scholarly journals Effects of heterogeneous reactions on tropospheric chemistry: a global simulation with the chemistry–climate model CHASER V4.0

2021 ◽  
Vol 14 (6) ◽  
pp. 3813-3841
Author(s):  
Phuc T. M. Ha ◽  
Ryoki Matsuda ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Kengo Sudo

Abstract. This study uses a chemistry–climate model CHASER (MIROC) to explore the roles of heterogeneous reactions (HRs) in global tropospheric chemistry. Three distinct HRs of N2O5, HO2, and RO2 are considered for surfaces of aerosols and cloud particles. The model simulation is verified with EANET and EMEP stationary observations; R/V Mirai ship-based data; ATom1 aircraft measurements; satellite observations by OMI, ISCCP, and CALIPSO-GOCCP; and reanalysis data JRA55. The heterogeneous chemistry facilitates improvement of model performance with respect to observations for NO2, OH, CO, and O3, especially in the lower troposphere. The calculated effects of heterogeneous reactions cause marked changes in global abundances of O3 (−2.96 %), NOx (−2.19 %), CO (+3.28 %), and global mean CH4 lifetime (+5.91 %). These global effects were contributed mostly by N2O5 uptake onto aerosols in the middle troposphere. At the surface, HO2 uptake gives the largest contributions, with a particularly significant effect in the North Pacific region (−24 % O3, +68 % NOx, +8 % CO, and −70 % OH), mainly attributable to its uptake onto clouds. The RO2 reaction has a small contribution, but its global mean negative effects on O3 and CO are not negligible. In general, the uptakes onto ice crystals and cloud droplets that occur mainly by HO2 and RO2 radicals cause smaller global effects than the aerosol-uptake effects by N2O5 radicals (+1.34 % CH4 lifetime, +1.71 % NOx, −0.56 % O3, +0.63 % CO abundances). Nonlinear responses of tropospheric O3, NOx, and OH to the N2O5 and HO2 uptakes are found in the same modeling framework of this study (R>0.93). Although all HRs showed negative tendencies for OH and O3 levels, the effects of HR(HO2) on the tropospheric abundance of O3 showed a small increment with an increasing loss rate. However, this positive tendency turns to reduction at higher rates (>5 times). Our results demonstrate that the HRs affect not only polluted areas but also remote areas such as the mid-latitude sea boundary layer and upper troposphere. Furthermore, HR(HO2) can bring challenges to pollution reduction efforts because it causes opposite effects between NOx (increase) and surface O3 (decrease).

2020 ◽  
Author(s):  
Phuc T. M. Ha ◽  
Fumikazu Taketani ◽  
Yugo Kanaya ◽  
Ryoki Matsuda ◽  
Kengo Sudo

Abstract. This study uses a chemistry-climate model CHASER (MIROC) to explore the roles of heterogeneous reactions (HRs) in global tropospheric chemistry. Three distinct HRs of N2O5, HO2, and RO2 are considered for surfaces of aerosols and cloud particles. The model simulation is verified with EANET and EMEP stationary observations, R/V MIRAI ship-based data, ATOM1 aircraft measurements, satellite observations by OMI, ISCCP, and CALIPSO-GOCCP, and reanalysis data JRA55. The heterogeneous chemistry facilitates improvement of model performance with respect to observations for NO2, OH, CO, and O3, especially in the lower troposphere. The calculated effects of heterogeneous reactions cause marked changes in global abundances of O3 (−3 %), NOx (−2.2 %), CO (+3.3 %), and global mean CH4 lifetime (+5.9 %). These global effects were contributed mostly by N2O5 uptake onto aerosols in the middle troposphere. At the surface, HO2 uptake gives the largest contributions, with a particularly significant effect in the North Pacific region (−24% O3, +68 % NOx, +8 % CO, and −70 % OH), mainly attributable to its uptake onto clouds. The RO2 reaction has a small contribution, but its global-mean negative effect on O3 is not negligible. In general, the uptakes onto ice crystals and cloud droplets that occur mainly by HO2 and RO2 radicals cause smaller global effects than the aerosol-uptake effects by N2O5 radicals (+1.34 % CH4 lifetime, +1.71 % NOx, −0.56 % O3, +0.63 % CO abundances). Nonlinear responses of tropospheric O3, NOx, and OH to the N2O5 and HO2 uptakes are found in the same modelling framework of this study (R > 0.93). Although all HRs showed negative tendencies for OH and O3 levels, the effects of HR(HO2) on the tropospheric abundance of O3 showed a small increment with an increasing loss rate. However, this positive tendency turns to reduction at higher rates (> 5 times). Our results demonstrate that the HRs affect not only polluted areas but also remote areas such as the mid-latitude sea boundary layer and upper troposphere. Furthermore, HR(HO2) can bring challenges to pollution reduction efforts because it causes opposite effects between NOx (increase) and surface O3 (decrease).


2021 ◽  
Author(s):  
Phuc Thi Minh Ha ◽  
Yugo Kanaya ◽  
Fumikazu Taketani ◽  
Maria Dolores Andrés Hernández ◽  
Benjamin Schreiner ◽  
...  

Abstract. Nitrous acid (HONO) is an important atmospheric gas given its contribution to the cycles of NOx and HOx, but its role in global atmospheric photochemistry is not fully understood. This study, for the first time, implemented three pathways of HONO formation in the chemistry-climate model CHASER (MIROC-ESM) to explore three physical phenomena: gas-phase kinetic reactions (GRs), direct emission (EM), and heterogeneous reactions on cloud/aerosol particles (HRs). We evaluated the simulations by the atmospheric measurements from the OMI (Ozone Monitoring Instrument), EANET (Acid Deposition Monitoring Network in eastern Asia) / EMEP (European Monitoring and Evaluation Programme) ground-based stationary observations, observations from the ship R/V Mirai, and aircraft-based measurements by ATom1 (atmospheric tomography) and EMeRGe-Asia-2018 (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global scales). We showed that the inclusion of the HONO chemistry in the modeling process reduces the model bias against the measurements for PM2.5, NO3−/HNO3, NO2, OH, O3, and CO, especially in the lower troposphere and the North Pacific (NP) region. We found that the retrieved global abundance of tropospheric HONO was 1.4 TgN. Of the three source pathways, HRs and EM contributed 63 % and 26 % to the net HONO production, respectively. We also observed that, reactions on the aerosol surfaces contributed larger amounts of HONO (51 %) than those on the cloud surfaces (12 %). The model exhibited significant negative biases for daytime HONO in the Asian off-coast region, compared with the airborne measurements by EMeRGe-Asia-2018, indicating the existence of unknown daytime HONO sources. Strengthening of aerosol uptake of NO2 near-surface and in the middle troposphere, cloud uptake, and direct HONO emission are all potential yet-unknown HONO sources. We also found that the simulated HONO abundance and its impact on NOx-O3 chemistry are sensitive to the yield of the heterogeneous conversion of NO2 to HONO (vs. HNO3). Inclusion of HONO reduces global tropospheric NOx (NO + NO2) levels by 20.4 %, thereby weakening the tropospheric oxidizing capacity, which in turn, increases CH4 lifetime (13 %) and CO abundance (8 %). HRs on the surfaces of cloud particles, which have been neglected in previous modeling studies, are the main drivers of these impacts. This effect is particularly salient for the substantial reductions of levels of OH (40–67 %) and O3 (30–45 %) in the NP region during summer given the significant reduction of NOx level (50–95 %). In contrast, HRs on aerosol surfaces in China (Beijing) enhance OH and O3 winter mean levels by 600–1700 % and 10–33 %, respectively, with regards to their minima in winter. Overall, our findings suggest that a global model that does not consider HONO heterogeneous mechanisms (especially HRs on cloud particle surfaces) may erroneously predict the effect of HONO in remote areas and polluted regions.


2019 ◽  
Vol 12 (9) ◽  
pp. 3863-3887 ◽  
Author(s):  
Aryeh Feinberg ◽  
Timofei Sukhodolov ◽  
Bei-Ping Luo ◽  
Eugene Rozanov ◽  
Lenny H. E. Winkel ◽  
...  

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.


2005 ◽  
Vol 5 (5) ◽  
pp. 10517-10612 ◽  
Author(s):  
G. A. Folberth ◽  
D. A. Hauglustaine ◽  
J. Lathière ◽  
F. Brocheton

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.


2009 ◽  
Vol 9 (14) ◽  
pp. 4653-4675 ◽  
Author(s):  
B. Croft ◽  
U. Lohmann ◽  
R. V. Martin ◽  
P. Stier ◽  
S. Wurzler ◽  
...  

Abstract. Wet deposition processes are highly efficient in the removal of aerosols from the atmosphere, and thus strongly influence global aerosol concentrations, and clouds, and their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain and snow are implemented in the ECHAM5-HAM global aerosol-climate model. Previously, below-cloud scavenging by rain in the ECHAM5-HAM was simply a function of the aerosol mode, and then scaled by the rainfall rate. The below-cloud scavenging by snow was a function of the snowfall rate alone. The global mean aerosol optical depth, and sea salt burden are sensitive to the below-cloud scavenging coefficients, with reductions near to 15% when the more vigorous size-dependent below-cloud scavenging by rain and snow is implemented. The inclusion of a prognostic rain scheme significantly reduces the fractional importance of below-cloud scavenging since there is higher evaporation in the lower troposphere, increasing the global mean sea salt burden by almost 15%. Thermophoretic effects are shown to produce increases in the global and annual mean number removal of Aitken size particles of near to 10%, but very small increases (near 1%) in the global mean below-cloud mass scavenging of carbonaceous and sulfate aerosols. Changes in the assumptions about the below-cloud scavenging by rain of particles with radius smaller than 10 nm do not cause any significant changes to the global and annual mean aerosol mass or number burdens, despite a change in the below-cloud number removal rate for nucleation mode particles by near to five-fold. Annual and zonal mean nucleation mode number concentrations are enhanced by up to 30% in the lower troposphere with the more vigourous size-dependent below-cloud scavenging. Closer agreement with different observations is found when the more physically detailed below-cloud scavenging parameterization is employed in the ECHAM5-HAM model.


2016 ◽  
Vol 16 (16) ◽  
pp. 10651-10669 ◽  
Author(s):  
Keren Mezuman ◽  
Susanne E. Bauer ◽  
Kostas Tsigaridis

Abstract. The spatial distribution of aerosols and their chemical composition dictates whether aerosols have a cooling or a warming effect on the climate system. Hence, properly modeling the three-dimensional distribution of aerosols is a crucial step for coherent climate simulations. Since surface measurement networks only give 2-D data, and most satellites supply integrated column information, it is thus important to integrate aircraft measurements in climate model evaluations. In this study, the vertical distribution of secondary inorganic aerosol (i.e., sulfate, ammonium, and nitrate) is evaluated against a collection of 14 AMS flight campaigns and surface measurements from 2000 to 2010 in the USA and Europe. GISS ModelE2 is used with multiple aerosol microphysics (MATRIX, OMA) and thermodynamic (ISORROPIA II, EQSAM) configurations. Our results show that the MATRIX microphysical scheme improves the model performance for sulfate, but that there is a systematic underestimation of ammonium and nitrate over the USA and Europe in all model configurations. In terms of gaseous precursors, nitric acid concentrations are largely underestimated at the surface while overestimated in the higher levels of the model. Heterogeneous reactions on dust surfaces are an important sink for nitric acid, even high in the troposphere. At high altitudes, nitrate formation is calculated to be ammonia limited. The underestimation of ammonium and nitrate in polluted regions is most likely caused by a too simplified treatment of the NH3 ∕ NH4+ partitioning which affects the HNO3 ∕ NO3− partitioning.


2009 ◽  
Vol 9 (2) ◽  
pp. 7873-7925 ◽  
Author(s):  
B. Croft ◽  
U. Lohmann ◽  
R. V. Martin ◽  
P. Stier ◽  
S. Wurzler ◽  
...  

Abstract. Wet deposition processes are highly efficient in the removal of aerosols from the atmosphere, and thus strongly influence global aerosol concentrations, and clouds, and their respective radiative forcings. In this study, physically detailed size-dependent below-cloud scavenging parameterizations for rain and snow are implemented in the ECHAM5-HAM global aerosol-climate model. Previously, below-cloud scavenging by rain in the ECHAM5-HAM was simply a function of the aerosol mode, and then scaled by the rainfall rate. The below-cloud scavenging by snow was a function of the snowfall rate alone. The global mean aerosol optical depth, and sea salt burden are sensitive to the below-cloud scavenging coefficients, with reductions near to 15% when the more vigorous size-dependent below-cloud scavenging by rain and snow is implemented. The inclusion of a prognostic rain scheme significantly reduces the fractional importance of below-cloud scavenging since there is higher evaporation in the lower troposphere, increasing the global mean sea salt burden by almost 15%. Thermophoretic effects are shown to produce increases in the global and annual mean below-cloud number removal of Aitken size particles of near to 15%, but very small increases (near 1%) in the global mean below-cloud mass scavenging of carbonaceous and sulfate aerosols. Changes in the assumptions about the below-cloud scavenging of ultra-fine particles by rain do not cause any significant changes to the global mean aerosol mass or number burdens, despite a change in the below-cloud number removal rate for nucleation mode particles by near to 10%. For nucleation mode particles, changes to the assumptions about the below-cloud scavenging by snow produce a greater change in the number removal rate, in excess of one order of magnitude. Closer agreement with different observations is found when the more physically detailed below-cloud scavenging parameterization is employed in the ECHAM5-HAM model.


2019 ◽  
Author(s):  
Vincent Huijnen ◽  
Kazuyuki Miyazaki ◽  
Johannes Flemming ◽  
Antje Inness ◽  
Takashi Sekiya ◽  
...  

Abstract. Global tropospheric ozone reanalyses constructed using different state-of-the-art satellite data assimilation systems, prepared as part of the Copernicus Atmosphere Monitoring Service (CAMS-iRean and CAMS-Rean) as well as two fully independent Tropospheric Chemistry Reanalyses (TCR-1 and TCR-2), have been inter-compared and evaluated for the past decade. The updated reanalyses (CAMS-Rean and TCR-2) generally show substantially improved agreements with independent ground and ozonesonde observations over their predecessor versions (CAMS-iRean and TCR-1) for the diurnal, synoptical, seasonal, and decadal variability. The improved performance can be attributed to a mixture of various upgrades, such as revisions in the chemical data assimilation, including the assimilated measurements, and the forecast model performance. The updated chemical reanalyses agree well with each other for most cases, which highlights the usefulness of the current chemical reanalyses in a variety of studies. Meanwhile, significant temporal changes in the reanalysis quality in all the systems can be attributed to discontinuities in the observing systems. To improve the temporal consistency, a careful assessment of changes in the assimilation configuration, such as a detailed assessment of biases between various retrieval products, is needed. Even though the assimilation of multi-species data influences the representation of the trace gases in all the systems and also the precursors’ emissions in the TCR reanalyses, the influence of persistent model errors remains a concern, especially for the lower troposphere. Our comparison suggests that improving the observational constraints, including the continued development of satellite observing systems, together with the optimization of model parameterisations, such as deposition and chemical reactions, will lead to increasingly consistent long-term reanalyses in the future.


2019 ◽  
Author(s):  
Aryeh Feinberg ◽  
Timofei Sukhodolov ◽  
Bei-Ping Luo ◽  
Eugene Rozanov ◽  
Lenny H. E. Winkel ◽  
...  

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 to 3.2 µm. Sheng et al. (2015) showed that SOCOL-AERv1 successfully matched observable quantities related to stratospheric aerosol, including a simulated stratospheric aerosol burden of 109 Gg of sulfur (S), very close to the satellite-derived estimate available in 2015, 112 Gg S. In the meantime, both the satellite retrieval and SOCOL-AER have undergone significant improvements. 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. Also, the volcanically quiescent total stratospheric aerosol burden simulated in SOCOL-AERv2, 160 Gg S, agrees very well with the new 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 lower 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 to atmospheric sulfur deposition due to variations in climate and emissions.


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