共查询到20条相似文献，搜索用时 31 毫秒
1.
A laboratory setup and a procedure for measuring the volume coefficients and mean cross sections of extinction, scattering, and absorption of soot particles in the medium of saturated water vapor are described. A method for hydrophilization of the surface of soot particles, which makes it possible to obtain model objects with specified hygroscopic properties, is presented. The processes of transformation of soot particles are analyzed with the use of data of electron-microscopic investigations on the basis of the fractal approach. The structural parameters of hydrophobic soot are shown to depend on the conditions of moistening, whereas hydrophilic particles are subject to substantial structural changes indicative of their watering. Investigation of the coagulation of soot particles with drops shows that hydrophobic particles form a weakly bound system; they coagulate on the surface of drops and cause no changes in the structure of soot aggregates. During the coagulation, hydrophilic soot particles penetrate inside a drop and irreversibly form a mixed system. 相似文献
2.
O. B. Popovicheva E. D. Kireeva M. A. Timofeev N. K. Shonija V. P. Mogil’nikov 《Izvestiya Atmospheric and Oceanic Physics》2010,46(3):339-346
This is a study of the physical and chemical properties of carbonaceous aerosols emitted by transport systems (namely, by
aircraft gas turbine engines and large ship diesel engines) into the atmosphere. A comparative analysis of the morphology,
size, elemental composition, and surface chemistry between aviation and diesel soot particles reveals the general and characteristic
features of emissions from each source. The high pollution rate of diesel soot particles, considerable fraction of metal admixtures,
and availability of char particles characterize the specific features of the formation of particles of this type. The main
characteristics characterizing the interaction between aviation and shipping emission aerosols in the moist atmosphere (the
composition of organic and water-soluble fractions at the surface) have been obtained. Due to high hygroscopicity, the microparticles
can generate cloud condensation nuclei and initiate contrails and additional tropospheric cloudiness. 相似文献
3.
This review describes the new results of analysis of both the physicochemical properties of soot particles emitted by commercial aircraft and subsequent variations in these properties under aircraft-contrail conditions. The results of the study of model laboratory soot samples are given for comparison. The state-of-the-art level of experimental studies of hygroscopicity of soot particles and their efficiency as crystallization centers are presented. The ability of soot aerosols to form condensation nuclei in aircraft contrails and ice nuclei in the upper troposphere is estimated. The estimates of the effects of aircraft soot emissions into the atmosphere are given. 相似文献
4.
用于海洋-大气辐射传递计算的光学参数数据库 总被引：1，自引：1，他引：1
开发和建立了用于海洋-大气辐射传递计算的光学参数数据库.它包括海中主要成分(纯海水、浮游植物、悬移质、可溶有机物)的固有光学参数(光谱吸收系数、光谱散射系数等)及大气中主要气溶胶的有关光学参数.在这些光学参数中,大多数是来自现场的直接测量,一些是间接测量获取,还有一些是通过理论计算得到. 相似文献
5.
D.G. Bowers K.M. Braithwaite W.A.M. Nimmo-Smith G.W. Graham 《Estuarine, Coastal and Shelf Science》2011,91(3):341-350
A correct understanding of the way in which light interacts with suspended particles is essential for quantitative interpretation of satellite visible band imagery of turbid shelf seas and estuaries. In this paper we describe new optical observations at 90 stations in the tidally energetic waters along the south and west coasts of Britain. The cross sectional area of the particles in suspension has been measured with a LISST laser diffraction instrument. Light scattering and absorption coefficients have been determined by applying Kirk’s method to radiometric measurements at 6 wavelengths. Results show that the scattering coefficient increases linearly with particle cross sectional area A per unit volume of water with a slope (scattering efficiency) of 1.96 (standard error 0.08) at 665 nm. Particle absorption coefficients aP also increase with particle cross sectional area but at the most turbid stations, particle absorption per unit area (aP/A) is observed to increase with the mean size of the particles in suspension. The particles are mostly mineral flocs which become more opaque as they grow larger and the photon path length through them increases. The implication of these results for remote sensing is that reflectance in the red part of the spectrum, which mainly depends on light scattering, is proportional to the cross sectional area of particles in suspension. Reflectance measurements in the green and blue parts of the spectrum, where particle absorption becomes more important, depend on the diameter of the particles as well as their cross sectional area. We show that simultaneous measurements of reflectance in the red and green parts of the spectrum can be used to derive both the area and size of the particles in suspension. 相似文献
6.
O. B. Popovicheva M. Kistler E. D. Kireeva N. M. Persiantseva M. A. Timofeev N. K. Shoniya V. M. Kopeikin 《Izvestiya Atmospheric and Oceanic Physics》2017,53(1):49-57
This is a comprehensive study of the physicochemical characterization of multicomponent aerosols in the smoky atmosphere of Moscow during the extreme wildfires of August 2010 and against the background atmosphere of August 2011. Thermal–optical analysis, liquid and ion chromatography, IR spectroscopy, and electron microscopy were used to determine the organic content (OC) and elemental content (EC) of carbon, organic/inorganic and ionic compounds, and biomass burning markers (anhydrosaccharides and the potassium ion) and study the morphology and elemental composition of individual particles. It has been shown that the fires are characterized by an increased OC/EC ratio and high concentrations of ammonium, potassium, and sulfate ions in correlation with an increased content of levoglucosan as a marker of biomass burning. The organic compounds containing carbonyl groups point to the process of photochemical aging and the formation of secondary organic aerosols in the urban atmosphere when aerosols are emitted from forest fires. A cluster analysis of individual particles has indicated that when the smokiest atmosphere is characterized by prevailing soot/tar ball particles, which are smoke-emission micromarkers. 相似文献
7.
Noboru Okami Motoaki Kishino Shigehiko Sugihara Sanae Unoki 《Journal of Oceanography》1982,38(4):208-214
By using the two-flow optical model, the variation in the irradiance reflectance of the ocean just below the surface has been calculated for varying water optical properties, for the interpretation of remotely-sensed ocean color data. The input variables used in our model are the concentration of phytoplankton (chlorophyll-a), the absorption coeffiicient of yellow substance, the particle scattering coefficient, the ratio of the back-scattering coefficient to the total scattering coefficient of particles, and the ratio of the absorption to scattering coefficients for particles.The irradiance reflectance increases monotonically with the ratio of the back-scattering coefficient to the total scattering coefficient. Spectral changes occur in the irradiance reflectance for increases in chlorophyll-a concentration and yellow substance as well as the ratio of the absorption to scattering coefficients.Because slightly different mathematical expressions have been derived by other investigators using the two-flow model, an evaluation of the resulting calculation differences is presented and discussed. 相似文献
8.
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
9.
Application of data on seawater light scattering for the study of marine particles: a selective review focusing on Russian literature 总被引：1，自引：1，他引：0
Oleg V. Kopelevich 《Geo-Marine Letters》2012,32(2):183-193
This paper presents a selective review of applications of data on seawater light scattering for the study and monitoring of
marine particles. Particular emphasis is placed on ocean waters and the seas surrounding Russia, where earlier studies by
the author with his coworkers are little known because published mostly in Russian. In those assessments, methods of solving
the inverse problem of seawater light scattering have been developed. Low-parametric models of optical properties were created
by means of statistical analyses of experimental data, solving the inverse problem and comparing results derived from optical
methods with those based on particle counts. Estimates of the volume and mass concentrations of suspended matter and its components
were derived from light-scattering data for different regions. The potential of using optical methods for assessing spatiotemporal
variability in suspended matter supply, propagation, and distribution is also considered. 相似文献
10.
菲律宾海三种微微型浮游生物颗粒丰度及其光散射作用 总被引：1，自引：0，他引：1
2004年秋季在菲律宾海取得了微微型生物颗粒样品和光衰减剖面资料,然后对三种常见的微微型颗粒(原绿球藻,聚球藻和自养真核细胞)丰度及其光学性质做了初步分析和估算。研究结果表明,菲律宾海原绿球藻的丰度最高,其次为聚球藻,自养真核细胞的丰度最低。3种微微型颗粒的光散射系数同水体剖面的光衰减系数(cp)具有明显的相关关系。3种微微型颗粒的散射作用仅占总光衰减系数的5.1%,其中原绿球藻、自养真核细胞和聚球藻分别占2.6%,2.2%和0.3%。 相似文献
11.
1 IntroductionIntheHuanghaiSea, seafogisaprimarymeteo-rologicalphenom enon significantlyaffectingvisibility.Having fog alm ostonce every 3 d in the fog season,the HuanghaiSea is a m aritime area where sea fogshappen themostin theseasofChina. Theseafog ish… 相似文献
12.
We demonstrate the possibility of determination of the spectral characteristics of absorption and backward scattering of light
in the Black Sea according to the data of a SeaWiFS satellite device. We use specially selected data of observations obtained under favorable atmospheric conditions. It is shown
that the results of calculations performed by using different methods are almost identical and weakly depend on the model
parameters of the spectral course of the coefficients of absorption of light by yellow substance and its scattering by suspended
particles. 相似文献
13.
Jennifer L. Dearman W. William Wilson Rudy E. Rogers Guochang Zhang 《Marine Chemistry》2009,115(1-2):21-30
Gas hydrates accumulate on the Gulf of Mexico seafloor around hydrocarbon seeps in waters sufficiently deep to provide adequate pressure/temperature combinations. High microbial activities occur around the hydrate accumulations. To understand apparent catalytic effects of bioproducts on hydrate formation, the mechanism of sII hydrate nucleation in unconsolidated porous media was investigated in our laboratory. Because smectite clays interacting with biopolymers had been shown to promote laboratory hydrates by decreasing induction times, increasing formation rates and altering morphology, these materials commonly found in near-surface sediments were selected for study as possible nucleating agents. Dynamic light scattering (DLS) with a helium–neon laser was used to measure particle diameters down to about 2 nm. Scanning electron microscopy (SEM) was utilized to verify particle sizes and to give additional information on biopolymer–clay associations. This paper presents evidence that nanometer-sized particles of mineral–bioproduct associations of about 80 nm–450 nm diameter may act as nucleation sites for hydrate crystal initiations in sediments and then remain dispersed throughout the accumulated hydrate mass. Emulsan biopolymer was shown by SEM to apparently unfold and associate with the smectite (nontronite) in a backbone arrangement and to give multiple hydrate nucleation sites along a linear network. SEM and DLS measurements were in agreement on particle sizes and shapes. X-ray diffraction suggested that biopolymer intercalates the smectite interlayer, probably driven by clay associations with biopolymer hydrophilic groups. It is hypothesized that hydrocarbon gases attach to biopolymer hydrophobic fatty-acid branches protruding from clay interlayers and subsequently facilitate hydrate structure formation by interacting with nearby water associated with the hydrophilic segments of the biopolymer. 相似文献
14.
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
15.
浮游藻类是海水中的重要组成成分,对其固有光学特性的研究有助于深入了解水体光学的辐射传输。在过去的30年中,大量的研究都集中在藻类吸收特性上,缺少对其散射特性的认识。本文利用分光光度计设计了在实验室中测量含颗粒水体散射和后向散射特性的方法,并利用标准球形颗粒对该方法的可行性进行验证,结果表明,在400~700 nm范围内,散射测量结果与理论值的一致性较好,最大误差小于3%,而后向散射测量结果在蓝紫光处的一致性较好,在近红外波段处有一定误差。运用这两种测量方法对东中国海常见的赤潮藻种中肋骨条藻Skeletonema costatum和东海原甲藻Prorocentrum donghaiense进行测量,结果显示:中肋骨条藻与东海原甲藻的散射系数幅值相近但谱形差异较大,前者随波长增加散射强度递减,后者则相反;在色素吸收较强的波段,两者散射强度均出现与其它波长位置变化趋势相反的情况,这主要是受细胞物质物理性质的影响。两者的后向散射差异较小,但可以看出其谱形受色素吸收的影响很大,在幅值上,东海原甲藻略高于中肋骨条藻,在550 nm处分别为0.001 74,0.001 43 m2/mg(以藻类叶绿素a浓度归一化),后向散射概率分别为1.104%和0.723%。 相似文献
16.
石油类污染水体后向散射特性分析——以辽宁省盘锦市双台子河和绕阳河为例 总被引：5，自引：1，他引：4
水体悬浮物对溶解在水中的油及乳化油有吸附作用,这种作用会叠加在颗粒物上,对水体的后向散射系数产生影响,而水体后向散射系数是水色遥感的重要参数之一,对建立遥感反演石油类污染浓度半分析模型起着关键性的作用。根据2008年5月在辽宁省盘锦市辽河油田境内双台子河和绕阳河现场测定的水样,对水体组分进行浓度分析,并分别利用分光光度计及后向散射系数测量仪测定水色三要素的吸收系数和水体后向散射系数。根据获取的数据,对石油类污染水体后向散射特性进行分析,分别建立了(1)石油类污染水体后向散射系数光谱模型;(2)石油类污染水体和非石油类污染水体后向散射系数与无机悬浮物浓度的关系模型。研究结果表明:(1)在建立的后向散射系数光谱模型中,幂函数指数平均值为0.87;(2)从相关系数分析来看,对后向散射系数起主要作用的是无机悬浮物浓度,其次是石油类物质浓度,而有机悬浮物浓度几乎没有影响;(3)对于无石油类污染水体,后向散射系数与无机悬浮物浓度为对数关系模型,而与有石油类污染水体更接近线性关系模型。 相似文献
17.
18.
O. K. Voitsekhovskaya I. V. Golub’ A. Yu. Zapryagaev O. V. Shefer 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):55-59
The influence of the aerosol component on the total transmission of sounding IR radiation is analyzed. The emissions of both
industrial and natural origins into the atmosphere were regarded as the medium. It is noted that, in studying the radiative
transport through gas-aerosol mixtures, it is necessary to take into account both molecular absorption and scattering from
aerosol particles. It is shown that there are certain boundary values of the microphysical parameters of aerosol where it
is sufficient to take into account only one of the above-mentioned factors of radiation extinction. The quantitative values
of the parameters of an aerosol medium, on the basis of which the solution of the transport equation can be significantly
simplified, are given. 相似文献
19.
Aitken mode atmospheric particles largely control the formation and transformation of cloud systems, which in turn have an effect on their radiative properties. In this paper, a measurement technique for the cloud condensation nuclei (CCN) activity of monodisperse particles is described and the measurement data (results) obtained for monodisperse aerosol fractions with diameters of 60, 80, and 100 nm are presented. The measurements were performed during March and April 2014 at the urban background station located in a suburban area of St. Petersburg. The CCN concentration in the water-vapor supersaturation range of 0.1–1.1% and the cloud particle activation parameters were determined. The fraction of active particles capable to serve as CCN is found to be less than 33%, which is characteristic of anthropogenic aerosols containing hydrophobic organic components. Based on the measurement data, the hygroscopicity parameter κ characterizing the chemical composition effect on condensational properties of particles has been determined. During the measurement campaign, the value of the hygroscopicity parameter varied between 0.1 and 0.8. The lower limit of κ corresponds to organic species and its higher values occurs due to presence of hygroscopically active inorganic species in particles. The average value of κ was estimated to be 0.34 ± 0.19, which is in good agreement with literature data obtained for megapolises and European continental aerosols. 相似文献
20.
Intertidal marine macroalgae experience periodical exposures during low tide due to their zonational distribution. The duration of such emersion leads to different exposures of the plants to light and aerial CO2, which then affect the physiology of them to different extents.The ecophysiological responses to light and CO2 were investigated during emersion in two red algae Gloiopeltis furcata and Gigartina interrnedia, and two brown algae Petaloniafascia and Sargassum hemiphyllum, growing along the Shantou coast of China. The light-saturated net photosynthesis in G. furcata and P. fascia showed an increase followed by slightly desiccation, whereas that in G.interrnedia and S. hemiphyllum exhibited a continuous decrease with water loss. In addition, the upper-zonated G. furcata and P. fascia,exhibited higher photosynthetic tolerance to desiccation and required higher light level to saturate their photosynthesis than the lower-zonated G. interrnedia and S. hemiphyllum. Desiccation had less effect on dark respiration in these four algae compared with photosynthesis. The light-saturated net photosynthesis increased with increased CO2 concentrations, being saturated at CO2 concentrations higher than the present atmospheric level in G. furcata, G. intermedia and S. hemiphyllum during emersion. It was evident that the relative enhancement of photosynthesis by elevated CO2 in those three algae increased, though the absolute values of photosynthetic enhancement owing to CO2 increase were reduced when the desiccation statuses became more severe. However, in the case of desiccated P. fascia (water loss being greater than 20 %), light saturated net photosynthesis was saturated with current ambient atmospheric CO2 level. It is proposed that increasing atmospheric CO2 will enhance the daily photosynthetic production in intertidal macroalgae by varied extents that were related to the species and zonation. 相似文献