scholarly journals Supplementary material to "Implementation of HONO into the chemistry-climate model CHASER (V4.0): roles in tropospheric chemistry"

2021 ◽  
Author(s):  
Phuc Thi Minh Ha ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Maria Dolores Andrés Hernández ◽  
Benjamin Schreiner ◽  
...  
Keyword(s):  
Climate Model ◽  
Tropospheric Chemistry ◽  
Supplementary Material

scholarly journals Improved tropospheric and stratospheric sulfur cycle in the aerosol–chemistry–climate model SOCOL-AERv2

2019 ◽  
Vol 12 (9) ◽  
pp. 3863-3887 ◽  
Author(s):  
Aryeh Feinberg ◽  
Timofei Sukhodolov ◽  
Bei-Ping Luo ◽  
Eugene Rozanov ◽  
Lenny H. E. Winkel ◽  
...  
Keyword(s):  
Climate Model ◽  
Model Performance ◽  
Stratospheric Aerosol ◽  
Sulfur Cycle ◽  
Sulfate Aerosol ◽  
Tropospheric Chemistry ◽  
Sulfur Deposition ◽  
Aerosol Chemistry ◽  
Deposition Fluxes ◽  
Aerosol Model

Abstract. SOCOL-AERv1 was developed as an aerosol–chemistry–climate model to study the stratospheric sulfur cycle and its influence on climate and the ozone layer. It includes a sectional aerosol model that tracks the sulfate particle size distribution in 40 size bins, between 0.39 nm and 3.2 µm. Sheng et al. (2015) showed that SOCOL-AERv1 successfully matched observable quantities related to stratospheric aerosol. In the meantime, SOCOL-AER has undergone significant improvements and more observational datasets have become available. In producing SOCOL-AERv2 we have implemented several updates to the model: adding interactive deposition schemes, improving the sulfate mass and particle number conservation, and expanding the tropospheric chemistry scheme. We compare the two versions of the model with background stratospheric sulfate aerosol observations, stratospheric aerosol evolution after Pinatubo, and ground-based sulfur deposition networks. SOCOL-AERv2 shows similar levels of agreement as SOCOL-AERv1 with satellite-measured extinctions and in situ optical particle counter (OPC) balloon flights. The volcanically quiescent total stratospheric aerosol burden simulated in SOCOL-AERv2 has increased from 109 Gg of sulfur (S) to 160 Gg S, matching the newly available satellite estimate of 165 Gg S. However, SOCOL-AERv2 simulates too high cross-tropopause transport of tropospheric SO2 and/or sulfate aerosol, leading to an overestimation of lower stratospheric aerosol. Due to the current lack of upper tropospheric SO2 measurements and the neglect of organic aerosol in the model, the lower stratospheric bias of SOCOL-AERv2 was not further improved. Model performance under volcanically perturbed conditions has also undergone some changes, resulting in a slightly shorter volcanic aerosol lifetime after the Pinatubo eruption. With the improved deposition schemes of SOCOL-AERv2, simulated sulfur wet deposition fluxes are within a factor of 2 of measured deposition fluxes at 78 % of the measurement stations globally, an agreement which is on par with previous model intercomparison studies. Because of these improvements, SOCOL-AERv2 will be better suited to studying changes in atmospheric sulfur deposition due to variations in climate and emissions.

scholarly journals Supplementary material to "Effects of Strongly Enhanced Atmospheric Methane Concentrations in a Fully Coupled Chemistry-Climate Model"

2020 ◽  
Author(s):  
Laura Stecher ◽  
Franziska Winterstein ◽  
Martin Dameris ◽  
Patrick Jöckel ◽  
Michael Ponater ◽  
...  
Keyword(s):  
Climate Model ◽  
Atmospheric Methane ◽  
Supplementary Material ◽  
Fully Coupled ◽  
Methane Concentrations

scholarly journals Impact of biogenic hydrocarbons on tropospheric chemistry: results from a global chemistry-climate model

2005 ◽  
Vol 5 (5) ◽  
pp. 10517-10612 ◽  
Author(s):  
G. A. Folberth ◽  
D. A. Hauglustaine ◽  
J. Lathière ◽  
F. Brocheton
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Climate Model ◽  
Primary Source ◽  
Tropospheric Chemistry ◽  
Secondary Source ◽  
Peroxy Radicals ◽  
Substantial Impact ◽  
The Impact ◽  
Global Mean

Abstract. We present a description and evaluation of LMDz-INCA, a global three-dimensional chemistry-climate model, pertaining to its recently developed NMHC version. In this substantially extended version of the model a comprehensive representation of the photochemistry of non-methane hydrocarbons (NMHC) and volatile organic compounds (VOC) from biogenic, anthropogenic, and biomass-burning sources has been included. The tropospheric annual mean methane (9.2 years) and methylchloroform (5.5 years) chemical lifetimes are well within the range of previous modelling studies and are in excellent agreement with estimates established by means of global observations. The model provides a reasonable simulation of the horizontal and vertical distribution and seasonal cycle of CO and key non-methane VOC, such as acetone, methanol, and formaldehyde as compared to observational data from several ground stations and aircraft campaigns. LMDz-INCA in the NMHC version reproduces tropospheric ozone concentrations fairly well throughout most of the troposphere. The model is applied in several sensitivity studies of the biosphere-atmosphere photochemical feedback. The impact of surface emissions of isoprene, acetone, and methanol is studied. These experiments show a substantial impact of isoprene on tropospheric ozone and carbon monoxide concentrations revealing an increase in surface O3 and CO levels of up to 30 ppbv and 60 ppbv, respectively. Isoprene also appears to significantly impact the global OH distribution resulting in a decrease of the global mean tropospheric OH concentration by approximately 0.9×105 molecules cm−3 or roughly 10% and an increase in the global mean tropospheric methane lifetime by approximately four months. A global mean ozone net radiative forcing due to the isoprene induced increase in the tropospheric ozone burden of 0.09W m−2 is found. The key role of isoprene photooxidation in the global tropospheric redistribution of NOx is demonstrated. LMDz-INCA calculates an increase of PAN surface mixing ratios ranging from 75 to 750 pptv and 10 to 250 pptv during northern hemispheric summer and winter, respectively. Acetone and methanol are found to play a significant role in the upper troposphere/lower stratosphere (UT/LS) budget of peroxy radicals. Calculations with LMDz-INCA show an increase in HOx concentrations region of 8 to 15% and 10 to 15% due to methanol and acetone biogenic surface emissions, respectively. The model has been used to estimate the global tropospheric CO budget. A global CO source of 3019 TgCO yr−1 is estimated. This source divides into a primary source of 1533 TgCO yr−1 and secondary source of 1489 TgCO yr−1 deriving from VOC photooxidation. Global VOC-to-CO conversion efficiencies of 90% for methane and between 20 and 45% for individual VOC are calculated by LMDz-INCA.

scholarly journals Preindustrial-to-present-day radiative forcing by tropospheric ozone from improved simulations with the GISS chemistry-climate GCM

2003 ◽  
Vol 3 (5) ◽  
pp. 1675-1702 ◽  
Author(s):  
D. T. Shindell ◽  
G. Faluvegi ◽  
N. Bell
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Tropospheric Chemistry ◽  
True Value ◽  
Tropopause Region ◽  
Dynamics Simulations ◽  
Goddard Institute

Abstract. Improved estimates of the radiative forcing from tropospheric ozone increases since the preindustrial have been calculated with the tropospheric chemistry model used at the Goddard Institute for Space Studies (GISS) within the GISS general circulation model (GCM). The chemistry in this model has been expanded to include simplified representations of peroxyacetylnitrates and non-methane hydrocarbons in addition to background NOx-HOx-Ox-CO-CH4 chemistry. The GCM has improved resolution and physics in the boundary layer, improved resolution near the tropopause, and now contains a full representation of stratospheric dynamics. Simulations of present-day conditions show that this coupled chemistry-climate model is better able to reproduce observed tropospheric ozone, especially in the tropopause region, which is critical to climate forcing. Comparison with preindustrial simulations gives a global annual average radiative forcing due to tropospheric ozone increases of 0.30 W/m2 with standard assumptions for preindustrial emissions. Locally, the forcing reaches more than 0.8 W/m2 in parts of the northern subtropics during spring and summer, and is more than 0.6 W/m2 through nearly all the Northern subtropics and mid-latitudes during summer. An alternative preindustrial simulation with soil NOx emissions reduced by two-thirds and emissions of isoprene, paraffins and alkenes from vegetation increased by 50% gives a forcing of 0.33 W/m2. Given the large uncertainties in preindustrial ozone amounts, the true value may lie well outside this range.

21st century trends in stratosphere-to-troposphere transport

2020 ◽  
Author(s):  
Marta Abalos ◽  
Clara Orbe ◽  
Douglas Kinnison ◽  
David Plummer ◽  
Luke Oman ◽  
...  
Keyword(s):  
Climate Change Scenario ◽  
Climate Model ◽  
Hadley Cell ◽  
Tropospheric Chemistry ◽  
Change Scenario ◽  
Upper Troposphere ◽  
Deep Branch ◽  
Two Factors ◽  
Eddy Transport ◽  
Key Questions

<p>One of the key questions in the air quality and climate sciences is how will tropospheric ozone concentrations change in the future. This will depend on two factors: changes in stratosphere-to-troposphere transport (STT) and changes in tropospheric chemistry. Here we aim to identify robust changes in STT using simulations from the Chemistry Climate Model Initiative (CCMI) under a common climate change scenario (RCP6.0). We use two idealized stratospheric tracers implemented in the models to examine changes in transport. We find that the strengthening of the shallow branch of the Brewer-Dobson circulation (BDC) in the lower stratosphere and of the upper part of the Hadley cell in the upper troposphere lead to enhanced STT in the subtropics. The acceleration of the deep branch of the BDC in the NH and changes in eddy transport contribute to increase STT at high latitudes. In the SH, the deep branch does not accelerate due to the dynamical effects of the ozone hole recovery.</p>

Investigation of strongly enhanced methane Part I: Chemical feedbacks and rapid adjustments.

2020 ◽  
Author(s):  
Franziska Winterstein ◽  
Patrick Jöckel ◽  
Martin Dameris ◽  
Michael Ponater ◽  
Fabian Tanalski ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Model ◽  
Numerical Study ◽  
Stratospheric Ozone ◽  
Lower Boundary ◽  
Tropospheric Chemistry ◽  
Substantial Part ◽  
Mixing Ratios ◽  
The Impact

<p>Methane (CH<sub>4</sub>) is the second most important greenhouse gas, which atmospheric concentration is influenced by human activities and currently on a sharp rise. We present a study with numerical simulations using a Chemistry-Climate-Model (CCM), which are performed to assess possible consequences of strongly enhanced CH<sub>4</sub> concentrations in the Earth's atmosphere for the climate.</p><p>Our analysis includes experiments with 2xCH<sub>4</sub> and 5xCH<sub>4</sub> present day (2010) lower boundary mixing ratios using the CCM EMAC. The simulations are conducted with prescribed oceanic conditions, mimicking present day tropospheric temperatures as its changes are largely suppressed. By doing so we are able to investigate the quasi-instantaneous chemical impact on the atmosphere. We find that the massive increase in CH<sub>4</sub> strongly influences the tropospheric chemistry by reducing the OH abundance and thereby extending the tropospheric CH<sub>4</sub> lifetime as well as the residence time of other chemical pollutants. The region above the tropopause is impacted by a substantial rise in stratospheric water vapor (SWV). The stratospheric ozone (O<sub>3</sub>) column increases overall, but SWV induced stratospheric cooling also leads to enhanced ozone depletion in the Antarctic lower stratosphere. Regional  patterns of ozone change are affected by modification of stratospheric dynamics, i.e. increased tropical up-welling and stronger meridional transport  towards the polar regions. We calculate the net radiative impact (RI) of the 2xCH<sub>4</sub> experiment to be 0.69 W m<sup>-2</sup> and for the 5xCH<sub>4</sub> experiment to be 1.79 W m<sup>-2</sup>. A substantial part of the RI is contributed by chemically induced O<sub>3</sub> and SWV changes, in line with previous radiative forcing estimates and is for the first time splitted and spatially asigned to its chemical contributors.</p><p>This numerical study using a CCM with prescibed oceanic conditions shows the rapid responses to significantly enhanced CH<sub>4</sub> mixing ratios, which is the first step towards investigating the impact of possible strong future CH<sub>4</sub> emissions on atmospheric chemistry and its feedback on climate.</p>

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