共查询到20条相似文献，搜索用时 62 毫秒
1.
V. A. Korshunov 《Izvestiya Atmospheric and Oceanic Physics》2007,43(5):618-633
A scheme of interpreting the data of two-wavelength lidar sounding is proposed. The scheme is based on functional relationships between the lidar ratios and between some integral characteristics of aerosol and the ratio of the backscattering coefficients at the sounding wavelengths. The AERONET data, results of contact aerosol measurements and multiwavelength lidar sounding, and the OPAC aerosol model are used to find these functional relationships, which are statistical in character. Analysis of data is made separately for continental, dust, oceanic, and smoke aerosols. Backscattering for mineral aerosol fractions are calculated for a model of randomly oriented spheroids. A numerical experiment shows that the errors in determining a number of integral parameters of aerosol (extinction coefficient, characteristic radius of particles, volume concentrations) that are due to the statistical straggling of lidar ratios and other specified integral characteristics are no greater than 32% if the optical thickness of the sounding layer is no greater than 1. 相似文献
2.
A method for reconstructing the parameters of postvolcanic stratospheric aerosol from the results of joint measurements of the aerosol backscattering coefficient with lidar systems based on the Nd:YAG laser and the aerosol extinction coefficient with the SAGE III satellite instrumentation is developed. The most informative set of optical characteristics is determined for each of the microphysical parameters under consideration (concentration, surface area, volume, and effective size of particles of the fine and coarse aerosol fractions). Multiple polynomial regressions between optical and microphysical characteristics of aerosol are obtained. These regressions make it possible to determine the microphysical characteristics of aerosol within a wide range without solving incorrect inverse problems. The results are compared with independent experimental data. The errors of reconstructing microphysical parameters of aerosol are estimated for different situations in the stratosphere. The influence of the shape of particles of the dust fraction on the results of a reconstruction of the microphysical parameters of aerosol is considered. 相似文献
3.
Mitsuhiro Toratani Hajime Fukushima Hiroshi Murakami Akihiko Tanaka 《Journal of Oceanography》2007,63(3):525-532
The present study proposes an atmospheric correction scheme for Advanced Earth Observation Satellite II (ADEOS-II)/Global
Imager (GLI) ocean color retrieval that corrects for the atmospheric absorptive aerosol effect. Radiative transfer simulations
were conducted assuming a non-absorptive model aerosol with a soot-type aerosol at various mixture ratios. The results indicate
that while the spectral dependency of aerosol reflectance does not change in the longer (>550 nm) wavelength region, the reflectance
at shorter wavelengths is highly variable and depends on the mixture ratio. The influence of aerosol absorption was also investigated
using GLI data from ocean areas adjacent to Japan in the presence of absorptive Siberian fire smoke aerosol in the spring
of 2003. The spectral curvature of the aerosol was estimated from the data obtained. An empirical, iterative scheme that detects
and evaluates the influence of absorptive aerosols was developed by comparing 380 nm GLI-observed aerosol reflectance with
predicted reflectances derived using an in-water optical model. To evaluate the performance of this scheme, satellite-derived
normalized water-leaving radiances were compared with those measured from a ferry servicing Nagasaki and Fukue. The results
of data acquired on March 20, 2003, indicate that this absorption correction scheme improved root mean square estimation error
for normalized water-leaving radiance by approximately 40% in the 380, 400, and 412 nm bands. This atmospheric correction
algorithm was used as a part of the second version of the GLI standard ocean color data process system at Japan Aerospace
Exploration Agency (JAXA). 相似文献
4.
利用Nd:YAG纳秒激光(波长为532和355 nm)对单晶硅在真空中进行了累积脉冲辐照,研究了表面微结构的演化情况.在激光辐照的初始阶段,532和355 nm激光脉冲均在硅表面诱导出了波纹结构,后者辐照硅表面后形成了近似同心但稍显混乱的环形波纹结构.随着脉冲数的增加,波纹结构逐渐演化为一种类似珠形的凹凸结构,最后形成准规则排列的微米量级锥形结构,该微结构的生长依赖于表面张力波和结构自组织.分析发现,形成的交叉环形结构主要是在355 nm激光辐照硅的过程中,表面张力波导致波纹结构部分叠加的结果. 相似文献
5.
G. I. Gorchakov A. V. Karpov N. V. Pankratova E. G. Semoutnikova A. V. Vasiliev I. A. Gorchakova 《Izvestiya Atmospheric and Oceanic Physics》2017,53(9):875-884
We have investigated the variability of smoke aerosol absorbing ability with variations in the content of brown carbon (BrC) and black carbon (BC). Using monitoring data on radiative characteristics of smoke aerosol at AERONET stations and the spatial distribution of aerosol optical depth (AOD) obtained by the MODIS spectrometer (Terra satellite), we have detected large-scale smokes during boreal forest fires in Russia and Canada (1995–2012). The spatial distribution (50°–70° N, 95°–125° W) and temporal variability (at AERONET station Fort McMurray) of AOD during the smoking of a part of Canada in July 2012 have been analyzed. AOD probability distributions for July 14–18, 2012, and an estimate of aerosol radiative forcing of smoke aerosol at the upper boundary of the atmosphere have been obtained. We have proposed a technique for the diagnostics of BrC and BC in smoke aerosol particles from the spectral dependence of the imaginary part of the refractive index. At a wavelength of 440 nm, the contributions of BrC and BC to the smokeaerosol absorbing abitity can be comparable in magnitude. In many cases, the absorption spectra of smoke aerosol can be adequately approximated by either power or exponential functions. The presence of BrC in smoke-aerosol particles highly extends the variety of observed absorption spectra in a smoky atmosphere and spectral dependences of single scattering albedo. In the spectral range of 440–1020 nm, the radiative characteristics of smoke aerosol are largely contributed by its fine mode. 相似文献
6.
O. A. Bukin K. A. Shmirko A. Yu. Maior A. N. Pavlov S. Yu. Stolyarchuk G. I. Kornienko D. V. Erofeev 《Izvestiya Atmospheric and Oceanic Physics》2010,46(2):178-183
The distribution functions of atmospheric aerosol obtained on the basis of lidar sounding and photometric measurements over
marine water areas in continental and transition zones are analyzed. Changes in the microphysical parameters of the distribution
function in the continent-ocean transition zone with height are considered on the basis of data taken from three-frequency
lidar sounding. Specific features of changes in the particle size distribution with height during intense dust storms and
records of volcanogenic aerosol in the tropopause region in the summer of 2008 are described. 相似文献
7.
发展机载激光荧光雷达系统测量叶绿素a的浓度,模拟了采用三倍频355 nm波长激光作为激发光,机载海洋激光荧光雷达在不同飞行高度和测量不同深度水层的情况下,测量海表叶绿素a浓度的相对误差。依据模拟的参数建立机载激光荧光雷达系统并进行初步机载实验,获得了同经验数据较为一致的测量结果。 相似文献
8.
以渤海海域为试验区,对经过时间、空间和波段匹配的 MODIS/Aqua 550 nm 气溶胶光学厚度产品与 CALIOP 532 nm 通道反演得到的气溶胶信息在五种不同空间采样窗口(10 km ×10 km,30 km ×30 km,50 km ×50 km,70 km ×70 km 和90 km ×90 km)、三种不同时间尺度(日、月、季度)下进行了相关性拟合分析.研究发现,较小的空间采样窗口可以更准确地反映气溶胶的局部变化特征,而以季度为时间统计单元能更好地体现气溶胶的季节变化特性.实验结果表明,在10 km ×10 km 采样窗口中,春季的日数据之间相关性较高;春季和秋季的月均值之间高度相关(R 均大于0.950).从而证明,在特定时间和空间尺度下,上述两种数据之间确存在良好的相关性,为利用遥感数据反演渤海海域气溶胶光学厚度信息提供了新的途径. 相似文献
9.
黄海、东海海区水体散射特性研究 总被引：32，自引：0，他引：32
半分析模型是水色遥感反演算法的研究热点,而水体后向散射系数对建立半分析水色反演模型是非常重要的参数.通过对黄海、东海海区的水体固有光学量测量数据进行分析,得到水体总后向散射系数与水体总散射系数的关系为乘幂关系,颗粒物后向散射系数随光谱变化的指数在高低浑浊度水体有很大差异,并初步得到黄海、东海海区水体的后向散射系数与总悬浮物浓度的关系,从而为水色半分析模型建立和水光学辐射计算提供一组散射特性模型. 相似文献
10.
Ya. A. Virolainen Yu. M. Timofeev A. V. Polyakov H. Steele M. Newchurch 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):752-764
A statistical ensemble of microphysical parameters of the background stratospheric aerosol at altitudes of 15 to 30 km is modeled on the basis of experimental data. The aerosol attenuation coefficients (AACs) in the wavelength range 0.38–16.3 μm are calculated for all realizations of the ensemble by algorithms of the Mie theory. Analysis of correlations between the AACs and the microphysical parameters indicate that the AAC correlates most strongly with the total volume V and area S of all particles. The errors of determining the microphysical parameters from AAC measurements are analyzed via the method of linear regression. It is shown that, if the AAC is measured with an error of 5%, the errors of determining both the particle size distribution (PSD) for particles with sizes of 0.4 to 4 μm and the parameter S are an order of magnitude smaller than the prior uncertainty, whereas the error of determining V is two orders of magnitude smaller than the prior uncertainty. Schemes of AAC measurements with the SAGE III, ISAMS, CLAES, HALOE instruments and an IR interferometer in the visible and IR regions are discussed. It is shown that combining the schemes makes it possible to extend the range of particle sizes for which the PSD is retrieved with a satisfactory accuracy and to increase the accuracy of determining S and V substantially and the accuracy of determining the total number of particles N opt to a lesser extent. Examples of interpreting AAC measurements carried out simultaneously with the SAGE III and HALOE instruments within the same spatial region are presented. A systematic discrepancy between vertical profiles of S and V obtained from SAGE III and HALOE measurements is revealed. 相似文献
11.
V. V. Bychkov A. S. Perezhogin B. M. Shevtsov V. N. Marichev P. V. Novikov A. A. Cheremisin 《Izvestiya Atmospheric and Oceanic Physics》2011,47(5):603-609
The behavior of the vertical aerosol structure (profiles of the ratio of the coefficients of the backward total and molecular scattering) in the height interval 30–80 km is analyzed from the results of lidar observations in Kamchatka over the period from October 2007 through December 2009. The obtained data revealed a regular two-layer aerosol structure in this height range with the maxima of the ratio of the scattering coefficients in the upper stratosphere at heights 35–50 km and in the mesosphere at heights of 60–75 km, as well as a relation between seasonal variations in the aerosol stratification and the circumpolar vortex affecting dynamic processes in the atmosphere of midlatitudes. The procedure of including the aftereffect of the Hamamatsu-M8259-01 PEM, which influences the error in the calculation of the ratio of scattering coefficients, is described. 相似文献
12.
I. A. Gorchakova T. A. Tarasova M. A. Sviridenkov P. P. Anikin E. V. Romashova 《Izvestiya Atmospheric and Oceanic Physics》2009,45(4):467-477
The solar radiation flux incident on the land surface and aerosol radiative forcing are calculated from measurements carried
out under clear skies during the summers of 2004 and 2005 at the Zvenigorod Scientific Station (ZSS) of the A.M. Obukhov Institute
of Atmospheric Physics, Russian Academy of Sciences. In these calculations, the following five models of aerosol optical parameters
are used: a standard model of continental aerosol, a semiempirical model based on measurement data, and three models obtained
from calculations on the basis of the Mie scattering theory for the mean size distribution of aerosol particles (which is
retrieved from aureole measurements). A study of the sensitivity of the flux and forcing to the choice of aerosol model has
shown that the relative error related to the model choice is not large (<5%) for the incident radiation flux and reaches 120%
for aerosol forcing at the atmospheric upper boundary. The aerosol radiative forcing at the atmospheric upper boundary is
also estimated and, according to our calculations, varies from −15 to −2 W/m2. The use (in calculations) of the values of the albedo of single-scattering and the factor of scattering-indicatrix asymmetry
at a wavelength of 550 nm, which were obtained for each of the observation periods, has made it possible to significantly
refine the value of aerosol radiative forcing (compared to that calculated for the means of these parameters over all the
periods). An even more accurate determination of aerosol radiative forcing is possible only when data on the size-distribution
of aerosol particles and their chemical composition for a certain situation under analysis are available. As a result of this
study, two models of the optical parameters of background aerosol have been proposed for use in radiation calculations: a
semiempirical model and a mean model obtained from the calculations based on the theory of scattering. Both models use the
values of the albedo of single scattering and the factor of asymmetry (at a wavelength of 550 nm) retrieved from the measurements
for each of the observation periods. 相似文献
13.
14.
水下光谱辐射计光学特性的测试与分析 总被引：1，自引：0，他引：1
为适应高精度水下光学测量的需求，设计研制了多通道水下光谱辐射计。该辐射计可同步测量12波段的下行／上行光谱辐照度和7波段的上行光谱辐亮度。对该辐射计的主要性能指标，如余弦响应特性、浸没因子、光谱辐射精度、稳定性和重复性进行了室内测试和分析，用MonteCarlo方法模拟了阴影误差，给出并分析了现场实验数据及部分推导的物理量。结果表明，该光谱辐射计各波段的中心波长和带宽偏差小于1．6nm，稳定性优于5％，阴影误差可控制在5％之内，具有良好的余弦响应特性，满足当前定量化水色遥感现象光辐射测量的技术要求。 相似文献
15.
We describe software for an IBM compatible personal computer (PC) that we have developed and used to collect and analyze backscatter data from a multi-wavelength Mie-Rayleigh scanning lidar system. Both one and two-dimensional distributions of optical scattering coefficients are calculated from the lidar return signals and displayed in real time. Although we are using the software for analyzing marine aerosols, the modular nature of the software and data acquisition drivers make it straightforward to adapt the software to different systems, such as differential absorption lidar (DIAL) and oceanic lidars. We show examples of both horizontal and vertical Mie-Rayleigh lidar scans collected at the Makai Pier and Bellows Beach on the northeast side of the island of Oahu. 相似文献
16.
17.
研究了以InAs量子点为有源区的二维GaAs基光子晶体微腔的设计与制作,测试并分析了室温下微腔的光谱特性.观察到了波长约为1137 nm,谱线半高宽度约为1 nm的尖锐低阶谐振模式发光峰.我们比较了不同刻蚀条件下光子晶体微腔的发光谱线,结果表明空气孔洞截面的垂直度是影响光子晶体微腔发光特性的重要因素之一.通过调节干法刻蚀工艺,改变空气孔半径与晶格常数的比率,可以在较大范围内调节谐振模式发光峰位置,达到谐振模式与量子点发光峰调谐的目的. 相似文献
18.
A lidar method for determining internal wave characteristics 总被引：1，自引：0，他引：1
L. S. Dolin I. S. Dolina V. A. Savel’ev 《Izvestiya Atmospheric and Oceanic Physics》2012,48(4):444-453
An analytical model of lidar imaging of pycnoclinic internal waves (IWs) is developed. The IW image is shown to represent a superposition of two images: reflective and shadow. The former reflects perturbations in the profile of the light backscattering coefficient in the IW field, and the latter reflects perturbations in the optical thickness of the water layer, in which the IW disturbed the horizontal uniformity of optical characteristics. Algorithms for reconstructing the IW field from these images are proposed. It is shown that the shadow image, unlike the reflective one, is insensitive to fine details of the profiles of hydrooptical characteristics and can be used for determining IW parameters on the basis of very rough data on optical properties of water. The possibility of determining the mode composition as well as the lengths and amplitudes of IW modes is demonstrated by using the Barents Sea as an example and invoking actual and simultaneously measured profiles of the water density and light attenuation coefficient. 相似文献
19.
A. M. Chayka Yu. M. Timofeyev A. V. Polyakov 《Izvestiya Atmospheric and Oceanic Physics》2008,44(2):193-206
The surface area and volume densities (S and V) of the particles of stratospheric background aerosol in the 15–20 km and 20–25 km layers for 2002–2005 were obtained from measurements of the aerosol extinction coefficient with the SAGE III instrument by using the linear-regression method of solving the inverse problem. The measurements were taken within the latitudinal belts 43°–80°N and 34°–58°S. The spatial and temporal dependences of S and V demonstrate homogeneous distribution fields in summer, whereas noticeable inhomogeneities are observed in winter and early spring. In all years of the measurements, an increase in the integral characteristics of stratospheric background aerosol was observed during the fall-to-winter transition period. Longitudinal variations in S and V can be both slight and significant (50–70%). Analysis of the interannual variability of the mean areas and volumes of aerosol particles shows that their minima (as a rule) were observed in 2002 and their maxima were observed in 2005. In most of the cases, no monotonic annual variations in the aerosol characteristics are noted. The dependence of the aerosol parameters on the phase of the quasi-biennial oscillations of zonal wind in the stratosphere is observed. The data obtained for 2002–2005 are, on the whole, in good agreement with the climatological data obtained for 1996–1999. 相似文献
20.
太湖水中可溶性有机质,悬浮质和浮游藻类色素的光学特性的测定 总被引：1，自引：0，他引：1
本文着重分析了分光光度计测定的太湖水体中悬浮质、可溶性有机质和浮游藻类色素在可见光波段(400nm—700nm)的吸收;讨论了对池塘及两种高等植物色素吸收的对比测定;并利用迭代回归方法对测试样品的散射效应进行了订正。结果表明:(1)可溶性有机质吸收在短波部分较强;并且随着入射波长的增大,吸收几乎呈指数律减小,减小速率比国外海洋中的测量结果小。(2)水中悬浮质对光具有较强的散射作用,散射系数约按入射波长呈倒数变化。(3)不同植物中的色素的吸收光谱有明显差异。此外,利用所测数据,本文还对冬季太湖水体的反射光谱和向下光照衰减系数进行了数值计算,表明该水体对入射光照的反射和衰减与纯净水情况有很大差别,目此,太湖水光学特性研究中必须考虑水中物质的影响。 相似文献