的关键问题是通过辐射传输方程计算天线入瞳处亮温。根据辐射传输方程,海面成份对亮温的影响包括海面的微波辐射和对下行大气辐射的反射,其中的关键参数分别为海面发射率ep和海表面反射率R。文中对平静海面Fresnel反射率模式和粗糙海面反射率模式进行了研究分析,在此基础上着重研究了海面温度TS、海面盐度SS、海面风速W、以及观测角度θ等物理参数对海面发射率ep的影响,进而分析了这些物理参数的测量误差对亮温的计算精度的影响。 相似文献
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The probability distribution of the sea surface slope has been estimated using sun glitter images derived from the visible
wavelength radiometer on the Geostationary Meteorological Satellite (GMS) and surface vector winds observed by spaceborne
scatterometers. The brightness of the visible images is converted to the probability of wave surfaces which reflect the sunlight
toward GMS in grids of 0.25° × 0.25° (latitude × longitude). The slope and azimuth angle required for the reflection of the
sun's rays toward GMS are calculated for each grid from the geometry of GMS observation and location of the sun. The GMS images
are then collocated with surface wind data observed by three scatterometers. Using the collocated data set of about 30 million
points obtained in a period of 4 years from 1995 to 1999, the probability distribution function of the surface slope is estimated
as a function of wind speed and azimuth angle relative to the wind direction. The results are compared with those of Cox and
Munk (1954a). The surface slope estimated by the present method shows a narrower distribution and much less directivity relative
to the wind direction than that reported by Cox and Munk. It is expected that their data were obtained under conditions of
growing wind waves. In general, wind waves are not always developing, and the slope distribution might differ from the results
of Cox and Munk. Most of our data are obtained in the subtropical seas under clear-sky conditions. This difference in the
conditions may be the reason for the difference of slope distribution.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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海面风应力偏离风向的观测与分析 总被引：1，自引：0，他引：1
针对海气界面风应力方向与风向不一致的现象,2015年2月4日至3月12日在南海博贺观测平台开展了综合观测,利用涡动相关法计算了海气界面风应力,并在3类大气稳定度条件下分析了风应力矢量偏离风矢量的角度变化,进一步讨论了大气层结稳定时两者角度之差与风速的参数化关系。结果表明:在大气层结稳定条件下,风应力矢量偏向风矢量左侧,且偏离角度随逆波龄和风速增大而减小;当大气层结不稳定时,风应力矢量一般偏向风矢量右侧。海气界面风应力矢量受海表面风、波浪以及大气层结的共同调制。 相似文献
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利用高空间分辨率卫星影像准确监测浒苔绿潮对灾害早期发现、动态跟踪以及沿岸防御具有重要应用价值。目前面向高分辨率遥感影像已有多种浒苔提取方法,但不同遥感算法受到海水背景(浑浊和清澈海水)和外界观测环境(如云层、太阳耀斑、观测几何条件)等干扰,其监测效果可能受到不同程度影响。为此,以国产高分辨率GF-WFV和HJ-CCD影像为例,充分对比了归一化差值植被指数(normalized difference vegetation index,NDVI)、漂浮藻类高度虚拟基线指数(virtual baseline floating macroalgae height,VB-FAH)和绿度指数(tasseled cap greenness,TCG)在常见多种环境背景下提取浒苔的优势和不足。研究结果表明:在清澈海水、浑浊海水和弱太阳耀斑背景下,NDVI、VB-FAH和TCG三种算法均有较好的浒苔识别能力,其精度评价指标F1-score和总体分类精度(overall accuracy, OA)分别超过95.6%和95.2%。对于几何观测条件,VB-FAH和TCG算法对观测几何角度的变化不敏感并表现较高的稳定性,要优于NDVI方法。在云层覆盖和强太阳耀斑背景下,TCG算法的浒苔判识能力最好,并可有效排除云覆盖和强太阳耀斑的干扰,其精度评价指标F1-score和OA分别超过95.2%和95.0%。 相似文献
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中等海况下,星载合成孔径雷达(Synthetic Aperture Radar,SAR)已经广泛应用于海洋动力环境要素的监测(风场、波浪、流场)。近年来,SAR高海况遥感,尤其是探测台风海面风场、巨浪、流场已经成为国内外研究热点,并突破了一些关键技术。利用SAR多极化成像模式对海观测和新发展的地球物理模式函数,可以提取高海况下的海面风速、风向、有效波高、流速和流向等海洋表面关键物理参数。这些环境要素可以用于海洋灾害监测预警;为海洋和大气数值模式提供准确的初始场和同化源,改进模式预报精度;为研究全球气候变化提供有力的观测依据。 相似文献
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As a new remote sensing technology, the global navigation satellite system (GNSS) reflection signals can be used to collect the information of ocean surface wind, surface roughness and sea surface height. Ocean altimetry based on GNSS reflection technique is of low cost and it is easy to obtain large amounts of data thanks to the global navigation satellite constellation. We can estimate the sea surface height as well as the position of the specular reflection point. This paper focuses on the study of the algorithm to determine the specular reflection point and altimetry equations to estimate the sea surface height over the reflection region. We derive the error equation of sea surface height based on the error propagation theory. Effects of the Doppler shift and the size of the glistening zone on the altimetry are discussed and analyzed at the same time. Finally, we calculate the sea surface height based on the simulated GNSS data within the whole day and verify the sea surface height errors according to the satellite elevation angles. The results show that the sea surface height can reach the precision of 6 cm for elevation angles of 55° to 90°, and the theoretical error and the calculated error are in good agreement. 相似文献
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K. A. Shmirko O. G. Konstantinov Yu. N. Kul’chin S. Yu. Stolyarchuk A. N. Pavlov M. Yu. Korenskii 《Izvestiya Atmospheric and Oceanic Physics》2017,53(3):373-381
A continuation of the work dedicated to the study of slicks and film formations on the sea surface is presented. A vector model for the calculation of reflected radiation by the wavy sea surface with respect to the contribution of upwelling radiation from under the sea surface (the second type of waters) is described briefly in [5]. This work contains an analysis of numerical calculations according to the developed procedure and the search for optimal conditions of slick detection. The best conditions for detecting slicks on the sea surface are reached when a P-polarization component of reflected radiation is recorded. In this case, the value of contrast between a slick and a clean surface is 30% higher on average than in recording a contrast without using a polarization filter and is 50% higher than in the case of recording a contrast with a filter oriented to the maximum transmission of S polarization component of reflected radiation. It is shown that, under clear sky conditions, the optimal condition for recording slicks on a sea surface is videotaping in the plane of solar vertical at viewing angles sliding towards the sea surface and when a polarization filter that identifies the Р polarization component of sea radiation is used. In contrast, under overcast sky conditions, it is best to perform observations in the plane that has a wind velocity vector. 相似文献
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基于浮标实测数据的WindSat海洋反演产品精度分析 总被引：1，自引：1，他引：0
To evaluate the ocean surface wind vector and the sea surface temperature obtained from Wind Sat, we compare these quantities over the time period from January 2004 to December 2013 with moored buoy measurements. The mean bias between the Wind Sat wind speed and the buoy wind speed is low for the low frequency wind speed product(WSPD_LF), ranging from –0.07 to 0.08 m/s in different selected areas. The overall RMS error is 0.98 m/s for WSPD_LF, ranging from 0.82 to 1.16 m/s in different selected regions. The wind speed retrieval result in the tropical Ocean is better than that of the coastal and offshore waters of the United States. In addition, the wind speed retrieval accuracy of WSPD_LF is better than that of the medium frequency wind speed product. The crosstalk analysis indicates that the Wind Sat wind speed retrieval contains some cross influences from the other geophysical parameters, such as sea surface temperature, water vapor and cloud liquid water. The mean bias between the Wind Sat wind direction and the buoy wind direction ranges from –0.46° to 1.19° in different selected regions. The overall RMS error is 19.59° when the wind speed is greater than 6 m/s. Measurements of the tropical ocean region have a better accuracy than those of the US west and east coasts. Very good agreement is obtained between sea surface temperatures of Wind Sat and buoy measurements in the tropical Pacific Ocean; the overall RMS error is only 0.36°C, and the retrieval accuracy of the low latitudes is better than that of the middle and high latitudes. 相似文献