scholarly journals Implementation of the Community Earth System Model (CESM) version 1.2.1 as a new base model into version 2.50 of the MESSy framework

2016 ◽  
Vol 9 (1) ◽  
pp. 125-135 ◽  
Author(s):  
A. J. G. Baumgaertner ◽  
P. Jöckel ◽  
A. Kerkweg ◽  
R. Sander ◽  
H. Tost
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Model ◽  
The United States ◽  
Earth System Model ◽  
System Model ◽  
Climate Modelling ◽  
Earth System ◽  
Spectral Transform ◽  
Community Earth System Model ◽  
Component Models

Abstract. The Community Earth System Model (CESM1), maintained by the United States National Centre for Atmospheric Research (NCAR) is connected with the Modular Earth Submodel System (MESSy). For the MESSy user community, this offers many new possibilities. The option to use the Community Atmosphere Model (CAM) atmospheric dynamical cores, especially the state-of-the-art spectral element (SE) core, as an alternative to the ECHAM5 spectral transform dynamical core will provide scientific and computational advances for atmospheric chemistry and climate modelling with MESSy. The well-established finite volume core from CESM1(CAM) is also made available. This offers the possibility to compare three different atmospheric dynamical cores within MESSy. Additionally, the CESM1 land, river, sea ice, glaciers and ocean component models can be used in CESM1/MESSy simulations, allowing the use of MESSy as a comprehensive Earth system model (ESM). For CESM1/MESSy set-ups, the MESSy process and diagnostic submodels for atmospheric physics and chemistry are used together with one of the CESM1(CAM) dynamical cores; the generic (infrastructure) submodels support the atmospheric model component. The other CESM1 component models, as well as the coupling between them, use the original CESM1 infrastructure code and libraries; moreover, in future developments these can also be replaced by the MESSy framework. Here, we describe the structure and capabilities of CESM1/MESSy, document the code changes in CESM1 and MESSy, and introduce several simulations as example applications of the system. The Supplements provide further comparisons with the ECHAM5/MESSy atmospheric chemistry (EMAC) model and document the technical aspects of the connection in detail.

scholarly journals Implementation of the Community Earth System Model (CESM1, version 1.2.1) as a new basemodel into version 2.50 of the MESSy framework

2015 ◽  
Vol 8 (8) ◽  
pp. 6523-6550
Author(s):  
A. J. G. Baumgaertner ◽  
P. Jöckel ◽  
A. Kerkweg ◽  
R. Sander ◽  
H. Tost
Keyword(s):  
Surface Pressure ◽  
Atmospheric Chemistry ◽  
The United States ◽  
Earth System Model ◽  
System Model ◽  
Climate Modelling ◽  
Earth System ◽  
Dynamical Core ◽  
Community Earth System Model ◽  
Component Models

Abstract. The Community Earth System Model (CESM1), maintained by the United States National Centre for Atmospheric Research (NCAR) is connected with the Modular Earth Submodel System (MESSy). For the MESSy user community, this offers many new possibilities. The option to use the CESM1(CAM) atmospheric dynamical cores, especially the spectral element (SE) core, as an alternative to the ECHAM5 spectral transform dynamical core will provide scientific and computational advances for atmospheric chemistry and climate modelling with MESSy. The SE dynamical core does not require polar filters since the grid is quasi-uniform. By advecting the surface pressure rather then the logarithm of surface pressure the SE core locally conserves energy and mass. Furthermore, it has the possibility to scale to up to 105 compute cores, which is useful for current and future computing architectures. The well-established finite volume core from CESM1(CAM) is also made available. This offers the possibility to compare three different atmospheric dynamical cores within MESSy. Additionally, the CESM1 land, river, sea ice, glaciers and ocean component models can be used in CESM1/MESSy simulations, allowing to use MESSy as a comprehensive Earth System Model. For CESM1/MESSy setups, the MESSy process and diagnostic submodels for atmospheric physics and chemistry are used together with one of the CESM1(CAM) dynamical cores; the generic (infrastructure) submodels support the atmospheric model component. The other CESM1 component models as well as the coupling between them use the original CESM1 infrastructure code and libraries, although in future developments these can also be replaced by the MESSy framework. Here, we describe the structure and capabilities of CESM1/MESSy, document the code changes in CESM1 and MESSy, and introduce several simulations as example applications of the system. The Supplements provide further comparisons with the ECHAM5/MESSy atmospheric chemistry (EMAC) model and document the technical aspects of the connection in detail.

scholarly journals CAM-chem: description and evaluation of interactive atmospheric chemistry in the Community Earth System Model

2012 ◽  
Vol 5 (2) ◽  
pp. 369-411 ◽  
Author(s):  
J.-F. Lamarque ◽  
L. K. Emmons ◽  
P. G. Hess ◽  
D. E. Kinnison ◽  
S. Tilmes ◽  
...  
Keyword(s):  
United States ◽  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
The United States ◽  
Earth System Model ◽  
System Model ◽  
Ozone Production ◽  
Positive Bias ◽  
Earth System ◽  
Community Earth System Model

Abstract. We discuss and evaluate the representation of atmospheric chemistry in the global Community Atmosphere Model (CAM) version 4, the atmospheric component of the Community Earth System Model (CESM). We present a variety of configurations for the representation of tropospheric and stratospheric chemistry, wet removal, and online and offline meteorology. Results from simulations illustrating these configurations are compared with surface, aircraft and satellite observations. Major biases include a negative bias in the high-latitude CO distribution, a positive bias in upper-tropospheric/lower-stratospheric ozone, and a positive bias in summertime surface ozone (over the United States and Europe). The tropospheric net chemical ozone production varies significantly between configurations, partly related to variations in stratosphere-troposphere exchange. Aerosol optical depth tends to be underestimated over most regions, while comparison with aerosol surface measurements over the United States indicate reasonable results for sulfate , especially in the online simulation. Other aerosol species exhibit significant biases. Overall, the model-data comparison indicates that the offline simulation driven by GEOS5 meteorological analyses provides the best simulation, possibly due in part to the increased vertical resolution (52 levels instead of 26 for online dynamics). The CAM-chem code as described in this paper, along with all the necessary datasets needed to perform the simulations described here, are available for download at www.cesm.ucar.edu.

scholarly journals Description and evaluation of tropospheric chemistry and aerosols in the Community Earth System Model (CESM1.2)

2014 ◽  
Vol 7 (6) ◽  
pp. 8875-8940 ◽  
Author(s):  
S. Tilmes ◽  
J.-F. Lamarque ◽  
L. K. Emmons ◽  
D. E. Kinnison ◽  
P.-L. Ma ◽  
...  
Keyword(s):  
Surface Area ◽  
Atmospheric Chemistry ◽  
Earth System Model ◽  
Tropospheric Chemistry ◽  
System Model ◽  
Earth System ◽  
Chemical Production ◽  
Area Density ◽  
Community Earth System Model ◽  
The Difference

Abstract. The Community Atmosphere Model (CAM), version 5, is now coupled to extensive tropospheric and stratospheric chemistry, called CAM5-chem, and is available in addition to CAM4-chem in the Community Earth System Model (CESM) version 1.2. Both configurations are well suited as tools for atmospheric-chemistry modeling studies in the troposphere and lower stratosphere, whether with internally derived "free running" (FR) meteorology, or "specified dynamics" (SD). The main focus of this paper is to compare the performance of these configurations against observations from surface, aircraft, and satellite, as well as understand the origin of the identified differences. We particularly focus on comparing present-day methane lifetime estimates within the different model configurations, which range between 7.8 years in the SD configuration of CAM5-chem and 8.8 years in the FR configuration of CAM4-chem. We find that tropospheric surface area density is an important factor in controlling the burden of the hydroxyl radical (OH), which causes differences in tropical methane lifetime of about half a year between CAM4-chem and CAM5-chem. In addition, different distributions of nitrogen oxides (NOx) produced from lightning production explain about half of the difference between SD and FR model versions in both CAM4-chem and CAM5-chem. Remaining differences in the tropical OH burden are due to enhanced tropical ozone burden in SD configurations compared to the FR versions, which are not only caused by differences in chemical production or loss, but also by transport and mixing. For future studies, we recommend the use of CAM5-chem, due to improved aerosol description and inclusion of aerosol-cloud interactions. However, smaller tropospheric surface area density in the current version of CAM5-chem compared to CAM4-chem results in larger oxidizing capacity in the troposphere and therefore a shorter methane lifetime.

scholarly journals Representation of the Community Earth System Model (CESM1) CAM4-chem within the Chemistry-ClimateModel Initiative (CCMI)

2016 ◽  
Author(s):  
S. Tilmes ◽  
J.-F. Lamarque ◽  
L. K. Emmons ◽  
D. E. Kinnison ◽  
D. Marsh ◽  
...  
Keyword(s):  
Climate Model ◽  
Evaluation Studies ◽  
Surface Ozone ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Earth System Model ◽  
System Model ◽  
Good Representation ◽  
Earth System ◽  
Community Earth System Model

Abstract. The Community Earth System Model, CESM1 CAM4-chem has been used to perform the Chemistry Climate Model Initiative (CCMI) reference and sensitivity simulations. In this model, the Community Atmospheric Model Version 4 (CAM4) is fully coupled to tropospheric and stratospheric chemistry. Details and specifics of each configuration, including new developments and improvements are described. CESM1 CAM4-chem is a low top model that reaches up to approximately 40 km and uses a horizontal resolution of 1.9° latitude and 2.5° longitude. For the specified dynamics experiments, the model is nudged to Modern-Era Retrospective Analysis For Research And Applications (MERRA) reanalysis. We summarize the performance of the three reference simulations suggested by CCMI, with a focus on the observed period. Comparisons with elected datasets are employed to demonstrate the general performance of the model. We highlight new datasets that are suited for multi-model evaluation studies. Most important improvements of the model are the treatment of stratospheric aerosols and the corresponding adjustments for radiation and optics, the updated chemistry scheme including improved polar chemistry and stratospheric dynamics, and improved dry deposition rates. These updates lead to a very good representation of tropospheric ozone within 20 % of values from available observations for most regions. In particular, the trend and magnitude of surface ozone has been much improved compared to earlier versions of the model. Furthermore, stratospheric column ozone of the Southern Hemisphere in winter and spring is reasonably well represented. All experiments still underestimate CO most significantly in Northern Hemisphere spring and show a significant underestimation of hydrocarbons based on surface observations.

scholarly journals Analysis of Secondary Organic Aerosol Simulation Bias in the Community Earth System Model (CESM2.1)

2020 ◽  
Author(s):  
Yaman Liu ◽  
Xinyi Dong ◽  
Minghuai Wang ◽  
Louisa K. Emmons ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Climate Models ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
The United States ◽  
Earth System Model ◽  
Basis Set ◽  
System Model ◽  
Earth System ◽  
Model Version ◽  
Community Earth System Model

Abstract. Organic aerosol (OA) has been considered as one of the most important uncertainties in climate modeling due to the complexity in presenting its chemical production and depletion mechanisms. To better understand the capability of climate models and probe into the associated uncertainties in simulating OA, we evaluate the Community Earth System Model version 2.1 (CESM2.1) configured with the Community Atmosphere Model version 6 (CAM6) with comprehensive tropospheric and stratospheric chemistry representation (CAM6-Chem), through a long-term simulation (1988–2019) with observations collected from multiple datasets in the United States. We find that CESM generally reproduces the inter-annual variation and seasonal cycle of OA mass concentration at surface layer with correlation of 0.40 as compared to ground observations, and systematically overestimates (69 %) in summer and underestimates (−19 %) in winter. Through a series of sensitivity simulations, we reveal that modeling bias is primarily related to the dominant fraction of monoterpene-formed secondary organic aerosol (SOA), and a strong positive correlation of 0.67 is found between monoterpene emission and modeling bias in eastern US during summer. In terms of vertical profile, the model prominently underestimates OA and monoterpene concentrations by 37–99 % and 82–99 % respectively in the upper air (> 500 m) as validated against aircraft observations. Our study suggests that the current Volatility Basis Set (VBS) scheme applied in CESM might be parameterized with too high monoterpene SOA yields which subsequently result in strong SOA production near emission source area. We also find that the model has difficulty in reproducing the decreasing trend of surface OA in southeast US, probably because of employing pure gas VBS to represent isoprene SOA which is in reality mainly formed through multiphase chemistry, thus the influence of aerosol acidity and sulfate particle change on isoprene SOA formation has not been fully considered in the model. This study reveals the urgent need to improve the SOA modeling in climate models.

scholarly journals Aviation 2006 NO<sub>x</sub>-induced effects on atmospheric ozone and HO<sub>x</sub> in Community Earth System Model (CESM)

2014 ◽  
Vol 14 (18) ◽  
pp. 9925-9939 ◽  
Author(s):  
A. Khodayari ◽  
S. Tilmes ◽  
S. C. Olsen ◽  
D. B. Phoenix ◽  
D. J. Wuebbles ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Photochemical Reactions ◽  
Earth System Model ◽  
Design Tool ◽  
System Model ◽  
Nox Emissions ◽  
Earth System ◽  
Community Earth System Model ◽  
Aerosol Module

Abstract. The interaction between atmospheric chemistry and ozone (O3) in the upper troposphere–lower stratosphere (UTLS) presents a major uncertainty in understanding the effects of aviation on climate. In this study, two configurations of the atmospheric model from the Community Earth System Model (CESM), Community Atmosphere Model with Chemistry, Version 4 (CAM4) and Version 5 (CAM5), are used to evaluate the effects of aircraft nitrogen oxide (NOx = NO + NO2) emissions on ozone and the background chemistry in the UTLS. CAM4 and CAM5 simulations were both performed with extensive tropospheric and stratospheric chemistry including 133 species and 330 photochemical reactions. CAM5 includes direct and indirect aerosol effects on clouds using a modal aerosol module (MAM), whereby CAM4 uses a bulk aerosol module, which can only simulate the direct effect. To examine the accuracy of the aviation NOx-induced ozone distribution in the two models, results from the CAM5 and CAM4 simulations are compared to ozonesonde data. Aviation NOx emissions for 2006 were obtained from the AEDT (Aviation Environmental Design Tool) global commercial aircraft emissions inventory. Differences between simulated O3 concentrations and ozonesonde measurements averaged at representative levels in the troposphere and different regions are 13% in CAM5 and 18% in CAM4. Results show a localized increase in aviation-induced O3 concentrations at aviation cruise altitudes that stretches from 40° N to the North Pole. The results indicate a greater and more disperse production of aviation NOx-induced ozone in CAM5, with the annual tropospheric mean O3 perturbation of 1.2 ppb (2.4%) for CAM5 and 1.0 ppb (1.9%) for CAM4. The annual mean O3 perturbation peaks at about 8.2 ppb (6.4%) and 8.8 ppb (5.2%) in CAM5 and CAM4, respectively. Aviation emissions also result in increased hydroxyl radical (OH) concentrations and methane (CH4) loss rates, reducing the tropospheric methane lifetime in CAM5 and CAM4 by 1.69 and 1.40%, respectively. Aviation NOx emissions are associated with an instantaneous change in global mean short-term O3 radiative forcing (RF) of 40.3 and 36.5 mWm−2 in CAM5 and CAM4, respectively.

scholarly journals Analysis of Secondary Organic Aerosol Simulation Bias in the Community Earth System Model (CESM2.1)

2021 ◽  
Author(s):  
Yaman Liu ◽  
Xinyi Dong ◽  
Minghuai Wang ◽  
Louisa Emmons ◽  
Yawen Liu ◽  
...  
Keyword(s):  
Climate Models ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
The United States ◽  
Earth System Model ◽  
Basis Set ◽  
System Model ◽  
Earth System ◽  
Model Version ◽  
Community Earth System Model

&lt;p&gt;Organic aerosol (OA) has been considered as one of the most important uncertainties in climate modeling due to the complexity in presenting its chemical production and depletion mechanisms. To better understand the capability of climate models and probe into the associated uncertainties in simulating OA, we evaluate the Community Earth System Model version 2.1 (CESM2.1) configured with the Community Atmosphere Model version 6 (CAM6) with comprehensive tropospheric and stratospheric chemistry representation (CAM6-Chem), through a long-term simulation (1988&amp;#8211;2019) with observations collected from multiple datasets in the United States. We find that CESM generally reproduces the inter-annual variation and seasonal cycle of OA mass concentration at surface layer with correlation of 0.40 as compared to ground observations, and systematically overestimates (69 %) in summer and underestimates (-19 %) in winter. Through a series of sensitivity simulations, we reveal that modeling bias is primarily related to the dominant fraction of monoterpene-formed secondary organic aerosol (SOA), and a strong positive correlation of 0.67 is found between monoterpene emission and modeling bias in eastern US during summer. In terms of vertical profile, the model prominently underestimates OA and monoterpene concentrations by 37&amp;#8211;99 % and 82&amp;#8211;99 % respectively in the upper air (&gt;500 m) as validated against aircraft observations. Our study suggests that the current Volatility Basis Set (VBS) scheme applied in CESM might be parameterized with too high monoterpene SOA yields which subsequently result in strong SOA production near emission source area. We also find that the model has difficulty in reproducing the decreasing trend of surface OA in southeast US, probably because of employing pure gas VBS to represent isoprene SOA which is in reality mainly formed through multiphase chemistry, thus the influence of aerosol acidity and sulfate particle change on isoprene SOA formation has not been fully considered in the model. This study reveals the urgent need to improve the SOA modeling in climate models.&lt;/p&gt;

scholarly journals Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)

2017 ◽  
Author(s):  
Daniel J. Milroy ◽  
Allison H. Baker ◽  
Dorit M. Hammerling ◽  
Elizabeth R. Jessup
Keyword(s):  
Atmospheric Model ◽  
Earth System Model ◽  
System Model ◽  
Small Scale ◽  
Earth System ◽  
Consistency Test ◽  
Robust Test ◽  
Community Land Model ◽  
Community Earth System Model ◽  
Statistical Consistency

Abstract. The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite by the addition of an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

scholarly journals Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)

2018 ◽  
Vol 11 (2) ◽  
pp. 697-711 ◽  
Author(s):  
Daniel J. Milroy ◽  
Allison H. Baker ◽  
Dorit M. Hammerling ◽  
Elizabeth R. Jessup
Keyword(s):  
Atmospheric Model ◽  
Earth System Model ◽  
System Model ◽  
Small Scale ◽  
Earth System ◽  
Consistency Test ◽  
Robust Test ◽  
Community Land Model ◽  
Community Earth System Model ◽  
Statistical Consistency

Abstract. The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

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