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61.
Quasi-Analytical Algorithms (QAAs) are based on radiative transfer equations and have been used to derive inherent optical properties (IOPs) from the above surface remote sensing reflectance (Rrs) in aquatic systems in which phytoplankton is the dominant optically active constituents (OACs). However, Colored Dissolved Organic Matter (CDOM) and Non Algal Particles (NAP) can also be dominant OACs in water bodies and till now a QAA has not been parametrized for these aquatic systems. In this study, we compared the performance of three widely used QAAs in two CDOM dominated aquatic systems which were unsuccessful in retrieving the spectral shape of IOPS and produced minimum errors of 350% for the total absorption coefficient (a), 39% for colored dissolved matter absorption coefficient (aCDM) and 7566.33% for phytoplankton absorption coefficient (aphy). We re-parameterized a QAA for CDOM dominated (hereafter QAACDOM) waters which was able to not only achieve the spectral shape of the OACs absorption coefficients but also brought the error magnitude to a reasonable level. The average errors found for the 400–750 nm range were 30.71 and 14.51 for a, 14.89 and 8.95 for aCDM and 25.90 and 29.76 for aphy in Funil and Itumbiara Reservoirs, Brazil respectively. Although QAACDOM showed significant promise for retrieving IOPs in CDOM dominated waters, results indicated further tuning is needed in the estimation of a(λ) and aphy(λ). Successful retrieval of the absorption coefficients by QAACDOM would be very useful in monitoring the spatio-temporal variability of IOPS in CDOM dominated waters. 相似文献
62.
遥感数据融合的进展与前瞻 总被引:1,自引:0,他引:1
数据融合是提升遥感影像应用能力的重要手段,一直是遥感信息处理与应用领域的研究热点。本文系统综述了遥感数据融合的进展与前瞻:首先对数据融合的层次与分类进行了总结和归纳,将遥感数据融合划分为同质遥感数据融合、异质遥感数据融合、遥感—站点数据融合、遥感—非观测数据融合4大类;在此基础上,重点针对时—空—谱光学遥感数据的融合,从多视超分辨率融合、多尺度融合、空—谱融合、时—空融合、时—空—谱一体化融合等方面进行了详细阐述;最后总结了遥感数据融合的前瞻研究方向,包括时—空—谱一体化融合的拓展、空天地观测数据的跨尺度融合、传感网环境下的在线融合、面向应用的融合方法等。 相似文献
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64.
本文基于海浪波折射现象和浅水波理论,提出了一种基于单景高分辨率光学遥感影像的浅海地形提取方法。首先,基于浅水波理论推导出适用于浅海区域的水深与海浪波长、频率的定量关系,针对近岸光学遥感图像复杂的海浪特征,讨论了两种海浪波长提取方法,即FFT方法和剖面线法。然后提出了基于长距离波长波动分析的海浪频率计算方法,解决了单景遥感影像的波浪频率计算难题。最后,利用单景QuickBird高分辨率光学遥感影像,以海南岛三亚湾为研究区域进行了应用实验,结果表明,对12m以浅的浅海区域,在不需要任何辅助参数的情况下,反演获得了浅海地形(DEM),经与1:25000比例尺海图的水深对比验证,地形趋势吻合良好,反演水深的均方根误差为1.07m,相对水深误差为16.2%,表明该方法适合于浅海水下地形的提取,且具有无需实测水深数据和环境参数的支持的优点。 相似文献
65.
Li-Chung Wu Dong-Jiing Doong Beng-Chun Lee Laurence Zsu-Hsin Chuang Chia Chuen Kao 《Marine Geophysical Researches》2008,29(1):43-50
The purpose of this study is to discuss the influence of signal nonlinearity upon X-band radar observations. A method for
estimating the degree of nonlinearity by bispectral analysis was applied and discussed. We found that bispectral analyses
from spatial radar backscatter series are similar to results obtained from water level time series. In addition, the average
nonlinear degree from radar backscatter is related to wind speed. The accuracy of wave observations derived by consideration
of the nonlinear effect from radar backscatter was also investigated. The estimated error in wave height from the radar data
is also related to the degree of nonlinearity. In order to improve accuracy, the modulation transfer function method was applied
in order to eliminate the influence of nonlinearity. 相似文献
66.
The sensitivity of the suspended sediment flux is tested with respect to rapid changes in bed-level across the surf zone of a sandy beach. The suspended flux was computed using a fixed instrument array, but bed-level changes due to ripple migration caused the instrument elevations to be significantly changed during the course of the experiment. The nominal elevations of the instruments were adjusted during data processing (using the MOBS array) to maintain a fixed elevation with respect to bed-level changes. The resultant suspended sediment concentrations and fluxes were significantly different from the unadjusted data, and for the present data set O(35%) less when averaged over the tide. The maximum difference between adjusted and unadjusted fluxes may be O(260%). The results indicate that changes in bed-level, particularly those due to bedform migration, must be accounted for when processing OBS data if reliable estimates of suspended sediment transport are to be obtained in the field. 相似文献
67.
68.
The drilling parameter monitor is an important tool in drilling engineering applied to monitoring drilling process, carrying out scientific analysis and decision-making. Based on discussing the present development situation of the domestic and foreign drilling machine parameter monitors, the metering scheme for vehicle-loaded drilling parameter monitor was designed. By using detection system for MSP430 single-chip microcomputer (SCM) in combination with peripheral circuit such as sensors, the drilling-rig control system was obtained to detect, and for every parameter in real-time display in order to keep operating the drilling rig status. The experiment shows that the drilling parameter monitor reaches design requirements and can be applied to drilling engineering monitoring, which has characters such as simple structure, high credibility and low cost. 相似文献
69.
70.