Atmosphere

5924 KiB

Open AccessArticle

Evaluating Summer-Time Ozone Enhancement Events in the Southeast United States

by Matthew S. Johnson, Shi Kuang, Lihua Wang and M. J. Newchurch

Atmosphere 2016, 7(8), 108; https://doi.org/10.3390/atmos7080108 - 19 Aug 2016

Cited by 15 | Viewed by 4778

This study evaluates source attribution of ozone (O₃) in the southeast United States (US) within O₃ lamina observed by the University of Alabama in Huntsville (UAH) Tropospheric Ozone Lidar Network (TOLNet) system during June 2013. This research applies surface-level and [...] Read more.

This study evaluates source attribution of ozone (O₃) in the southeast United States (US) within O₃ lamina observed by the University of Alabama in Huntsville (UAH) Tropospheric Ozone Lidar Network (TOLNet) system during June 2013. This research applies surface-level and airborne in situ data and chemical transport model simulations (GEOS-Chem) in order to quantify the impact of North American anthropogenic emissions, wildfires, lightning NO_x, and long-range/stratospheric transport on the observed O₃ lamina. During the summer of 2013, two anomalous O₃ layers were observed: (1) a nocturnal near-surface enhancement and (2) a late evening elevated (3–6 km above ground level) O₃ lamina. A “brute force” zeroing method was applied to quantify the impact of individual emission sources and transport pathways on the vertical distribution of O₃ during the two observed lamina. Results show that the nocturnal O₃ enhancement on 12 June 2013 below 3 km was primarily due to wildfire emissions and the fact that daily maximum anthropogenic emission contributions occurred during these night-time hours. During the second case study it was predicted that above average contributions from long-range/stratospheric transport was largely contributing to the O₃ lamina observed between 3 and 6 km on 29 June 2013. Other models, remote-sensing observations, and ground-based/airborne in situ data agree with the source attribution predicted by GEOS-Chem simulations. Overall, this study demonstrates the dynamic atmospheric chemistry occurring in the southeast US and displays the various emission sources and transport processes impacting O₃ enhancements at different vertical levels of the troposphere. Full article

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6758 KiB

Open AccessArticle

Effects of Plastic Mulch on Soil Heat Flux and Energy Balance in a Cotton Field in Northwest China

by Nana Li, Fuqiang Tian, Hongchang Hu, Hui Lu and Guanghui Ming

Atmosphere 2016, 7(8), 107; https://doi.org/10.3390/atmos7080107 - 19 Aug 2016

Cited by 17 | Viewed by 6206

Abstract

Surface energy balance (SEB) is a basic principle for all of the atmospheric circulation models, and surface soil heat flux (G₀) is an important component of energy balance. Plastic mulch is widely used in arid regions and alters land surface [...] Read more.

Surface energy balance (SEB) is a basic principle for all of the atmospheric circulation models, and surface soil heat flux (G₀) is an important component of energy balance. Plastic mulch is widely used in arid regions and alters land surface processes. In this study, hourly/daily G₀ and SEB over a mulched cotton field were analyzed in Northwest China. The net radiation beneath the mulch was simulated using transmitted down short-wave and down long-wave radiation through the mulch and up short-wave and up long-wave radiation from the soil beneath mulch. The results show that: (1) on the hourly time scale, G₀ in mulched soil is much smaller than that in non-mulched soil, day and night. This implies that mulch prevents energy going into the soil during the daytime and reduces soil heat loss at night. On the daily time scale, G₀ is similar in mulched and non-mulched soil. (2) During the seedling emergence period when the cotton is small, the energy balance closure over mulched soil (0.79) is slightly smaller than that over non-mulched soil (0.81). (3) Comparing to soil temperature in non-mulched soil, there’s a time offset on soil temperature in mulched soil at the same depth, which will bring a hysteresis on G₀ and SEB. Full article

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2102 KiB

Open AccessArticle

An Improved Iterative Fitting Method to Estimate Nocturnal Residual Layer Height

by Wei Wang, Wei Gong, Feiyue Mao and Zengxin Pan

Atmosphere 2016, 7(8), 106; https://doi.org/10.3390/atmos7080106 - 17 Aug 2016

Cited by 19 | Viewed by 5332

Abstract

The planetary boundary layer (PBL) is an atmospheric region near the Earth’s surface. It is significant for weather forecasting and for the study of air quality and climate. In this study, the top of nocturnal residual layers—which are what remain of the daytime [...] Read more.

The planetary boundary layer (PBL) is an atmospheric region near the Earth’s surface. It is significant for weather forecasting and for the study of air quality and climate. In this study, the top of nocturnal residual layers—which are what remain of the daytime mixing layer—are estimated by an elastic backscatter Lidar in Wuhan (30.5°N, 114.4°E), a city in Central China. The ideal profile fitting method is widely applied to determine the nocturnal residual layer height (RLH) from Lidar data. However, the method is seriously affected by an optical thick layer. Thus, we propose an improved iterative fitting method to eliminate the optical thick layer effect on RLH detection using Lidar. Two typical case studies observed by elastic Lidar are presented to demonstrate the theory and advantage of the proposed method. Results of case analysis indicate that the improved method is more practical and precise than profile-fitting, gradient, and wavelet covariance transform method in terms of nocturnal RLH evaluation under low cloud conditions. Long-term observations of RLH performed with ideal profile fitting and improved methods were carried out in Wuhan from 28 May 2011 to 17 June 2016. Comparisons of Lidar-derived RLHs with the two types of methods verify that the improved solution is practical. Statistical analysis of a six-year Lidar signal was conducted to reveal the monthly average values of nocturnal RLH in Wuhan. A clear RLH monthly cycle with a maximum mean height of about 1.8 km above ground level was observed in August, and a minimum height of about 0.7 km was observed in January. The variation in monthly mean RLH displays an obvious quarterly dependence, which coincides with the annual variation in local surface temperature. Full article

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2717 KiB

Open AccessArticle

Seasonal Variation of Nitrate Concentration and Its Direct Radiative Forcing over East Asia

by Jiawei Li and Zhiwei Han

Atmosphere 2016, 7(8), 105; https://doi.org/10.3390/atmos7080105 - 10 Aug 2016

Cited by 10 | Viewed by 4700

Abstract

This study investigated the seasonal variation of nitrate concentration and its radiative forcing over East Asia by using an online-coupled regional climate model. Comparison with a series of in-situ observations from Acid Deposition Monitoring Network in East Asia (EANET) and China demonstrated a [...] Read more.

This study investigated the seasonal variation of nitrate concentration and its radiative forcing over East Asia by using an online-coupled regional climate model. Comparison with a series of in-situ observations from Acid Deposition Monitoring Network in East Asia (EANET) and China demonstrated a good skill of the model in reproducing the magnitude and seasonality of nitrate concentration across East Asia. It was found that nitrate concentration in Beijing and Tianjin exhibited the maximum in summer and the minimum in winter possibly due to stronger chemical oxidation and regional transport effect of larger emissions from the north China Plain in summer, whereas in most areas of East Asia, nitrate concentration was higher in winter and lower in summer, consistent with the seasonality of NO_x emission. Surface nitrate concentration was higher over the lower reaches of the Yellow River, followed by the middle to lower reaches of the Yangtze River and portions of south China, and lower in Korean Peninsula and Japan. The annual mean surface nitrate concentration was predicted to be 2.9 μg·m⁻³ for East Asia and 8.5 μg·m⁻³ for east China. All-sky direct radiative forcing (DRF) due to nitrate at the top of the atmosphere (TOA) exhibited the largest forcing up to −7 W·m⁻² over the lower reaches of the Yellow River, and lower forcing of ~−2 W·m⁻² in the Korean Peninsula and Japan. Clear-sky DRF by nitrate reached the maximum in spring and the minimum in summer over both East Asia and east China, whereas DRF under all-sky condition showed its maximum in autumn, associated with seasonalities of nitrate column burden, relative humidity, and cloud effect. Annual mean all-sky DRFs at TOA were estimated to be −1.7 W·m⁻² and −3.7 W·m⁻² over East Asia and east China, respectively, significantly larger than global annual mean, suggesting the important role of nitrate aerosol in environment and climate change over East Asia. Full article

(This article belongs to the Special Issue Atmospheric Aerosols and Their Radiative Effects)

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1815 KiB

Open AccessArticle

Retention of Atmospheric Particles by Local Plant Leaves in the Mount Wutai Scenic Area, China

by Shuai Shi, Zhihui Wu, Fenwu Liu and Wenhua Fan

Atmosphere 2016, 7(8), 104; https://doi.org/10.3390/atmos7080104 - 08 Aug 2016

Cited by 7 | Viewed by 4919

Abstract

To evaluate the characteristics of atmospheric particle retention by plant leaves during the tourism season in Buddhism-based scenic areas, plants distributed in the core area of the Mount Wutai scenic area were selected for study: Populus davidiana (Po. davidiana), Rosa hugonis [...] Read more.

To evaluate the characteristics of atmospheric particle retention by plant leaves during the tourism season in Buddhism-based scenic areas, plants distributed in the core area of the Mount Wutai scenic area were selected for study: Populus davidiana (Po. davidiana), Rosa hugonis Hemsl. (R. hugonis), Betula platyphylla Suk. (B. platyphylla), Rosa xanthina Lindl. (R. xanthina), Periploca sepium Bunge (Pe. sepium), Spiraea salicifolia L. (S. salicifolia), Vitex negundo var. Heterophylla (V. negundo var. heterophylla) and Pinus tabuliformis Carrière (Pi. tabuliformis). Before rain, the atmospheric suspended particle-retaining weight of the plant leaves varied in the range of 6.95 ± 1.55 (Pi. tabuliformis) to 38.60 ± 18.32 mg/cm² (Po. davidiana); the light shaded areas caused by particles on leaves were in the range of 7.25 ± 0.04 (Pi. tabuliformis) to 126.50 ± 6.66 cm²/leaf (Po. davidiana); and the atmospheric particle-retaining horizontal density of leaves varied in the range of 110 ± 2 (Pi. tabuliformis) to 255 ± 11 per cm² (Po. davidiana). After rain, the atmospheric suspended particle-retaining quality of plant leaves varied in the range of 0.65 ± 0.23 (Pi. tabuliformis) to 3.50 ± 1.83 mg/cm² (Po. davidiana); the light shaded areas by particles on leaves were in the range of 4.26 ± 0.02 (Pi. tabuliformis) to 45.96 ± 2.42 cm²/leaf (Po. davidiana); and the atmospheric particle-retaining horizontal density of leaves was in the range of 97 ± 2 (Pi. tabuliformis) to 147 ± 7 per cm² (Po. davidiana). The broad-leaved plants, particularly Po. davidiana, R. hugonis and B. platyphylla, were appropriate species for purification of atmospheric particles. Plants with lower dust-retention abilities than the above three species (e.g., R. xanthina, Pe. sepium, S. salicifolia and V. negundo var. heterophylla) could be alternative plants for purification. However, the needle-leaved plant Pi. tabuliformis was not recommended as a tree species for purification of atmospheric particles in the core area of the Mount Wutai scenic area. Full article

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5993 KiB

Open AccessArticle

Investigation of the Optical Properties of Aerosols over the Coastal Region at Dalian, Northeast China

by Hujia Zhao, Huizheng Che, Yaqiang Wang, Hong Wang, Yanjun Ma, Yangfeng Wang and Xiaoye Zhang

Atmosphere 2016, 7(8), 103; https://doi.org/10.3390/atmos7080103 - 05 Aug 2016

Cited by 8 | Viewed by 4073

Abstract

Measurements of the aerosol optical depth (AOD) and the Ångström exponent were retrieved from level 1.5 data obtained by the CE318 sun photometer at Dalian monitoring station from April 2007 to April 2012 to characterize the aerosol spatial and temporal characteristics in this [...] Read more.

Measurements of the aerosol optical depth (AOD) and the Ångström exponent were retrieved from level 1.5 data obtained by the CE318 sun photometer at Dalian monitoring station from April 2007 to April 2012 to characterize the aerosol spatial and temporal characteristics in this coastal region of Northeast China. The results suggest that the highest mean ± SD value for the AOD over Dalian occurred in the month of July (0.86 ± 0.45), whereas a lower value was observed in the month of January (0.42 ± 0.31). The monthly mean Ångström exponent was at a maximum (about 1.27) in September and October and the minimum value of about 0.60 was recorded in March. The frequency distributions of the AOD and Ångström exponent at Dalian both presented a single peak distribution, with peak values of 0.26 and 1.06, respectively. The scatter grams of the AOD and Ångström exponent suggested that the aerosol size in Dalian was affected by both fine and coarse particles in different seasons. The spectral difference in Ångström exponent wavelength pairs between 440–675 and 675–870 nm indicate that high AOD_{440 nm} values (>1.50) could be clearly identified by the fine mode growth in summer and the addition of coarse mode particles in spring over Dalian. The AOD_{440 nm} value on a foggy day was almost 2.15 times larger than that on a day with high levels of dust. The Ångström exponents (440–870 nm) were about 0.13 and 1.46 on the days with high levels of dust and on the foggy days, respectively. Full article

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4949 KiB

Open AccessArticle

Water-Soluble Ionic Composition of Aerosols at Urban Location in the Foothills of Himalaya, Pokhara Valley, Nepal

by Lekhendra Tripathee, Shichang Kang, Dipesh Rupakheti, Qianggong Zhang, Jie Huang and Mika Sillanpää

Atmosphere 2016, 7(8), 102; https://doi.org/10.3390/atmos7080102 - 05 Aug 2016

Cited by 35 | Viewed by 6643

Abstract

The total suspended particulate (TSP) samples were collected from April 2013 to April 2014 at the urban location of Pokhara valley in western Nepal. The major aims were to study, quantify, and understand the concentrations and variations of TSP and major water-soluble inorganic [...] Read more.

The total suspended particulate (TSP) samples were collected from April 2013 to April 2014 at the urban location of Pokhara valley in western Nepal. The major aims were to study, quantify, and understand the concentrations and variations of TSP and major water-soluble inorganic ions (WSIIs) in the valley with limited data. The annual average TSP mass concentration was 135.50 ± 62.91 µg/m³. The average analyzed total WSIIs accounted for 14.4% of total TSP mass. Major anions and cations in TSP samples were SO₄²⁻ and Ca²⁺, respectively. Seasonal differences in atmospheric conditions explain the clear seasonal variations of ions, with higher concentrations during pre-monsoon and winter and lower concentrations during the monsoon period. Neutralization factor calculations suggested that Ca²⁺ in the Pokhara valley mostly neutralizes the acidity in the atmosphere. Principle component analysis, NO₃⁻/SO₄²⁻ ratio, and non-sea salt fraction calculations suggested that the WSIIs in the valley were mostly derived from anthropogenic activities and crustal mineral dust, which was also supported by the results from precipitation chemistry over the central Himalayas, Nepal. In addition, back trajectories analysis has suggested that the air pollution transported from and through Indo-Gangetic Plains (IGP) during the dry periods, which has resulted in high ionic loadings during this period. Average NO₃⁻/SO₄²⁻ ratio was found to be 0.69, indicating the dominance of stationary sources of TSP in Pokhara valley. Secondary inorganic aerosols can have an adverse health impact on the human population in the valley. The data set from this one-year study provides new insights into the composition of WSIIs in the foothills of the Himalayas, which can be of great importance for understanding the atmospheric environment in the region. Full article

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831 KiB

Open AccessArticle

GNSS Measurement of Rain Rate by Polarimetric Phase Shift: Theoretical Analysis

by Hao An, Wei Yan, Yunxian Huang, Weihua Ai, Yingqiang Wang, Xianbin Zhao and Xiaoying Huang

Atmosphere 2016, 7(8), 101; https://doi.org/10.3390/atmos7080101 - 05 Aug 2016

Cited by 5 | Viewed by 4140

Abstract

In this paper, a novel method for rain rate estimation is researched by polarimetric phase shift of the Global Navigation Satellite System (GNSS). The physical process of GNSS signals propagating through rain-filled medium is investigated, by which the cause of polarimetric phase shift [...] Read more.

In this paper, a novel method for rain rate estimation is researched by polarimetric phase shift of the Global Navigation Satellite System (GNSS). The physical process of GNSS signals propagating through rain-filled medium is investigated, by which the cause of polarimetric phase shift is explored. Then, a theoretical model between polarimetric phase shift

Δ ϕ

and rain rate R is established and simulated, which is based on the oblate spheroid raindrop model, four different popular raindrop size distribution models and raindrop canting angle distribution across the Space-Earth rain path. Additionally, effects of raindrop size distribution, rain path length, raindrop canting angle and temperature on the

Δ ϕ

-R relation are discussed systematically. Other factors in the slant path such as ice crystals, melting particles and ionosphere are also researched preliminarily. The results show that polarimetric phase shift of GNSS signals, which has a strong correlation with rain rate, can be used to estimate the rain rate, and these influencing factors, raindrop size distribution, rain path length, raindrop canting angle and temperature, are quite important in the process of rain rate measurement. It can be also found that the effect of ice crystals can be negligible, while that of melting particles should be considered, and though ionosphere effects are not obvious, the ionospheric anomalies cannot be neglected in future experiments. This method has potential applications in real-time, continuous, extreme precipitation reconnaissance and numerical weather prediction. Full article

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1966 KiB

Open AccessArticle

Effects of Mixed Phase Microphysical Process on Precipitation in a Simulated Convective Cloud

by Jing Sun, Zheng Shi, Jian Chai, Guirong Xu and Ben Niu

Atmosphere 2016, 7(8), 97; https://doi.org/10.3390/atmos7080097 - 29 Jul 2016

Cited by 7 | Viewed by 4682

Abstract

The effects of the liquid water content (LWC) and mixing ratio of hydrometeors in the simulation of convective precipitation in Wuhan, Hubei Province, China, are investigated using a three-dimensional convective rainstorm model. The microphysical processes of warm and cold clouds are considered into [...] Read more.

The effects of the liquid water content (LWC) and mixing ratio of hydrometeors in the simulation of convective precipitation in Wuhan, Hubei Province, China, are investigated using a three-dimensional convective rainstorm model. The microphysical processes of warm and cold clouds are considered into microphysical parameterization. The warm-cloud process is dominated by the combined effects of condensation and drop coalescence. The cold-cloud process is initiated mainly by production of graupel, and the microphysical parameterizations are used to predict the mixing ratio of cloud droplets, rain, ice crystals, snow, and graupel. The simulations results show that 80% rainfall is derived from warm cloud microphysical processes, and the rest is produced by cold cloud microphysical processes. The mixed phase microphysical process can invigorate the production of convective rainfall and enhance the liquid water content (LWC). In addition, the vertical distribution of LWC is mainly concentrated at the height isotherms of −10 to −20 °C in precipitation and the concentration area of LWC matches the distribution range of graupel particles. However, the growth of graupel particles depend on the microphysical processes of nucleation and propagation between rain and graupel particles (NUrg) and collision and coalescence between cloud droplets and graupel (CLcg), in which NUrg is a major source of graupel particles and the contribution of the process accounts for 77% of the amount of graupel particles. Full article

(This article belongs to the Special Issue Advances in Clouds and Precipitation)

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1632 KiB

Open AccessArticle

Effects of Aerosols on Radiative Forcing and Climate Over East Asia With Different SO₂ Emissions

by Xiaoning Xie, Xiaodong Liu, Hongli Wang and Zhaosheng Wang

Atmosphere 2016, 7(8), 99; https://doi.org/10.3390/atmos7080099 - 28 Jul 2016

Cited by 11 | Viewed by 5683

Abstract

It is known that aerosol and precursor gas emissions over East Asia may be underestimated by 50% due to the absence of data on regional rural and township industries. As the most important element of anthropogenic emissions, sulphur dioxide (SO

_{2}

) can [...] Read more.

It is known that aerosol and precursor gas emissions over East Asia may be underestimated by 50% due to the absence of data on regional rural and township industries. As the most important element of anthropogenic emissions, sulphur dioxide (SO

_{2}

) can form sulfate aerosols through several chemical processes, thus affecting the regional and global climate. In this study, we use the Community Atmospheric Model 5.1 (CAM5.1) to investigate the effects of anthropogenic aerosols on radiative forcing and the climate over East Asia, taking into consideration various SO

_{2}

emission levels, including double the amount of SO

_{2}

emissions over East Asia. Numerical experiments are performed using high-resolution CAM5.1 with pre-industrial (PI) and present day (PD) aerosol emission levels, and with PD aerosol emission levels with double SO

_{2}

emissions over East Asia (PD2SO2). The simulated aerosol optical depth and surface sulfate concentrations over East Asia are significantly increased in PD2SO2, which is in better agreement with the observational results. The simulation results show extensive aerosol direct and indirect radiative forcing for PD−PI (the difference between PI and PD), which significantly weakens the large-scale intensity of the East Asian summer monsoon (EASM) and reduces the summer precipitation. Compared to PD, the aerosol direct radiative forcing is significantly increased in PD2SO2, whereas the aerosol indirect radiative forcing is markedly decreased due to the inhibition of cloud formation, especially over North China. The increase in aerosol direct radiative forcing and decrease in aerosol indirect radiative forcing result in insignificant changes in the total amount of aerosol radiative forcing. These results also show that the large-scale intensity of the EASM and the associated summer precipitation are insensitive to the doubling of current SO

_{2}

emissions. Full article

(This article belongs to the Special Issue Advances in Clouds and Precipitation)

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3260 KiB

Open AccessArticle

Potential Sources and Formations of the PM_2.5 Pollution in Urban Hangzhou

by Jian Wu, Chang Xu, Qiongzhen Wang and Wen Cheng

Atmosphere 2016, 7(8), 100; https://doi.org/10.3390/atmos7080100 - 28 Jul 2016

Cited by 38 | Viewed by 6300

Abstract

Continuous measurements of meteorological parameters, gaseous pollutants, particulate matters, and the major chemical species in PM_2.5 were conducted in urban Hangzhou from 1 September to 30 November 2013 to study the potential sources and formations of PM_2.5 pollution. The average PM [...] Read more.

Continuous measurements of meteorological parameters, gaseous pollutants, particulate matters, and the major chemical species in PM_2.5 were conducted in urban Hangzhou from 1 September to 30 November 2013 to study the potential sources and formations of PM_2.5 pollution. The average PM_2.5 concentration was 69 µg·m⁻³, ~97% higher than the annual concentration limit in the national ambient air quality standards (NAAQS) of China. Relative humidity (RH) and wind speed (WS) were two important factors responsible for the increase of PM_2.5 concentration, with the highest value observed under RH of 70%–90%. PM_2.5 was in good correlation with both NO₂ and CO, but not with SO₂, and the potential source contribution function (PSCF) results displayed that local emissions were important potential sources contributing to the elevated PM_2.5 and NO₂ in Hangzhou. Thus, local vehicle emission was suggested as a major contribution to the PM_2.5 pollution. Concentrations of NO₂ and CO significantly increased in pollution episodes, while the SO₂ concentration even decreased, implying local emission rather than region transport was the major source contributing to the formation of pollution episodes. The sum of SO₄²⁻, NO₃⁻, and NH₄⁺ accounted for ~50% of PM_2.5 in mass in pollution episodes and the NO₃⁻/EC ratios were significantly elevated, revealing that the formation of secondary inorganic species, particularly NO₃⁻, was an important contributor to the PM_2.5 pollution in Hangzhou. This study highlights that controlling local pollution emissions was essential to reduce the PM_2.5 pollution in Hangzhou, and the control of vehicle emission in particular should be further promoted in the future. Full article

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2731 KiB

Open AccessArticle

Source Apportionment of Sulfate and Nitrate over the Pearl River Delta Region in China

by Xingcheng Lu and Jimmy C. H. Fung

Atmosphere 2016, 7(8), 98; https://doi.org/10.3390/atmos7080098 - 27 Jul 2016

Cited by 25 | Viewed by 5252

Abstract

In this work, the Weather Research Forecast (WRF)–Sparse Matrix Operator Kernel Emission (SMOKE)–Comprehensive Air Quality Model with Extensions (CAMx) modeling system with particulate source apportionment technology (PSAT) module was used to study and analyze the source apportionment of sulfate and nitrate particulate matter [...] Read more.

In this work, the Weather Research Forecast (WRF)–Sparse Matrix Operator Kernel Emission (SMOKE)–Comprehensive Air Quality Model with Extensions (CAMx) modeling system with particulate source apportionment technology (PSAT) module was used to study and analyze the source apportionment of sulfate and nitrate particulate matter in the Pearl River Delta region (PRD). The results show that superregional transport was an important contributor for both sulfates and nitrates in all 10 cities in this region in both February (winter) and August (summer). Especially in February, the average super-regional contribution of sulfate and nitrate reached up to 80% and 56% respectively. For the local and regional source category, power plant emissions (coal-fired and oil-fired) and industry emissions were important for sulfate formation in this region. Industry emissions and mobile emissions are important for nitrate formation in this region. In August, the sum of these two sources contributed around over 60% of local and regional nitrate. The contributions from power plant emissions and marine emissions became important in August due to the southerly prevailing wind direction. Area sources and biogenic emissions were negligible for sulfate and nitrate formation in this region. Our results reveal that cross-province cooperation is necessary for control of sulfates and nitrates in this region. Full article

(This article belongs to the Special Issue Air Quality and Source Apportionment)

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4627 KiB

Open AccessArticle

Characteristics of Ultrafine Particles and Their Relationships with Meteorological Factors and Trace Gases in Wuhan, Central China

by Tianhao Zhang, Zhongmin Zhu, Wei Gong, Hao Xiang, Ying Li and Zhenzhen Cui

Atmosphere 2016, 7(8), 96; https://doi.org/10.3390/atmos7080096 - 23 Jul 2016

Cited by 12 | Viewed by 4801

Abstract

Ultrafine particles with a diameter below 1 μm are strongly linked to traffic and industrial emissions, causing a growing global health concern. In order to reveal the characteristics of ultrafine particles in central China, which makes up the sparse research in industrial cities [...] Read more.

Ultrafine particles with a diameter below 1 μm are strongly linked to traffic and industrial emissions, causing a growing global health concern. In order to reveal the characteristics of ultrafine particles in central China, which makes up the sparse research in industrial cities of a developing country, particle number concentrations (PNC) together with meteorological parameters and concentrations of trace gases were measured over one year in Wuhan. The number concentration of ultrafine particles peaked in winter and was the lowest in summer across the entire size range monitored. Further, particles with a diameter smaller than 30 nm increased dramatically in concentration with decreasing diameter. The monthly averaged number concentrations of particles discriminated in three size ranges formed a near- inverse parabolic distribution peaking in January. This trend is supported by a negative correlation between PNC and precipitation, temperature, and mixing layer height, which emphasizes the effect of these meteorological parameters on scouring, convection, and diffusion of particles. However, since wind not only disperses particulate matter but also brings in exogenous particles, wind speed plays an equivocal role in particle number concentrations. The diurnal analysis indicates that hourly measurements of trace gases concentrations could be used as a proxy for dense industrial activities and to reveal some complex chemical reactions. The results of this study offer reasonable estimations of particle impacts and provide references for policymaking of emission control in the industrial cities of developing countries. Full article

(This article belongs to the Special Issue Ultrafine Particles: Determination, Behavior and Human Health Effects)

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