scholarly journals The aerosol-climate model ECHAM5-HAM

2005 ◽  
Vol 5 (4) ◽  
pp. 1125-1156 ◽  
Author(s):  
P. Stier ◽  
J. Feichter ◽  
S. Kinne ◽  
S. Kloster ◽  
E. Vignati ◽  
...  
Keyword(s):  
Size Distribution ◽  
Climate Model ◽  
Normal Modes ◽  
Anthropogenic Activity ◽  
Climate Modelling ◽  
Extensive Evaluation ◽  
Wide Range ◽  
Log Normal ◽  
Year 2000

Abstract. The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SU: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced.

scholarly journals The aerosol-climate model ECHAM5-HAM

2004 ◽  
Vol 4 (5) ◽  
pp. 5551-5623 ◽  
Author(s):  
P. Stier ◽  
J. Feichter ◽  
S. Kinne ◽  
S. Kloster ◽  
E. Vignati ◽  
...  
Keyword(s):  
Size Distribution ◽  
Climate Model ◽  
Normal Modes ◽  
Anthropogenic Activity ◽  
Climate Modelling ◽  
Extensive Evaluation ◽  
Wide Range ◽  
Log Normal ◽  
Year 2000

Abstract. The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SO4: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced.

scholarly journals Simulation of mineral dust aerosol with piecewise log-normal approximation (PLA) in CanAM4-PAM

2011 ◽  
Vol 11 (9) ◽  
pp. 26477-26520
Author(s):  
Y. Peng ◽  
K. von Salzen ◽  
J. Li
Keyword(s):  
Climate Model ◽  
Normal Approximation ◽  
Global Climate ◽  
Global Climate Model ◽  
Dust Aerosol ◽  
Radiative Properties ◽  
Fourth Generation ◽  
Surface Measurements ◽  
Log Normal ◽  
Year 2000

Abstract. A new size-resolved dust scheme based on the numerical method of piecewise log-normal approximation (PLA) was developed and implemented in the fourth generation of the Canadian Atmospheric Global Climate Model with the PLA Aerosol Module (CanAM4-PAM). The total simulated annual mean dust burden is 37.8 mg m−2 for year 2000, which is consistent with estimates from other models. Results from simulations are compared with multiple surface measurements near and away from dust source regions, validating the generation, transport and deposition of dust in the model. Most discrepancies between model results and surface measurements are due to unresolved aerosol processes. Radiative properties of dust aerosol are derived from approximated parameters in two size modes using Mie theory. The simulated aerosol optical depth (AOD) is compared with several satellite observations and shows good agreements. The model yields a dust AOD of 0.042 and total AOD of 0.126 for the year 2000. The simulated aerosol direct radiative forcings (ADRF) of dust and total aerosol over ocean are −1.24 W m−2 and −4.76 W m−2 respectively, which show good consistency with satellite estimates for the year 2001.

scholarly journals An Intermediate Complexity Climate Model (ICCM) based on the GFDL Flexible Modelling System

2009 ◽  
Vol 2 (1) ◽  
pp. 341-383
Author(s):  
R. Farneti ◽  
G. K. Vallis
Keyword(s):  
Climate Model ◽  
Ocean Model ◽  
Primitive Equations ◽  
Climate Modelling ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Intermediate Complexity ◽  
Wide Range ◽  
Ocean Atmosphere ◽  
Ice Model ◽  
Modelling System

Abstract. An intermediate complexity coupled ocean-atmosphere-land-ice model, based on the Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modelling System (FMS), has been developed to study mechanisms of ocean-atmosphere interactions and natural climate variability at interannual to interdecadal and longer time scales. The model uses the three-dimensional primitive equations for both ocean and atmosphere, but is simplified from a "state of the art" coupled model in two respects: it uses simplified physics and parameterisation schemes, especially in the atmosphere, and idealised geometry and geography. These simplifications provide considerable savings in computational expense and, perhaps more importantly, allow mechanisms to be investigated more cleanly and thoroughly than with a more elaborate model. For example, the model allows integrations of several millennia as well as broad parameter studies. For the ocean, the model uses the free surface primitive equations Modular Ocean Model (MOM) and the GFDL/FMS sea-ice model (SIS) is coupled to the oceanic grid. The atmospheric component consists of the FMS B-grid moist primitive equations atmospheric dynamical core with highly simplified physical parameterisations. A simple bucket model is implemented for our idealised land following the GFDL/FMS Land model. Here we describe the model components and present a climatology of coupled simulations achieved with two different geometrical configurations. Throughout the paper, we give a flavour of the potential for this model to be a powerful tool for the climate modelling community by mentioning a wide range of studies that are currently being explored.

scholarly journals Latitudinal aerosol size distribution variation in the Eastern Atlantic Ocean measured aboard the FS-Polarstern

2006 ◽  
Vol 6 (6) ◽  
pp. 12865-12893 ◽  
Author(s):  
P. I. Williams ◽  
G. McFiggans ◽  
M. W. Gallagher
Keyword(s):  
Size Distribution ◽  
Normal Modes ◽  
Aerosol Size Distribution ◽  
Wind Speeds ◽  
Eastern Atlantic Ocean ◽  
German Research ◽  
The Mean ◽  
A New Technique ◽  
Log Normal ◽  
Good Agreement

Abstract. Aerosol size distribution measurements from 0.03 μm to 25 μm diameter were taken at ambient humidity aboard the German research vessel, FS-Polarstern, during a transect from Bremerhaven in northern Germany, to Cape Town in South Africa across latitudes 53°32' N to 33°55' S, denoted cruise number ANT XXI/1. The data were segregated according to air mass history, wind speed and latitude. Under clean marine conditions, the averaged size distributions were generally in good agreement with those reported previously for diameters less than 0.5 μm and can be approximated by two log-normal modes, with significant variation in the mean modal diameters. Two short periods of tri-modal behaviour were observed. Above 0.5 μm, there is indication of a limit to the mechanical generation of marine aerosol over the range of wind speeds observed. A new technique to determine the errors associated with aerosol size distribution measurements using Poisson statistics has been applied to the dataset, providing a tool to determine the necessary sample or averaging times for correct interpretation of such data. Finally, the data were also used to investigate the loss rate of condensing gases with potentially important consequences for heterogeneous marine photochemical cycles.

scholarly journals In situ constraints on the vertical distribution of global aerosol

2019 ◽  
Vol 19 (18) ◽  
pp. 11765-11790 ◽  
Author(s):  
Duncan Watson-Parris ◽  
Nick Schutgens ◽  
Carly Reddington ◽  
Kirsty J. Pringle ◽  
Dantong Liu ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Upper Troposphere ◽  
Aerosol Forcing ◽  
Wide Range ◽  
Vertical Distributions ◽  
The Vertical Distribution ◽  
Unique Dataset

Abstract. Despite ongoing efforts, the vertical distribution of aerosols globally is poorly understood. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. Using the Global Aerosol Synthesis and Science Project (GASSP) database – the largest synthesised collection of in situ aircraft measurements currently available, with more than 1000 flights from 37 campaigns from around the world – we investigate the vertical structure of submicron aerosols across a wide range of regions and environments. The application of this unique dataset to assess the vertical distributions of number size distribution and cloud condensation nuclei (CCN) in the global aerosol–climate model ECHAM-HAM reveals that the model underestimates accumulation-mode particles in the upper troposphere, especially in remote regions. The processes underlying this discrepancy are explored using different aerosol microphysical schemes and a process sensitivity analysis. These show that the biases are predominantly related to aerosol ageing and removal rather than emissions.

scholarly journals An Intermediate Complexity Climate Model (ICCMp1) based on the GFDL flexible modelling system

2009 ◽  
Vol 2 (2) ◽  
pp. 73-88 ◽  
Author(s):  
R. Farneti ◽  
G. K. Vallis
Keyword(s):  
Climate Model ◽  
Ocean Model ◽  
Primitive Equations ◽  
Climate Modelling ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Intermediate Complexity ◽  
Wide Range ◽  
Ocean Atmosphere ◽  
Ice Model ◽  
Modelling System

Abstract. An intermediate complexity coupled ocean-atmosphere-land-ice model, based on the Geophysical Fluid Dynamics Laboratory (GFDL) Flexible Modelling System (FMS), has been developed to study mechanisms of ocean-atmosphere interactions and natural climate variability at interannual to interdecadal and longer time scales. The model uses the three-dimensional primitive equations for both ocean and atmosphere but is simplified from a "state of the art" coupled model by using simplified atmospheric physics and parameterisation schemes. These simplifications provide considerable savings in computational expense and, perhaps more importantly, allow mechanisms to be investigated more cleanly and thoroughly than with a more elaborate model. For example, the model allows integrations of several millennia as well as broad parameter studies. For the ocean, the model uses the free surface primitive equations Modular Ocean Model (MOM) and the GFDL/FMS sea-ice model (SIS) is coupled to the oceanic grid. The atmospheric component consists of the FMS B-grid moist primitive equations atmospheric dynamical core with highly simplified physical parameterisations. A simple bucket model is implemented for our idealised land following the GFDL/FMS Land model. The model is supported within the standard MOM releases as one of its many test cases and the source code is thus freely available. Here we describe the model components and present a climatology of coupled simulations achieved with two different geometrical configurations. Throughout the paper, we give a flavour of the potential for this model to be a powerful tool for the climate modelling community by mentioning a wide range of studies that are currently being explored.

scholarly journals Effective radiative forcing in the aerosol–climate model CAM5.3-MARC-ARG

2018 ◽  
Vol 18 (21) ◽  
pp. 15783-15810 ◽  
Author(s):  
Benjamin S. Grandey ◽  
Daniel Rothenberg ◽  
Alexander Avramov ◽  
Qinjian Jin ◽  
Hsiang-He Lee ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Climate Model ◽  
Regional Distribution ◽  
Normal Modes ◽  
Radiative Effect ◽  
Anthropogenic Aerosols ◽  
Cloud Radiative Effect ◽  
Log Normal ◽  
Aerosol Module ◽  
Aerosol Emissions

Abstract. We quantify the effective radiative forcing (ERF) of anthropogenic aerosols modelled by the aerosol–climate model CAM5.3-MARC-ARG. CAM5.3-MARC-ARG is a new configuration of the Community Atmosphere Model version 5.3 (CAM5.3) in which the default aerosol module has been replaced by the two-Moment, Multi-Modal, Mixing-state-resolving Aerosol model for Research of Climate (MARC). CAM5.3-MARC-ARG uses the ARG aerosol-activation scheme, consistent with the default configuration of CAM5.3. We compute differences between simulations using year-1850 aerosol emissions and simulations using year-2000 aerosol emissions in order to assess the radiative effects of anthropogenic aerosols. We compare the aerosol lifetimes, aerosol column burdens, cloud properties, and radiative effects produced by CAM5.3-MARC-ARG with those produced by the default configuration of CAM5.3, which uses the modal aerosol module with three log-normal modes (MAM3), and a configuration using the modal aerosol module with seven log-normal modes (MAM7). Compared with MAM3 and MAM7, we find that MARC produces stronger cooling via the direct radiative effect, the shortwave cloud radiative effect, and the surface albedo radiative effect; similarly, MARC produces stronger warming via the longwave cloud radiative effect. Overall, MARC produces a global mean net ERF of -1.79±0.03 W m−2, which is stronger than the global mean net ERF of -1.57±0.04 W m−2 produced by MAM3 and -1.53±0.04 W m−2 produced by MAM7. The regional distribution of ERF also differs between MARC and MAM3, largely due to differences in the regional distribution of the shortwave cloud radiative effect. We conclude that the specific representation of aerosols in global climate models, including aerosol mixing state, has important implications for climate modelling.

Are detailed urban canopy parameters necessary for modelling the urban climate in Africa?

2020 ◽  
Author(s):  
Oscar Brousse ◽  
Jonas Van de Walle ◽  
Lien Arnalsteen ◽  
Matthias Demuzere ◽  
Wim Thiery ◽  
...  
Keyword(s):  
Climate Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Sub Saharan Africa ◽  
Climate Modelling ◽  
Local Climate ◽  
African Cities ◽  
Local Climate Zones ◽  
The City

<p>Local Climate Zones (LCZ) have now been widely accepted and used by the urban climate community (Ching et al., 2018). However, their use over Sub-Saharan Africa has still been limited because of data scarcity in the region. Brousse et al. (2019, 2020) demonstrated the added value of applying spatially variant urban canyon parameters derived from LCZ in the urban climate model TERRA_URB – embedded in the COSMO-CLM model. Despite its promising results, thermal and morphological parameters extracted out of the ranges proposed by Stewart and Oke (2012) are mostly derived from Western cities. Hence, uncertainties related to the use of unascertained urban forms and functions of African cities for urban climate modelling have not yet been evaluated.</p><p>To quantify the sensitivity of the model to more representative urban canopy parameters of African cities, this study sets up a methodology for: (i) obtaining from in situ measurements archetypal parameters of LCZ classes for Kampala (Uganda); and (ii) simulating the potential effect of the newly defined urban structure on the local climate.</p><p>In situ data were obtained during field work held in the summer months of 2018. A representative sample of 1300 measurement points was selected throughout the city of Kampala, for which both quantitative (road width, distance between houses, heights of buildings) and qualitatively estimated (vegetation fraction, road-wall-roof material) variables were collected.  These variables enabled the development of an updated LCZ map of the city of Kampala.</p><p>To evaluate the model’s sensitivity to the new spatially explicit urban morphological and thermal parameters, this new information was fed into the TERRA_URB scheme at a horizontal resolution of 1 km for a 3-months period (December 2017 – February 2018). The run was nested within a 12 km simulation forced by ERA-Interim reanalysis data. Results show tangible effects of the updated parameters on the 2-meter air temperature, land surface temperature and surface energy balance components. Still, no major improvements in model skill compared to the default LCZ framework proposed by Brousse et al. (2020) were found. [1] [WT2] This study is among the first studies to test the sensitivity of an urban climate model to more realistic urban parameters in Africa and aims at triggering more research to be done in the area with a variety of urban climate models.</p>

scholarly journals In-situ constraints on the vertical distribution of global aerosol

2019 ◽  
Author(s):  
Duncan Watson-Parris ◽  
Nick Schutgens ◽  
Carly Reddington ◽  
Kirsty J. Pringle ◽  
Dantong Liu ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Upper Troposphere ◽  
Aerosol Forcing ◽  
Wide Range ◽  
Vertical Distributions ◽  
The Vertical Distribution ◽  
Unique Dataset

Abstract. Despite ongoing efforts, the vertical distribution of aerosols globally is poorly understood. This in turn leads to large uncertainties in the contributions of the direct and indirect aerosol forcing on climate. Using the Global Aerosol Synthesis and Science Project (GASSP) database – the largest synthesised collection of in-situ aircraft measurements currently available, with more than 1000 flights from 37 campaigns from around the world – we investigate the vertical structure of sub-micron aerosols across a wide range of regions and environments. The application of this unique dataset to assess the vertical distributions of number size distribution and Cloud Condensation Nuclei (CCN) in the global aerosol-climate model ECHAM-HAM reveals that the model underestimates accumulation mode particles in the upper troposphere, especially in remote regions. The processes underlying this discrepancy are explored using different aerosol microphysical schemes and a process sensitivity analysis. These show that the biases are predominantly related to aerosol ageing and removal rather than emissions.

scholarly journals Age Spectra and Other Transport Diagnostics in the North American Monsoon UTLS from SEAC<sup>4</sup>RS In Situ Trace Gas Measurements

2021 ◽  
Author(s):  
Eric A. Ray ◽  
Elliot L. Atlas ◽  
Sue Schauffler ◽  
Sofia Chelpon ◽  
Laura Pan ◽  
...  
Keyword(s):  
Climate Model ◽  
Monsoon Season ◽  
Trace Gas ◽  
North American Monsoon ◽  
Surface Source ◽  
The North ◽  
Source Regions ◽  
Wide Range ◽  
Gas Measurements

Abstract. The upper troposphere and lower stratosphere (UTLS) during the summer monsoon season over North America (NAM) is influenced by the transport of air from a variety of source regions over a wide range of time scales (hours to years). Age spectra are useful for characterizing the transport into such a region and in this study we use and build on recently developed techniques to infer age spectra from trace gas measurements with photochemical lifetimes from days to centuries. We show that the measurements taken by the Whole Air Sampler instrument during the SEAC4RS campaign can be used to not only derive age spectra, but also path-integrated lifetimes of each of the trace gases and surface source regions. The method used here can also clearly identify and adjust for measurement outliers that were influenced by polluted surface source regions. The results are generally consistent with expected transport features of the NAM but also provide a range of transport diagnostics that have not previously been computed solely from in situ measurements. These methods may be applied to many other existing in situ datasets and the transport diagnostics can be compared with chemistry-climate model transport in the UTLS.

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