scholarly journals ModelE2-TOMAS development and evaluation using aerosol optical depths, mass and number concentrations

2014 ◽  
Vol 7 (5) ◽  
pp. 5831-5918 ◽  
Author(s):  
Y. H. Lee ◽  
P. J. Adams ◽  
D. T. Shindell
Keyword(s):  
Organic Matter ◽  
General Circulation ◽  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Circulation Model ◽  
Convective Transport ◽  
Sea Salt ◽  
Computationally Efficient ◽  
Anthropogenic Aerosol ◽  
Aerosol Model

Abstract. The TwO-Moment Aerosol Sectional microphysics model (TOMAS) has been integrated into the state-of-the-art general circulation model, GISS ModelE2. TOMAS has the flexibility to select a size resolution as well as the lower size cutoff. A computationally efficient version of TOMAS is used here, which has 15 size bins covering 3 nm to 10 μm aerosol dry diameter. For each bin, it simulates the total aerosol number concentration and mass concentrations of sulphate, pure elementary carbon (hydrophobic), mixed elemental carbon (hydrophilic), hydrophobic organic matter, hydrophilic organic matter, sea salt, mineral dust, ammonium, and aerosol-associated water. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the TOMAS model is compared to the default aerosol model in ModelE2, which is a bulk aerosol model. Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement with observations of sulphur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as the bulk aerosol model) cannot capture the observed vertical distribution of sulphur dioxide over the Pacific Ocean possibly due to overly strong convective transport. The TOMAS model successfully captures observed aerosol number concentrations and cloud condensation nuclei concentrations. Anthropogenic aerosol burdens in the bulk aerosol model running in the same host model as TOMAS (ModelE2) differ by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. Larger differences are found for naturally emitted aerosols such as sea salt and mineral dust. With TOMAS, ModelE2 has three different aerosol models (the bulk aerosol model and modal-based aerosol microphysics model, MATRIX) and allows exploration of the uncertainties associated with aerosol modelling within the same host model, NASA GISS ModelE2.

scholarly journals Evaluation of the global aerosol microphysical ModelE2-TOMAS model against satellite and ground-based observations

2015 ◽  
Vol 8 (3) ◽  
pp. 631-667 ◽  
Author(s):  
Y. H. Lee ◽  
P. J. Adams ◽  
D. T. Shindell
Keyword(s):  
General Circulation ◽  
Cloud Condensation Nuclei ◽  
Circulation Model ◽  
Convective Transport ◽  
Emission Rates ◽  
Anthropogenic Aerosol ◽  
Aerosol Model ◽  
Cloud Processing ◽  
Aerosol Mass ◽  
The Pacific

Abstract. The TwO-Moment Aerosol Sectional (TOMAS) microphysics model has been integrated into the state-of-the-art general circulation model, GISS ModelE2. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the ModelE2-TOMAS model is compared to the default aerosol model in ModelE2, which is a one-moment aerosol (OMA) model (i.e. no aerosol microphysics). Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement (mostly within a factor of 2) with observations of sulfur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as ModelE2-OMA) cannot capture the observed vertical distribution of sulfur dioxide over the Pacific Ocean, possibly due to overly strong convective transport and overpredicted precipitation. The ModelE2-TOMAS model simulates observed aerosol number concentrations and cloud condensation nuclei concentrations roughly within a factor of 2. Anthropogenic aerosol burdens in ModelE2-OMA differ from ModelE2-TOMAS by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. We observed larger differences for naturally emitted aerosols such as sea salt and mineral dust, as those emission rates are quite different due to different upper size cutoff assumptions.

scholarly journals The global aerosol–climate model ECHAM6.3–HAM2.3 – Part 1: Aerosol evaluation

2019 ◽  
Vol 12 (4) ◽  
pp. 1643-1677 ◽  
Author(s):  
Ina Tegen ◽  
David Neubauer ◽  
Sylvaine Ferrachat ◽  
Colombe Siegenthaler-Le Drian ◽  
Isabelle Bey ◽  
...  
Keyword(s):  
Climate Model ◽  
Mineral Dust ◽  
Sea Salt ◽  
Carbonaceous Aerosol ◽  
Anthropogenic Aerosol ◽  
Aerosol Model ◽  
Online Computation ◽  
Climate Interactions ◽  
Cloud Activation ◽  
Aerosol Emissions

Abstract. We introduce and evaluate aerosol simulations with the global aerosol–climate model ECHAM6.3–HAM2.3, which is the aerosol component of the fully coupled aerosol–chemistry–climate model ECHAM–HAMMOZ. Both the host atmospheric climate model ECHAM6.3 and the aerosol model HAM2.3 were updated from previous versions. The updated version of the HAM aerosol model contains improved parameterizations of aerosol processes such as cloud activation, as well as updated emission fields for anthropogenic aerosol species and modifications in the online computation of sea salt and mineral dust aerosol emissions. Aerosol results from nudged and free-running simulations for the 10-year period 2003 to 2012 are compared to various measurements of aerosol properties. While there are regional deviations between the model and observations, the model performs well overall in terms of aerosol optical thickness, but may underestimate coarse-mode aerosol concentrations to some extent so that the modeled particles are smaller than indicated by the observations. Sulfate aerosol measurements in the US and Europe are reproduced well by the model, while carbonaceous aerosol species are biased low. Both mineral dust and sea salt aerosol concentrations are improved compared to previous versions of ECHAM–HAM. The evaluation of the simulated aerosol distributions serves as a basis for the suitability of the model for simulating aerosol–climate interactions in a changing climate.

scholarly journals The aerosol-climate model ECHAM6.3-HAM2.3: Aerosol evaluation

2018 ◽  
Author(s):  
Ina Tegen ◽  
David Neubauer ◽  
Sylvaine Ferrachat ◽  
Colombe Siegenthaler-Le Drian ◽  
Isabelle Bey ◽  
...  
Keyword(s):  
Climate Model ◽  
Mineral Dust ◽  
Sea Salt ◽  
Carbonaceous Aerosol ◽  
Anthropogenic Aerosol ◽  
Aerosol Model ◽  
Online Computation ◽  
Climate Interactions ◽  
Cloud Activation ◽  
Aerosol Emissions

Abstract. We introduce and evaluate the aerosol simulations with the global aerosol-climate model ECHAM6.3-HAM2.3, which is the aerosol component of the fully coupled aerosol-chemistry-climate model ECHAM-HAMMOZ. Both the host atmospheric climate model ECHAM6.3 and the aerosol model HAM2.3 were updated from previous versions. The updated version of the HAM aerosol model contains improved parameterizations of aerosol processes such as cloud activation, as well as updated emission fields for anthropogenic aerosol species and modifications in the online computation of sea salt and mineral dust aerosol emissions. Aerosol results from nudged and free running simulations for the 10-year period 2003 to 2012 are compared to various measurements of aerosol properties. While there are regional deviations between model and observations, the model performs well overall in terms of aerosol optical thickness, but may underestimate coarse mode aerosol concentrations to some extent, so that the modeled particles are smaller than indicated by the observations. Sulfate aerosol measurements in the US and Europe are reproduced well by the model, while carbonaceous aerosol species are biased low. Both mineral dust and sea salt aerosol concentrations are improved compared to previous versions of ECHAM-HAM. The evaluation of the simulated aerosol distributions serves as a basis for the suitability of the model for simulating aerosol-climate interactions in a changing climate.

scholarly journals Climatic effects of 1950–2050 changes in US anthropogenic aerosols – Part 1: Aerosol trends and radiative forcing

2011 ◽  
Vol 11 (8) ◽  
pp. 24085-24125 ◽  
Author(s):  
E. M. Leibensperger ◽  
L. J. Mickley ◽  
D. J. Jacob ◽  
W.-T. Chen ◽  
J. H. Seinfeld ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
General Circulation ◽  
Transport Model ◽  
Circulation Model ◽  
Anthropogenic Sources ◽  
So2 Emissions ◽  
Anthropogenic Aerosols ◽  
Climatic Effects ◽  
Anthropogenic Aerosol ◽  
Direct Forcing

Abstract. We use the GEOS-Chem chemical transport model combined with the GISS general circulation model to calculate the aerosol direct and indirect (warm cloud) radiative forcings from US anthropogenic sources over the 1950–2050 period, based on historical emission inventories and future projections from the IPCC A1B scenario. The aerosol simulation is evaluated with observed spatial distributions and 1980–2010 trends of aerosol concentrations and wet deposition in the contiguous US. The radiative forcing from US anthropogenic aerosols is strongly localized over the eastern US. We find that it peaked in 1970–1990, with values over the eastern US (east of 100° W) of −2.0 W m−2 for direct forcing including contributions from sulfate (−2.0 W m−2), nitrate (−0.2 W m−2), organic carbon (−0.2 W m−2), and black carbon (+0.4 W m−2). The aerosol indirect effect is of comparable magnitude to the direct forcing. We find that the forcing declined sharply from 1990 to 2010 (by 0.8 W m−2 direct and 1.0 W m−2 indirect), mainly reflecting decreases in SO2 emissions, and project that it will continue declining post-2010 but at a much slower rate since US SO2 emissions have already declined by almost 60 % from their peak. This suggests that much of the warming effect of reducing US anthropogenic aerosol sources may have already been realized by 2010, however some additional warming is expected through 2020. The small positive radiative forcing from US BC emissions (+0.3 W m−2 over the eastern US in 2010) suggests that an emission control strategy focused on BC would have only limited climate benefit.

Nonlinear Climate and Hydrological Responses to Aerosol Effects

2009 ◽  
Vol 22 (6) ◽  
pp. 1329-1339 ◽  
Author(s):  
Yi Ming ◽  
V. Ramaswamy
Keyword(s):  
Surface Temperature ◽  
Northern Hemisphere ◽  
Indirect Effects ◽  
General Circulation ◽  
Cloud Condensation Nuclei ◽  
Circulation Model ◽  
Geophysical Fluid Dynamics Laboratory ◽  
High Latitudes ◽  
Hydrological Responses ◽  
Aerosol Effects

Abstract The equilibrium temperature and hydrological responses to the total aerosol effects (i.e., direct, semidirect, and indirect effects) are studied using a modified version of the Geophysical Fluid Dynamics Laboratory atmosphere general circulation model (AM2.1) coupled to a mixed layer ocean model. The treatment of aerosol–liquid cloud interactions and associated indirect effects is based upon a prognostic scheme of cloud droplet number concentration, with an explicit representation of cloud condensation nuclei activation involving sulfate, organic carbon, and sea salt aerosols. Increasing aerosols from preindustrial (1860) to present-day (1990) levels leads to a decrease of 1.9 K in the global annual mean surface temperature. The cooling is relatively strong over the Northern Hemisphere midlatitude land owing to the high aerosol burden there, while being amplified at high latitudes. When being subject to aerosols and radiatively active gases (i.e., well-mixed greenhouse gases and ozone) simultaneously, the model climate behaves nonlinearly; the simulated increase in surface temperature (0.55 K) is considerably less than the arithmetic sum of separate aerosol and gas effects (0.86 K). The thermal responses are accompanied by the nonlinear changes in cloud fields, which are amplified owing to the surface albedo feedback at high latitudes. The two effects completely offset each other in the Northern Hemisphere, while gas effect is dominant in the Southern Hemisphere. Both factors are crucial in shaping the regional responses. Interhemispheric asymmetry in aerosol-induced cooling yields a southward shift of the intertropical convergence zone, thus giving rise to a significant reduction in precipitation north of the equator, and an increase to the south. The simulations show that the change of precipitation in response to the simultaneous increases in aerosols and gases not only largely follows the same pattern as that for aerosols alone, but that it is also substantially strengthened in terms of magnitude south of 10°N. This is quite different from the damping expected from adding up individual responses, and further indicates the nonlinearity in the model’s hydrological response.

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.

scholarly journals Parameterization of convective transport in the boundary layer and its impact on the representation of the diurnal cycle of wind and dust emissions

2015 ◽  
Vol 15 (12) ◽  
pp. 6775-6788 ◽  
Author(s):  
F. Hourdin ◽  
M. Gueye ◽  
B. Diallo ◽  
J.-L. Dufresne ◽  
J. Escribano ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Diurnal Cycle ◽  
General Circulation ◽  
Surface Wind ◽  
Circulation Model ◽  
Convective Transport ◽  
Strong Nonlinearity ◽  
Thermal Plumes ◽  
Near Surface ◽  
Dust Emissions

Abstract. We investigate how the representation of the boundary layer in a climate model impacts the representation of the near-surface wind and dust emission, with a focus on the Sahel/Sahara region. We show that the combination of vertical turbulent diffusion with a representation of the thermal cells of the convective boundary layer by a mass flux scheme leads to realistic representation of the diurnal cycle of wind in spring, with a maximum near-surface wind in the morning. This maximum occurs when the thermal plumes reach the low-level jet that forms during the night at a few hundred meters above surface. The horizontal momentum in the jet is transported downward to the surface by compensating subsidence around thermal plumes in typically less than 1 h. This leads to a rapid increase of wind speed at surface and therefore of dust emissions owing to the strong nonlinearity of emission laws. The numerical experiments are performed with a zoomed and nudged configuration of the LMDZ general circulation model coupled to the emission module of the CHIMERE chemistry transport model, in which winds are relaxed toward that of the ERA-Interim reanalyses. The new set of parameterizations leads to a strong improvement of the representation of the diurnal cycle of wind when compared to a previous version of LMDZ as well as to the reanalyses used for nudging themselves. It also generates dust emissions in better agreement with current estimates, but the aerosol optical thickness is still significantly underestimated.

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