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Characteristics of the Diffuse Attenuation Coefficient and Its Impact on Aquatic Ecology Environment

HUANG Chang-chun,LI Yun-mei,SUN De-yong,LE Cheng-feng,WU Lan,WANG Li-zhen,WANG Xing,

环境科学 , 2009,
Abstract: According to the optical property data measured in Taihu Lake at October and November 2006,the characteristics of the diffuse attenuation coefficient(K_d),the contribution of each factor effecting on K_d and the effect of K_d on the aquatic ecology environment were analyzed.The results indicate that,the diffuse attenuation coefficient K_d of Taihu Lake has two main trends in the whole visible wavelength range(400-700 nm).The first type is that,K_d decreases with the wavelengths by exponential style in the r...
Determination of the Attenuation Coefficient of Surface Acoustic Wave by Means of the Light Interference

光子学报 , 2005,
Abstract: A practicable method for liquid-surface acoustic-wave at the frequencies of a few tens Hertz, based on the combination of optical interference and scanning wave slope, has been developed. Moreover, this technique was used to determine the attenuation coefficient of the surface wave at these frequencies in real time.
On the attenuation coefficient of monomode periodic waveguides  [PDF]
Alexandre Baron,Simon Mazoyer,Wojciech Smigaj,Philippe Lalanne
Physics , 2011, DOI: 10.1103/PhysRevLett.107.153901
Abstract: It is widely accepted that, on ensemble average, the transmission T of guided modes decays exponentially with the waveguide length L due to small imperfections, leading to the important figure of merit defined as the attenuation-rate coefficient alpha = -/L. In this letter, we evidence that the exponential-damping law is not valid in general for periodic monomode waveguides, especially as the group velocity decreases. This result that contradicts common beliefs and experimental practices aiming at measuring alpha is supported by a theoretical study of light transport in the limit of very small imperfections, and by numerical results obtained for two waveguide geometries that offer contrasted damping behaviours.
Scanning Lidar Based Atmospheric Monitoring for Fluorescent Detectors of Cosmic Showers  [PDF]
A. Filipcic,M. Horvat,D. Veberic,D. Zavrtanik,M. Zavrtanik
Physics , 2002, DOI: 10.1016/S0927-6505(02)00162-7
Abstract: Measurements of the cosmic-ray air-shower fluorescence at extreme energies require precise knowledge of atmospheric conditions. The absolute calibration of the cosmic-ray energy depends on the absorption of fluorescence light between its origin and point of its detection. To reconstruct basic atmospheric parameters we review a novel analysis method based on two- and multi-angle measurements performed by the scanning backscatter lidar system. Applied inversion methods, optical depth, absorption and backscatter coefficient, as well as other parameters that enter the lidar equation are discussed in connection to the attenuation of the light traveling from shower to fluorescence detector.
The atmospheric transparency measured with a LIDAR system at the Telescope Array experiment  [PDF]
Takayuki Tomida,Yusuke Tsuyuguchi,Takahito Arai,Takuya Benno,Michiyuki Chikawa,Koji Doura,Masaki Fukushima,Kazunori Hiyama,Ken Honda,Daisuke Ikeda,John N. Matthews,Toru Nakamura,Daisuke Oku,Hiroyuki Sagawa,Hisao Tokuno,Yuichiro Tameda,Gordon B. Thomson,Yoshiki Tsunesada,Shigeharu Udo,Hisashi Ukai
Physics , 2011, DOI: 10.1016/j.nima.2011.07.012
Abstract: An atmospheric transparency was measured using a LIDAR with a pulsed UV laser (355nm) at the observation site of Telescope Array in Utah, USA. The measurement at night for two years in $2007\sim 2009$ revealed that the extinction coefficient by aerosol at the ground level is $0.033^{+0.016}_{-0.012} \rm km^{-1}$ and the vertical aerosol optical depth at 5km above the ground is $0.035^{+0.019}_{-0.013}$. A model of the altitudinal aerosol distribution was built based on these measurements for the analysis of atmospheric attenuation of the fluorescence light generated by ultra high energy cosmic rays.
Seasonal Variation of the Aerosol Light Scattering Coefficient in Marine Air of the Northeast Atlantic  [PDF]
Aditya Vaishya,S. G. Jennings,Colin O'Dowd
Advances in Meteorology , 2011, DOI: 10.1155/2011/170490
Abstract: Aerosol light scattering measurements were carried out using a TSI 3563 Nephelometer at the Mace Head Atmospheric Research Station, on the west coast of Ireland from year 2001–2010. A strong seasonal trend in the aerosol light scattering coefficient at 550?nm ( ), for clean marine air masses, is observed with a high value, [average (geometric mean)] of 35.3?Mm?1 (29.5?Mm?1), in January and a low value of 13.7?Mm?1 (10.2?Mm?1), in July. This near threefold increase in the value during the winter season is because of the large contribution of wind-speed generated sea-salt particles in the marine boundary layer. A high positive correlation coefficient of 0.82 was found between the percentage occurrence of relatively large ?ngstr?m exponent (?) values (>1.2) and the percentage occurrence of lower values (5–15?Mm?1) in the summer season. and wind-speed have a high positive correlation coefficient of 0.88 whereas ? and wind-speed have a negative correlation coefficient of ?0.89. ? values during the summer months indicate the dominance of sub- m particles thus indicating the contribution of non-sea-salt sulphate and organics towards the as these species show an enhanced concentration during the summer months. 1. Introduction Knowledge of the light scattering properties of atmospheric aerosol particles is of vital importance in estimating the radiative forcing of climate and in global radiation budget studies. Uncertainties in the global aerosol direct and indirect effects are nearly the same or twice as much as the magnitude of the effect itself as estimated by the Intergovernmental Panel on Climate Change (IPCC) in its 4th assessment report [1]. Several-long term measurements of key aerosol properties (e.g., aerosol light scattering and aerosol light absorption coefficient, condensation nuclei number concentration, etc.) at various measurement stations across the globe, for example [2–6], have been reported. Such long-term measurements of key aerosol properties at worldwide locations will be effective in reducing the uncertainties associated with aerosol direct and indirect effects. The aerosol light scattering coefficient, an extensive optical property, can yield crucial information about the aerosol size distribution and composition if its wavelength dependence from which the ?ngstr?m exponent—an intensive optical property (independent of particle number concentration) is derived [7]. In the marine environment, the main constituent of aerosol particles is wind speed-generated sea salt [8, 9]. Non-sea salt (nss) sulphate and organics also can dominate the
A Simple Method of Determining the Effective Attenuation Coefficient
Grzegorz Domański , Bogumi Konarzewski , Zdzis aw Paw owski , Krzysztof Zaremba , Janusz Marzec , Artur Trybu a , Robert Kurjata
Polish Journal of Medical Physics And Engineering , 2007, DOI: 10.2478/v10013-007-0001-x
Abstract: This paper presents a simple method of determining the effective attenuation coefficient from steady-state diffuse reflectance measurements.
Light Attenuation at Molasses Reef
Ashley Earls
Undergraduate Journal of Mathematical Modeling : One + Two , 2010, DOI: 10.5038/2326-3652.3.1.20
Abstract: Estimating the amount of light available at different depths of the ocean is important for gaining a better understanding of coral reefs. It is especially useful to be able to get such estimates without having to perform direct measurements. Although accurate, the direct measurements are costly, time consuming, and usually limited to relatively small areas of interest. One statistic that could be useful for estimating the amount of available light is the rate at which it declines with depth (the rate of light attenuation). In this project, this rate is calculated for four different wavelengths using data for 30m water column profile collected in upper Florida Keys. The rate of light attenuation is calculated for the entire profile as well as the intervals corresponding to 5m increments.
Density on Measurement of Beam Attenuation in Ship Wakes

SUN Chun-sheng,ZHANG Xiao-hui,ZHU Dong-hua,

光子学报 , 2009,
Abstract: To measure the beam attenuation in ship wakes accurately and improve the reliability of detecting ship wakes by forward light attenuation,the influence of bubbles′ number density on the measurement of beam attenuation in wakes was investigated.The scattered power and un-scattered power on the detector cross-section were derived based on radiative transfer equation in small angle approximation.According to the measurement condition,transmission function,which is the ratio of the received power by detector in wakes to the received power by detector in non-wakes marine environment,was introduced.Correction coefficient,denoting the extent of multiple scattering,was further introduced.Given a typical bubble distribution in wakes,the numerical results relating the transmission function and correction coefficient to bubbles′ number density under different measuring conditions were presented.The numerical results show that,the correction coefficient increases monotonously but the transmission function decreases monotonously as the bubbles′ number density increases|the influence of bubbles′ number density on beam attenuation is different as the measurement conditions change.The results show that,given a measurement condition and transmission function,the bubbles′ number density can be quantified by means of radiative transfer equation in small angle approximation.
Extragalactic Background Light and Gamma-Ray Attenuation  [PDF]
Joel R. Primack,Alberto Dominguez,Rudy C. Gilmore,Rachel S. Somerville
Physics , 2011, DOI: 10.1063/1.3635825
Abstract: Data from (non-) attenuation of gamma rays from active galactic nuclei (AGN) and gamma ray bursts (GRBs) give upper limits on the extragalactic background light (EBL) from the UV to the mid-IR that are only a little above the lower limits from observed galaxies. These upper limits now rule out some EBL models and purported observations, with improved data likely to provide even stronger constraints. We present EBL calculations both based on multiwavelength observations of thousands of galaxies and also based on semi-analytic models, and show that they are consistent with these lower limits from observed galaxies and with the gamma-ray upper limit constraints. Such comparisons "close the loop" on cosmological galaxy formation models, since they account for all the light, including that from galaxies too faint to see. We compare our results with those of other recent works, and discuss the implications of these new EBL calculations for gamma ray attenuation. Catching a few GRBs with groundbased atmospheric Cherenkov Telescope (ACT) arrays or water Cherenkov detectors could provide important new constraints on the high-redshift star formation history of the universe.
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