共查询到20条相似文献，搜索用时 406 毫秒
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Victor S. Kuwahara Grace Chang Xiaobing Zheng Tommy D. Dickey Songnian Jiang 《Journal of Oceanography》2008,64(5):691-703
Buoy-mooring platforms are advantageous for time-series validation and vicarious calibration of ocean color satellites because
of their high temporal resolution and ability to perform under adverse weather conditions. Bio-optical data collected on the
Bermuda Testbed Mooring (BTM) were used for comparison with satellite ocean color data in an effort to further standardize
sampling and data processing methods for high quality satellite-mooring comparisons. Average percentage differences between
satellite-measured and mooring-derived water leaving radiances were about 20% at the blue wavelengths, decreasing to as low
as 11% in the blue-green to green wavebands. Based on a series of data processing methods and analyses, recommendations concerning
rigor of quality control for collected data, optimal averaging of high-frequency data, sensor self-shading wind corrections,
and instrumentation placement requirements are given for the design and application of optical moorings for ocean color satellite
validation. Although buoy-mooring platforms are considered to be among the very best methods to validate ocean color satellite
measurements, match-up discrepancies due to water column variability and atmospheric corrections remain important issues. 相似文献
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Long-Term Validation of Wave Height Measurements from Altimeters 总被引：1，自引：0，他引：1
Pierre Queffeulou 《Marine Geodesy》2004,27(3):495-510
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. 相似文献
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PIERRE QUEFFEULOU 《Marine Geodesy》2013,36(3-4):495-510
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. 相似文献
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卫星雷达高度计正从传统星下点的剖面测量向宽刈幅干涉测量发展,利用卫星观测二维的高分辨率、高精度海面高度正在成为可能,国外研究人员提出SWOT(Surface Water and Ocean Topography)干涉雷达高度计计划和我国新一代海洋科学卫星任务等计划有望实现海洋亚中尺度现象的观测。定标检验是评价卫星观测资料精度和质量的必要工作,传统高度计的定标检验均为基于验潮站、GNSS(Global Navigation Satellite System)浮标、有源定标器等方式的单点比对,难以满足干涉高度计的需求。目前国内外研究人员在干涉雷达高度计的定标检验中采用了全新的技术方案,并已利用机载试验和理论模拟开展了验证工作。对近10 a干涉雷达高度计定标检验的新技术方法进行介绍和总结,希望对我国的干涉雷达高度计卫星定标计划起到借鉴作用。 相似文献
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Multi‐channel Advanced Very‐High Resolution Radiometer (AVHRR) images of sea surface temperature (SST) in the New Zealand region have been archived since 1989. A comparison of these data with conductivity‐temperature‐depth (CTD) and expendable bathythermograph (XBT) data shows that the AVHRR temperatures are about 7% too high (when expressed in °C). Once the AVHRR temperatures have been corrected, they measure SST with an uncertainty of about 0.7°C. 相似文献
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Preliminary Assessment of SARAL/AltiKa Observations over the Ganges-Brahmaputra and Irrawaddy Rivers
Radar altimetry has demonstrated strong capabilities for the monitoring of water levels of lakes, rivers and wetlands over the last 20 years. The Indo-French SARAL/AltiKa mission, launched in February 2013, is the first satellite radar altimetry mission to carry onboard a Ka-band sensor. We propose here to evaluate the potential of this new instrument for land hydrology through comparisons with other altimetry-derived stages and discharges in the Ganges-Brahmaputra and Irrawaddy river basins using its first year of data. Due to the lack of concomitant in situ measurements for the current period, Jason-2 data, previously evaluated against in situ gauge records, were used as reference. Comparisons between Jason-2 and SARAL-derived water levels and discharges, and Jason-2 and Envisat (which flew the same orbit as SARAL from 2002 to 2010)-derived ones, was performed. Time-series of only one year of SARAL-derived water levels and discharges present better performances (lower RMSE and higher R, generally greater than 0.95) than the ones derived from Envisat when compared with Jason-2. 相似文献
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Jason-1 global statistical evaluation and performance assessment: Calibration and cross-calibration results 总被引：1，自引：0，他引：1
Since Jason-1launch, extensive validation of Jason-1 data and cross-calibration relative to TOPEX/Poseidon (T/P) have been performed by the CLS validation team within the CNES Jason-1 project. These validation activities are routinely operated as part of the Jason-1 ground segment, and often lead to in-depth studies to understand all validation conclusions. This paper presents the main results in terms of Jason-1 data quality: verification of data availability and validity, monitoring of the most relevant altimeter and radiometer parameters, assessment of the Jason-1 altimeter system performances. From global statistical analysis of more than 2 years of Jason-1 GDR data, results for all components of the altimeter measurement are derived in terms of bias, trend and precision. This work also represents a contribution to the estimation of the Jason-1 error budget. Thorough studies have been more focused on specific issues in relation to data quality: this is the case for the analysis of the high frequency content of the Jason-1 data and its impact on the T/P to Jason-1 comparison. From the results presented in this paper, it is demonstrated that the Jason-1 mission fulfils the requirements of high precision altimetry. In particular, it allows continuing the observation of the Mean Sea Level (MSL) variations at the same accuracy as T/P, which was one of the challenges of the Jason-1 mission. Potential improvements and open issues are also identified, with the objective of still making progress in terms of altimeter data quality. 相似文献
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Jason-1 global statistical evaluation and performance assessment: Calibration and cross-calibration results 总被引：2，自引：0，他引：2
Since Jason-1launch, extensive validation of Jason-1 data and cross-calibration relative to TOPEX/Poseidon (T/P) have been performed by the CLS validation team within the CNES Jason-1 project. These validation activities are routinely operated as part of the Jason-1 ground segment, and often lead to in-depth studies to understand all validation conclusions. This paper presents the main results in terms of Jason-1 data quality: verification of data availability and validity, monitoring of the most relevant altimeter and radiometer parameters, assessment of the Jason-1 altimeter system performances. From global statistical analysis of more than 2 years of Jason-1 GDR data, results for all components of the altimeter measurement are derived in terms of bias, trend and precision. This work also represents a contribution to the estimation of the Jason-1 error budget. Thorough studies have been more focused on specific issues in relation to data quality: this is the case for the analysis of the high frequency content of the Jason-1 data and its impact on the T/P to Jason-1 comparison. From the results presented in this paper, it is demonstrated that the Jason-1 mission fulfils the requirements of high precision altimetry. In particular, it allows continuing the observation of the Mean Sea Level (MSL) variations at the same accuracy as T/P, which was one of the challenges of the Jason-1 mission. Potential improvements and open issues are also identified, with the objective of still making progress in terms of altimeter data quality. 相似文献
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A high-resolution downward surface solar radiation (DSSR) dataset has been produced using geostationary meteorological satellite
measurements. Its validation with in situ observations shows that the daily satellite DSSRs are highly accurate. Comparing
the satellite DSSRs with reanalysis DSSR datasets, the former has higher probability density in a low value range, and lower
density in a high value range. Overestimations of the reanalysis DSSR are significant in the low range. Correlations between
the reanalysis DSSRs and the satellite DSSR are relatively low in the tropics. It is suggested that the satellite DSSRs have
good potential to capture cloud behavior in the tropics. 相似文献
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台湾海峡及周边海区MODIS气溶胶光学厚度有效性验证 总被引：11，自引：2，他引：11
大气气溶胶通常是指悬浮在大气中直径小于10μm的液态或固态的微小粒子.对流层气溶胶是陆地-大气-海洋系统的重要组成部分.它通过直接或间接辐射强迫强烈地影响着地-气系统的辐射收支平衡,进而影响全球环境和气候,是气候变化研究的一个重要因子.气溶胶光学厚度是气溶胶最重要的参数之一,是表征大气浑浊度的重要物理量,也是确定气溶胶气候效应的一个关键因子和大气模型的一个重要参量[1].探测气溶胶光学厚度可以采用陆基探测方法,如太阳辐射计、天空辐射计、日射强度计等,也可以采用卫星遥感观测的方法. 相似文献
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海洋叶绿素a质量浓度遥感产品是海洋初级生产力与海洋生态系统固碳能力研究的重要数据源,为了保证数据的可靠性,对遥感产品进行精度验证以及验证误差的成因分析尤为重要。遥感产品的验证过程中,由于空间变异的存在,使得遥感像元尺度内的实测数据具有不同的离散程度和统计分布特征,并由此产生了不同的误差统计结果。本文选择MODIS-Aqua、MODIS-Terra、MERIS、SeaWiFS等卫星传感器叶绿素a质量浓度遥感产品为研究对象,统计分析了数据产品的空间变异与验证精度的关系。结果表明:空间变异是造成验证误差的直接原因之一,平均绝对百分比误差(Mean Absolute Percentage Error:MAPE)与空间变异系数(Coefficient of Variation: CV)呈幂指数模型关系;当CV＜0.05时,MAPE随CV的增加明显;当CV＞0.15时,MAPE的变化趋于平缓。不同卫星传感器叶绿素a质量浓度产品验证结果表明,SeaWiFS精度最高,MERIS次之,MODIS-Terra精度最低。 相似文献
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《African Journal of Marine Science》2013,35(3):455-458
Flathead mullet Mugil cephalus and freshwater mullet Myxus capensis are important components in South African estuarine fish communities and fisheries, but there is little information on their age and growth or age validation. This study validated the periodicity of growth zone formation in sectioned sagittal otoliths and scales of fish of known age that had been at liberty for 10 years. For both M. cephalus and M. capensis, the number of growth zones counted on otolith sections did not differ significantly from the known age of the fish. There were significantly fewer growth zones on scales than the known age of both M. cephalus and M. capensis. Growth zone deposition rate could therefore be validated as annual for otoliths but not for scales of the two species. It is recommended that future ageing studies focus on otoliths rather than scales. 相似文献
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A semiempirical algorithm for SAR wave height retrieval and its validation using Envisat ASAR wave mode data 总被引：2，自引：2，他引：0
Many synthetic aperture radar(SAR) wave height retrieval algorithms have been developed.However,the wave height retrievals from most existing methods either depend on other input as the first guess or are restricted to the long wave regime.A semiempirical algorithm is presented,which has the objective to estimate the wave height from SAR imagery without any prior knowledge.The proposed novel algorithm was developed based on the theoretical SAR ocean wave imaging mechanism and the empirical relation between two types of wave period.The dependency of the proposed model on radar incident and wave direction was analyzed.For Envisat advanced synthetic aperture radar(ASAR) wave mode data,the model can be reduced to the simple form with two input parameters,i.e.,the cutoff wavelength and peak wavelength of ocean wave,which can be retrieved from SAR imagery without any prior knowledge of wind or wave.Using Envisat ASAR wave mode data and the collocated buoy measurements from NDBC,the semiempirical algorithm is validated and compared with the Envisat ASAR level 2 products.The root-mean-square-error(RMSE) and scatter index(SI) in respect to the in situ measurements are 0.52 m and 19% respectively.Validation results indicate that,for Envisat ASAR wave mode data,the proposed method works well. 相似文献