scholarly journals Organic pollutants from Indonesian peatland fires: regional influences and its impact on lower the stratospheric composition

2021 ◽  
Author(s):  
Simon Rosanka ◽  
Bruno Franco ◽  
Lieven Clarisse ◽  
Pierre-François Coheur ◽  
Andreas Wahner ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Chemical Production ◽  
Global Atmospheric Model ◽  
Reservoir Species ◽  
Upward Transport ◽  
High Concentrations ◽  
Stratospheric Composition ◽  
The Impact

<p>In 2015, the particularly strong dry season in Indonesia, caused by an exceptional strong El Niño, led to severe peatland fires. Due to the high carbon content of peatland, these fires are characterised by high volatile organic compound (VOC) biomass burning emissions. The resulting primary and secondary pollutants are efficiently transported to the upper troposphere/lower stratosphere (UTLS) by the developing Asian monsoon anticyclone (ASMA) and the general upward transport in the intertropical convergence zone (ITCZ). In this study, we assess the importance of these VOC emissions for the composition of the lower troposphere and the UTLS by performing multiple chemistry simulations using the global atmospheric model ECHAM/MESSy (EMAC). In a first step, we find that EMAC properly captures the exceptional strength of the Indonesian fires based on the comparison of modelled columns of the biomass burning marker hydrogen cyanide (HCN) to spaceborne measurements from the Infrared Atmospheric Sounding Interferometer (IASI). In the lower troposphere, the increase in VOC levels is higher in Indonesia compared to other biomass burning regions. This directly impacts the oxidation capacity and leads to a high reduction in hydroxyl radicals (OH) and nitrogen oxides (NO<sub>x</sub>). In general, an increase in ozone (O<sub>3</sub>) is predicted close to the peatland fires. However, particular high concentrations of phenols lead to an O<sub>3</sub> depletion in eastern Indonesia. By employing the detailed in-cloud OVOC oxidation scheme Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC), we find that the predicted changes are dampened and that by ignoring these processes, global models tend to overestimate the impact of such extreme pollution events. The upward transport in the ASMA and the ITCZ leads to elevated VOC concentrations in the UTLS region. This also results in a depletion of lower stratospheric O<sub>3</sub>. We find that this is caused by a high destruction of O<sub>3</sub> by phenoxy radicals and by the increased formation of NO<sub>x</sub> reservoir species, which dampen the chemical production of O<sub>3</sub>.</p>

scholarly journals Organic pollutants from tropical peatland fires: regional influences and its impact on lower stratospheric ozone

2020 ◽  
Author(s):  
Simon Rosanka ◽  
Bruno Franco ◽  
Lieven Clarisse ◽  
Pierre-François Coheur ◽  
Andreas Wahner ◽  
...  
Keyword(s):  
Biomass Burning ◽  
El Niño ◽  
El Nino ◽  
Stratospheric Ozone ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Chemical Production ◽  
Global Models ◽  
Upward Transport ◽  
The Impact

Abstract. The particularly strong dry season in Indonesia in 2015, caused by an exceptional strong El Niño, led to severe peatland fires resulting in high volatile organic compound (VOC) biomass burning emissions. At the same time, the developing Asian monsoon anticyclone (ASMA) and the general upward transport in the intertropical convergence zone (ITCZ) efficiently transported the resulting primary and secondary pollutants to the upper troposphere/lower stratosphere (UTLS). In this study, we assess the importance of these VOC emissions for the composition of the lower troposphere and the UTLS, and we investigate the effect of in-cloud oxygenated VOC (OVOC) oxidation during such a strong pollution event. This is achieved by performing multiple chemistry simulations using the global atmospheric model ECHAM/MESSy (EMAC). By comparing modelled columns of the biomass burning marker hydrogen cyanide (HCN) to spaceborne measurements from the Infrared Atmospheric Sounding Interferometer (IASI), we find that EMAC properly captures the exceptional strength of the Indonesian fires. In the lower troposphere, the increase in VOC levels is higher in Indonesia compared to other biomass burning regions. This has a direct impact on the oxidation capacity, resulting in the largest regional reduction in hydroxyl radicals (OH) and nitrogen oxides (NOx). Even though an increase in ozone (O3) is predicted close to the peatland fires, particular high concentrations of phenols lead to an O3 depletion in eastern Indonesia. By employing the detailed in-cloud OVOC oxidation scheme Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC), we find that the predicted changes are dampened and that by ignoring these processes, global models tend to overestimate the impact of such extreme pollution events. In the ASMA and the ITCZ, the upward transport leads to elevated VOC concentrations in the UTLS region, which results in a depletion of lower stratospheric O3. We find that this is caused by a high destruction of O3 by phenoxy radicals and by the increased formation of NOx reservoir species, which dampen the chemical production of O3. The Indonesian peatland fires regularly occur during El Niño years and contribute to the depletion of O3. In the time period from 2001 to 2016, we find that the lower stratospheric O3 is reduced by about 0.38 DU and contributes to about 25 % to the lower stratospheric O3 reduction observed by remote sensing. By not considering these processes, global models might not be able to reproduce this variability in lower stratospheric O3.

scholarly journals The impact of organic pollutants from Indonesian peatland fires on the tropospheric and lower stratospheric composition

2021 ◽  
Vol 21 (14) ◽  
pp. 11257-11288
Author(s):  
Simon Rosanka ◽  
Bruno Franco ◽  
Lieven Clarisse ◽  
Pierre-François Coheur ◽  
Andrea Pozzer ◽  
...  
Keyword(s):  
Biomass Burning ◽  
El Niño ◽  
Lower Stratosphere ◽  
El Nino ◽  
Lower Troposphere ◽  
Atmospheric Composition ◽  
Voc Emissions ◽  
Upper Troposphere ◽  
Upward Transport ◽  
The Impact

Abstract. The particularly strong dry season in Indonesia in 2015, caused by an exceptionally strong El Niño, led to severe peatland fires resulting in high volatile organic compound (VOC) biomass burning emissions. At the same time, the developing Asian monsoon anticyclone (ASMA) and the general upward transport in the Intertropical Convergence Zone (ITCZ) efficiently transported the resulting primary and secondary pollutants to the upper troposphere and lower stratosphere (UTLS). In this study, we assess the importance of these VOC emissions for the composition of the lower troposphere and the UTLS and investigate the effect of in-cloud oxygenated VOC (OVOC) oxidation during such a strong pollution event. This is achieved by performing multiple chemistry simulations using the global atmospheric model ECHAM/MESSy (EMAC). By comparing modelled columns of the biomass burning marker hydrogen cyanide (HCN) and carbon monoxide (CO) to spaceborne measurements from the Infrared Atmospheric Sounding Interferometer (IASI), we find that EMAC properly captures the exceptional strength of the Indonesian fires. In the lower troposphere, the increase in VOC levels is higher in Indonesia compared to other biomass burning regions. This has a direct impact on the oxidation capacity, resulting in the largest regional reduction in the hydroxyl radical (OH) and nitrogen oxides (NOx). While an increase in ozone (O3) is predicted close to the peatland fires, simulated O3 decreases in eastern Indonesia due to particularly high phenol concentrations. In the ASMA and the ITCZ, the upward transport leads to elevated VOC concentrations in the lower stratosphere, which results in the reduction of OH and NOx and the increase in the hydroperoxyl radical (HO2). In addition, the degradation of VOC emissions from the Indonesian fires becomes a major source of lower stratospheric nitrate radicals (NO3), which increase by up to 20 %. Enhanced phenol levels in the upper troposphere result in a 20 % increase in the contribution of phenoxy radicals to the chemical destruction of O3, which is predicted to be as large as 40 % of the total chemical O3 loss in the UTLS. In the months following the fires, this loss propagates into the lower stratosphere and potentially contributes to the variability of lower stratospheric O3 observed by satellite retrievals. The Indonesian peatland fires regularly occur during El Niño years, and the largest perturbations of radical concentrations in the lower stratosphere are predicted for particularly strong El Niño years. By activating the detailed in-cloud OVOC oxidation scheme Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC), we find that the predicted changes are dampened. Global models that neglect in-cloud OVOC oxidation tend to overestimate the impact of such extreme pollution events on the atmospheric composition.

scholarly journals Inclusion of biomass burning in WRF-Chem: impact of wildfires on weather forecasts

2011 ◽  
Vol 11 (11) ◽  
pp. 5289-5303 ◽  
Author(s):  
G. Grell ◽  
S. R. Freitas ◽  
M. Stuefer ◽  
J. Fast
Keyword(s):  
Biomass Burning ◽  
Cloud Model ◽  
Cloud Condensation Nuclei ◽  
Cloud Microphysics ◽  
Fire Season ◽  
Strong Impact ◽  
Emission Rates ◽  
Weather Forecasts ◽  
High Concentrations ◽  
The Impact

Abstract. A plume rise algorithm for wildfires was included in WRF-Chem, and applied to look at the impact of intense wildfires during the 2004 Alaska wildfire season on weather simulations using model resolutions of 10 km and 2 km. Biomass burning emissions were estimated using a biomass burning emissions model. In addition, a 1-D, time-dependent cloud model was used online in WRF-Chem to estimate injection heights as well as the vertical distribution of the emission rates. It was shown that with the inclusion of the intense wildfires of the 2004 fire season in the model simulations, the interaction of the aerosols with the atmospheric radiation led to significant modifications of vertical profiles of temperature and moisture in cloud-free areas. On the other hand, when clouds were present, the high concentrations of fine aerosol (PM2.5) and the resulting large numbers of Cloud Condensation Nuclei (CCN) had a strong impact on clouds and cloud microphysics, with decreased precipitation coverage and precipitation amounts during the first 12 h of the integration. During the afternoon, storms were of convective nature and appeared significantly stronger, probably as a result of both the interaction of aerosols with radiation (through an increase in CAPE) as well as the interaction with cloud microphysics.

Climate Change effects on the River Discharge in Bulgaria

2020 ◽  
Author(s):  
Maria Mavrova-Guirguinova
Keyword(s):  
Climate Change ◽  
River Discharge ◽  
Simulation Models ◽  
Atmospheric Model ◽  
Future Climate Change ◽  
Local Version ◽  
Hydrological Simulation ◽  
Climate Change Effects ◽  
Global Atmospheric Model ◽  
The Impact

<p>The impact of future climate change under IPCC scenarios RCP4.5 and RCP8.5 on hydrological regimes in plain catchments up to 650 m high and in mountainous areas of Bulgaria is discussed. A hydrological simulation models (TUWmodel) were calibrated on recorded data and ‘forced’ in the selected scenarios with precipitation and air temperature data from ALADIN 5.2, a local version of the French global atmospheric model ARPEGE, downscaled to a grid of 12 km. Simulations for the future periods 2013-2042, 2021-2050 and 2071-2100 are compared to the flows in the reference period 1976-2005.</p><p>Results indicate increased seasonality of flows, with noticeably drier summers and increase of river discharge in winter. In most of the cases the analysis of extreme events suggests significant increases in the frequency of both high‐ and low‐flow events. The change in the extreme runoff with a large repetition period required for the design of flood protection structures and systems has been investigated in regions with different mechanisms for flood generation. With the push of RCP4.5 or RCP8.5 scenarios the significant increase in flood peaks is observed in most of the river basins. There is a general trend of decreasing runoff with a 95% probability of exceedance.</p>

scholarly journals Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

2017 ◽  
Vol 17 (11) ◽  
pp. 6925-6955 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
High Concentrations ◽  
Intercomparison Study ◽  
The Impact

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

scholarly journals The impact of deep convection representation in a global atmospheric model on the warm conveyor belt and jet stream during NAWDEX IOP6

2021 ◽  
Author(s):  
Gwendal Rivière ◽  
Meryl Wimmer ◽  
Philippe Arbogast ◽  
Jean-Marcel Piriou ◽  
Julien Delanoë ◽  
...  
Keyword(s):  
Heating Rate ◽  
Large Scale ◽  
Deep Convection ◽  
Atmospheric Model ◽  
Conveyor Belt ◽  
The Other ◽  
Jet Stream ◽  
Field Campaign ◽  
Global Atmospheric Model ◽  
The Impact

Abstract. The effect of parameterized deep convection on warm conveyor belt (WCB) activity and jet stream is investigated by performing simulations of an explosively-developing large-scale cyclone that occurred during the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) field campaign using the Météo-France global atmospheric model ARPEGE. Three simulations differing only from their deep convection representation are analysed. The first one was performed with the Bougeault et al. (1985) scheme (B85), the second one with the Prognostic Condensates Microphysics and Transport (PCMT) scheme of Piriou et al. (2007), and the third one without any parameterized deep convection. In the latter simulation, the release of convective instability at the resolved scales of the model generates localized cells marked by strong heating with few degrees extent in longitude and latitude along the fronts. In runs with active parameterized deep convection (B85, PCMT), the heating rate is more homogeneously distributed along fronts as the instability release happens at sub-grid scales. This difference leads to more rapid and abrupt ascents in the WCB without parameterized deep convection, and more moderate but more sustained ascents with parameterized deep convection. While the number of WCB trajectories does not differ much between the three simulations, the averaged heating rates over the WCB trajectories exhibits distinct behavior. After one day of simulations, the upper-level heating rate is in average larger with B85 scheme leading to stronger potential vorticity (PV) destruction. The difference comes from the large-scale heating and not the parameterized heating.A comparison with (re)analyses and a large variety of airborne observations from the NAWDEX field campaign (Doppler radar, Doppler lidar, dropsondes) made during the coordinated flights of two aircraft in the WCB outflow region shows that B85 performs better in the representation of the double jet structure at 1-day lead time than the other two simulations. That can be attributed to the more active WCB at upper levels. However this effect is too strong and that simulation becomes less realistic at longer forecast range (1.5 to 2 days) than the other ones. The simulation with PCMT scheme has an intermediate behavior between the one with B85 scheme and without parameterized deep convection but its impact on the jet stream is closer to the latter one. Finally, additional numerical experiments show that main differences in the impact on the jet between PCMT and B85 largely come from the chosen closure, the former being based on CAPE and the latter on moisture convergence.

scholarly journals Impact of biomass burning and stratospheric intrusions in the remote South Pacific Ocean troposphere

2021 ◽  
Author(s):  
Nikos Daskalakis ◽  
Laura Gallardo ◽  
Maria Kanakidou ◽  
Rasmus Nüß ◽  
Camilo Menares ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Biomass Burning ◽  
Transport Model ◽  
Lower Troposphere ◽  
South Pacific ◽  
Global Ocean ◽  
Rapa Nui ◽  
South Pacific Ocean ◽  
The Impact ◽  
Stratospheric Intrusions

Abstract. The ozone mixing ratio spatio-temporal variability in the pristine southern Pacific Ocean is studied, for the first time, using 21-year long ozone (O3) records from the entire southern tropical and subtropical Pacific, between 1994 and 2014. The analysis considered regional O3 vertical observations from ozonesondes, surface carbon monoxide (CO) observations from flasks and three-dimensional chemistry-transport model simulations of the global troposphere. Two 21-year long numerical simulations, with and without biomass burning emissions, were performed to disentangle the importance of biomass burning relative to stratospheric intrusions for ambient ozone levels in the region. Tagged tracers of O3 from the stratosphere and CO from various biomass burning regions have been used to track the impact of these different regions on the southern tropical Pacific O3 and CO levels. Patterns have been analyzed based on atmospheric dynamics variability. Considering the interannual variability in the observations, the model can capture the observed ozone gradients in the troposphere with a positive bias of 7.5 % in the upper troposphere/low stratosphere (UTLS), as well as near the surface. Remarkably, even the most pristine region of the global ocean is affected by distant biomass burning emissions by convective outflow through the mid and high troposphere and subsequent subsidence over the pristine oceanic region. Therefore, the biomass burning contribution to tropospheric CO levels maximizes in the UTLS. The Southeast Asian open fires have been identified as the major contributing source to CO from biomass burning in the tropical southern Pacific, contributing on average for the study period about 8.5 and 13 ppbv of CO at Rapa Nui and Samoa, respectively, at an altitude of around 12 km during the burning season in the spring of the Southern Hemisphere. South America is the second most important biomass burning source region that influences the study area. Its impact maximizes in the lower troposphere (6.5 ppbv for Rapa Nui and 3.8 ppbv for Samoa). All biomass burning sources contribute about 15–23 ppbv of CO, accounting for about 25 % of the total CO in the entire troposphere of the tropical and subtropical South Pacific. This impact is also seen on tropospheric O3, to which biomass burning O3 precursor emissions contribute only a few ppbv during the burning period, while the stratosphere-troposphere exchange is the most important source of O3 for the mid-troposphere of the south Pacific Ocean, contributing about 15–20 ppbv in the subtropics.

The impact of spatially varying wetland source signatures on the atmospheric variability of δ D-CH 4

2021 ◽  
Vol 379 (2210) ◽  
pp. 20200442
Author(s):  
Angharad C. Stell ◽  
Peter M. J. Douglas ◽  
Matthew Rigby ◽  
Anita L. Ganesan
Keyword(s):  
Spatial Information ◽  
Regional Scale ◽  
Atmospheric Model ◽  
Hemispheric Difference ◽  
Atmospheric Variability ◽  
Spatially Resolved ◽  
Global Atmospheric Model ◽  
Spatially Varying ◽  
The Impact ◽  
Global Mean

We present the first spatially resolved distribution of the δ D-CH 4 signature of wetland methane emissions and assess its impact on atmospheric δ D-CH 4 . The δ D-CH 4 signature map is derived by relating δ D-H 2 O of precipitation to measured δ D-CH 4 of methane wetland emissions at a variety of wetland types and locations. This results in strong latitudinal variation in the wetland δ D-CH 4 source signature. When δ D-CH 4 is simulated in a global atmospheric model, little difference is found in global mean, inter-hemispheric difference and seasonal cycle if the spatially varying δ D-CH 4 source signature distribution is used instead of a globally uniform value. This is because atmospheric δ D-CH 4 is largely controlled by OH fractionation. However, we show that despite these small differences, using atmospheric records of δ D-CH 4 to infer changes in the wetland emissions distribution requires the use of the more accurate spatially varying δ D-CH 4 source signature. We find that models will only be sensitive to changes in emissions distribution if spatial information can be exploited through the spatially resolved source signatures. In addition, we also find that on a regional scale, at sites measuring excursions of δ D-CH 4 from background levels, substantial differences are simulated in atmospheric δ D-CH 4 if using spatially varying or uniform source signatures. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 1)’.

scholarly journals Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions

2011 ◽  
Vol 11 (15) ◽  
pp. 7817-7838 ◽  
Author(s):  
K. Zhang ◽  
J. Feichter ◽  
J. Kazil ◽  
H. Wan ◽  
W. Zhuo ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Radioactive Decay ◽  
Lower Troposphere ◽  
Atmospheric Model ◽  
Ionization Rate ◽  
Aerosol Size Distribution ◽  
High Concentration ◽  
Near Surface ◽  
Global Estimate ◽  
The Impact

Abstract. The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. Near-surface radon concentrations simulated with this new map compare well with measurements. Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. During cold seasons, at locations where high concentration of sulfuric acid gas and low temperature provide potentially favorable conditions for nucleation, the coexistence of high ionization rate may help enhance the particle formation processes. This suggests that it is probably worth investigating the impact of radon-induced ionization on aerosol-climate interaction in global models.

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