Method for determining microphysical parameters of atmospheric aerosol from the results of satellite and ground-based multifrequency sounding

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.     

Study of continental material transported through the atmosphere to the oeean

I am deeply honored to have been selected as a recipient of the 1987 Okada Prize by the Oceanographical Society of Japan. The present paper reviews my work and recent studies of other investigators concerning mineral aerosol (dust) particles in the marine atmosphere over the Pacific Ocean. I would like to emphasize the importance of atmospheric deposition of continental substances to the ocean environment. From consecutive measurements of atmospheric dust concentrations and total deposition fluxes at 13 island stations in the Pacific Ocean, a strong seasonal transfort pattern of dust particles was found at most of the stations. High atmospheric dust concentrations occurred during the spring in both hemispheres. There was a latitudinal gradient in both the atmospheric dust concentration and flux, with the highest values observed at midlatitudes. When combined with observations of dust storms in Asia and isentropic trajectory analysis, it was clear that the dust over the central North Pacific was transported by the upper westerly winds from the arid desert regions in central and eastern Asia. Transport times were 1–2 weeks, and in some cases, atmospheric transport paths of over 10,000 km were observed. Infrequent short-term dust events contributed most of annual atmospheric dust flux to the open ocean. These sporadic inputs are major sources for both suspended mineral matter in the water column and the non-biogenic component of deep-sea sediments in the Pacific Ocean. The impact of atmospheric dust fluxes on chemical and biological processes in the water column remains to be determined.     

Retrieval of integral parameters of tropospheric aerosol from two-wavelength lidar sounding

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.     

沙尘粒子在我国内陆传输过程中对硫酸盐和硝酸盐生成的影响

2001年春季在青岛采集了3次沙尘暴过境时的大气气溶胶粒子，并利用单个气溶胶粒子分析方法对沙尘粒子含有硫酸盐和硝酸盐的状况进行了分析研究。结果发现3％～13％的沙尘粒子含有硫酸盐，6％～10％的沙尘粒子含有硝酸盐。这些比例远小于无沙尘时北京、青岛等城市污染大气中矿物粒子所含这些成分的比例，表明沙尘粒子在从内陆源区传输到沿海地区的过程中对大气中硫酸盐和硝酸盐生成的促进作用远不如城市污染大气中的矿物粒子明显。     

Ground-based measurements of total ozone content by the infrared method

To interpret the ground-based measurements of the spectra of direct solar infrared radiation with the help of a Brucker Fourier-spectrometer, a technique for determining the total ozone content (TOC) was developed and implemented. The TOC was determined using six spectral intervals of an ozone-absorption band of 9.6 μm and the shortwave panel of a carbon-dioxide-absorption band of 15 μm, where the impact of other atmospheric parameters on the measured solar radiation was reduced to a minimum. The potential errors of the infrared method for determining the TOC for the chosen spectral scheme with the influence of measurement errors and vertical profiles of temperature are less than 1% for different signal-to-noise ratios and zenith angles of the sun. We analyzed 269 high-resolution (0.005–0.008 cm^?1) spectra of solar infrared radiation measured in Peterhof over 52 days from March to November, 2009. The resulting values of TOC were compared with the results of independent ground-based TOC measurements in Voeikovo (Main Geophysical Observatory) using a Dobson spectrophotometer and an M-124 ozonometer, as well as with the Ozone Monitoring Instrument (OMI) satellite data. The mean errors between the results of TOC measurements with the help of the three ground-based probes constitute no more than 0.4%. The rms errors between data obtained by the Brucker spectrometer and the given satellite and ground-based probes constitute 3–4%. A comparison between different series of measurements indicated that the upper estimate for the error of TOC measurements by the Brucker spectrometer was 2.5–3% (when the possible spatial and temporal errors in measurements are disregarded). An analysis of the diurnal variations in the TOC measurements for stable atmospheric conditions yields an upper estimate of ～3 DU (around 1%) for the random component of error in TOC measurements by the Brucker spectrometer.     

Modeling radiative forcing by background aerosol on the basis of measurement data

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.     

Eclipse effects in the atmospheric boundary layer

The influence of a solar eclipse on solar-radiation fluxes, meteorological parameters, turbulence characteristics, and vertical temperature profiles in the atmospheric boundary layer is analyzed. Air-temperature variations caused by an eclipse and time delays of these variations with respect to the onset of the total-eclipse phase in the atmospheric surface and boundary layers are determined. The influence of a solar eclipse on the turbulent kinetic energy, turbulent heat flux, and variance and spectral density of the power of air-temperature pulsations are estimated. Variations in aerosol parameters and concentrations of light ions during a total solar eclipse are discussed.     

Effect of the 11-year cycle of solar activity on characteristics of the total ozone annual variation

The goal of the paper is an analysis of changes in the amplitude and phase characteristics of the annual variation (AC) of total ozone (TO) from ground-based and satellite (TOMS) measurements and their interpretation with a two-dimensional photochemical model. According to ground-based TO measurements, two characteristic types of quasi-decadal variations in the phase of the annual harmonic (AH) of total ozone have been noted: variations in phase and antiphase with solar activity (SA). Changes in the TO AH phase opposite to solar activity variation are noted the high latitudes of the North Atlantic region and in the tropical belt, and in-phase changes are observed in the middle and subtropical latitudes of both hemispheres. Variations in the TO AH amplitude (hence, in the TO AV amplitude) and in the annual mean TO usually coincide in phase with the SA cycle. Analysis of satellite data shows that the 0-phase of the AV and the phase of the AH of the zonal mean TO at middle latitudes vary synchronously with the 11-year solar cycle. Model simulations have shown that the stratospheric ozone influx to the middle latitudes increases in the fall and winter period during a period of maximum solar activity. This dynamic mechanism accounts for up to 30% of the winter ozone increase in the ozone maximum layer in the Southern Hemisphere midlatitudes during the solar maximum as compared with the solar minimum. In the northern midlatitudes, the dynamic mechanism makes the main contribution to ozone changes during the latter half of winter under SA variations. The stratospheric ozone inflow change induced by SA variations affects the annual variation of ozone.     

Correction of atmospheric effect on ADEOS/OCTS ocean color data: Algorithm description and evaluation of its performance

This paper first describes the atmospheric correction algorithm for OCTS visible band data used at NASDA/EOC. Sharing a basic structure with Gordon and Wang’s Sea WiFS algorithm, it uses 10 candidate aerosol models including the “Asian dust model” introduced in consideration of the unique feature of aerosols over the east Asian waters. Based on the observations at 670 and 865 nm bands, the algorithm selects a pair of aerosol models that account best for the observed spectral reflectances, and synthesizes the aerosol reflectance used for the atmospheric correction. Two different schemes for determining the value of the parameter for the aerosol model selection are presented and their anticipated estimation error is analyzed in terms of retrieved water reflectance at 443 nm. The results of our numerical simulation show that the standard deviation of the estimation error of the “weighted average” scheme is mostly within the permissible level of ±0.002, reducing the error by 18% on average compared to the “simple average” scheme. The paper further discusses the expected error under the old CZCS-type atmospheric correction, which assumes constant aerosol optical properties throughout the given image. Although our algorithm has a better performance than the CZCS algorithm, further analysis shows that the error induced by the assumption taken in the algorithm that the water-leaving radiance at 670 nm band is negligibly small may be large in high pigment concentration waters, indicating the necessity for future improvements.     

FY-1C/1D全球海上气溶胶业务反演算法研究

介绍了基于FY-1C/1D气象卫星数据进行全球海洋气溶胶反演的业务算法,主要论述了海上气溶胶反演的单通道算法基本原理.该算法的核心内容是建立气溶胶光学厚度查算表,该查算表基于6S辐射传输模式,在假定气溶胶模式条件下,卫星的表观反射率是卫星观测几何(太阳卫星角)和气溶胶光学厚度函数,最终由卫星观测表观反射率反演出气溶胶光学厚度.业务反演过程中还考虑到数据质量检验、云检测处理和太阳耀斑区去除等.利用该算法对FY-1C卫星自2001年起的部分资料进行反演试验,并在FY-1D卫星发射后投入业务应用,自2002年8月开始能实时得到每天和每月的全球气溶胶光学厚度产品.从两颗卫星两年多连续反演结果分析可以非常清晰地发现全球气溶胶主要排放源地和全球海上气溶胶分布的季节变化,与国外卫星反演结果十分接近.     

Determining Both Tropospheric and Stratospheric СО2 Contents Using a Ground-Based IR Spectroscopic Method

Izvestiya, Atmospheric and Oceanic Physics - Results obtained from ground-based high spectral resolution measurements of solar IR radiation absorption spectra are analyzed. These measurements have...     

Ground-based measurements of total column of hydrogen chloride in the atmosphere near St. Petersburg

We present ground-based spectroscopic measurements of the total hydrogen chloride in the atmosphere of Peterhof near St. Petersburg from April 2009 to March 2012. The well-known computer code SFIT-2 (Zephyr-2) was used to interpret the spectra of the solar IR radiation. The random and systematic errors of total column (TC) HCl measurements did not exceed 3.8 and 4.5%. The seasonal behavior of TC HCl in Peterhof is characterized by the presence of a maximum in March–April and a minimum in October–November. There are also extremely small TC HCl values in January–February. The time behavior obtained for Peterhof agrees well with data from nearest stations in the NDACC international network. The ground-based measurements of the TC HCl were compared with satellite measurements with the help of ACE-FTS and MLS instruments. The direct comparisons of coincident (within a day) and collocated (within 500 km) satellite and ground-based measurements showed a correspondence of results within their total errors.     

Seasonal and areal variation of continental aerosol in the surface air over the western North Pacific region

Weekly aerosol samples were collected for two years from 1981 at six stations in the western North Pacific region. The samples were analyzed for aluminum to determine the mineral dust concentration in the air. By combining our data with observations in the central and eastern North Pacific by a US research group, the following results and conclusions have been obtained. Spring peaks in atmospheric mineral dust were observed at all the stations accompanied byKosa episodes (hazes due to mineral dust of Chinese origin). The spring peaks, however, varied from year to year. The mean concentration of mineral dust depends not only on the distance from the Asian coast but also on the latitude of the sampling station. The half-decrease distance of the atmospheric mineral dust turned out to be 500–600 km for all latitudes in the western North Pacific. This indicates that the rate of deposition of mineral dust in the western North Pacific is much larger than that in the central and eastern North Pacific.     

Dusty Plasma of a Wind-Sand Flux in Desertified Areas

Izvestiya, Atmospheric and Oceanic Physics - Measurements of electric currents of saltation in the wind-sand flux and currents caused by the wind transport of dust aerosol particles have been...     

Studies of temperature effects of dust storms

We studied the temperature variations of the lower air layer caused by dust content using a dust storm in Dushanbe in November 2007 as an example. Quantitative estimates of air cooling and a decrease in the diurnal temperature difference due to a diminishing horizontal visibility range are given. Observations of air temperature variations due to the dust content of the atmosphere in an arid zone are presented. The critical value of aerosol concentration for toggling between the greenhouse and antigreenhouse effects is determined. The long-term effect of dust aerosol on climate is analyzed.     

Intercomparison of satellite and ground-based ozone total column measurements

Ozone total column (OTC) measurements made in 2009–2012 near St. Petersburg by a Fourier Transform Infrared (FTIR) spectrometer (Peterhof, St. Petersburg State University (SPbSU)), an M-124 filter ozonometer, and a Dobson spectrophotometer (Voeikovo, MGO), as well as measurements made by a spectrometer ozone monitoring instrument (OMI) (onboard the AURA satellite) have been analyzed and compared. Comparisons have been performed both between ensembles of ground-based measurement data, as well as between ground-based and satellite data. It has been shown that the standard deviation for all devices is 2.5–4.5%; here, the FTIR and Dobson instruments measuring the direct sun are in better agreement with OMI than the M-124 ozonometer measuring the zenith-scattered solar radiation as well. A seasonal cycle in discrepancy with amplitude of 1.5% has been detected between two series of OTC measurements made by M-124 and OMI instruments for a total of 850 days. In fall and winter, the ground-based measurements underestimate the OTC values in comparison with satellite data; in spring and summer, the situation is reversed: ground-based data overestimate the OTC values. Also, it has been revealed that FTIR measurements systematically overestimate the OTC values in comparison with other instruments: from 1.4% (for Dobson) to 3.4% (for OMI). Taking into account the spatial and temporal discrepancy of independent ensembles of measurements and an analysis of standard deviations between ground-based and satellite measurement data, the FTIR spectrometer (SPbSU) can be recommended for OTC satellite data validation.     

Optical and microphysical parameters of arid dust aerosol

The parameters of heavily dusty air in an aerosol chamber under the conditions of an arid zone are studied. The transmission, optical density, Angstrom parameter, aerosol absorption coefficient, and visibility range are calculated. The temporal and spectral dependences of the optical parameters are analyzed. The regularities of the particle-size distribution function in strongly inhomogeneous dust aerosol are studied for coarsely (with a diameter more than 1 μm) and finely dispersed (with a diameter of less than 1 μm) fractions. The sizes and concentrations of the aerosol particles in air were determined using a photoelectric aerosol counter together with a 15-channel analyzer. We present the absorption spectra of coarsely and finely dispersed dust aerosol collected under different meteorological conditions. The possible mechanisms of variations in the aerosol disperse composition are analyzed.     

Integral microphysical parameters of stratospheric background aerosol for 2002–2005 (the SAGE III satellite experiment)

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.     

LONG-DISTANCE ATMOSPHERIC TRANSPORT OF DUST FROM CHINESE DESERT TO THE NORTH PACIFIC

The Chinese desert is one of the major sources of atmospheric mineral dust transported for a long distance to the North Pacific by the atmospheric circulation. The characteristic of the aerosol in the North Pacific is smilar to that of the aerosol in North China with a considerable concentration of mineral in spring due to the large-scale dust storm occurring in North China. The study of isotope tracer indicates that the concentration of Al is significantly related to 210Pb, suggesting that the mineral aerosol in the North Pacific may origir ate from the desert in Northwest China by using air mass trajectory analysis. About 6-12×106 tons of Chinese desert mineral dust per year would be transported to the North Pacific.     

珠江口海域气溶胶中重金属含量的时间变化特征及入海通量初步估算

采用2009～2011年珠江口海域获取的代表春、夏、秋、冬4个季节的240个气溶胶样品,分析重金属（Cu、Pb、Zn、ca）质量浓度和大气干沉降通量的年、季变化特征．结果表明：气溶胶中zn的质量浓度最高,其次是Pb和Cu,Cd的质量浓度最低,年平均质量浓度依次为69,2、31．2、12．6和0．58ng／m3．Cu、Pb和Zn的年平均质量浓度和入海通量表现为2009年〉2011年〉2010年．Cd的年平均质量浓度和入海通量呈现逐年递减的变化趋势．各金属质量浓度及大气干沉降通量均为秋季最高,冬春季次之,夏季最低,这种季节性差异主要与季风和雨水冲刷作用有关．气溶胶中Cu、Ph、Cd和Zn平均质量浓度的较低值出现在2010年夏季．Pb在4个季节的平均质量浓度低值均出现在2010年,平均质量浓度依次为18．9、3．8、56．7、20．2ng／m3,表明加强人为污染物排放的控制,可有效地降低气溶胶中重金属的含量,提高环境空气质量．通过评估金属元素分别从大气和河流进入珠江口海域的输入量,该海域金属物质输送入海仍以河流输入为主,但大气中Pb对该海域的输入具有重要作用．