Atmosphere

4934 KiB

Open AccessArticle

Satellite-Observed Transport of Dust to the East China Sea and the North Pacific Subtropical Gyre: Contribution of Dust to the Increase in Chlorophyll during Spring 2010

by Saichun Tan, Jiawei Li, Huiwang Gao, Hong Wang, Huizheng Che and Bin Chen

Atmosphere 2016, 7(11), 152; https://doi.org/10.3390/atmos7110152 - 23 Nov 2016

Cited by 21 | Viewed by 6309

Abstract

Multiple data sets were combined to investigate five dust storm events over East Asia in spring 2010 and their impacts on chlorophyll in the East China Sea (ECS) and the North Pacific Subtropical Gyre (NPSG). Satellite-observed column aerosol images were able to show [...] Read more.

Multiple data sets were combined to investigate five dust storm events over East Asia in spring 2010 and their impacts on chlorophyll in the East China Sea (ECS) and the North Pacific Subtropical Gyre (NPSG). Satellite-observed column aerosol images were able to show the spatial distribution of the transport of dust from the source regions to the two seas for some of the dust storm events. The CALIPSO satellite showed the vertical structure of dust aerosol for a greater number of dust storm events, including some weak events. This was confirmed by simulations of dust deposition and backward trajectories traced to dust source regions. The simulated dust deposition flux for five dust storms ranged from 13.0 to 145.6 mg·m⁻²·d⁻¹ in the ECS and from 0.6 to 5.5 mg·m⁻²·d⁻¹ in the NPSG, suggesting that the highest deposition was about one order of magnitude higher than the lowest. The estimated nutrients from dust showed that dust containing iron had the greatest effect on phytoplankton growth in both seas; the iron deposited by one dust storm event accounted for at least 5% of growth and satisfied the increase in demand required for chlorophyll a concentration. Full article

(This article belongs to the Special Issue Dust Storms and Associated Impacts to Human Health and the Environment)

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Figure 1

Figure 1
(a,b) Satellite-derived climatological annual chlorophyll a concentration from SeaWiFS (1997–2010) and MODIS (2002–2010) data, respectively. The contours labels are the annual mean surface concentrations of nitrate (a) and phosphate (b) from the World Ocean Atlas (2009). The rectangles labeled ECS (123°–129°E and 25°–32°N) and NPSG (160°E to 160°W and 13°–29°N) represent the two study regions. Full article ">Figure 2
(A) CALIPSO orbit tracks. Each track shown in different colors is labeled a1, a2, etc., and the date of each track is also shown. (B) Altitude-orbit cross-section of aerosol types for each satellite track in part (A); the bright yellow color represents dust aerosols. (C) Vertical profiles of averaged extinction coefficient at 532 nm (km−1) for dust aerosols. The colors of the profiles correspond to those in part (A). The altitude in parts (B) and (C) is above ground level. Full article ">Figure 3
(a,b) Daily aerosol index, aerosol optical depth (AOD) and coarse mode AOD over the East China Sea from 1 March to 31 August 2010; (c,d) daily aerosol index, AOD and coarse mode AOD over the North Pacific Subtropical Gyre; and (e,f) spatial distribution of aerosol index and AOD averaged during dust days. Black arrows represent mean NCEP/NCAR wind velocities during the period. Labels A and B in (e,f) show the Taklimakan Desert and the Gobi Desert, respectively. Label H shows high pressure center. The small rectangle shows the East China Sea (123°–129°E and 25°–32°N) and the big one shows the North Pacific Subtropical Gyre (160°E to 160°W and 13°–29°N). Full article ">Figure 4
Backward trajectories from the altitudes showing the locations of the dust aerosol observed by the CALIOP instrument; the range of altitudes is also shown. The colors of the tracks are the same as in <a href="#atmosphere-07-00152-f002" class="html-fig">Figure 2</a>A. ECS: East China Sea; NPSG: North Pacific Subtropical Gyre. Full article ">Figure 5
(a) Daily chlorophyll a concentration ((Chl), mg·m−3) and area of (Chl) higher than the spring climatological mean in the East China Sea. The three peaks of (Chl) are shown as peaks (1), (2), and (3). (b) Daily (Chl) and area of (Chl) higher than the background value in the North Pacific Subtropical Gyre. Green triangles show the start and end date of the bloom. The eight-day averaged sea surface temperature (SST) and photosynthetic available radiation (PAR) are also shown. Full article ">Figure 6
Daily or several-day averaged chlorophyll a concentrations (mg·m−3) in the East China Sea before, during and after the spring 2010 phytoplankton bloom. Full article ">Figure 7
Daily or several-day averaged chlorophyll a concentration (mg·m−3) in the North Pacific Subtropical Gyre before, during and after summer 2010 phytoplankton bloom. Full article ">Figure 8
Simulated total dust deposition (mg·m−2) in the East China Sea for 20–23 March 2010 (a); and the North Pacific Subtropical Gyre for 13–18 April 2010 (b). Full article ">

1521 KiB

Open AccessArticle

On the Momentum Transported by the Radiation Field of a Long Transient Dipole and Time Energy Uncertainty Principle

by Vernon Cooray and Gerald Cooray

Atmosphere 2016, 7(11), 151; https://doi.org/10.3390/atmos7110151 - 23 Nov 2016

Cited by 5 | Viewed by 5247

Abstract

The paper describes the net momentum transported by the transient electromagnetic radiation field of a long transient dipole in free space. In the dipole a current is initiated at one end and propagates towards the other end where it is absorbed. The results [...] Read more.

The paper describes the net momentum transported by the transient electromagnetic radiation field of a long transient dipole in free space. In the dipole a current is initiated at one end and propagates towards the other end where it is absorbed. The results show that the net momentum transported by the radiation is directed along the axis of the dipole where the currents are propagating. In general, the net momentum

P

transported by the electromagnetic radiation of the dipole is less than the quantity

U / c

, where

U

is the total energy radiated by the dipole and c is the speed of light in free space. In the case of a Hertzian dipole, the net momentum transported by the radiation field is zero because of the spatial symmetry of the radiation field. As the effective wavelength of the current decreases with respect to the length of the dipole (or the duration of the current decreases with respect to the travel time of the current along the dipole), the net momentum transported by the radiation field becomes closer and closer to

U / c

, and for effective wavelengths which are much shorter than the length of the dipole,

P \approx U / c

. The results show that when the condition

P \approx U / c

is satisfied, the radiated fields satisfy the condition

Δ t Δ U \geq h / 4 π

where

Δ t

is the duration of the radiation,

Δ U

is the uncertainty in the dissipated energy and

h

is the Plank constant. Full article

(This article belongs to the Special Issue Electromagnetic Fields and Waves with Special Attention to Lightning Flashes)

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1427 KiB

Open AccessArticle

Patterns of Dekadal Rainfall Variation Over a Selected Region in Lake Victoria Basin, Uganda

by Isaac Mugume, Michel D. S. Mesquita, Charles Basalirwa, Yazidhi Bamutaze, Joachim Reuder, Alex Nimusiima, Daniel Waiswa, Godfrey Mujuni, Sulin Tao and Triphonia Jacob Ngailo

Atmosphere 2016, 7(11), 150; https://doi.org/10.3390/atmos7110150 - 22 Nov 2016

Cited by 16 | Viewed by 9372

Abstract

Understanding variations in rainfall in tropical regions is important due to its impacts on water resources, health and agriculture. This study assessed the dekadal rainfall patterns and rain days to determine intra-seasonal rainfall variability during the March–May season using the Mann–Kendall ( [...] Read more.

Understanding variations in rainfall in tropical regions is important due to its impacts on water resources, health and agriculture. This study assessed the dekadal rainfall patterns and rain days to determine intra-seasonal rainfall variability during the March–May season using the Mann–Kendall (

M K

) trend test and simple linear regression (

S L R

) over the period 2000–2015. Results showed an increasing trend of both dekadal rainfall amount and rain days (third and seventh dekads). The light rain days (

S L R

= 0.181;

M K

= 0.350) and wet days (

S L R

= 0.092;

M K

= 0.118) also depict an increasing trend. The rate of increase of light rain days and wet days during the third dekad (light rain days:

S L R

= 0.020;

M K

= 0.279 and wet days:

S L R

= 0.146;

M K

= 0.376) was slightly greater than during the seventh dekad (light rain days:

S L R

= 0.014;

M K

= 0.018 and wet days:

S L R

= 0.061;

M K

= 0.315) dekad. Seventy-four percent accounted for 2–4 consecutive dry days, but no significant trend was detected. The extreme rainfall was increasing over the third (

M K

= 0.363) and seventh (

M K

= 0.429) dekads. The rainfall amount and rain days were highly correlated (r: 0.43–0.72). Full article

(This article belongs to the Special Issue Global Precipitation with Climate Change)

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4565 KiB

Open AccessArticle

Impact of Stratospheric Volcanic Aerosols on Age-of-Air and Transport of Long-Lived Species

by Giovanni Pitari, Irene Cionni, Glauco Di Genova, Daniele Visioni, Ilaria Gandolfi and Eva Mancini

Atmosphere 2016, 7(11), 149; https://doi.org/10.3390/atmos7110149 - 22 Nov 2016

Cited by 21 | Viewed by 5912

Abstract

The radiative perturbation associated to stratospheric aerosols from major explosive volcanic eruptions may induce significant changes in stratospheric dynamics. The aerosol heating rates warm up the lower stratosphere and cause a westerly wind anomaly, with additional tropical upwelling. Large scale transport of stratospheric [...] Read more.

The radiative perturbation associated to stratospheric aerosols from major explosive volcanic eruptions may induce significant changes in stratospheric dynamics. The aerosol heating rates warm up the lower stratosphere and cause a westerly wind anomaly, with additional tropical upwelling. Large scale transport of stratospheric trace species may be perturbed as a consequence of this intensified Brewer–Dobson circulation. The radiatively forced changes of the stratospheric circulation during the first two years after the eruption of Mt. Pinatubo (June 1991) may help explain the observed trend decline of long-lived greenhouse gases at surface stations (approximately −8 and −0.4 ppbv/year for CH₄ and N₂O, respectively). This decline is partly driven by the increased mid- to high-latitude downward flux at the tropopause and also by an increased isolation of the tropical pipe in the vertical layer near the tropopause, with reduced horizontal eddy mixing. Results from a climate-chemistry coupled model are shown for both long-lived trace species and the stratospheric age-of-air. The latter results to be younger by approximately 0.5 year at 30 hPa for 3–4 years after the June 1991 Pinatubo eruption, as a result of the volcanic aerosols radiative perturbation and is consistent with independent estimates based on long time series of in situ profile measurements of SF₆ and CO₂. Younger age of air is also calculated after Agung, El Chichón and Ruiz eruptions, as well as negative anomalies of the N₂O growth rate at the extratropical tropopause layer. This type of analysis is made comparing the results of two ensembles of model simulations (1960–2005), one including stratospheric volcanic aerosols and their radiative interactions and a reference case where the volcanic aerosols do not interact with solar and planetary radiation. Full article

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

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Graphical abstract

3909 KiB

Open AccessShort Note

Short-Term Effects of Drying and Rewetting on CO₂ and CH₄ Emissions from High-Altitude Peatlands on the Tibetan Plateau

by Xiaoyang Zeng and Yongheng Gao

Atmosphere 2016, 7(11), 148; https://doi.org/10.3390/atmos7110148 - 20 Nov 2016

Cited by 15 | Viewed by 4364

Abstract

This study used mesocosms to examine the effects of alternate drying and rewetting on CO₂ and CH₄ emissions from high-altitude peatlands on the Tibetan Plateau. The drying and rewetting experiment conducted in this study included three phases: a 10-day predrying phase, [...] Read more.

This study used mesocosms to examine the effects of alternate drying and rewetting on CO₂ and CH₄ emissions from high-altitude peatlands on the Tibetan Plateau. The drying and rewetting experiment conducted in this study included three phases: a 10-day predrying phase, a 32-day drying phase, and an 18-day rewetting phase. During the experiment, the water table varied between 0 and 50 cm with respect to the reference peat column where the water table stayed constant at 0 cm. The study found that drying and rewetting had no significant effect on CO₂ emissions from the peatland, while CH₄ emissions decreased. The cumulative CH₄ emissions in the control group was 2.1 times higher than in the drying and rewetting treatment over the study period. Moreover, CO₂ and CH₄ emissions were positively correlated with soil temperature, and the drying process increased the goodness of fit of the regression models predicting the relationships between CO₂ and CH₄ emissions and temperature. These results indicate that small-scale water table variation has a limited effect on CO₂ emissions, but might reduce CH₄ emissions in high-altitude peatlands on the Tibetan Plateau. Full article

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1826 KiB

Open AccessArticle

A Methodology to Reduce the Computational Effort in the Evaluation of the Lightning Performance of Distribution Networks

by Ilaria Bendato, Massimo Brignone, Federico Delfino, Renato Procopio and Farhad Rachidi

Atmosphere 2016, 7(11), 147; https://doi.org/10.3390/atmos7110147 - 20 Nov 2016

Cited by 7 | Viewed by 4148

Abstract

The estimation of the lightning performance of a power distribution network is of great importance to design its protection system against lightning. An accurate evaluation of the number of lightning events that can create dangerous overvoltages requires a huge computational effort, as it [...] Read more.

The estimation of the lightning performance of a power distribution network is of great importance to design its protection system against lightning. An accurate evaluation of the number of lightning events that can create dangerous overvoltages requires a huge computational effort, as it implies the adoption of a Monte Carlo procedure. Such a procedure consists of generating many different random lightning events and calculating the corresponding overvoltages. The paper proposes a methodology to deal with the problem in two computationally efficient ways: (i) finding out the minimum number of Monte Carlo runs that lead to reliable results; and (ii) setting up a procedure that bypasses the lightning field-to-line coupling problem for each Monte Carlo run. The proposed approach is shown to provide results consistent with existing approaches while exhibiting superior Central Processing Unit (CPU) time performances. Full article

(This article belongs to the Special Issue Electromagnetic Fields and Waves with Special Attention to Lightning Flashes)

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Figure 1
Geometry of the Multiconductor Transmission Line (MTL) system. Full article ">Figure 2
Distribution network topology for the three considered tests. Panels (a–c) show the networks for Test1, Test2, and Test3, respectively. Full article ">Figure 3
Graphical evolution of <math display="inline"> <semantics> <mrow> <msub> <mi>E</mi> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (a) and (b)), <math display="inline"> <semantics> <mrow> <msub> <mi>δ</mi> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (c) and (d)), confidence strip and <math display="inline"> <semantics> <mrow> <msub> <mover accent="true"> <mi>p</mi> <mo>¯</mo> </mover> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (e) and (f)) as a function of N for CFO = 150 kV. Full article ">Figure 3 Cont.
Graphical evolution of <math display="inline"> <semantics> <mrow> <msub> <mi>E</mi> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (a) and (b)), <math display="inline"> <semantics> <mrow> <msub> <mi>δ</mi> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (c) and (d)), confidence strip and <math display="inline"> <semantics> <mrow> <msub> <mover accent="true"> <mi>p</mi> <mo>¯</mo> </mover> <mi>N</mi> </msub> </mrow> </semantics> </math> (Panel (e) and (f)) as a function of N for CFO = 150 kV. Full article ">Figure 4
Comparison of the proposed approach with the ones in [<a href="#B3-atmosphere-07-00147" class="html-bibr">3</a>,<a href="#B4-atmosphere-07-00147" class="html-bibr">4</a>] in the evaluation of the lightning performance of a complex distribution network. Panels (a–c) show the results for Test1, Test2, and Test3, respectively. Full article ">Figure 5
Graphical representation of the domain D defined in Equations (15)–(17). Full article ">Figure 6
Comparison of the proposed approach performed on the original domain (blue) and on the reduced one (red). Panels (a–c) show the results for Test1, Test2, and Test3, respectively. Full article ">Figure 6 Cont.
Comparison of the proposed approach performed on the original domain (blue) and on the reduced one (red). Panels (a–c) show the results for Test1, Test2, and Test3, respectively. Full article ">

1927 KiB

Open AccessArticle

Characteristics of PM₁₀ Chemical Source Profiles for Geological Dust from the South-West Region of China

by Yayong Liu, Wenjie Zhang, Zhipeng Bai, Wen Yang, Xueyan Zhao, Bin Han and Xinhua Wang

Atmosphere 2016, 7(11), 146; https://doi.org/10.3390/atmos7110146 - 19 Nov 2016

Cited by 12 | Viewed by 5122

Abstract

Ninety-six particulate matter (PM₁₀) chemical source profiles for geological sources in typical cities of southwest China were acquired from Source Profile Shared Service in China. Twenty-six elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, [...] Read more.

Ninety-six particulate matter (PM₁₀) chemical source profiles for geological sources in typical cities of southwest China were acquired from Source Profile Shared Service in China. Twenty-six elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sn, Sb, Ba, Be, Tl and Pb), nine ions (F⁻, Cl⁻, SO₄²⁻, NO₃⁻, Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺), and carbon-containing species (organic carbon and elemental carbon) were determined to construct these profiles. Individual source profiles were averaged and compared to quantify similarities and differences in chemical abundances using the profile-compositing method. Overall, the major components of PM₁₀ in geological sources were crustal minerals and undefined fraction. Different chemical species could be used as tracers for various types of geological dust in the region that resulted from different anthropogenic influence. For example, elemental carbon, V and Zn could be used as tracers for urban paved road dust; Al, Si, K⁺ and NH₄⁺ for agricultural soil; Al and Si for natural soil; and SO₄²⁻ for urban resuspended dust. The enrichment factor analysis showed that Cu, Se, Sr and Ba were highly enriched by human activities in geological dust samples from south-west China. Elemental ratios were taken to highlight the features of geological dust from south-west China by comparing with northern urban fugitive dust, loess and desert samples. Low Si/Al and Fe/Al ratios can be used as markers to trace geological sources from southwestern China. High Pb/Al and Zn/Al ratios observed in urban areas demonstrated that urban geological dust was influenced seriously by non-crustal sources. Full article

(This article belongs to the Special Issue Dust Storms and Associated Impacts to Human Health and the Environment)

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34485 KiB

Open AccessArticle

Evaluation of Optimized WRF Precipitation Forecast over a Complex Topography Region during Flood Season

by Yuan Li, Guihua Lu, Zhiyong Wu, Hai He, Jun Shi, Yuexiong Ma and Shichuang Weng

Atmosphere 2016, 7(11), 145; https://doi.org/10.3390/atmos7110145 - 17 Nov 2016

Cited by 20 | Viewed by 6422

Abstract

In recent years, the Weather Research and Forecast (WRF) model has been utilized to generate quantitative precipitation forecasts with higher spatial and temporal resolutions. However, factors including horizontal resolution, domain size, and the physical parameterization scheme have a strong impact on the dynamic [...] Read more.

In recent years, the Weather Research and Forecast (WRF) model has been utilized to generate quantitative precipitation forecasts with higher spatial and temporal resolutions. However, factors including horizontal resolution, domain size, and the physical parameterization scheme have a strong impact on the dynamic downscaling ability of the WRF model. In this study, the influence of these factors has been analyzed in precipitation forecasting for the Xijiang Basin, southern China—a region with complex topography. The results indicate that higher horizontal resolutions always result in higher Critical Success Indexes (CSI), but higher biases as well. Meanwhile, the precipitation forecast skills are also influenced by the combination of microphysics parameterization scheme and cumulus convective parameterization scheme. On the basis of these results, an optimized configuration of the WRF model is built in which the horizontal resolution is 10 km, the microphysics parameterization is the Lin scheme, and the cumulus convective parameterization is the Betts–Miller–Janjic scheme. This configuration is then evaluated by simulating the daily weather during the 2013–2014 flood season. The high Critical Success Index scores and low biases at various thresholds and lead times confirm the high accuracy of the optimized WRF model configuration for Xijiang Basin. However, the performance of the WRF model varies from different sub-basins due to the complexity of the mesoscale convective system (MCS) over this region. Full article

(This article belongs to the Special Issue WRF Simulations at the Mesoscale: From the Microscale to Macroscale)

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1605 KiB

Open AccessArticle

Removal of Low-Molecular Weight Aldehydes by Selected Houseplants under Different Light Intensities and CO₂ Concentrations

by Jian Li, Chun-Juan Xie, Jing Cai, Liu-Shui Yan and Ming-Ming Lu

Atmosphere 2016, 7(11), 144; https://doi.org/10.3390/atmos7110144 - 11 Nov 2016

Cited by 3 | Viewed by 6258

Abstract

The removal of five low-molecular weight aldehydes by two houseplants (Schefflera octophylla (Lour.) Harms and Chamaedorea elegans) were investigated in a laboratory simulation environment with short-term exposure to different low light intensities and CO₂ concentrations. Under normal circumstances, the C [...] Read more.

The removal of five low-molecular weight aldehydes by two houseplants (Schefflera octophylla (Lour.) Harms and Chamaedorea elegans) were investigated in a laboratory simulation environment with short-term exposure to different low light intensities and CO₂ concentrations. Under normal circumstances, the C₁–C₅ aldehyde removal rates of Schefflera octophylla (Lour.) Harms and Chamaedorea elegans (Lour.) Harms ranged from 0.311 μmol/m²/h for valeraldehyde to 0.677 μmol/m²/h for formaldehyde, and 0.526 μmol/m²/h for propionaldehyde to 1.440 μmol/m²/h for formaldehyde, respectively. However, when the light intensities varied from 0 to 600 lx, a significant correlation between the aldehyde removal rate and the light intensity was found. Moreover, the CO₂ experiments showed that the total aldehyde removal rates of Schefflera octophylla (Lour.) Harms and Chamaedorea elegans (Lour.) Harms decreased 32.0% and 43.2%, respectively, with increasing CO₂ concentrations from 350 ppmv to 1400 ppmv. This might be explained by the fact that the excessive CO₂ concentration decreased the stomatal conductance which limited the carbonyl uptake from the stomata. Full article

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Figure 1
Scheme (a) and pictures (b,c) of the experimental apparatus for measuring the removal of aldehyde by plants. (A: pump; B: valve; C: flowmeter; D: Dinitrophenylhydrazine (DNPH)-Acid aqueous solution; E: activated charcoal; F: CO2 gas; G: aldehydes solution injection port; H: gas mixing bag; I: buffer vessel; J: gas sampling port; K: lamp; L: water tank; M: fan; N: potting-plant; O: exposure chamber. All apparatus were connected by Teflon tubes.) Full article ">Figure 2
SIM Ion: selective ion monitoring ion Gas Chromatograms of standard mixture of Pentafluorophenyl hydrazine (PFPH) derivatives. Peaks 0: PFPH; 1: formaldehyde; 2 and 2′: acetaldehyde; 3 and 3′: propionaldehyde; 4 and 4′: n-butyraldehyde; 5 and 5′: valeraldehyde; 6 and 6′: 4-fluorobenzaldehyde (IS). The numbers from 2′ to 6′ are the isomers of the corresponding aldehydes. Full article ">Figure 3
The mass spectrum of the PFPH-hydrazone derivatives of formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, and valeraldehyde. SIM Ion: selective ion monitoring ion; Qion: quantification ion. Full article ">Figure 4
The ratios of peak area derived from GC of C1–C5 aldehydes (Ai) to internal standard (As) from the inlet gas (white bars) and the outlet gas (grey bars) of the Schefflera octophylla (Lour.) Harms (a) and Chamaedorea elegans (Lour.) Harms (b), species enclosed in the chamber at light intensity of about 600 lx respectively. Mean ± S.E. are shown. Full article ">Figure 5
Relationship between the removal rate of C1–C5 aldehydes of the two houseplant species and the C1–C5 aldehydes concentration. (a) Schefflera octophylla (Lour.) Harms (R2 = 0.778~0.979); (b) Chamaedorea elegans. (R2 = 0.890~0.928) C1: Formaldehyde; C2: Acetaldehyde; C3: Propionaldehyde; C4: N-butyraldehyde; C5: Valeraldehyde. Significant differences for p < 0.05 are shown with least significant (LSD) test. Full article ">Figure 6
The removal rate of C1–C5 aldehydes of Schefflera octophylla (Lour.) Harms (a) and Chamaedorea elegans (Lour.) Harms (b). C1: formaldehyde; C2: acetaldehyde; C3: propionaldehyde; C4: N-butyraldehyde; C5: valeraldehyde. Significant differences for p < 0.05 are shown with least significant (LSD) test. Full article ">Figure 7
Relationship between the removal rates of C1–C5 aldehydes and the transpiration rate for the two houseplant species. (a) Schefflera octophylla (Lour.) Harms (R2 = 0.720–0.837); (b) Chamaedorea elegans (R2 = 0.607–0.932). C1: formaldehyde; C2: acetaldehyde; C3: propionaldehyde; C4: N-butyraldehyde; C5: valeraldehyde; transpiration rate was measured by weighing the whole plant before and after exposing to a specific light intensity according to previous research [<a href="#B49-atmosphere-07-00144" class="html-bibr">49</a>]. Significant differences for p < 0.05 are shown with least significant (LSD) test. Full article ">Figure 8
The removel capacity on formaldehyde, actealdehyde, propionaldehyde, n-butyraldehyde, valeraldehyde by (a) Schefflera octophylla (Lour.) Harms; and (b) Chamaedorea elegans (Lour.) Harms at three CO2 concentrations (350, 700, 1400 ppmv). C1: formaldehyde; C2: acetaldehyde; C3: propionaldehyde; C4: N-butyraldehyde; C5: valeraldehyde Means (n = 3) ± S.E. are shown. Significant differences for p < 0.05 are shown with least significant (LSD) test. Full article ">

3165 KiB

Open AccessArticle

The Effect of Freezing Drizzle, Sleet and Snow on Microphysical Characteristics of Supercooled Fog during the Icing Process in a Mountainous Area

by Yue Zhou, Shengjie Niu, Jingjing Lü and Yuehua Zhou

Atmosphere 2016, 7(11), 143; https://doi.org/10.3390/atmos7110143 - 11 Nov 2016

Cited by 7 | Viewed by 4573

Abstract

Both the similar and different effects of freezing drizzle, sleet and snow on microphysical properties of supercooled fog were analyzed for fourteen events during a comprehensive wire icing, fog, and precipitation observation experiment conducted at Enshi radar station (30°17′N, 109°16′E; 1722 m a.s.l.) [...] Read more.

Both the similar and different effects of freezing drizzle, sleet and snow on microphysical properties of supercooled fog were analyzed for fourteen events during a comprehensive wire icing, fog, and precipitation observation experiment conducted at Enshi radar station (30°17′N, 109°16′E; 1722 m a.s.l.) on a hilltop in Shibanling, Hubei, China. Liquid precipitation is in a relatively stable form in mountainous areas. Short-term precipitation (1–3 h) is dominant with temperature below 0 °C. The wet scavenging effect of freezing drizzle on small fog droplets with a size range less than 6–12 μm is weak but is stronger for fog droplets with a larger size, which is opposite to the effects of solid precipitation, broadening the fog droplet spectra significantly. As the fog droplet diameter increases, the distributions of droplet spectra change from leptokurtosis to platykurtosis and from positive skewness to negative skewness. Occurrence of freezing drizzle would improve the positive correlation of N-r in dissipation and oscillation periods, resulting in the N-r relationship having a weak negative correlation in the maturity period, and resulting in the transition of the N-L and N-r relationships into positive correlations in the development period. Meanwhile, the emergence of solid precipitation particles would result in negative values for the correlation coefficients of N-L and N-r. The change in relationships among the microphysical properties was caused by the occurrence of different phase precipitation, showing the influence on the main microphysical mechanisms of supercooled fog. Full article

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1739 KiB

Open AccessArticle

Bacterial and Fungal Aerosols in Rural Nursery Schools in Southern Poland

by Ewa Brągoszewska, Anna Mainka and Jozef S. Pastuszka

Atmosphere 2016, 7(11), 142; https://doi.org/10.3390/atmos7110142 - 9 Nov 2016

Cited by 33 | Viewed by 5612

Abstract

This study aimed to characterize airborne bacteria and fungi populations present in rural nursery schools in the Upper Silesia region of Poland during winter and spring seasons through quantification and identification procedures. Bacterial and fungal concentration levels and size distributions were obtained by [...] Read more.

This study aimed to characterize airborne bacteria and fungi populations present in rural nursery schools in the Upper Silesia region of Poland during winter and spring seasons through quantification and identification procedures. Bacterial and fungal concentration levels and size distributions were obtained by the use of a six-stage Andersen cascade impactor. Results showed a wide range of indoor bioaerosols levels. The maximum level of viable bacterial aerosols indoors was about 2600 CFU·m⁻³, two to three times higher than the outdoor level. Fungi levels were lower, from 82 to 1549 CFU·m⁻³, with indoor concentrations comparable to or lower than outdoor concentrations. The most prevalent bacteria found indoors were Gram-positive cocci (>65%). Using the obtained data, the nursery school exposure dose (NSED) of bioaerosols was estimated for both the children and personnel of nursery schools. The highest dose for younger children was estimated to range: 327–706 CFU·kg⁻¹ for bacterial aerosols and 31–225 CFU·kg⁻¹ for fungal aerosols. These results suggest an elevated risk of adverse health effects on younger children. These findings may contribute to the promotion and implementation of preventative public health programs and the formulation of recommendations aimed at providing healthier school environments. Full article

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301 KiB

Open AccessReview

Particulate Matter Emission Factors for Biomass Combustion

by Simone Simões Amaral, João Andrade de Carvalho, Maria Angélica Martins Costa and Cleverson Pinheiro

Atmosphere 2016, 7(11), 141; https://doi.org/10.3390/atmos7110141 - 31 Oct 2016

Cited by 51 | Viewed by 12655

Abstract

Emission factor is a relative measure and can be used to estimate emissions from multiple sources of air pollution. For this reason, data from literature on particulate matter emission factors from different types of biomass were evaluated in this paper. Initially, the main [...] Read more.

Emission factor is a relative measure and can be used to estimate emissions from multiple sources of air pollution. For this reason, data from literature on particulate matter emission factors from different types of biomass were evaluated in this paper. Initially, the main sources of particles were described, as well as relevant concepts associated with particle measurements. In addition, articles about particle emissions were classified and described in relation to the sampling environment (open or closed) and type of burned biomass (agricultural, garden, forest, and dung). Based on this analysis, a set of emission factors was presented and discussed. Important observations were made about the main emission sources of particulate matter. Combustion of compacted biomass resulted in lower particulate emission factors. PM_2.5 emissions were predominant in the burning of forest biomass. Emission factors were more elevated in laboratory burning, followed by burns in the field, residences and combustors. Full article

(This article belongs to the Special Issue Biomass Burning)

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2782 KiB

Open AccessArticle

Characteristics of Particulate Carbon in Precipitation during the Rainy Season in Xiamen Island, China

by Shuhui Zhao, Liqi Chen, Jinpei Yan, Peng Shi, Yun Li and Wei Li

Atmosphere 2016, 7(11), 140; https://doi.org/10.3390/atmos7110140 - 28 Oct 2016

Cited by 10 | Viewed by 4603

Abstract

Measuring wet deposition of organic carbon (OC) and elemental carbon (EC) aerosol is crucial for the understanding of their circulation and climate effect. To further understand the wet deposition of particulate carbon (OC and EC), precipitation samples were collected from April to August [...] Read more.

Measuring wet deposition of organic carbon (OC) and elemental carbon (EC) aerosol is crucial for the understanding of their circulation and climate effect. To further understand the wet deposition of particulate carbon (OC and EC), precipitation samples were collected from April to August 2014 on Xiamen Island in China. EC and water insoluble organic carbon (WIOC) concentrations were analyzed using a thermal optical method to investigate temporal variations and wet deposition fluxes. The average EC and WIOC concentrations were 7.3 μgC·L⁻¹ and 495.3 μgC·L⁻¹, respectively, which are both comparable to the results reported in European areas. EC and WIOC concentrations were higher in spring than in summer. Higher EC concentrations were found in April, which were probably associated with the transport of air masses from northern continental areas. Higher WIOC concentrations were found in May and were mainly attributed to air masses from the South China Sea. Lower concentrations of EC and WIOC in the summer were primarily due to the clean air masses transported from the ocean. The wet deposition flux was calculated as the product of concentration and precipitation amount. Average wet deposition fluxes of EC and WIOC were estimated to be 0.6 mgC·m⁻²·month⁻¹ and 36.7 mgC·m⁻²·month⁻¹, respectively. Wet deposition fluxes of EC and WIOC exhibited similar concentration trends. The largest flux in EC wet deposition occurred in April (1.8 mgC·m⁻²·month⁻¹), while the largest flux in WIOC wet deposition occurred in May (63.1 mgC·m⁻²·month⁻¹). Full article

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Atmosphere, Volume 7, Issue 11 (November 2016) – 13 articles

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