scholarly journals Impacts of long-range transported mineral dust on summertime convective cloud and precipitation: a case study over the Taiwan region

2021 ◽  
Author(s):  
Yanda Zhang ◽  
Fangqun Yu ◽  
Gan Luo ◽  
Jiwen Fan ◽  
Shuai Liu
Keyword(s):  
Long Range ◽  
Transport Model ◽  
Mineral Dust ◽  
Convective Cloud ◽  
Dust Particles ◽  
Chemical Transport Model ◽  
Dust Aerosols ◽  
Low Altitude ◽  
Water Contents

Abstract. As one of the most abundant atmospheric aerosols and effective ice nuclei, mineral dust particles affect clouds and precipitation in the Earth system. Here numerical experiments are carried out to investigate the impacts of dust aerosols on summertime convective clouds and precipitation over the mountainous region in Taiwan. We run the Weather Research and Forecasting model (WRF) coupled with the spectral-bin microphysics (SBM) and Morrison two-moment (Morr2) schemes at 3 km resolution, with the dust number concentrations from a global chemical transport model (GEOS-Chem-APM). The case study indicates that the long-range transported dust, with relatively low number concentrations, can notably affect the properties of convective cloud (ice/liquid water contents, cloud top height, and cloud coverage) and precipitation (spatial pattern and intensity). The dust effects are evident during the strong convective periods, significantly increasing the ice water contents in the mixed-phase regime via the enhanced heterogeneous freezing. With both the Morr2 and SBM schemes, we see invigoration effects of dust aerosols on the convective intensity through enhanced condensation and deposition latent heating. In this process, the low-altitude dust particles are uplifted to the freezing level by updrafts which, in turn, enhance the convective cloud development through immersion freezing and convective invigoration. Comparing to the Morr2 scheme, the SBM scheme predicts more realistic precipitation and different invigoration effects of dust. The differences are partially attributed to the saturation adjustment approach utilized in the bulk scheme, leading to the stronger enhancement of condensation at mid-low altitude and weaker deposition increase at the upper level.

scholarly journals Impacts of long-range-transported mineral dust on summertime convective cloud and precipitation: a case study over the Taiwan region

2021 ◽  
Vol 21 (23) ◽  
pp. 17433-17451
Author(s):  
Yanda Zhang ◽  
Fangqun Yu ◽  
Gan Luo ◽  
Jiwen Fan ◽  
Shuai Liu
Keyword(s):  
Long Range ◽  
Transport Model ◽  
Mineral Dust ◽  
Convective Cloud ◽  
Dust Particles ◽  
Chemical Transport Model ◽  
Dust Aerosols ◽  
Convective Clouds ◽  
Water Contents

Abstract. As one of the most abundant atmospheric aerosols and effective ice nuclei, mineral dust affects clouds and precipitation in the Earth system. Here numerical experiments are carried out to investigate the impacts of dust aerosols on summertime convective clouds and precipitation over the mountainous region of Taiwan by acting as ice-nucleating particles. We run the Weather Research and Forecasting model (WRF) with the Morrison two-moment and spectral-bin microphysics (SBM) schemes at 3 km resolution, using dust number concentrations from a global chemical transport model (GEOS-Chem-APM). The case study indicates that the long-range-transported mineral dust, with relatively low number concentrations, can notably affect the properties of convective clouds (ice and liquid water contents, cloud top height, and cloud coverage) and precipitation (spatial pattern and intensity). The effects of dust are evident during strong convective periods, with significantly increased ice water contents in the mixed-phase regime via the enhanced heterogeneous freezing. With both the Morrison and SBM schemes, we see the invigoration effects of dust aerosols on the convective intensity through enhanced condensation and deposition latent heating. The low-altitude dust particles are uplifted to the freezing level by updrafts, which, in turn, enhance the convective cloud development through immersion freezing and convective invigoration. Compared to the Morrison scheme, the SBM scheme predicts more realistic precipitation and different invigoration effects of dust. The differences are partially attributed to the saturation adjustment approach utilized in the bulk scheme, which leads to a stronger enhancement of condensation at midlatitudes to low altitudes and a weaker deposition increase at the upper level.

scholarly journals Influence of measurement uncertainties on soluble aerosol iron over the oceans

2015 ◽  
Vol 12 (17) ◽  
pp. 14377-14400 ◽  
Author(s):  
N. Meskhidze ◽  
M. S. Johnson ◽  
D. Hurley ◽  
K. Dawson
Keyword(s):  
Transport Model ◽  
Mineral Dust ◽  
Operational Definition ◽  
Dust Aerosol ◽  
Global Ocean ◽  
Dust Particles ◽  
Chemical Transport Model ◽  
Water Leaching ◽  
Wide Range ◽  
Flow Through

Abstract. The atmospheric supply of dust iron (Fe) plays a crucial role in the Earth's biogeochemical cycle and is of specific importance as a micronutrient in the marine environment. Observations show several orders of magnitude variability in the fractional solubility of Fe in dust aerosols, making it hard to assess the role of mineral dust for global ocean biogeochemical Fe cycle. In this study we compare the operational solubility of dust aerosol Fe associated with one of the flow-through leaching protocols to the results of the global 3-D chemical transport model GEOS-Chem. In the protocol aerosol Fe is defined soluble by first deionized water leaching of mineral dust through a 0.45 μm pore size membrane followed by acidification and storage of the leachate over a long period of time prior to the analysis. To assess the concentrations of soluble Fe inferred by this flow-through leaching protocol we are using in situ measurements of dust size distribution with the prescribed of 50 % fractional solubility of Fe in less than 0.45 μm sized dust particles collected in the leachate. In the model, the fractional solubility of Fe is either explicitly calculated using complex dust Fe dissolution module, or prescribed to be 1 and 4 %. Calculations show that the fractional solubility of Fe derived through the flow-through leaching is typically higher compared to the model results. The largest differences (>30 %) are predicted to occur farther away from the dust source regions, over the areas where sub-0.45 μm sized mineral dust particles contribute a larger fraction of the total dust mass. This study suggests that inconsistences in the operational definition of soluble Fe could contribute to the wide range of the fractional solubility of dust aerosol Fe reported in the literature.

scholarly journals Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

2013 ◽  
Vol 6 (1) ◽  
pp. 1901-1947 ◽  
Author(s):  
M. S. Johnson ◽  
N. Meskhidze
Keyword(s):  
Transport Model ◽  
Mineral Dust ◽  
Atmospheric Transport ◽  
Redox Cycling ◽  
Dust Particles ◽  
Dust Deposition ◽  
Chemical Transport Model ◽  
Cloud Processing ◽  
Form Model ◽  
Global Oceans

Abstract. Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe) to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed) deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust taking into account inorganic and organic (oxalate)-promoted Fe dissolution processes, photochemical redox cycling between ferric (Fe(III)) and ferrous (Fe(II)) forms of Fe, dissolution of three different Fe-containing minerals (hematite, goethite, and aluminosilicates), and detailed mineralogy of wind-blown dust from the major desert regions. Our calculations suggest that during the yearlong simulation ~ 0.26 Tg (1 Tg = 1012 g) of Fed was deposited to global oceanic regions. Compared to simulations only taking into account proton-promoted Fe dissolution, the addition of oxalate to the dust-Fe mobilization scheme increased total annual model-predicted Fed deposition to global oceanic regions by ~ 75%. The implementation of Fe(II)/Fe(III) photochemical redox cycling in the model allows for the distinction between different oxidation states of deposited Fed. Our calculations suggest that during the daytime, large fractions of Fed deposited to the global oceans is likely to be in Fe(II) form, while nocturnal fluxes of Fed are largely in Fe(III) form. Model simulations also show that atmospheric fluxes of Fed can be strongly influenced by the mineralogy of Fe-containing compounds. This study indicates that Fed deposition to the oceans is controlled by total dust-Fe mass concentrations, mineralogy, the surface area of dust particles, atmospheric chemical composition, cloud processing, and meteorological parameters and exhibits complex and spatiotemporally variable patterns. Our study suggests that the explicit model representation of individual processes leading to Fed production within mineral dust are needed to improve the understanding of the atmospheric Fe cycle, and quantify the effect of dust-Fe on ocean biological productivity, carbon cycle, and climate.

scholarly journals Atmospheric dissolved iron deposition to the global oceans: effects of oxalate-promoted Fe dissolution, photochemical redox cycling, and dust mineralogy

2013 ◽  
Vol 6 (4) ◽  
pp. 1137-1155 ◽  
Author(s):  
M. S. Johnson ◽  
N. Meskhidze
Keyword(s):  
Transport Model ◽  
Mineral Dust ◽  
Atmospheric Transport ◽  
Redox Cycling ◽  
Dust Particles ◽  
Dust Deposition ◽  
Chemical Transport Model ◽  
Cloud Processing ◽  
Form Model ◽  
Global Oceans

Abstract. Mineral dust deposition is suggested to be a significant atmospheric supply pathway of bioavailable iron (Fe) to Fe-depleted surface oceans. In this study, mineral dust and dissolved Fe (Fed) deposition rates are predicted for March 2009 to February 2010 using the 3-D chemical transport model GEOS-Chem implemented with a comprehensive dust-Fe dissolution scheme. The model simulates Fed production during the atmospheric transport of mineral dust, taking into account inorganic and organic (oxalate)-promoted Fe dissolution processes, photochemical redox cycling between ferric (Fe(III)) and ferrous (Fe(II)) forms of Fe, dissolution of three different Fe-containing minerals (hematite, goethite, and aluminosilicates), and detailed mineralogy of wind-blown dust from the major desert regions. Our calculations suggest that during the year-long simulation ~0.26 Tg (1 Tg = 1012 g) of Fed was deposited to global oceanic regions. Compared to simulations only taking into account proton-promoted Fe dissolution, the addition of oxalate and Fe(II)/Fe(III) redox cycling to the dust-Fe mobilization scheme increased total annual model-predicted Fed deposition to global oceanic regions by ~75%. The implementation of Fe(II)/Fe(III) photochemical redox cycling in the model also allows for the distinction between different oxidation states of deposited Fed. Our calculations suggest that during the daytime, large fractions of Fed deposited to the global oceans is likely to be in Fe(II) form, while nocturnal fluxes of Fed are largely in Fe(III) form. Model sensitivity simulations suggest Fed fluxes to the oceans can range from ~50% reduction to ~150% increase associated with the uncertainty in Fe-containing minerals commonly found in dust particles. This study indicates that Fed deposition to the oceans is controlled by total dust-Fe mass concentrations, mineralogy, the surface area of dust particles, atmospheric chemical composition, cloud processing, and meteorological parameters and exhibits complex and spatiotemporally variable patterns. Our study suggests that the explicit model representation of individual processes leading to Fed production within mineral dust are needed to improve the understanding of the atmospheric Fe cycle, and quantify the effect of dust-Fe on ocean biological productivity, carbon cycle, and climate.

scholarly journals Response of acid mobilization of iron-containing mineral dust to improvement of air quality projected in the future

2013 ◽  
Vol 13 (10) ◽  
pp. 28173-28223 ◽  
Author(s):  
A. Ito ◽  
L. Xu
Keyword(s):  
Air Quality ◽  
Environmental Changes ◽  
Transport Model ◽  
Mineral Dust ◽  
Chemical Transport Model ◽  
Iron Solubility ◽  
The Future ◽  
Northeastern Pacific ◽  
Combustion Aerosols ◽  
Quantitative Understanding

Abstract. Acidification of dust aerosols may increase aerosol iron (Fe) solubility, which is linked to mineral properties. Combustion aerosols can also elevate aerosol iron solubility when aerosol loading is low. Here, we use an atmospheric chemical transport model to investigate the deposition of filterable iron and its response to changes in anthropogenic emissions of both combustion aerosols and precursor gases. By introducing three classes of iron-containing minerals into the detailed aerosol chemistry model, we provide a theoretical examination of the effects of different dissolution behaviors on the acid mobilization of iron. Comparisons of modeled Fe dissolution curves with the measured dissolution rates for African (Tibesti) and Asian (Beijing) dust samples show overall good agreement under acidic conditions. The improved treatment of Fe in mineral dust and its dissolution scheme results in reasonable predictive capability for iron solubility over the oceans in the Northern Hemisphere. Our model results suggest that the improvement of air quality projected in the future will lead to a decrease of the filterable iron deposition from iron-containing mineral dust to the northeastern Pacific due to less acidification in Asian dust, which is mainly associated with the reduction of nitrogen oxides (NOx) emissions. These results could have important implications for iron fertilization of phytoplankton growth, and highlight the necessity of improving the process-based quantitative understanding of the response of the chemical modification in iron-containing minerals to environmental changes.

scholarly journals Long range transport of mercury to the Arctic and across Canada

2010 ◽  
Vol 10 (2) ◽  
pp. 4673-4717 ◽  
Author(s):  
D. Durnford ◽  
A. Dastoor ◽  
D. Figueras-Nieto ◽  
A. Ryjkov
Keyword(s):  
North America ◽  
Long Range ◽  
Transport Model ◽  
Extensive Study ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Long Range Transport ◽  
Chemical Transport Model ◽  
Transport Pathways ◽  
Range Transport

Abstract. This study is the most extensive study to date on the transport of mercury to the Arctic. Moreover, it is the first such study to use a fully-coupled, online chemical transport model, Environment Canada's Global/Regional Atmospheric Heavy Metals model (GRAHM), where the meteorology and mercury processes are fully integrated. It is also the only study to date on the transport of mercury across Canada. We determined source attribution from Asia, North America, Russia and Europe at six arctic verification stations, as well as three subarctic and eight midlatitude Canadian stations. We have found that Asia, despite having transport efficiencies that were almost always lower than those of North America and often lower than those of Russia, was the dominant source of gaseous atmospheric mercury at all verification stations: it contributed the most mercury (29–37% at all stations, seasons and levels considered), its concentrations frequently explained nearly 100% of the variability in the concentrations produced by the simulation performed with full global emissions, particularly in the absence of local sources, and it generated the most long range transport (LRT) events, causing 43%, 67% and 75% of the events at the arctic, subarctic and midlatitude stations, respectively. For the Arctic, Russian transport efficiencies tended to be the strongest, as expected, while European and Asian efficiencies were lower and higher, respectively, than those found in the literature. This disagreement is likely produced by mercury's long lifetime relative to that of other pollutants. The accepted springtime preference for the trans-Pacific transport of Asian pollution was evident only in the midlatitude group of stations, being masked in the arctic and subarctic groups by the occurrence of atmospheric mercury depletion events. Some neighbouring arctic stations recorded dissimilar numbers of LRT events; despite their proximity, the behaviour of mercury at these stations was governed by different dynamics and transport pathways. The column burden of GEM in the lowest 5 km of the Northern Hemisphere was largest in summer from Asia, North America and Russia, but in winter from Europe. In the vertical, transport of mercury from all source regions occurred principally in the mid-troposphere.

scholarly journals Interannual variability of long-range transport as seen at the Mt. Bachelor Observatory

2008 ◽  
Vol 8 (4) ◽  
pp. 16335-16379 ◽  
Author(s):  
D. R. Reidmiller ◽  
D. A. Jaffe ◽  
D. Chand ◽  
S. Strode ◽  
P. Swartzendruber ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Interannual Variability ◽  
Long Range ◽  
Biomass Burning ◽  
Transport Model ◽  
Long Range Transport ◽  
Naval Research ◽  
Chemical Transport Model ◽  
Northeast Pacific ◽  
Range Transport

Abstract. Interannual variations in background tropospheric trace gases (such as carbon monoxide, CO) are largely driven by variations in emissions (especially wildfires), transport pathways and tropospheric oxidizing capacity. Understanding this variability is essential to quantify the intercontinental contribution to US air quality. We investigate the interannual variability of long-range transport of Asian pollutants to the Northeast Pacific via measurements from the Mt. Bachelor Observatory (MBO: 43.98° N, 121.69° W; 2.7 km above sea level) and GEOS-Chem chemical transport model simulations in spring 2005 vs. the INTEX-B campaign during spring 2006. Measurements of CO at MBO were significantly enhanced during spring 2005 relative to the same time in 2006 (the INTEX-B study period); a monthly mean decline in CO of 41 ppbv was observed between April 2005 and April 2006. Meteorological indices show that long-range transport of CO from the heavily industrialized region of East Asia was significantly greater in 2005 than in 2006. In addition, spring 2005 was an anomalously strong biomass burning season in Southeast Asia. Data presented by Yurganov et al. (2008) using MOPITT satellite retrievals from this area reveal an average CO burden anomaly (referenced to March 2000–February 2002 mean values) between October 2004 through April 2005 of 2.6 Tg CO vs. 0.6 Tg CO for the same period a year later. The Naval Research Laboratory's global aerosol transport model shows that emissions from these fires were efficiently transported to MBO throughout April 2005. Asian dust transport, however, was substantially greater in 2006 than 2005, particularly in May. Monthly mean aerosol light scattering coefficient at 532 nm (σsp) at MBO more than doubled from 2.7 Mm−1 in May 2005 to 6.2 Mm−1 in May 2006. We also evaluate CO interannual variability throughout the western US via Earth System Research Laboratory ground site data and throughout the Northern Hemisphere via MOPITT and TES satellite observations. Both in the Northeast Pacific and on larger scales, we reveal a significant decrease (from 2–21%) in springtime maximum CO between 2005 and 2006, evident in all platforms and the GEOS-Chem model. We attribute this to (a) anomalously strong biomass burning in Southeast Asia during winter 2004 through spring 2005, and (b) the transport pattern in 2006 which limited the inflow of Asian pollution to the lower free troposphere over western North America.

scholarly journals Contributions of local and regional sources to fine PM in the megacity of Paris

2013 ◽  
Vol 13 (10) ◽  
pp. 25769-25799 ◽  
Author(s):  
K. Skyllakou ◽  
B. N. Murphy ◽  
A. G. Megaritis ◽  
C. Fountoukis ◽  
S. N. Pandis
Keyword(s):  
Particulate Matter ◽  
Long Range ◽  
Transport Model ◽  
Organic Aerosol ◽  
Photochemical Activity ◽  
Chemical Transport Model ◽  
Regional Sources ◽  
Range Transport ◽  
Local Sources ◽  
Local Emissions

Abstract. The Particulate Matter Source Apportionment Technology (PSAT) is used together with PMCAMx, a regional chemical transport model, to estimate how local emissions and pollutant transport affect primary and secondary particulate matter mass concentration levels in Paris. During the summer and the winter periods examined, only 13% of the PM2.5 is predicted to be due to local Paris emissions, with 36% coming from mid range (50–500 km from the center of the Paris) sources and 51% from long range transport (more than 500 km from Paris). The local emissions contribution to predicted elemental carbon (EC) is significant, with almost 60% of the EC originating from local sources during both summer and winter. Approximately 50% of the predicted fresh primary organic aerosol (POA) originated from local sources and another 45% from areas 100–500 km from the receptor region during summer. Regional sources dominated the secondary PM components. During summer more than 70% of the predicted sulfate originated from SO2 emitted more than 500 km away from the center of the Paris. Also more than 45% of secondary organic aerosol (SOA) was due to the oxidation of VOC precursors that were emitted 100–500 km from the center of the Paris. The model predicts more contribution from long range secondary PM sources during winter because the timescale for its production is longer due to the slower photochemical activity. PSAT results for contributions of local and regional sources were compared with observation-based estimates from field campaigns that took place during the MEGAPOLI project. PSAT predictions are in general consistent (within 20%) with these estimates for OA and sulfate. The only exception is that PSAT predicts higher local EC contribution during the summer compared to that estimated from observations.

scholarly journals Mineral Dust and Iron Solubility: Effects of Composition, Particle Size, and Surface Area

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 533
Author(s):  
Aurelie R. Marcotte ◽  
Ariel D. Anbar ◽  
Brian J. Majestic ◽  
Pierre Herckes
Keyword(s):  
Particle Size ◽  
Surface Area ◽  
Pure Iron ◽  
Mineral Dust ◽  
Dust Particles ◽  
Acidic Ph ◽  
Iron Solubility ◽  
Dust Aerosols ◽  
Iron Bearing ◽  
Mineral Dust Aerosols

There is significant iron deposition in the oceans, approximately 14–16 Tg annually from mineral dust aerosols, but only a small percentage (approx. 3%) of it is soluble and, thus, bioavailable. In this work, we examine the effect of mineralogy, particle size, and surface area on iron solubility in pure mineral phases to simulate atmospheric processing of mineral dust aerosols during transport. Pure iron-bearing minerals common to Saharan dust were partitioned into four size fractions (10–2.5, 2.5–1, 1–0.5, and 0.5–0.25 µm) and extracted into moderately acidic (pH 4.3) and acidic (pH 1.7) leaching media to simulate mineral processing during atmospheric transport. Results show that, in general, pure iron-bearing clay materials present an iron solubility (% dissolved Fe/total Fe in the mineral) an order of magnitude higher than pure iron oxide minerals. The relative solubility of iron in clay particles does not depend on particle size for the ranges examined (0.25–10 μm), while iron in hematite and magnetite shows a trend of increasing solubility with decreasing particle size in the acidic leaching medium. Our results indicate that while mineralogy and aerosol pH have an effect on the solubilization of iron from simulated mineral dust particles, surface processes of the aerosol might also have a role in iron solubilization during transport. The surface area of clay minerals does not change significantly as a function of particle size (10–0.25 µm), while the surface area of iron oxides is strongly size dependent. Overall, these results show how mineralogy and particle size can influence iron solubility in atmospheric dust.

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