Soliciting Contributions to a Special Issue of "Current Research on Atmospheric Aerosols and Trace Gases over the Polar Regions" in Advances in Polar Science

Dear Colleagues, We would like to invite you to submit manuscripts to a special issue entitled ＂Current Research on Atmospheric Aerosols and Trace Gases over the Polar Regions＂ of the Journal Advances in Polar Science （APS）. APS is an international, peer-reviewed journal jointly sponsored by the Polar Research Institute of China （PRIC） and the Chinese Arctic and Antarctic Administration （CAA）. It is a quarterly journal published in March, June, September and December by Science Press of China and circulated internationally （ISSN 1674-9928, CN 31-2050/P）. Articles published in APS are free of charge with generous funding from PRIC. For more details, please visit the APS＇s websites. Thank you in advance for your consideration to submit manuscripts to this special issue, and we encourage you to share this announcement broadly with interested colleagues.

Effect of atmospheric aerosols on UV-B radiation reaching the ground

Solar ultraviolet radiation reaching the ground can be reduced due to light scattering of atmospheric aerosols. Aerosol pollution has led to the decrease in biological active UV-B radiation by about 45% and 10% in city and rural areas, respectively. In populated areas, effect of aerosol scattering on UV-B radiation may offset the increased amount of UV-B caused by ozone depletion, but in clean areas such as two poles, ozone depletion may have great damage effects on ecosystems.

Water-soluble brown carbon in atmospheric aerosols from the resource-dependent cities:Optical properties,chemical compositions and sources

As a vital type of light-absorbing aerosol,brown carbon(BrC)presents inherent associations with atmospheric photochemistry and climate change.However,the understanding of the chemical and optical properties of BrC is limited,especially in some resource-dependent cities with long heating periods in northwest China.This study showed that the annual average abundances of Water-soluble BrC(WS-BrC)were 9.33±7.42 and 8.69±6.29μg/m^(3)in Baotou and Wuhai and the concentrations,absorption coefficient(Abs_(365)),and mass absorption efficiency(MAE365)of WS-BrC presented significant seasonal patterns,with high values in the heating season and low values in the non-heating season;while showing opposite seasonal trends for the Absorption Angstr?m exponent(AAE_(300-400)).Comparatively,the levels of WS-BrC in developing regions(such as cities in Asia)were higher than those in developed regions(such as cities in Europe and Australia),indicating the significant differences in energy consumption in these regions.By combining fluorescence excitation-emission matrix(EEM)spectra with the parallel factor(PARAFAC)model,humic-like(C1 and C2)and proteinlike(C3)substances were identified,and accounted for 61.40%±4.66%and 38.6%±3.78%at Baotou,and 60.33%±6.29%and 39.67%±4.17%at Wuhai,respectively.The results of source apportionment suggested that the potential source regions of WS-BrC varied in heating vs.non-heating seasons and that the properties of WS-BrC significantly depended on primary emissions(e.g.,combustion emissions)and secondary formation.

MEASUREMENTS OF THE ABSORPTION COEFFICIENT OF ATMOSPHERIC AEROSOLS

This paper discusses the measurement of the absorption coefficient of atmospheric aerosols and its meas- uring system based on the principle of integrating plate. Measurements in Beijing show that the absorption coefficient of atmospheric aerosols in the heating period varies in a range of 10to 10mand in the non-heating period, its values are near 10m.

VERTICAL DISTRIBUTION CHARACTERISTICS OF ATMOSPHERIC AEROSOLS IN LIAONING

16 aircraft missions were conducted for the measurement of atmospheric aerosols in separate days of late spring and early summer of 1996 and 1997.The paper deals with detailed analysis of the variation in vertical/horizontal distributions of the concentration of the particles and their size distribution at 0—5 km above ground,and with the relations to temperature and relative humidity documented in general.Evidence suggests that the concentrations show different distribution features in vertical above and below the cap of the mixed layer:the particle size distribution is subject to a range of forming mechanisms,displaying a multi-modal pattern:the horizontal concentration experiences remarkable variation:temperature and relative humidity stratifications have conspicuous influence on the concentration and size distribution of aerosols.

Analysis on the Distribution Characteristics of Atmospheric Aerosol Particles in Hebei Area in the Cloudy Day Condition

By using the probe data of two sorties airplane in the middle and southern parts of Hebei Province in 2007 spring,the characteristics of atmospheric aerosol particles concentration and size distribution in the area in the cloudy day situation were analyzed.The results showed that the overall trend of aerosol particles concentration in the weather systems which included the south branch trough and North China low vortex was the decrease as the height increased.However,if the cirrostratus was in the high altitude,it increased as the height increased.In the bottom of inversion layer,there existed the obvious accumulation of aerosol and cloud droplet.Affected by the complex weather systems,the aerosol particle size distribution presented the multi-peak type for the disturbance of updraft or turbulence.

Lidar Measurements of Aerosols in the Tropical Atmosphere

Measurements of atmospheric aerosols and trace gases using the laser radar (lidar) techniques, have been in progress since 1985 at the Indian Institute of Tropical Meteorology, Pune (18°32'N, 73°51'E, 559 m AMSL), India. These observations carried out during nighttime in the lower atmosphere (up to 5.5 km AGL), employing an Argon ion / Helium-Neon lidar provided information on the nature, size, concentration and other characteristics of the constituents present in the tropical atmosphere. The time-height variations in aerosol concentration and associated layer structure exhibit marked differences between the post-sunset and pre-sunrise periods besides their seasonal variation with maximum concentration during pre-monsoon / winter and minimum concentration during monsoon months. These observations also revealed the influence of the terrain of the experimental site and some selected meteorological parameters on the aerosol vertical distributions. The special observations of aerosol vertical profiles obtained in the nighttime atmospheric boundary layer during October 1986 through September 1989 showed that the most probable occurrence of mixing depth lies between 450 and 550 m, and the multiple stably stratified aerosol layers present above the mixing depth with maximum frequency of occurrence at around 750 m. This information on nighttime mixing depth / stable layer derived from lidar aerosol observations showed good agreement with the height of the ground-based shear layer / elevated layer observed by the simultaneously operated sodar at the lidar site.

Preliminary Research on the Size Distribution of Aerosols in Beijing

Number concentration and size distribution of atmospheric aerosols were measured in Beijing by an optical particle counter. The relationship between aerosol size distribution and relative humidity is discussed. The results show that the size distribution, diurnal variation, daily variation of atmospheric aerosols have a good relation to relative humidity and Richardson number. Key words Atmospheric aerosol - Number concentration - Size distribution - Relative humidity - Richardson number This work is financially supported by NKBRSF Project (G1999043400), Knowledge Creative Project (8-2101 and 82303) founded by TAP, CAS.The authors would like to express their thanks to Prof. Zhang Wen for his work in this observation.

The role of atmospheric aerosol composition in climate change

The chemical composition of atmospheric aerosols has been investigated. Contributions ofsulfate and soot in aerosols to the atmospheric extinction are studied. Discussions are made on the problems of aerosol emitted from volcano, forest fires in northern China, 1987 and oil field fires in Kuwait, 1991. It is indicated that the changes in concentration, particle size, and chemical composition of aerosol after those events could have impacts on the climate change either regionally or globally and that the impact of aerosol particles on climate change could compensate for some temperature increase caused by greenhouse gases and the increase of surface intensity of ultraviolet radiation due to ozone layer depletion.

Direct Radiative Effect of Aerosols on Net Ecosystem Carbon Exchange in the Pearl River Delta Region

The environmental impact of aerosols is currently a hot issue that has received worldwide attention. Lacking simultaneous observations of aerosols and carbon flux, the understanding of the aerosol radiative effect of urban agglomeration on the net ecosystem carbon exchange(NEE) is restricted. In 2009-2010, an observation of the aerosol optical property and CO_(2) flux was carried out at the Dongguan Meteorological Bureau Station(DMBS) using a sun photometer and eddy covariance systems. The different components of photosynthetically active radiation(PAR),including global PAR(GPAR), direct PAR(DPAR), and scattered PAR(FPAR), were calculated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART) model. The effects of PAR on the NEE between land-atmosphere systems were investigated. The results demonstrated that during the study period the aerosol optical depth(AOD)reduced the DPAR by 519.28±232.89 μmol photons · m^(-2)s^(-1), but increased the FPAR by 324.93±169.85μmol photons ·m^(-2)s^(-1),ultimately leading to 194.34±92.62 μmol photons · m^(-2)s^(-1);decrease in the GPAR. All the PARs(including GPAR,DPAR, and FPAR) resulted in increases in the NEE(improved carbon absorption), but the FPAR has the strongest effect with the light use efficiency(LUE) being 1.12 times the values for the DPAR. The absorption of DPAR by the vegetation exhibited photo-inhibition in the radiation intensity > 600 photons · m^(-2)s^(-1);in contrast, the absorptions of FPAR did not exhibit apparent photo-inhibition. Compared with the FPAR caused by aerosols, the DPAR was not the primary factor affecting the NEE. On the contrary, the increase in AOD significantly increased the FPAR, enhancing the LUE of vegetation ecosystems and finally promoting the photosynthetic CO_(2) absorption.

An Observational Study on Physical and Optical Properties of Atmospheric Aerosol in Autumn in Nanjing

Based on observing data of atmospheric aerosol in the north suburban area of Nanjing from September to November in 2007, the number concentration, mass concentration, size distribution and optical properties of atmospheric aerosol particles and the relation to meteorological factors were analyzed, and their concentration and optical properties during hazy and non-hazy days were compared. The results showed that aerosol pollution was serious in autumn in this region; the deterioration of visibility had close correlation to fine particles, that is, the average number concen- tration of aerosol was 17 044.2 cm^-3, in which ultra fine particles accounted for 64.3%; the daily average mass concentration of PM2.5 was 281 μg/m3, and the ratio of PM2.5 to PM10 was 0.74; the accumulation mode particles dominated in number and surface concentration distributions, while the volume concentration distribution presented a main peak at size of 1.0 -2.8 μm; fine particles increased during hazy days compared with non-hazy days; the scatter coefficient closely correlated to the particle size, concentration and atmospheric humidity. It was also indicated that meteorological conditions played a critical role in formation of hazy weather, that is, weak large-scale weather systems, low wind speed, high humidity and strong inversion were favorable conditions for hazy weather in autumn.

Diurnal Variation of Atmospheric Aerosol Particles in the Phyllostachys heterocycla Forest in Spring

Taking the Phyllostachys heterocycla forest in Qishan National Forest Park of Fuzhou for example, this study observed the diurnal variation of atmospheric aerosol particles in the forest in the growing season.The results showed that:(1) The diurnal variation curves of the particle concentration of the forest and the forest edge had "two peaks and two troughs", but the peaks and troughs of the forest edge were advanced or delayed.The concentrations of the particles in the forest and at the forest edge had two peaks at 11:00–13:00 and 17:00–19:00 and two troughs at 7:00–9:00 and 15:00–17:00.(2) For the forest and the forest edge, the diurnal variation trends of the particles of different particle sizes were generally similar, except that the peaks and troughs of fine particles were slightly earlier or lagging than that of coarse particles.(3) The concentrations of the particles were positively correlated with temperature, humidity and light, and negatively correlated with wind speed, and the concentrations of the particles at the forest edge were significantly negatively correlated with wind speed.

Performance evaluation of operational atmospheric correction algorithms over the East China Seas

To acquire high-quality operational data products for Chinese in-orbit and scheduled ocean color sensors, the performances of two operational atmospheric correction(AC) algorithms(ESA MEGS 7.4.1 and NASA Sea DAS 6.1) were evaluated over the East China Seas(ECS) using MERIS data. The spectral remote sensing reflectance R_(rs)(λ), aerosol optical thickness(AOT), and ?ngstr?m exponent(α) retrieved using the two algorithms were validated using in situ measurements obtained between May 2002 and October 2009. Match-ups of R_(rs), AOT, and α between the in situ and MERIS data were obtained through strict exclusion criteria. Statistical analysis of R_(rs)(λ) showed a mean percentage difference(MPD) of 9%–13% in the 490–560 nm spectral range, and significant overestimation was observed at 413 nm(MPD>72%). The AOTs were overestimated(MPD>32%), and although the ESA algorithm outperformed the NASA algorithm in the blue-green bands, the situation was reversed in the red-near-infrared bands. The value of α was obviously underestimated by the ESA algorithm(MPD=41%) but not by the NASA algorithm(MPD=35%). To clarify why the NASA algorithm performed better in the retrieval of α, scatter plots of the α single scattering albedo(SSA) density were prepared. These α-SSA density scatter plots showed that the applicability of the aerosol models used by the NASA algorithm over the ECS is better than that used by the ESA algorithm, although neither aerosol model is suitable for the ECS region. The results of this study provide a reference to both data users and data agencies regarding the use of operational data products and the investigation into the improvement of current AC schemes over the ECS.

A Multifunctional HTDMA System with a Robust Temperature Control

The hygroscopicity of atmospheric aerosols significantly influences their size distribution, cloud condensation nuclei ability, atmospheric residence time, and climate forcing. In order to investigate the hygroscopic behavior of aerosol particles and serious haze in China, a Hygroscopic Tandem Differential Mobility Analyzers （HTDMA） system was designed and constructed at Fudan University. It can function as a scanning mobility particle sizing system to measure particle size distribution in the range of 20-1000 nm in diameter, as well as a hygroscopicity analyzer for aerosol particles with diameters between 20-400 nm in the range of 20%-90% RH （relative humidity）. It can also measure the effect of uptake of inorganic acids or semiVOCs on the hygroscopic behavior of aerosols, such as typical inorganic salts in atmospheric dust or their mixtures. The performance tests show that the system measured particle size of the standard polystyrene latex spheres （PSLs） is 197 nm, which is in excellent agreement with the certified diameter D=199±6 nm, as well as a standard deviation of the repeated runs SD=8.9×10^-4. In addition, the measured hygroscopic growth factors of the model compounds, （NH4）2SO4 and NaNO3, agree with the Kohler theoretical curves. The results indicate that the HTDMA system is an excellent and powerful tool for studying the hygroscopic behavior of submicron aerosols and meets the demand required for laboratory research and fieldwork on atmospheric aerosols in China.

Multi-wavelength measurements of aerosol optical absorption coefficients using a photoacoustic spectrometer

The atmospheric aerosol absorption capacity is a critical parameter determining its direct and indirect effects on cli- mate. Accurate measurement is highly desired for the study of the radiative budget of the Earth. A multi-wavelength （405 rim, 532 nm, 780 nm） aerosol absorption meter based on photoacoustic spectroscopy （PAS） invovling a single cylin- drical acoustic resonator is developed for measuring the aerosol optical absorption coefficients （OACs）. A sensitivity of 1.3 Mm-l （at 532 nm） is demonstrated. The aerosol absorption meter is successfully tested through measuring the OACs of atmospheric nigrosin and ambient aerosols in the suburbs of Hefei city. The absorption cross section and absorption Angstrom exponent （AAE） for ambient aerosol are determined for characterizing the component of the ambient aerosol.

东亚有机气溶胶及其对下游大气影响的回顾（英文）

In this paper primary(i.e.,n-alkanes,PAHs,levoglucosan,and phthalates) and secondary organic aerosols(i.e.,dicarboxylic acids) are reviewed on a molecular level for their spatial distribution of concentrations over East Asia.Differences in the abundances and sources of those organic aerosols between China and India are further presented,along with a discussion on climate effect(e.g.,CCN activity and radiative forcing) of organic aerosols in the atmosphere.

Quantitative relationship between visibility and mass concentration of PM2.5 in Beijing

The pollution of particulate matter less than 2.5μm （PM2.5） is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U,S, national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles （PM2.5） cause atmospheric visibility deterioration through light extinction, The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different： power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5.

Aerosol Spectra and New Particle Formation Observed in Various Seasons in Nanjing

The aerosol number spectrum and gas pollutants were measured and the new particle formation （NPF） events were discussed in Nanjing. The results showed that the size distributions of aerosol number concen- trations exhibited distinct seasonal variations, implying the relations of particle sizes and their sources and sinks. The number concentrations of particles in the nuclei mode （10-30 nm）, Aitken mode （30-100 nm）, accumulation mode （100 -1000 nm） and coarse mode （〉1μm） varied in the order of summer 〉 spring 〉 autumn, summer 〉 autumn 〉 spring, autumn 〉 summer 〉 spring, and spring 〉 autumn 〉summer, re- spectively. The diurnal variation of total aerosol number concentrations showed three peaks in all observed periods, which corresponded to two rush hours and the photochemistry period at noon. In general, the NPF in summer occurred under the conditions of east winds and dominant air masses originating from marine areas with high relative humidity （50%-70%） and strong solar radiations （400 -700 W m-2）. In spring, the NPF were generally accompanied by low relative humidity （14%-30%） and strong solar radiations （400-600 W m-2）. The new particle growth rates （GR） were higher in the summertime in the range of 10- 16 nm h-1. In spring, the GR were 6.8-8.3 nm h-1. Under polluted air conditions, NPF events were seldom captured in autumn in Nanjing. During NPF periods, positive correlations between 10- 30 nm particles and 03 were detected, particularly in spring, indicating that NPF can be attributed to photochemical reactions.

Brown carbon in the cryosphere： Current knowledge and perspective

Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. Br C is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, Br C could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of Br C(in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic,and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of Br C like Absorption?ngstr€om Exponent(AAE) and Mass Absorption Efficiency(MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning Br C is available. Considering biomass burning as a dominant source of Br C, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of Br C merits more investigation in the future.

A Closure Study of Aerosol Hygroscopic Growth Factor during the 2006 Pearl River Delta Campaign

Measurements of aerosol physical, chemical and optical parameters were carried out in Guangzhou, China from 1 July to 31 July 2006 during the Pearl River Delta Campaign. The dry aerosol scattering coefficient was measured using an integrating nephelometer and the aerosol scattering coefficient for wet conditions was determined by subtracting the sum of the aerosol absorption coefficient, gas scattering coefficient and gas absorption coefficient from the atmospheric extinction coefficient. Following this, the aerosol hygroscopic growth factor, f（RH）, was calculated as the ratio of wet and dry aerosol scattering coefficients. Measurements of size-resolved chemical composition, relative humidity （RH）, and published functional relationships between particle chemical composition and water uptake were likewise used to find the aerosol scattering coe？cients in wet and dry conditions using Mie theory for internally- or externally-mixed particle species [（NH_4）_2SO_4, NH_4NO_3, NaCl, POM, EC and residue]. Closure was obtained by comparing the measured f（RH） values from the nephelometer and other in situ optical instruments with those computed from chemical composition and thermodynamics. Results show that the model can represent the observed f（RH） and is appropriate for use as a component in other higher-order models.