Double Beam Spectrophotometer for Simultaneous Measurements of the Upwelling Sea Radiance and the Incident See Irradiance

2019 ◽  
pp. 105-110
Author(s):  
Mikhail Yongon Lee ◽  
Sergei V. Fedorov
Keyword(s):  
Spectral Characteristics ◽  
Sea Surface ◽  
Input Port ◽  
Silicon Photodiode ◽  
New Approach ◽  
Surface Irradiance ◽  
Simultaneous Measurements ◽  
Double Beam

The article describes the structure and the operation principle of the spectrophotometer developed on the basis of a compact rapid monochromator with one input port and two output ports and a radiometric unit where upwelling radiation radiance and sea surface irradiance channels are located. A new approach to measurements of spectral characteristics of upwelling radiation of sea based on combination of advantages of a double beam photometer with a photomultiplier and a directreading photometer with a highstability silicon photodiode for its absolute adjustment in energy units is implemented.

scholarly journals Spectral characteristics of Atlantic seasonal storm frequency

MAUSAM ◽  
2021 ◽  
Vol 57 (4) ◽  
pp. 597-608
Author(s):  
R. P. KANE
Keyword(s):  
Time Series ◽  
Maximum Entropy Method ◽  
Southern Oscillation ◽  
Spectral Characteristics ◽  
Entropy Method ◽  
Sea Surface ◽  
Low Latitude ◽  
Storm Activity ◽  
Oscillation Phenomenon ◽  
Storm Frequency

lkj & o"kZ 1900&2000 dh vof/k esa vVykafVd egklkxj dh rwQkuh xfrfof/k ¼ftUgas rwQku] izpaM rwQku] vkfn uke fn, x, gaS½ ds fofHkUu lwpdkadksa ds dky Jsf.k;ksa dk vuqØe fo’ys"k.k ,e-b-,e-¼vf/kdre ,uVªkWih fof/k½ }kjk rFkk mldh vkofrZrk ds vk;ke ,e- vkj- ,- ¼cgqq lekJ;.k fo’ys"k.k½ }kjk izkIr fd, x, gaSA fiNys dqN o"kksZa ds vkadM+ksa ¼o"kZ 1950 ls vkxss½ ds vuqlkj budh egRoiw.kZ vkofrZrk,¡ n’kd lfgr( f}okf"kZd dYi] f=okf"kZd dYi {ks=ksa rFkk buls mPp {ks=ksa esa Hkh jghA 2-40 o"kkasZ esa 50 feyhckj ds fuEu v{kka’k {ks=h; iou vkSj 2-40 ,oa 2-85 o"kkasZ ds b- ,u- ,l- vks- ¼,y uhuks/nf{k.kh nksyu½ ?kVuk ds ln`’k f}o"khZ dYi nksyu {ks= esa ¼3&4 o"kkasZ½ rwQku lwpdkad 2-40 rFkk 2-85 o"kksZa ds djhc pje ij jgsA mPp vkofrZrk okys {ks=ksa esa rwQku lwpdkad 4-5&5-5-] 8&9] 11&12 rFkk 14&15 o"kkasZ esa pje ij jgs tcfd b- ,u- ,l- vks- 7-4 ,oa 12&14 o"kksZa esa pje ij jgsA cgq n’kdh; Js.kh esa 28&34]40]50&53]61&63]~70 ,oa ~80 o"kksZa esa ¼ijUrq fHkUu lwpdkadksa ds fy, fHkUu&fHkUu½ rwQku pje ij jgs tks LFky ,oa leqnzh lrg ds rkiekuksa ds leku pje ekuksa ds vuq:Ik jgsA dqy lwpdkadksa esa 90 o"kkZsa esa yxHkx 50 izfr’kr dh m/oZ izo`fr jghA     The time series of the various indices of Atlantic storm activity (number of named storms, hurricanes, etc.) for 1900-2000 were subjected to spectral analysis by MEM (Maximum Entropy Method) and amplitudes of the periodicities were obtained by MRA (Multiple Regression Analysis).  For recent data (1950 onwards), significant periodicities were in the quasi-biennial, quasi-triennial regions and also in higher regions, including decadal. In the QBO region (2-3 years), storm indices had peaks near 2.40 and 2.85 years, similar to 2.40 years of 50 hPa low latitude zonal wind and 2.40 and 2.85 years of ENSO (El Niño/Southern Oscillation) phenomenon. In the QTO region (3-4 years), storm indices and ENSO had common peaks near 3.5 years. In higher periodicity regions, storm indices had peaks at 4.5-5.5, 8-9, 11-12 and 14-15 years, while ENSO had peaks at 7.4 and 12-14 years. In the multi-decadal range, storm peaks were at 28-34, 40, 50-53, 61-63, ~70 and ~80 years (but different for different indices), which matched with similar peaks in land and sea surface temperatures. Some indices had large uptrends, ~50% in 90 years.

A New Model for Long-Term Stochastic Analysis and Prediction—Part I: Theoretical Background

1992 ◽  
Vol 36 (01) ◽  
pp. 1-16
Author(s):  
G. A. Athanassoulis ◽  
P. B. Vranas ◽  
T. H. Soukissian
Keyword(s):  
Time Scale ◽  
Random Function ◽  
Spectral Characteristics ◽  
Time History ◽  
Time Variable ◽  
Sea Surface ◽  
Surface Elevation ◽  
Fast Time ◽  
Slow Time

A new approach for calculating the long-term statistics of sea waves is proposed. A rational long-term stochastic model is introduced which recognizes that the wave climate at a given site in the ocean consists of a random succession of individual sea states, each sea state possessing its own duration and intensity. This model treats the sea-surface elevation as a random function of a "fast" time variable, and the time history of the spectral characteristics of the successive sea states as a random function of a "slow" time variable. By developing an appropriate conceptual framework, it becomes possible to express various probabilistic characteristics of the sea-surface elevation, which are sensible only in the fast-time scale, in terms of the statistics of sea-states duration and intensity, which is meaningful only in the slow-time scale. As an example, we study the random quantity MU(T) = "number of maxima of the sea-surface elevation lying above the level u and occurring during a long-term time period [0,T]." Exploiting the proposed framework, it is shown that, under certain clearly defined assumptions, Mu(T) can be given the structure of a renewal-reward (cumulative) process, whose interarrival times correspond to the duration of successive sea states. Thus, using renewal theory, the complete characterization of the probability structure of MU(T) is obtained. As a consequence, the long-term probability distribution function of the individual wave height is rigorously defined and calculated. The relation of the present results with corresponding ones previously obtained is thoroughly discussed. The proposed model can be extended twofold: either by replacing some of the simplifying assumptions by more realistic ones, or by extending the model for treating the corresponding problems for ship and structures responses.

scholarly journals Derivation of Three-Dimensional Radiation Stress Based on Lagrangian Solutions of Progressive Waves

2017 ◽  
Vol 47 (11) ◽  
pp. 2829-2842 ◽  
Author(s):  
Chao Ji ◽  
Qinghe Zhang ◽  
Yongsheng Wu
Keyword(s):  
Coordinate Transformation ◽  
Atmospheric Pressure ◽  
Three Dimensional ◽  
Sea Surface ◽  
Lagrangian Description ◽  
Radiation Stress ◽  
New Approach ◽  
Progressive Waves ◽  
Analytical Expressions ◽  
Sloping Bottom

AbstractA new approach has been proposed to derive the expressions for three-dimensional radiation stress using solutions of the pressure and velocity distributions and the coordinate transformation function that are derived from a Lagrangian description wherein the pressure is zero (relative to the atmospheric pressure) at the sea surface. Using this approach, analytical expressions of horizontal and vertical depth-dependent radiation stress are derived at a uniform depth and for a sloping bottom, respectively. The results of the depth integration of the expressions agree well with the theory of Longuet-Higgins and Stewart. In the case involving a sloping bottom, the radiation stress expressions from this study provide a better balance of the net momentum compared to those from previous studies.

Simultaneous measurements of sea surface temperature by GMS-1 and GMS-2

1983 ◽  
Vol 2 (6) ◽  
pp. 165-172 ◽  
Author(s):  
Y. Takayama ◽  
T. Takashima ◽  
K. Matsuura ◽  
K. Naito
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Simultaneous Measurements

scholarly journals Detection of Multi-pixel Low Contrast Object on a Real Sea Surface

2021 ◽  
Author(s):  
Victor Golikov ◽  
Oleg Samovarov ◽  
Daria Chernomorets ◽  
Marco Rodriguez-Blanco
Keyword(s):  
Spectral Characteristics ◽  
False Alarm Probability ◽  
Sea Surface ◽  
Statistical Characteristics ◽  
Statistical Parameters ◽  
Low Contrast ◽  
Video Images ◽  
Floating Object ◽  
The Difference ◽  
Floating Objects

The video images captured at long range usually have low contrast floating objects of interest on a sea surface. A comparative experimental study of the statistical characteristics of reflections from floating objects and from the agitated sea surface showed the difference in the correlation and spectral characteristics of these reflections. The functioning of the recently proposed modified matched subspace detector (MMSD) is based on the separation of the observed data spectrum on two subspaces: relatively low and relatively high frequencies. In the literature the MMSD performance has been evaluated in generally and moreover using only a sea model (additive Gaussian background clutter). This paper extends the performance evaluating methodology for low contrast object detection and moreover using only the real sea dataset. This methodology assumes an object of low contrast if the mean and variance of the object and the surrounding background are the same. The paper assumes that the energy spectrum of the object and the sea are different. The paper investigates a scenario in which an artificially created model of a floating object with specified statistical parameters is placed on the surface of a real sea image. The paper compares the efficiency of the classical Matched Subspace Detector (MSD) and MMSD for detecting low-contrast objects on the sea surface. The article analyzes the dependence of the detection probability at a fixed false alarm probability on the difference between the statistical means and variances of a floating object and the surrounding sea.

Simultaneous Measurements of Stress and Infrared Dichroism on Polymers I. Stress Relaxation of Vulcanized Natural Rubber

1967 ◽  
Vol 40 (2) ◽  
pp. 663-672
Author(s):  
Rempei Gotoh ◽  
Tohru Takenaka ◽  
Naomi Hayama
Keyword(s):  
Stress Relaxation ◽  
Absorption Band ◽  
Natural Rubber ◽  
Reference Beam ◽  
Simple Relationship ◽  
Absorption Bands ◽  
Simultaneous Measurements ◽  
Double Beam ◽  
The Difference ◽  
Infrared Dichroism

Abstract A method for simultaneous measurements of stress and infrared dichroism as time-dependent behavior of polymer films was devised using a double beam infrared spectrometer. The film sample held between clamps of a stretching device was placed just in front of the entrance slit of the spectrometer where the sample and reference beams came alternately. Two polarizers were used, one in the sample beam and the other in the reference beam. Thus the sample and reference beams were polarized to have the electric vectors parallel and perpendicular to the stretching direction of the sample, respectively. With this arrangement the spectrometer responded only to the difference in the transmittance of the two beams. Setting the spectrometer at one of the wavenumbers of the absorption band maxima, we could record continuously the change in its dichroism during mechanical treatments which gave rise to molecular orientation in the sample. The stress was recorded automatically by means of a pair of strain gauges pasted on the cantilever beam of the stretching device. By theoretical considerations, a simple relationship was found to exist between the quantity recorded on the spectrometer by this method and the orientation function of transition moment of a vibrational absorption band with respect to the stretching direction. The method was applied to the stress relaxation experiments of vulcanized natural rubber carried out at different elongations less than 600 per cent and at room temperature. Changes of infrared dichroism were measured for five absorption bands at 1664, 1380, 1361, 1129, and 844 cm−1, of which the last one is a crystalline band. From the results of this study, the stress relaxation observed was ascribed mainly to the amorphous orientation rather than to the crystalline orientation, which was completed almost immediately after elongation.

Fluctuations of a Fortnightly Abundance Index of the Ivoirian Coastal Pelagic Species and Associated Environmental Conditions

1987 ◽  
Vol 44 (2) ◽  
pp. 408-421 ◽  
Author(s):  
Roy Mendelssohn ◽  
Philippe Cury
Keyword(s):  
Time Series ◽  
Environmental Conditions ◽  
Ivory Coast ◽  
Missing Values ◽  
Multivariate Time Series ◽  
Sea Surface ◽  
New Approach ◽  
Pelagic Species ◽  
Biological Interpretation ◽  
Analyze Time Series

In this paper we analyze time series of catch per unit of effort (CPUE) from 1966 to 1982 of small pelagic species off the Ivory Coast using sea surface temperature (SST) collected by merchant ships. A fill-in model is used to estimate missing values of CPUE and SST in the areas in which the fishery operates. A multivariate time series model of the fortnightly data is able to explain 43% of the observed variance in CPUE from 1966 to 1982. A model estimated by using only the data from 1966 to 1980 produced reasonable forecasts of the fortnightly CPUE for 1981–82. A new approach for estimating optimal transformations of variables in the model is used to examine the form of the relationships between CPUE and its predictors. The biological interpretation of the estimated transformations is consistent with previous results on the dynamics of zooplankton in the same area.

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