共查询到20条相似文献，搜索用时 468 毫秒
1.
V. I. Man’kovskii G. A. Tolkachenko E. B. Shibanov O. V. Martynov E. N. Korchemkina D. V. Yakovleva I. A. Kalinskii 《Physical Oceanography》2010,20(3):207-230
We present the results of measurements of optical characteristics of waters (the beam attenuation coefficient, volume scattering
function, sea water reflectance, and Secchi depth) and optical characteristics of the atmosphere (aerosol optical thickness,
content of vapors, and the ?ngstr?m exponent) carried out in September 2008 on the oceanographic platform near Katsiveli.
We carried out the comparative analysis of hydrooptical characteristics measured in various years. The optical type of sea
waters in the period of observations is determined. 相似文献
2.
Measurements of underwater irradiance, transparency and Secchi disc depth were carried out in Liverpool Bay during 1974. The depth of the photic zone measured in the green portion of the spectrum ranged from 5 m to 50 m, depending on location and season. Inshore values of photic depth were smaller than those encountered offshore. By mid-summer the depth of the photic zone had reached or exceeded the depth of the sea bed over the whole study area.Consideration was given to the error terms associated with the optical measurements and to the problems of using standard optical relationships in coastal waters. The relationship between Secchi disc depth and the depth of the photic zone could not be taken as constant but was a function of the absorption and scattering properties of the water mass. 相似文献
3.
Oceanology - The article presents data of the beam attenuation coefficient, Secchi disk depth, and chlorophyll concentration in a survey area in the northern tropical zone of the Atlantic Ocean in... 相似文献
4.
S. I. Kropotov 《Physical Oceanography》1998,9(3):191-198
Equations are derived for calculating the depth of the Secchi disc, and the effect of various optical properties and observational
conditions upon the accuracy of measurements is estimated.
Translated by Vladimir A. Puchkin. 相似文献
5.
The spatial, seasonal, and interannual variability of the water’s transparency (Secchi depth) in the Sea of Azov is studied using the database of long term transparency measurements for the 1922–2009 period and relevant materials on the meteorological, hydrological, and hydrobiological parameters of the environment. We identified four main types of seasonal variability of the water’s transparency depending on the local conditions. The mean values of the Secchi depth are calculated for the different periods, which are distinguished by the differences in the relative role of the water transparency factors associated both with the climatic variations and the human activities. 相似文献
6.
由现场离水辐亮度估算黄海透明度几种方法的比较 总被引：1，自引：0，他引：1
本文根据黄海现场离水辐亮度及遥感反射比,采用４种统计算法估算海水透明度（Ｓｅｃｃｈｉ Ｄｉｓｃ Ｄｅｐｔｈ）。前２种算法中海水透明度作为因变量,两不同波段辐亮度之比及两辐亮度之和与第三者之比分别作为自变量,进行一元回归分析,前者相关系数ｒ２为０．９３３５。后者相关系数ｒ２为０．９４８３。第３种算法中,所有波段的遥感反射比做因子分析形成的主因子作为自变量,透明度作为因变量进行多元回归分析,子样全相关系数ｒ２为０．９６４９。第４种算法中,遥感反射比作为自变量,透明度作为因变量进行逐步回归分析,复相关系数ｒ２为０．９８１５。计算结果表明,多元统计分析的估算精度高于一元回归分析。 相似文献
7.
1998～2010年夏季台湾海峡西部沿岸海水遥感透明度的年际变化 总被引：1，自引：0，他引：1
通过比较分析不同的透明度卫星遥感算法,提出将一个基于固有光学特性的、适用于沿岸海域的算法应用于台湾海峡西岸海域,反演获得1998～2010年SeaWiFS遥感透明度时间序列.根据这组时间序列数据,发现该海域夏季透明度低值(<4 m)年份出现在1998、2001和2006年,高值(最高值达到10 m)年份出现在1999、2004和2010年.控制这一年际变动的因素,以目前有限的数据来看,主要是径流与上升流共同引发的水华强度的变化.此外,该海域透明度在研究时段内没有呈现一定的变化趋势,甚至在2006年之后,似乎在持续加深,说明海峡西岸活跃的经济活动,在1998～2010的13 a间,暂时没有对沿岸水质产生显著的破坏性的影响. 相似文献
8.
Average values of inherent optical properties for the 400–700 nm waveband were estimated from quantum irradiance measurements on 27 New Zealand lakes of diverse optical character, using published nomograms. Secchi disc depths, turbidity, algal pigment, non‐volatile suspended solids, and absorption by membrane‐filtered samples at 440 nm (g 440 ) were also measured. Turbidity (NTU) correlated closely with the scattering coefficient (m‐1) and these quantities were almost numerically equal, as found in other studies. The data were found to conform to an expression in the oceanographic literature relating Secchi disc depth to the beam attenuation and diffuse attenuation coefficients. Specific beam attenuation, scattering, and absorption coefficients were estimated from the coefficients of linear multiple regressions of the measured total coefficients on the variables: total pigment (chlorophyll a + phaeopigment), non‐volatile suspended solids, and g 440. The estimated values were in reasonable agreement with similar specific coefficients reported in the oceanographic literature. The coefficients provide a basis for predicting clarity in new impoundments or for predicting the effects of loading changes (e.g., of nutrients) on the clarity of existing lakes. The coefficients can be used for classifying lake waters into different optical types. 相似文献
9.
V. I. Man'kovsky 《Physical Oceanography》2001,11(3):299-304
On the basis of the data of optical investigations performed in the Black Sea, we develop a method for the evaluation of the
spectral values of underwater quantum irradiance within the band of photosynthetically active radiation according to the depth
of visibility of a Secchi disk and the intensity of illumination of the sea in luxes. The method is based on the use of the
correlations between the following optical parameters: of the vertical daylight attenuation factor α with the depth of visibility
of a Secchi disk and of the spectral values of α(λ) within the band of photosynthetically active radiation with α(λmin) for sea waters. This method is applicable in the winter-spring period when the seasonal thermocline is absent, the upper
layers of the sea are mixed, and the vertical distribution of α is uniform.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
10.
Jonathan M. Abell Paul van Dam-Bates Deniz Özkundakci David P. Hamilton 《新西兰海洋与淡水研究杂志》2020,54(4):636-657
ABSTRACT Knowledge of trophic status is fundamental to understanding the condition and function of lake ecosystems. We developed regression models to predict chlorophyll a concentrations (chl a) in New Zealand lakes for reference and current states, based on an existing dataset of total nitrogen (TN) and total phosphorus (TP) concentrations for 1031 lakes. Models were then developed to predict Secchi depth based on chl a and a sediment resuspension term applicable to shallow lakes. Estimates of all four Trophic Level Index (TLI) variables (chl a, TN, TP and Secchi depth) were analysed to estimate reference and current state TLI for the nationally representative sample of 1031 lakes. There was a trend of eutrophication between reference and current states, with systematic differences among lake geomorphic types. Mean chl a increased 3.5-fold (2.42?mg?m?3 vs. 8.32?mg?m?3) and mean Secchi depth decreased (indicating lower clarity) by approximately one-third (9.62?m vs. 6.48?m) between reference and current states. On average, TLI increased by 0.67, with the TLI increase >1 in approximately one-third (31%) of lakes. This study informs the status of lake ecosystems in NZ and provides benchmarks to guide management and assessment. 相似文献
11.
V. I. Mankovsky 《Oceanology》2014,54(1):32-37
A semi-empirical model of the relation between the diffuse attenuation coefficient α↓ and the Secchi depth Z w is suggested. According to the model, the parameter Ψ = α↓Z w is not a constant value; it increases when Z w increases. From experimental observation data, the relationship Ψ = f(Z w) has been established, which confirms the model calculations. 相似文献
12.
We study the space and time variations of the concentration of chlorophyll in the Black-Sea coastal zone (near Katsiveli)
in summer 2001–2002. Typical vertical profiles of the pigments are presented. The relations between the concentration of chlorophyll
and the optical parameters of seawater (including the Secchi depth, sea reflectance, effective wavelength of the upwelling
radiation, and the vertical attenuation coefficient of light) are analyzed. The equations for the biological parameters of
seawater and its optical characteristics are presented.
__________
Translated from Morskoi Gidrofizicheskii Zhurnal, No. 3, pp. 36–51, May–June, 2006. 相似文献
13.
Hydrooptical investigations were performed for three subsatellite test ranges located near the Rhodes Island in the Levant Sea, near Dardanelles in the north part of the Aegean Sea, and near the Crimean Peninsula in the northwest part of the Black Sea. In the course of observations, we measured the beam attenuation coefficient, the depth of visibility of the Secchi disk, and the color of water. These data are used to characterize the space and time variability of the optical properties of water in the investigated regions. 相似文献
14.
15.
A preliminary optical classification of lakes in Estonia and south Finland which can also be used for small bays of the Baltic Sea is elaborated. The classification is based on the optical properties of water (diffuse attenuation coefficient, diffuse reflectance) and parameters that are routinely monitored in water bodies (Secchi depth, concentration of chlorophyll-a, total suspended matter and yellow substance). The data complex used for our classification covers different types of water ecosystems (ranging from oligotrophic to hypertrophic) and the variability of water constituent concentrations in the ice-free period in Estonia and south Finland. Using cluster analysis, we found 5 optical classes of waters: clear (C), moderate (M), turbid (T), very turbid (V) and brown (B). There is satisfactory correspondence between class of water, shape of diffuse attenuation coefficient and diffuse reflectance spectra and trophic state of the lakes. 相似文献
16.
17.
V. I. Man’kovsky 《Physical Oceanography》2001,11(5):491-494
We present the parameters of empirical relationships between the depth of visibility of Secchi disk and optical and biological
characteristics of the Black-Sea surface waters.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
18.
水体透明度(Secchi Disk depth,SDD)是水环境监测的重要参数,遥感技术对于监测水体透明度具有重要的应用前景。本文旨在分类和比较当前用于监测水体透明度的算法,并提出未来研究的方向,以推动水环境监测技术的进一步发展。文章对目前检索水体透明度的算法进行分类和比较。其中,经验算法、半分析算法和机器学习算法是目前研究的主要方向。通过分析算法特性和优缺点,提出未来研究的重点和方向。经验算法基于透明度与光谱数据、叶绿素a浓度等的相关性,半分析算法基于水下能见度理论,机器学习算法则基于更优的数据特征学习能力。不同算法具有各自的适用范围和限制。未来的研究应该着重于整合多源遥感数据,改进QAA (quasi-analytical-algorithm),深入分析光学参数与水体透明度的关系,将机器学习算法应用到水体透明度模型的建立中,以建立具有高精度、适用性广的反演模型。 相似文献
19.
黄海、东海二类水体漫衰减系数与透明度反演模式研究 总被引：25，自引：0，他引：25
黄海、东海是典型的二类水体区域,总悬浮物含量高,水体光学特性复杂.利用2003年春秋季黄海、东海水色联合试验中获取的高质量现场实测数据,建立了由遥感反射比反演水体在490nm波段的漫衰减系数和海水透明度的统计反演模式.这两种模式皆采用490,555,670nm三个波段的组合,漫衰减系数的反演值和实测值的相关系数为0.96,平均相对误差为17.2%;透明度的反演值与实测值的相关系数为0.95,平均相对误差为16.8%.对两种反演模式对遥感反射比输入误差的敏感性进行了分析,结果表明反演模式对±5%的遥感反射比输入误差导致490nm波段的漫衰减系数反演误差最大为27.3%,透明度最大误差为22.7%,并利用2003年春秋季同一海区的实测数据对模型进行了检验,漫衰减系数的平均相对误差为25.0%,透明度的为16.5%.给出了412,443,510,520,555,565nm各波段的漫衰减系数同波段490nm的漫衰减系数之间的关系,结果表明,在400~600nm波段中的每一个波段的漫衰减系数与490nm波段的漫衰减系数的相关性较高,相关系数都超过了0.98.这样利用建立的各波段漫衰减系数关系模型可以从一个已知波段的漫衰减系数反演出其他任何波段的漫衰减系数,这就在水色反演和应用中大大减少了未知因子的个数. 相似文献
20.
Wave interaction with partially immersed twin vertical barriers 总被引：3，自引：0，他引：3
The wave transmission, reflection and energy dissipation characteristics of partially immersed twin vertical barriers and the water surface fluctuations in between the barriers were studied using physical models. Regular and random waves of wide ranges of wave heights and periods, nine different immersions of the barriers and a constant water depth were used for the investigation. The coefficient of transmission, and the coefficient of reflection were obtained from the measurements and coefficient of energy dissipation is estimated using the law of conservation of energy. It is found in general that the twin barrier is better in reducing the coefficient of transmission and increasing the coefficient of dissipation in random waves than with the regular waves, especially for increasing incident wave energy levels. The coefficient of transmission reduces significantly with the increased relative water depth. Increase of relative water depth from 0.09 to 0.45 resulted in reduction of transmission coefficient from 0.65 to 0.05. It is possible to achieve a transmission coefficient less than 0.20 for six immersion configurations with relative depth of immersions of the barrier less than (0.28, 0.43), especially in the region closer to deep water conditions. Coefficient of dissipation ranging from 0.65 to 0.85 can be obtained due to random wave interaction. 相似文献