Aerosol Optical Depth and Burden From Large Sea Salt Particles

2019 ◽  
Author(s):  
Ke‐ce Fei ◽  
Lin Wu ◽  
Qing‐cun Zeng
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Sea Salt

scholarly journals Modelling of nitrate and ammonium-containing aerosols in presence of sea salt

2006 ◽  
Vol 6 (12) ◽  
pp. 4809-4821 ◽  
Author(s):  
G. Myhre ◽  
A. Grini ◽  
S. Metzger
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Radiative Forcing ◽  
Transport Model ◽  
Meteorological Condition ◽  
Global Scale ◽  
Sea Salt ◽  
Aerosol Composition ◽  
Fine Mode ◽  
High Concentrations

Abstract. A thermodynamical model for treatment of gas/aerosol partitioning of semi volatile inorganic aerosols has been implemented in a global chemistry and aerosol transport model (Oslo CTM2). The sulphur cycle and sea salt particles have been implemented earlier in the Oslo CTM2 and the focus of this study is on nitrate partitioning to the aerosol phase and if particulate nitrate is expected to form in fine or coarse mode aerosols. Modelling of the formation of fine mode nitrate particles is complicated since it depends on other aerosol components and aerosol precursors as well as meteorological condition. The surface concentrations from the model are compared to observed surface concentrations at around 20 sites around Europe for nitrate and ammonium. The agreement for nitrate is good but the modelled values are somewhat underestimated compared to observations at high concentrations, whereas for ammonium the agreement is very good. However, we underscore that such a comparison is not of large importance for the aerosol optical depth of particulate nitrate since the vertical profile of aerosol components and their precursors are so important. Fine mode nitrate formation depends on vertical profiles of both ammonia/ammonium and sulphate. The model results show that fine mode particulate nitrate play a non-negligible role in the total aerosol composition in certain industrialized regions and therefore have a significant local radiative forcing. On a global scale the aerosol optical depth of fine mode nitrate is relatively small due to limited availability of ammonia and loss to larger sea salt particles. Inclusion of sea salt in the calculations reduces the aerosol optical depth and burden of fine mode nitrate by 25% on a global scale but with large regional variations.

scholarly journals Relationship between wind speed and aerosol optical depth over remote ocean

2010 ◽  
Vol 10 (13) ◽  
pp. 5943-5950 ◽  
Author(s):  
H. Huang ◽  
G. E. Thomas ◽  
R. G. Grainger
Keyword(s):  
Wind Speed ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Observation ◽  
Sea Salt ◽  
High Wind Speed ◽  
Sea Salt Aerosol ◽  
Linear Relationships ◽  
Speed Range ◽  
Highly Correlated

Abstract. The effect of wind speed on aerosol optical depth (AOD) at 0.55 μm over remote ocean regions is investigated. Remote ocean regions are defined by the combination of AOD from satellite observation and wind direction from ECMWF. According to our definition, many ocean regions cannot be taken as remote ocean regions due to long-range transportation of aerosol from continents. Highly correlated linear relationships are found in remote ocean regions with a wind speed range of 0–20 ms−1. The enhancement of AOD at high wind speed is explained as the increase of sea salt aerosol production.

scholarly journals The European aerosol budget in 2006

2010 ◽  
Vol 10 (9) ◽  
pp. 21391-21437 ◽  
Author(s):  
J. M. J. Aan de Brugh ◽  
M. Schaap ◽  
E. Vignati ◽  
F. Dentener ◽  
M. Kahnert ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Transport Model ◽  
Ground Level ◽  
Sea Salt ◽  
Optical Measurements ◽  
Aerosol Size Distribution ◽  
Anthropogenic Aerosols ◽  
Removal Rates ◽  
Wet Removal

Abstract. This paper presents the aerosol budget over Europe in 2006 calculated with the global transport model TM5 coupled to the size-resolved aerosol module M7. Comparison with ground observations indicates that the model reproduces the observed concentrations quite well with an expected slight underestimation of PM10 due to missing emissions (e.g. resuspension). We observe that a little less than half of the anthropogenic aerosols emitted in Europe are exported and the rest is removed by deposition. The anthropogenic aerosols are removed mostly by rain (95%) and only 5% is removed by dry deposition. For the larger natural aerosols, especially sea salt, a larger fraction is removed by dry processes (sea salt: 70%, mineral dust: 35%). We observe transport of aerosols in the jet stream in the higher atmosphere and an import of Sahara dust from the south at high altitudes. Comparison with optical measurements shows that the model reproduces the Ångström parameter very well, which indicates a correct simulation of the aerosol size distribution. However, we observe an underestimation of the aerosol optical depth. Because the surface concentrations are close to the observations, the shortage of aerosol in the model is probably at higher altitudes. We show that the discrepancies are mainly caused by an overestimation of wet-removal rates. To match the observations, the wet-removal rates have to be scaled down by a factor of about 5. In that case the modelled ground-level concentrations of sulphate and sea salt increase by 50% (which deteriorates the match), while other components stay roughly the same. Finally, it is shown that in particular events, improved fire emission estimates may significantly improve the ability of the model to simulate the aerosol optical depth. We stress that discrepancies in aerosol models can be adequately analysed if all models would provide (regional) aerosol budgets, as presented in the current study.

scholarly journals Aerosol Optical Depth of the Main Aerosol Species over Italian Cities Based on the NASA/MERRA-2 Model Reanalysis

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 709 ◽  
Author(s):  
Umberto Rizza ◽  
Enrico Mancinelli ◽  
Mauro Morichetti ◽  
Giorgio Passerini ◽  
Simone Virgili
Keyword(s):  
Air Quality ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Transport Model ◽  
Urban Air Pollution ◽  
Sea Salt ◽  
Anthropogenic Aerosols ◽  
National Scale ◽  
Global Coverage ◽  
Modern Era

The Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) provides data at 0.5° × 0.625° resolution covering a period from 1 January 1980 to the present. Natural and anthropogenic aerosols are simulated in MERRA-2, considering the Goddard chemistry, aerosol, radiation, and transport model. This model simulates the sources, sinks, and chemistry of mixed aerosol tracers: dust, sea salt, hydrophobic and hydrophilic black carbon and organic carbon, and sulfate. MERRA-2 aerosol reanalysis is a pioneering tool for investigating air quality issues, noteworthy for its global coverage and its distinction of aerosol speciation expressed in the form of aerosol optical depth (AOD). The aim of this work was to use the MERRA-2 reanalysis to study urban air pollution at a national scale by analyzing the AOD. AOD trends were evaluated for a 30-year period (1987–2017) over five Italian cities (Milan, Rome, Cagliari, Taranto, and Palermo) in order to investigate the impacts of urbanization, industrialization, air quality regulations, and regional transport on urban aerosol load. AOD evolution predicted by the MERRA-2 model in the period 2002–2017 showed a generalized decreasing trend over the selected cities. The anthropogenic signature on total AOD was between 50% and 80%, with the largest contribution deriving from sulfate.

scholarly journals Relationship between wind speed and aerosol optical depth over remote ocean

2009 ◽  
Vol 9 (6) ◽  
pp. 24511-24529 ◽  
Author(s):  
H. Huang ◽  
G. E. Thomas ◽  
R. G. Grainger
Keyword(s):  
Wind Speed ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Observation ◽  
Sea Salt ◽  
High Wind Speed ◽  
Sea Salt Aerosol ◽  
Linear Relationships ◽  
Speed Range ◽  
Highly Correlated

Abstract. The effect of wind speed on aerosol optical depth (AOD) at 550 nm over remote ocean regions is investigated. Remote ocean regions are defined by the combination of AOD from satellite observation and wind direction from ECMWF. According to our definition, many oceanic regions cannot be taken as remote ocean regions due to long-range transportation of aerosols from continents. Highly correlated linear relationships are found in remote ocean regions with a wind speed range of 4–20 ms−1. The enhancement of AOD at high wind speed is explained as the increase of sea salt aerosol production.

scholarly journals A 4-D climatology (1979–2009) of the monthly aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products

2012 ◽  
Vol 5 (6) ◽  
pp. 8469-8538 ◽  
Author(s):  
P. Nabat ◽  
S. Somot ◽  
M. Mallet ◽  
I. Chiapello ◽  
J. J. Morcrette ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Data ◽  
Mediterranean Region ◽  
Northern Africa ◽  
Sea Salt ◽  
Data Sets ◽  
Sulfate Aerosols ◽  
Aerosol Types

Abstract. Since the 1980s several spaceborne sensors have been used to retrieve the aerosol optical depth (AOD) over the Mediterranean region. In parallel, AOD climatologies coming from different numerical model simulations are now also available, permitting to distinguish the contribution of several aerosol types to the total AOD. In this work, we perform a comparative analysis of this unique multi-year database in terms of total AOD and of its apportionment by the five main aerosol types (soil dust, sea-salt, sulfate, black and organic carbon). We use 8 different satellite-derived monthly AOD products: NOAA/AVHRR, SeaWiFS, TERRA/MISR, TERRA/MODIS, AQUA/MODIS, ENVISAT/MERIS, PARASOL/POLDER and MSG/SEVIRI, as well as 3 more historical data sets: NIMBUS7/CZCS, NIMBUS7/TOMS and METEOSAT/MVIRI. Monthly model datasets include the aerosol climatology from Tegen et al. (1997), the climate-chemistry models LMDz-OR-INCA and RegCM-4, and the reanalyses GEMS and MACC. Ground-based Level-2 AERONET AOD observations from 47 stations around the basin are used here to evaluate the model and satellite data. The sensor MODIS (on AQUA and TERRA) has the best average AOD scores over this region, showing a relevant spatio-temporal variability and highlighting high dust loads over Northern Africa and the sea (spring and summer), and sulfate aerosols over continental Europe (summer). The comparison also shows limitations of certain data sets (especially MERIS and SeaWiFS standard products). Models reproduce the main patterns of the AOD variability over the basin. The MACC reanalysis is the closest to AERONET data but appears to underestimate dust over Northern Africa, where RegCM-4 is found closer to MODIS thanks to its interactive scheme for dust emissions. The vertical dimension is also investigated using the CALIOP instrument. This study confirms differences between dust aerosols which can be lifted up to 5000 m, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003–2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology. We extend the 2003–2009 reconstruction to the past up to 1979 using the 2003–2009 average and applying the decreasing trend in sulfate aerosols from the LMDz-OR-INCA model, based on the recent emission reconstruction proposed by Lamarque et al. (2010). Finally optical properties of the different aerosol types in this region are proposed from the literature so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

scholarly journals The European aerosol budget in 2006

2011 ◽  
Vol 11 (3) ◽  
pp. 1117-1139 ◽  
Author(s):  
J. M. J. Aan de Brugh ◽  
M. Schaap ◽  
E. Vignati ◽  
F. Dentener ◽  
M. Kahnert ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Transport Model ◽  
Ground Level ◽  
Sea Salt ◽  
Optical Measurements ◽  
Aerosol Size Distribution ◽  
Anthropogenic Aerosols ◽  
Removal Rates ◽  
Wet Removal

Abstract. This paper presents the aerosol budget over Europe in 2006 calculated with the global transport model TM5 coupled to the size-resolved aerosol module M7. Comparison with ground observations indicates that the model reproduces the observed concentrations quite well with an expected slight underestimation of PM10 due to missing emissions (e.g. resuspension). We model that a little less than half of the anthropogenic aerosols emitted in Europe are exported and the rest is removed by deposition. The anthropogenic aerosols are removed mostly by rain (95%) and only 5% is removed by dry deposition. For the larger natural aerosols, especially sea salt, a larger fraction is removed by dry processes (sea salt: 70%, mineral dust: 35%). We model transport of aerosols in the jet stream in the higher atmosphere and an import of Sahara dust from the south at high altitudes. Comparison with optical measurements shows that the model reproduces the Ångström parameter very well, which indicates a correct simulation of the aerosol size distribution. However, we underestimate the aerosol optical depth. Because the surface concentrations are close to the observations, the shortage of aerosol in the model is probably at higher altitudes. We show that the discrepancies are mainly caused by an overestimation of wet-removal rates. To match the observations, the wet-removal rates have to be scaled down by a factor of about 5. In that case the modelled ground-level concentrations of sulphate and sea salt increase by 50% (which deteriorates the match), while other components stay roughly the same. Finally, it is shown that in particular events, improved fire emission estimates may significantly improve the ability of the model to simulate the aerosol optical depth. We stress that discrepancies in aerosol models can be adequately analysed if all models would provide (regional) aerosol budgets, as presented in the current study.

scholarly journals A 4-D climatology (1979–2009) of the monthly tropospheric aerosol optical depth distribution over the Mediterranean region from a comparative evaluation and blending of remote sensing and model products

2013 ◽  
Vol 6 (5) ◽  
pp. 1287-1314 ◽  
Author(s):  
P. Nabat ◽  
S. Somot ◽  
M. Mallet ◽  
I. Chiapello ◽  
J. J. Morcrette ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Satellite Data ◽  
Mediterranean Region ◽  
Northern Africa ◽  
Sea Salt ◽  
Sulfate Aerosols ◽  
The Mediterranean ◽  
Aerosol Types

Abstract. Since the 1980s several spaceborne sensors have been used to retrieve the aerosol optical depth (AOD) over the Mediterranean region. In parallel, AOD climatologies coming from different numerical model simulations are now also available, permitting to distinguish the contribution of several aerosol types to the total AOD. In this work, we perform a comparative analysis of this unique multi-year database in terms of total AOD and of its apportionment by the five main aerosol types (soil dust, sea-salt, sulfate, black and organic carbon). We use 9 different satellite-derived monthly AOD products: NOAA/AVHRR, SeaWiFS (2 products), TERRA/MISR, TERRA/MODIS, AQUA/MODIS, ENVISAT/MERIS, PARASOL/POLDER and MSG/SEVIRI, as well as 3 more historical datasets: NIMBUS7/CZCS, TOMS (onboard NIMBUS7 and Earth-Probe) and METEOSAT/MVIRI. Monthly model datasets include the aerosol climatology from Tegen et al. (1997), the climate-chemistry models LMDz-OR-INCA and RegCM-4, the multi-model mean coming from the ACCMIP exercise, and the reanalyses GEMS and MACC. Ground-based Level-2 AERONET AOD observations from 47 stations around the basin are used here to evaluate the model and satellite data. The sensor MODIS (on AQUA and TERRA) has the best average AOD scores over this region, showing a relevant spatio-temporal variability and highlighting high dust loads over Northern Africa and the sea (spring and summer), and sulfate aerosols over continental Europe (summer). The comparison also shows limitations of certain datasets (especially MERIS and SeaWiFS standard products). Models reproduce the main patterns of the AOD variability over the basin. The MACC reanalysis is the closest to AERONET data, but appears to underestimate dust over Northern Africa, where RegCM-4 is found closer to MODIS thanks to its interactive scheme for dust emissions. The vertical dimension is also investigated using the CALIOP instrument. This study confirms differences of vertical distribution between dust aerosols showing a large vertical spread, and other continental and marine aerosols which are confined in the boundary layer. From this compilation, we propose a 4-D blended product from model and satellite data, consisting in monthly time series of 3-D aerosol distribution at a 50 km horizontal resolution over the Euro-Mediterranean marine and continental region for the 2003–2009 period. The product is based on the total AOD from AQUA/MODIS, apportioned into sulfates, black and organic carbon from the MACC reanalysis, and into dust and sea-salt aerosols from RegCM-4 simulations, which are distributed vertically based on CALIOP climatology. We extend the 2003–2009 reconstruction to the past up to 1979 using the 2003–2009 average and applying the decreasing trend in sulfate aerosols from LMDz-OR-INCA, whose AOD trends over Europe and the Mediterranean are median among the ACCMIP models. Finally optical properties of the different aerosol types in this region are proposed from Mie calculations so that this reconstruction can be included in regional climate models for aerosol radiative forcing and aerosol-climate studies.

scholarly journals A comparison of sea salt emission parameterizations in northwestern Europe using a chemistry transport model setup

2016 ◽  
Vol 16 (15) ◽  
pp. 9905-9933 ◽  
Author(s):  
Daniel Neumann ◽  
Volker Matthias ◽  
Johannes Bieser ◽  
Armin Aulinger ◽  
Markus Quante
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Wet Deposition ◽  
Transport Model ◽  
Deposition Velocity ◽  
Sea Salt ◽  
The North ◽  
Shaped Particle ◽  
The North Sea ◽  
Model Setup

Abstract. Atmospheric sea salt particles affect chemical and physical processes in the atmosphere. These particles provide surface area for condensation and reaction of nitrogen, sulfur, and organic species and are a vehicle for the transport of these species. Additionally, HCl is released from sea salt. Hence, sea salt has a relevant impact on air quality, particularly in coastal regions with high anthropogenic emissions, such as the North Sea region. Therefore, the integration of sea salt emissions in modeling studies in these regions is necessary. However, it was found that sea salt concentrations are not represented with the necessary accuracy in some situations.In this study, three sea salt emission parameterizations depending on different combinations of wind speed, salinity, sea surface temperature, and wave data were implemented and compared: GO03 (Gong, 2003), SP13 (Spada et al., 2013), and OV14 (Ovadnevaite et al., 2014). The aim was to identify the parameterization that most accurately predicts the sea salt mass concentrations at different distances to the source regions. For this purpose, modeled particle sodium concentrations, sodium wet deposition, and aerosol optical depth were evaluated against measurements of these parameters. Each 2-month period in winter and summer 2008 were considered for this purpose. The shortness of these periods limits generalizability of the conclusions on other years.While the GO03 emissions yielded overestimations in the PM10 concentrations at coastal stations and underestimations of those at inland stations, OV14 emissions conversely led to underestimations at coastal stations and overestimations at inland stations. Because of the differently shaped particle size distributions of the GO03 and OV14 emission cases, the deposition velocity of the coarse particles differed between both cases which yielded this distinct behavior at inland and coastal stations. The PM10 concentrations produced by the SP13 emissions generally overestimated the measured concentrations. The sodium wet deposition was generally underestimated by the model simulations but the SP13 cases yielded the least underestimations. Because the model tends to underestimate wet deposition, this result needs to be considered critically. Measurements of the aerosol optical depth (AOD) were underestimated by all model cases in the summer and partly in winter. None of the model cases clearly improved the modeled AODs. Overall, GO03 and OV14 produced the most accurate results, but both parameterizations revealed weaknesses in some situations.

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