scholarly journals Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere, Part I: model description, sea salt aerosols and pH

2008 ◽  
Vol 8 (2) ◽  
pp. 7217-7262 ◽  
Author(s):  
A. Kerkweg ◽  
P. Jöckel ◽  
A. Pozzer ◽  
H. Tost ◽  
R. Sander ◽  
...  
Keyword(s):  
Size Distribution ◽  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Reaction Rates ◽  
Sea Salt ◽  
Aerosol Size Distribution ◽  
Model Description ◽  
Aerosol Chemistry ◽  
Coarse Mode

Abstract. This is the first article of a series presenting a detailed analysis of bromine chemistry simulated with the atmospheric chemistry general circulation model ECHAM5/MESSy. Release from sea salt is an important bromine source, hence the model explicitly calculates aerosol chemistry and phase partitioning for coarse mode aerosol particles. Many processes including chemical reaction rates are influenced by the particle size distribution, and aerosol associated water strongly affects the aerosol pH. Knowledge of the aerosol pH is important as it determines the aerosol chemistry, e.g., the efficiency of sulphur oxidation and bromine release. Here, we focus on the simulated sea salt aerosol size distribution and the coarse mode aerosol pH. A comparison with available field data shows that the simulated aerosol distributions agree reasonably well within the range of measurements. In spite of the small number of aerosol pH measurements and the uncertainty in its experimental determination, the simulated aerosol pH compares well with the observations. The aerosol pH ranges from alkaline aerosol in areas of strong production down to pH values of 1 over regions of medium sea salt production and high levels of gas phase acids, mostly polluted regions over the oceans in the northern hemisphere.

scholarly journals Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere – Part 1: Model description, sea salt aerosols and pH

2008 ◽  
Vol 8 (19) ◽  
pp. 5899-5917 ◽  
Author(s):  
A. Kerkweg ◽  
P. Jöckel ◽  
A. Pozzer ◽  
H. Tost ◽  
R. Sander ◽  
...  
Keyword(s):  
Size Distribution ◽  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Reaction Rates ◽  
Sea Salt ◽  
Aerosol Size Distribution ◽  
Model Description ◽  
Aerosol Chemistry ◽  
Coarse Mode

Abstract. This is the first article of a series presenting a detailed analysis of bromine chemistry simulated with the atmospheric chemistry general circulation model ECHAM5/MESSy. Release from sea salt is an important bromine source, hence the model explicitly calculates aerosol chemistry and phase partitioning for coarse mode aerosol particles. Many processes including chemical reaction rates are influenced by the particle size distribution, and aerosol associated water strongly affects the aerosol pH. Knowledge of the aerosol pH is important as it determines the aerosol chemistry, e.g., the efficiency of sulphur oxidation and bromine release. Here, we focus on the simulated sea salt aerosol size distribution and the coarse mode aerosol pH. A comparison with available field data shows that the simulated aerosol distributions agree reasonably well within the range of measurements. In spite of the small number of aerosol pH measurements and the uncertainty in its experimental determination, the simulated aerosol pH compares well with the observations. The aerosol pH ranges from alkaline aerosol in areas of strong production down to pH-values of 1 over regions of medium sea salt production and high levels of gas phase acids, mostly polluted regions over the oceans in the Northern Hemisphere.

A New Instrument for Determining the Coarse-Mode Sea Salt Aerosol Size Distribution

2021 ◽  
Author(s):  
Chung Taing ◽  
Katherine L. Ackerman ◽  
Alison D. Nugent ◽  
Jorgen B. Jensen
Keyword(s):  
Size Distribution ◽  
Atmospheric Chemistry ◽  
Optical Microscope ◽  
Sea Salt ◽  
Aerosol Size Distribution ◽  
Sample Collection ◽  
Sea Salt Aerosol ◽  
Coarse Mode ◽  
New Instrument ◽  
Giant Nucleus

AbstractSea salt aerosol(s) (SSA) play a significant role in the atmosphere through aerosol direct and indirect effects, and in atmospheric chemistry as a source of tropospheric bromine. In-situ measurements of coarse-mode SSA particles are limited because of their low concentration and relatively large sizes (dry radius, rd > 0.5 μm). With this in mind, a new, low-cost, easily usable method for sampling coarse-mode SSA particles in the marine boundary layer was developed. A SSA particle sampler that uses an impaction method was designed and built using 3D printing and Arduino microcontrollers and sensors. It exposes polycarbonate slides to ambient airflow remotely on a kite-based platform to capture coarse-mode SSA particles. Because it is a smaller version of the Giant Nucleus Impactor (GNI), designed for use on aircraft, it is named the miniature-Giant Nucleus Impactor, or “mini-GNI”. After sample collection, the same optical microscope methodology utilized by the GNI was used to analyze the wetted salt particles that impacted onto the slides. In this proof-of-concept study, multiple mini-GNIs were attached serially to a kite string, allowing for sampling at multiple altitudes simultaneously. The robustness of the results from this new instrument and methodology for sampling at ambient RH (~ 75 %) the SSA particle size distribution with rd > 3.3 μ m are compared with a similar study. We find that the SSA particle number concentration decreases weakly with altitude and shows no correlation to instantaneous U10 wind speed along the windward coastline of O‘ ahu in the Hawaiian Islands.

scholarly journals Development of the global atmospheric chemistry general circulation model BCC-GEOS-Chem v1.0: model description and evaluation

2020 ◽  
Vol 13 (9) ◽  
pp. 3817-3838
Author(s):  
Xiao Lu ◽  
Lin Zhang ◽  
Tongwen Wu ◽  
Michael S. Long ◽  
Jun Wang ◽  
...  
Keyword(s):  
General Circulation Model ◽  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
General Circulation ◽  
Climate Models ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Circulation Model ◽  
Satellite Observations ◽  
Model Description

Abstract. Chemistry plays an indispensable role in investigations of the atmosphere; however, many climate models either ignore or greatly simplify atmospheric chemistry, limiting both their accuracy and their scope. We present the development and evaluation of the online global atmospheric chemical model BCC-GEOS-Chem v1.0, coupling the GEOS-Chem chemical transport model (CTM) as an atmospheric chemistry component in the Beijing Climate Center atmospheric general circulation model (BCC-AGCM). The GEOS-Chem atmospheric chemistry component includes detailed tropospheric HOx–NOx–volatile organic compounds–ozone–bromine–aerosol chemistry and online dry and wet deposition schemes. We then demonstrate the new capabilities of BCC-GEOS-Chem v1.0 relative to the base BCC-AGCM model through a 3-year (2012–2014) simulation with anthropogenic emissions from the Community Emissions Data System (CEDS) used in the Coupled Model Intercomparison Project Phase 6 (CMIP6). The model captures well the spatial distributions and seasonal variations in tropospheric ozone, with seasonal mean biases of 0.4–2.2 ppbv at 700–400 hPa compared to satellite observations and within 10 ppbv at the surface to 500 hPa compared to global ozonesonde observations. The model has larger high-ozone biases over the tropics which we attribute to an overestimate of ozone chemical production. It underestimates ozone in the upper troposphere which is likely due either to the use of a simplified stratospheric ozone scheme or to biases in estimated stratosphere–troposphere exchange dynamics. The model diagnoses the global tropospheric ozone burden, OH concentration, and methane chemical lifetime to be 336 Tg, 1.16×106 molecule cm−3, and 8.3 years, respectively, which is consistent with recent multimodel assessments. The spatiotemporal distributions of NO2, CO, SO2, CH2O, and aerosol optical depth are generally in agreement with satellite observations. The development of BCC-GEOS-Chem v1.0 represents an important step for the development of fully coupled earth system models (ESMs) in China.

scholarly journals A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC

2010 ◽  
Vol 3 (1) ◽  
pp. 321-328 ◽  
Author(s):  
A. J. G. Baumgaertner ◽  
P. Jöckel ◽  
B. Steil ◽  
H. Tost ◽  
R. Sander
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Reaction Rates ◽  
Heterogeneous Reactions ◽  
Tropospheric Chemistry ◽  
Box Model ◽  
Chemical Mechanism ◽  
Global Circulation Model ◽  
Stratospheric Chemistry

Abstract. The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx, and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM), and scavenging (substituting the existing submodel SCAV). We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.

scholarly journals Global aerosol modeling with MADE3 (v3.0) in EMAC (based on v2.53): model description and evaluation

2019 ◽  
Vol 12 (1) ◽  
pp. 541-579 ◽  
Author(s):  
J. Christopher Kaiser ◽  
Johannes Hendricks ◽  
Mattia Righi ◽  
Patrick Jöckel ◽  
Holger Tost ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Particle Deposition ◽  
Aerosol Particles ◽  
Circulation Model ◽  
Model Description ◽  
Size Spectrum ◽  
Near Surface ◽  
Station Network ◽  
Airborne Measurements

Abstract. Recently, the aerosol microphysics submodel MADE3 (Modal Aerosol Dynamics model for Europe, adapted for global applications, third generation) was introduced as a successor to MADE and MADE-in. It includes nine aerosol species and nine lognormal modes to represent aerosol particles of three different mixing states throughout the aerosol size spectrum. Here, we describe the implementation of the most recent version of MADE3 into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, including a detailed evaluation of a 10-year aerosol simulation with MADE3 as part of EMAC. We compare simulation output to station network measurements of near-surface aerosol component mass concentrations, to airborne measurements of aerosol mass mixing ratio and number concentration vertical profiles, to ground-based and airborne measurements of particle size distributions, and to station network and satellite measurements of aerosol optical depth. Furthermore, we describe and apply a new evaluation method, which allows a comparison of model output to size-resolved electron microscopy measurements of particle composition. Although there are indications that fine-mode particle deposition may be underestimated by the model, we obtained satisfactory agreement with the observations. Remaining deviations are of similar size to those identified in other global aerosol model studies. Thus, MADE3 can be considered ready for application within EMAC. Due to its detailed representation of aerosol mixing state, it is especially useful for simulating wet and dry removal of aerosol particles, aerosol-induced formation of cloud droplets and ice crystals as well as aerosol–radiation interactions. Besides studies on these fundamental processes, we also plan to use MADE3 for a reassessment of the climate effects of anthropogenic aerosol perturbations.

scholarly journals A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC

2010 ◽  
Vol 3 (1) ◽  
pp. 181-200
Author(s):  
A. J. G. Baumgaertner ◽  
P. Jöckel ◽  
B. Steil ◽  
H. Tost ◽  
R. Sander
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Reaction Rates ◽  
Heterogeneous Reactions ◽  
Tropospheric Chemistry ◽  
Box Model ◽  
Chemical Mechanism ◽  
Global Circulation Model ◽  
Stratospheric Chemistry

Abstract. The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM), and scavenging (substituting the existing submodel SCAV). We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.

scholarly journals Global aerosol modeling with MADE3 (v3.0) in EMAC (based on v2.53): model description and evaluation

2018 ◽  
Author(s):  
J. Christopher Kaiser ◽  
Johannes Hendricks ◽  
Mattia Righi ◽  
Patrick Jöckel ◽  
Holger Tost ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Particle Deposition ◽  
Aerosol Particles ◽  
Circulation Model ◽  
Model Description ◽  
Size Spectrum ◽  
Near Surface ◽  
Station Network ◽  
Airborne Measurements

Abstract. Recently, the aerosol microphysics submodel MADE3 was introduced as a successor to MADE and MADE-in. It includes nine aerosol species and nine lognormal modes to represent aerosol particles of three different mixing states throughout the aeroso size spectrum. Here we describe the implementation of the most recent version of MADE3 into the atmospheric chemistry general circulation model EMAC, including a detailed evaluation of a ten-year aerosol simulation with MADE3 as part of EMAC. We compare simulation output to station network measurements of near-surface aerosol component mass concentrations, to airborne measurements of aerosol mass mixing ratio and number concentration vertical profiles, to ground-based and airborne measurements of particle size distributions, and to station network and satellite measurements of aerosol optical depth. Furthermore, we describe and apply a new evaluation method, which allows a comparison of model output to size-resolved electron microscopy measurements of particle composition. Although there are indications that fine mode particle deposition may be underestimated by the model, we obtained satisfactory agreement with the observations. Remaining deviations are of similar size as those identified in other global aerosol model studies. Thus, MADE3 can be considered ready for application within EMAC. Due to its detailed representation of aerosol mixing state, it is especially useful for simulating wet and dry removal of aerosol particles, aerosol-induced formation of cloud droplets and ice crystals as well as aerosol-radiation interactions. Besides studies on these fundamental processes, we also plan to use MADE3 for a reassessment of the climate effects of anthropogenic aerosol perturbations.

scholarly journals Toward a minimal representation of aerosol direct and indirect effects: model description and evaluation

2011 ◽  
Vol 4 (4) ◽  
pp. 3485-3598 ◽  
Author(s):  
X. Liu ◽  
R. C. Easter ◽  
S. J. Ghan ◽  
R. Zaveri ◽  
P. Rasch ◽  
...  
Keyword(s):  
Developing Countries ◽  
Optical Properties ◽  
Size Distribution ◽  
Mineral Dust ◽  
Sea Salt ◽  
The Arctic ◽  
Aerosol Size Distribution ◽  
Model Description ◽  
Accumulation Mode ◽  
Model Version

Abstract. A modal aerosol module (MAM) has been developed for the Community Atmosphere Model version 5 (CAM5), the atmospheric component of the Community Earth System Model version 1 (CESM1). MAM is capable of simulating the aerosol size distribution and both internal and external mixing between aerosol components, treating numerous complicated aerosol processes and aerosol physical, chemical and optical properties in a physically based manner. Two MAM versions were developed: a more complete version with seven lognormal modes (MAM7), and a version with three lognormal modes (MAM3) for the purpose of long-term (decades to centuries) simulations. Major approximations in MAM3 include assuming immediate mixing of primary organic matter (POM) and black carbon (BC) with other aerosol components, merging of the MAM7 fine dust and fine sea salt modes into the accumulation mode, merging of the MAM7 coarse dust and coarse sea salt modes into the single coarse mode, and neglecting the explicit treatment of ammonia and ammonium cycles. Simulated sulfate and secondary organic aerosol (SOA) mass concentrations are remarkably similar between MAM3 and MAM7 as most (~90%) of these aerosol species are in the accumulation mode. Differences of POM and BC concentrations between MAM3 and MAM7 are also small (mostly within 10%) because of the assumed hygroscopic nature of POM, so that much of the freshly emitted POM and BC is wet-removed before mixing internally with soluble aerosol species. Sensitivity tests with the POM assumed to be hydrophobic and with slower aging increase the POM and BC concentrations, especially at high latitudes (by several times). The mineral dust global burden differs by 10% and sea salt burden by 30–40% between MAM3 and MAM7 mainly due to the different size ranges for dust and sea salt modes and different standard deviations of the log-normal size distribution for sea salt modes between MAM3 and MAM7. The model is able to qualitatively capture the observed geographical and temporal variations of aerosol mass and number concentrations, size distributions, and aerosol optical properties. However, there are noticeable biases, e.g., simulated sulfate and mineral dust concentrations at surface over the oceans are too low. Simulated BC concentrations are significantly lower than measurements in the Arctic. There is a low bias in modeled aerosol optical depth on the global scale, especially in the developing countries. There biases in aerosol simulations clearly indicate the need for improvements of aerosol processes (e.g., emission fluxes of anthropogenic aerosols and precursor gases in developing countries, boundary layer nucleation) and properties (e.g., primary aerosol emission size, POM hygroscopicity). In addition the critical role of cloud properties (e.g., liquid water content, cloud fraction) responsible for the wet scavenging of aerosol is highlighted.

scholarly journals Development of the global atmospheric general circulation-chemistry model BCC-GEOS-Chem v1.0: model description and evaluation

2019 ◽  
Author(s):  
Xiao Lu ◽  
Lin Zhang ◽  
Tongwen Wu ◽  
Michael S. Long ◽  
Jun Wang ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
General Circulation ◽  
Climate Models ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Circulation Model ◽  
Satellite Observations ◽  
Model Description ◽  
Atmospheric General Circulation

Abstract. Chemistry plays an indispensable role in investigations of the atmosphere, however, many climate models either ignore or greatly simplify atmospheric chemistry, limiting both their accuracy and their scope. We present the development and evaluation of the online global atmospheric chemical model BCC-GEOS-Chem v1.0, coupling the GEOS-Chem chemical transport model (CTM) as an atmospheric chemistry component in the Beijing Climate Center atmospheric general circulation model (BCC-AGCM). The GEOS-Chem atmospheric chemistry component includes detailed tropospheric HOx-NOx-VOC-ozone-bromine-aerosol chemistry and online dry and wet deposition schemes. We then demonstrate the new capabilities of BCC-GEOS-Chem v1.0 relative to the base BCC-AGCM model through a three-year (2012–2014) simulation with anthropogenic emissions from the Community Emissions Data System (CEDS) used in the Coupled Model Intercomparison Project Phase 6 (CMIP6). The model well captures the spatial distributions and seasonal variations in tropospheric ozone, with seasonal mean biases of 0.4–2.2 ppbv at 700–400 hPa compared to satellite observations and within 10 ppbv at the surface-500 hPa compared to global ozonesonde observations. The model has larger high ozone biases over the tropics which we attribute to an overestimate of ozone chemical production. It underestimates ozone in the upper troposphere which likely due to either the use of a simplified stratospheric ozone scheme and/or to biases in estimated stratosphere-troposphere exchange dynamics. The model diagnoses the global tropospheric ozone burden, OH concentration, and methane chemical lifetime to be 336 Tg, 1.16 × 106 molecule cm−3, and 8.3 years, respectively, consistent with recent multi-model assessments. The spatiotemporal distributions of NO2, CO, SO2, CH2O, and aerosols optical depth are generally in agreement with satellite observations. The development of BCC-GEOS-Chem v1.0 represents an important step for the development of fully coupled earth system models (ESMs) in China.

scholarly journals The Sectional Stratospheric Sulfate Aerosol module (S3A-v1) within the LMDZ general circulation model: description and evaluation against stratospheric aerosol observations

2017 ◽  
Vol 10 (9) ◽  
pp. 3359-3378 ◽  
Author(s):  
Christoph Kleinschmitt ◽  
Olivier Boucher ◽  
Slimane Bekki ◽  
François Lott ◽  
Ulrich Platt
Keyword(s):  
Atmospheric Chemistry ◽  
General Circulation ◽  
Circulation Model ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Climate Impacts ◽  
Radiative Heating ◽  
Model Description ◽  
Quasi Biennial Oscillation ◽  
Microphysical Processes

Abstract. Stratospheric aerosols play an important role in the climate system by affecting the Earth's radiative budget as well as atmospheric chemistry, and the capabilities to simulate them interactively within global models are continuously improving. It is important to represent accurately both aerosol microphysical and atmospheric dynamical processes because together they affect the size distribution and the residence time of the aerosol particles in the stratosphere. The newly developed LMDZ-S3A model presented in this article uses a sectional approach for sulfate particles in the stratosphere and includes the relevant microphysical processes. It allows full interaction between aerosol radiative effects (e.g. radiative heating) and atmospheric dynamics, including e.g. an internally generated quasi-biennial oscillation (QBO) in the stratosphere. Sulfur chemistry is semi-prescribed via climatological lifetimes. LMDZ-S3A reasonably reproduces aerosol observations in periods of low (background) and high (volcanic) stratospheric sulfate loading, but tends to overestimate the number of small particles and to underestimate the number of large particles. Thus, it may serve as a tool to study the climate impacts of volcanic eruptions, as well as the deliberate anthropogenic injection of aerosols into the stratosphere, which has been proposed as a method of geoengineering to abate global warming.

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