scholarly journals Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling

2015 ◽  
Vol 8 (2) ◽  
pp. 129-150 ◽  
Author(s):  
R. Locatelli ◽  
P. Bousquet ◽  
F. Hourdin ◽  
M. Saunois ◽  
A. Cozic ◽  
...  

Abstract. Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterizations recently implemented in the atmospheric global climate model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three-dimensional simulations, by a much improved reproduction of the radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers) significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing modify chemical reaction rates, which perturb chemical equilibriums of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger amount of high-frequency data sampled at high-variability stations. Others implications are discussed at the end of the paper.

2014 ◽  
Vol 7 (4) ◽  
pp. 4993-5048 ◽  
Author(s):  
R. Locatelli ◽  
P. Bousquet ◽  
F. Hourdin ◽  
M. Saunois ◽  
A. Cozic ◽  
...  

Abstract. Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterisations recently implemented in the Atmospheric Global Climate Model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL), and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three dimensional simulations, by a much improved reproduction of the Radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers) significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing, significantly modify chemical reaction rates and the equilibrium value of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger amount of high-frequency data sampled at high-variability stations. Others implications are discussed at the end of the paper.


2008 ◽  
Vol 2008 (6) ◽  
pp. 783-792 ◽  
Author(s):  
Patricia Scanlan ◽  
Holly Elmendorf ◽  
Hari Santha ◽  
James Rowan

2006 ◽  
Vol 19 (13) ◽  
pp. 3055-3069 ◽  
Author(s):  
Peter A. Stott ◽  
John F. B. Mitchell ◽  
Myles R. Allen ◽  
Thomas L. Delworth ◽  
Jonathan M. Gregory ◽  
...  

Abstract This paper investigates the impact of aerosol forcing uncertainty on the robustness of estimates of the twentieth-century warming attributable to anthropogenic greenhouse gas emissions. Attribution analyses on three coupled climate models with very different sensitivities and aerosol forcing are carried out. The Third Hadley Centre Coupled Ocean–Atmosphere GCM (HadCM3), Parallel Climate Model (PCM), and GFDL R30 models all provide good simulations of twentieth-century global mean temperature changes when they include both anthropogenic and natural forcings. Such good agreement could result from a fortuitous cancellation of errors, for example, by balancing too much (or too little) greenhouse warming by too much (or too little) aerosol cooling. Despite a very large uncertainty for estimates of the possible range of sulfate aerosol forcing obtained from measurement campaigns, results show that the spatial and temporal nature of observed twentieth-century temperature change constrains the component of past warming attributable to anthropogenic greenhouse gases to be significantly greater (at the 5% level) than the observed warming over the twentieth century. The cooling effects of aerosols are detected in all three models. Both spatial and temporal aspects of observed temperature change are responsible for constraining the relative roles of greenhouse warming and sulfate cooling over the twentieth century. This is because there are distinctive temporal structures in differential warming rates between the hemispheres, between land and ocean, and between mid- and low latitudes. As a result, consistent estimates of warming attributable to greenhouse gas emissions are obtained from all three models, and predictions are relatively robust to the use of more or less sensitive models. The transient climate response following a 1% yr−1 increase in CO2 is estimated to lie between 2.2 and 4 K century−1 (5–95 percentiles).


Author(s):  
Ingeborg Levin ◽  
Samuel Hammer ◽  
Elke Eichelmann ◽  
Felix R. Vogel

Independent verification of greenhouse gas emissions reporting is a legal requirement of the Kyoto Protocol, which has not yet been fully accomplished. Here, we show that dedicated long-term atmospheric measurements of greenhouse gases, such as carbon dioxide (CO 2 ) and methane (CH 4 ), continuously conducted at polluted sites can provide the necessary tool for this undertaking. From our measurements at the semi-polluted Heidelberg site in the upper Rhine Valley, we find that in the catchment area CH 4 emissions decreased on average by 32±6% from the second half of the 1990s until the first half of the 2000s, but the observed long-term trend of emissions is considerably smaller than that previously reported for southwest Germany. In contrast, regional fossil fuel CO 2 levels, estimated from high-precision 14 CO 2 observations, do not show any significant decreasing trend since 1986, in agreement with the reported emissions for this region. In order to provide accurate verification, these regional measurements would best be accompanied by adequate atmospheric transport modelling as required to precisely determine the relevant catchment area of the measurements. Furthermore, reliable reconciliation of reported emissions will only be possible if these are known at high spatial resolution in the catchment area of the observations. This information should principally be available in all countries that regularly report their greenhouse gas emissions to the United Nations Framework Convention on Climate Change.


2022 ◽  
Vol 37 ◽  
Author(s):  
Christopher M. Wade ◽  
Justin S. Baker ◽  
Jason P. H. Jones ◽  
Kemen G. Austin ◽  
Yongxia Cai ◽  
...  

Author(s):  
Ioana-Miruna Tătaru ◽  
Elena Fleacă ◽  
Bogdan Fleacă

AbstractTo perform their business operations, telecommunication companies need to consume energy. This paper aims to analyze and compare the energy consumption and their greenhouse gas emissions for there of the biggest telecommunication companies: Vodafone, Orange and Telekom. Although the scientific literature proposed some analysis on the environmental measures that the telecommunication companies have to take, there is a shortage of researchers focused on GRI reporting data and the pairwise comparison method. The authors compared these telecommunication companies’ emissions under the following criteria: energy consumption (GRI 302-1), scope 1 (GRI 305-1), scope 2 (GRI 305-2) and scope 3 (GRI 305-3) greenhouse gas emissions, reduction of emissions (GRI 305-5), using the pairwise comparison method. To reduce their emissions, companies developed a sustainability strategy. This paper will further emphasize what are the plans to reduce emissions for the company which, following the analysis, pollutes the most. To provide an overview of the future of the company which, by the analysis, pollutes the most, the authors have identified and analyzed what are the main actions that the company should take to reduce their impact on the environment. To do so, the authors firstly analyze the causes of the pollution produced by the telecommunication company using Ishikawa diagram. Then, it identifies what are the main organizational processes that can be improved using APQC standardization, to show that the improvement can be made if the organization adjusts their organizational processes. This paper is an enhancement to the studies form the field because it provides a comparative analysis on three of the most competitive telecommunication companies in the world, uses GRI criteria and pairwise comparison method and gives an overview on the next steps for the telecommunication company to reduce their greenhouse gas emissions.


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