scholarly journals Impacts of aerosol indirect effect on past and future changes in tropospheric composition

2009 ◽  
Vol 9 (1) ◽  
pp. 4691-4725 ◽  
Author(s):  
N. Unger ◽  
S. Menon ◽  
D. T. Shindell ◽  
D. M. Koch
Keyword(s):  
Air Quality ◽  
Indirect Effect ◽  
Wet Deposition ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Aerosol Indirect Effect ◽  
Sulfate Production ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact

Abstract. The development of effective emissions control policies that are beneficial to both climate and air quality requires a detailed understanding of all the feedbacks in the atmospheric composition and climate system. We perform sensitivity studies with a global atmospheric composition-climate model to assess the impact of aerosols on tropospheric chemistry through their modification on clouds, the aerosol indirect effect (AIE). The model includes coupling between both tropospheric gas-phase and aerosol chemistry and aerosols and liquid-phase clouds. We investigate past impacts from preindustrial (PI) to present day (PD) and future impacts from PD to 2050 (for the moderate IPCC A1B scenario) that embrace a wide spectrum of precursor emission changes and consequential aerosol-cloud interactions. The AIE is estimated to be −2.0 W m−2 for PD–PI and −0.6 W m−2 for 2050–PD, at the high end of current estimates. Inclusion of aerosol-cloud interactions substantially impacts changes in global mean methane lifetime across both time periods, enhancing the past and future increases by 10% and 30%, respectively. In regions where pollution emissions increase, inclusion of aerosol-cloud effects leads to 20% enhancements in in-cloud sulfate production and ~10% enhancements in sulfate wet deposition that is displaced away from the immediate source regions. The enhanced in-cloud sulfate formation leads to larger increases in surface sulfate across polluted regions (~10–30%). Nitric acid wet deposition is dampened by 15–20% across the industrialized regions due to AIE allowing additional re-release of reactive nitrogen that contributes to 1–2 ppbv increases in surface ozone in outflow regions. Our model findings indicate that aerosol-cloud interactions must be considered in studies of methane trends and projections of future changes to particulate matter air quality.

scholarly journals Impacts of aerosol-cloud interactions on past and future changes in tropospheric composition

2009 ◽  
Vol 9 (12) ◽  
pp. 4115-4129 ◽  
Author(s):  
N. Unger ◽  
S. Menon ◽  
D. M. Koch ◽  
D. T. Shindell
Keyword(s):  
Air Quality ◽  
Wet Deposition ◽  
Wide Spectrum ◽  
Surface Ozone ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Sulfate Production ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact

Abstract. The development of effective emissions control policies that are beneficial to both climate and air quality requires a detailed understanding of all the feedbacks in the atmospheric composition and climate system. We perform sensitivity studies with a global atmospheric composition-climate model to assess the impact of aerosols on tropospheric chemistry through their modification on clouds, aerosol-cloud interactions (ACI). The model includes coupling between both tropospheric gas-phase and aerosol chemistry and aerosols and liquid-phase clouds. We investigate past impacts from preindustrial (PI) to present day (PD) and future impacts from PD to 2050 (for the moderate IPCC A1B scenario) that embrace a wide spectrum of precursor emission changes and consequential ACI. The aerosol indirect effect (AIE) is estimated to be −2.0 Wm−2 for PD-PI and −0.6 Wm−2 for 2050-PD, at the high end of current estimates. Inclusion of ACI substantially impacts changes in global mean methane lifetime across both time periods, enhancing the past and future increases by 10% and 30%, respectively. In regions where pollution emissions increase, inclusion of ACI leads to 20% enhancements in in-cloud sulfate production and ~10% enhancements in sulfate wet deposition that is displaced away from the immediate source regions. The enhanced in-cloud sulfate formation leads to larger increases in surface sulfate across polluted regions (~10–30%). Nitric acid wet deposition is dampened by 15–20% across the industrialized regions due to ACI allowing additional re-release of reactive nitrogen that contributes to 1–2 ppbv increases in surface ozone in outflow regions. Our model findings indicate that ACI must be considered in studies of methane trends and projections of future changes to particulate matter air quality.

scholarly journals Radiative forcing of climate change from the Copernicus reanalysis of atmospheric composition

2020 ◽  
Vol 12 (3) ◽  
pp. 1649-1677 ◽  
Author(s):  
Nicolas Bellouin ◽  
Will Davies ◽  
Keith P. Shine ◽  
Johannes Quaas ◽  
Johannes Mülmenstädt ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Global Average ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact

Abstract. Radiative forcing provides an important basis for understanding and predicting global climate changes, but its quantification has historically been done independently for different forcing agents, has involved observations to varying degrees, and studies have not always included a detailed analysis of uncertainties. The Copernicus Atmosphere Monitoring Service reanalysis is an optimal combination of modelling and observations of atmospheric composition. It provides a unique opportunity to rely on observations to quantify the monthly and spatially resolved global distributions of radiative forcing consistently for six of the largest forcing agents: carbon dioxide, methane, tropospheric ozone, stratospheric ozone, aerosol–radiation interactions, and aerosol–cloud interactions. These radiative-forcing estimates account for adjustments in stratospheric temperatures but do not account for rapid adjustments in the troposphere. On a global average and over the period 2003–2017, stratospherically adjusted radiative forcing of carbon dioxide has averaged +1.89 W m−2 (5 %–95 % confidence interval: 1.50 to 2.29 W m−2) relative to 1750 and increased at a rate of 18 % per decade. The corresponding values for methane are +0.46 (0.36 to 0.56) W m−2 and 4 % per decade but with a clear acceleration since 2007. Ozone radiative-forcing averages +0.32 (0 to 0.64) W m−2, almost entirely contributed by tropospheric ozone since stratospheric ozone radiative forcing is only +0.003 W m−2. Aerosol radiative-forcing averages −1.25 (−1.98 to −0.52) W m−2, with aerosol–radiation interactions contributing −0.56 W m−2 and aerosol–cloud interactions contributing −0.69 W m−2 to the global average. Both have been relatively stable since 2003. Taking the six forcing agents together, there is no indication of a sustained slowdown or acceleration in the rate of increase in anthropogenic radiative forcing over the period. These ongoing radiative-forcing estimates will monitor the impact on the Earth's energy budget of the dramatic emission reductions towards net-zero that are needed to limit surface temperature warming to the Paris Agreement temperature targets. Indeed, such impacts should be clearly manifested in radiative forcing before being clear in the temperature record. In addition, this radiative-forcing dataset can provide the input distributions needed by researchers involved in monitoring of climate change, detection and attribution, interannual to decadal prediction, and integrated assessment modelling. The data generated by this work are available at https://doi.org/10.24380/ads.1hj3y896 (Bellouin et al., 2020b).

scholarly journals The role of aerosol-cloud interactions in linking anthropogenic pollution over southern West Africa and dust emission over the Sahara

2019 ◽  
Author(s):  
Laurent Menut ◽  
Paolo Tuccella ◽  
Cyrille Flamant ◽  
Adrien Deroubaix ◽  
Marco Gaetani
Keyword(s):  
West Africa ◽  
Mineral Dust ◽  
Surface Wind ◽  
Dust Emission ◽  
Atmospheric Composition ◽  
Anthropogenic Emissions ◽  
Dust Emissions ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact

Abstract. The aerosol direct and indirect effects are studied over West Africa in the summer of 2016 using the coupled WRF-CHIMERE regional model including aerosol-cloud interaction parametrization. First, a reference simulation is performed and compared with observations acquired during the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) field campaign which took place in June and July 2016. Sensitivity experiments are also designed to gain insights into the impact of the aerosols dominating the atmospheric composition in southern West Africa (one simulation with halved anthropogenic emissions and one with halved mineral dust emissions). The most important effect of aerosol-cloud interactions is found for the mineral dust scenario and it is shown that halving the emissions of mineral dust decreases the 2-m temperature by 0.5 K and the boundary layer height by 25 m in monthly average and over the Saharan region. The presence of dust aerosols also increases (resp. decreases) the shortwave (resp. longwave) radiation at the surface by 25 W/m2. It is also shown that the decrease of anthropogenic emissions along the coast has an impact on the mineral dust load over West Africa by increasing their emissions in Saharan region. It is due to a mechanism where particulate matter concentrations are decreased along the coast, imposing a latitudinal shift of the monsoonal precipitation, and, in turn, an increase of the surface wind speed over arid areas, inducing more mineral dust emissions.

Recent updates to the atmospheric aerosol modelling of the ECMWF IFS in support to CAMS

2021 ◽  
Author(s):  
Samuel Remy ◽  
Zak Kipling ◽  
Vincent Huijnen ◽  
Johannes Flemming ◽  
Swen Metzger ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Deposition Velocity ◽  
Surface Concentration ◽  
Atmospheric Composition ◽  
Small Scale ◽  
Skill Scores ◽  
Simulated Surface ◽  
The Impact

<p>The Integrated Forecasting System (IFS) of ECMWF is used within the Copernicus Atmosphere Monitoring Service (CAMS) to provide global analyses and forecasts of atmospheric composition, including aerosols as well as reactive trace gases and greenhouse gases.</p><p>The aerosol model of the IFS, IFS-AER, is a simple sectional-bulk scheme that forecasts seven species:  dust, sea-salt, black carbon, organic matter, sulfate, and  since July 2019, nitrate and ammonium.  The main developments that have been recently carried out, tested and are now contemplated for implementation in the next operational version (known as cycle 48r1) are presented here.</p><p>The dry deposition velocities are computed as a function of roughness length, particle size and surface friction velocity, while wet deposition depends mainly on the precipitation fluxes. The parameterizations of both dry and wet deposition have been upgraded with more recent schemes, which have been shown to improve the simulated deposition fluxes for several aerosol species. The impact of this upgrade on the skill scores of simulated aerosol optical depth (AOD) and surface particulate matter concentrations against a range of observations is very positive.</p><p>The simulated surface concentration of nitrate and ammonium are frequently strongly overestimated over Europe and the  United States in the current version of the IFS. Nitrate, ammonium, and their precursors nitric acid and ammonia, were evaluated against a range of ground and remote data and it was found that the recently-implemented gas-particle partitioning scheme is too efficient in producing nitrate and ammonium particles.</p><p>A series of small-scale changes, such as adjusting nitrate dry deposition velocity, direct particulate sulphate emission, and limiting nitrate/ammonium production by the concentration of mineral cations, have been implemented and shown to be effective in improving the simulated surface concentration of  nitrate and ammonium.</p><p>The representation of secondary organic aerosol (SOA) in the IFS has been overhauled with the introduction of a new SOA species, distinct from primary organic matter, with anthropogenic and biogenic components. The implementation of this new species leads to a significant improvement of the simulated surface concentration of organic carbon. An evaluation of simulated SOA concentrations at the surface against climatological values derived from observations using Positive Matrix Factorisation (PMF) techniques also shows a reasonable agreement.</p>

scholarly journals Aerosol–Cloud Closure Study on Cloud Optical Properties using Remotely Piloted Aircraft Measurements during a BACCHUS Field Campaign in Cyprus

2019 ◽  
Author(s):  
Radiance Calmer ◽  
Gregory C. Roberts ◽  
Kevin J. Sanchez ◽  
Jean Sciare ◽  
Karine Sellegri ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Radiation ◽  
Shortwave Radiation ◽  
Cloud Base ◽  
Field Campaign ◽  
Aerosol Cloud ◽  
Remotely Piloted Aircraft ◽  
Aerosol Cloud Interactions ◽  
The Impact ◽  
Adiabatic Case

Abstract. In the framework of the EU-FP7 BACCHUS project, an intensive field campaign was performed in Cyprus (2015/03). Remotely Piloted Aircraft System (RPAS), ground-based instruments, and remote-sensing observations were operating in parallel to provide an integrated characterization of aerosol-cloud interactions. Remotely Piloted Aircraft (RPA) were equipped with a 5-hole probe, pyranometers, pressure, temperature and humidity sensors, and measured updraft velocity at cloud base and cloud optical properties of a stratocumulus layer. Ground-based measurements of dry aerosol size distributions and cloud condensation nuclei spectra, and RPA observations of vertical wind velocity and meteorological state parameters are used here to initialize an Aerosol–Cloud Parcel Model (ACPM) and compare the in situ observations of cloud optical properties measured by the RPA to those simulated in the ACPM. Two different cases are studied with the ACPM, including an adiabatic case and an entrainment case, in which the in-cloud temperature profile from RPA is taken into account. Adiabatic ACPM simulation yields cloud droplet number concentrations at cloud base (ca. 400 cm−3) that are similar to those derived from a Hoppel minimum analysis. Cloud optical properties have been inferred using the transmitted fraction of shortwave radiation profile measured by downwelling and upwelling pyranometers mounted on a RPA, and the observed transmitted fraction of solar radiation is then compared to simulations from the ACPM. ACPM simulations and RPA observations show better agreement when associated with entrainment compared to that of an adiabatic case. The mean difference between observed and adiabatic profiles of transmitted fraction of solar radiation is 0.12, while this difference is only 0.03 between observed and entrainment profiles. A sensitivity calculation is then conducted to quantify the relative impacts of two-fold changes in aerosol concentration, and updraft velocity to highlight the importance of accounting for the impact of entrainment in deriving cloud optical properties, as well as the ability of RPAs to leverage ground-based observations for studying aerosol–cloud interactions.

scholarly journals The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

2011 ◽  
Vol 366 (1582) ◽  
pp. 3210-3224 ◽  
Author(s):  
J. A. Pyle ◽  
N. J. Warwick ◽  
N. R. P. Harris ◽  
Mohd Radzi Abas ◽  
A. T. Archibald ◽  
...  
Keyword(s):  
Land Use ◽  
Air Quality ◽  
Land Use Change ◽  
Spatial Scales ◽  
Model Performance ◽  
Atmospheric Composition ◽  
Model Studies ◽  
Uncertainty Model ◽  
Emission Changes ◽  
The Impact

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO x emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

scholarly journals Impact of lightning-NO on Eastern United States photochemistry during the summer of 2006 as determined using the CMAQ model

2011 ◽  
Vol 11 (6) ◽  
pp. 17699-17757 ◽  
Author(s):  
D. J. Allen ◽  
K. E. Pickering ◽  
R. W. Pinder ◽  
B. H. Henderson ◽  
K. W. Appel ◽  
...  
Keyword(s):  
United States ◽  
Air Quality ◽  
Wet Deposition ◽  
Surface Ozone ◽  
Convective Precipitation ◽  
Eastern United States ◽  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
The Impact

Abstract. A lightning-nitrogen oxide (NO) algorithm is developed for the regional Community Multiscale Air Quality Model (CMAQ) and used to evaluate the impact of lightning-NO emissions (LNOx) on tropospheric photochemistry over the Eastern United States during the summer of 2006. The scheme assumes flash rates are proportional to the model convective precipitation rate but then adjusts the flash rates locally to match monthly average observations. Over the Eastern United States, LNOx is responsible for 20–25 % of the tropospheric nitrogen dioxide (NO2) column. This additional NO2 reduces the low-bias of simulated NO2 columns with respect to satellite-retrieved Dutch Ozone Monitoring Instrument NO2 (DOMINO) columns from 41 to 14 %. It also adds 10–20 ppbv to upper tropospheric ozone and 1.5–4.5 ppbv to 8-h maximum surface layer ozone, although, on average, the contribution of LNOx to surface ozone is 1–2 ppbv less on poor air quality days. Biases between modeled and satellite-retrieved tropospheric NO2 columns vary greatly between urban and rural locations. In general, CMAQ overestimates columns at urban locations and underestimates columns at rural locations. These biases are consistent with in situ measurements that also indicate that CMAQ has too much NO2 in urban regions and not enough in rural regions. However, closer analysis suggests that most of the differences between modeled and satellite-retrieved urban to rural ratios are likely a consequence of the horizontal and vertical smoothing inherent in columns retrieved by the Ozone Monitoring Instrument (OMI). Within CMAQ, LNOx increases wet deposition of nitrate by 50 % and total deposition of nitrogen by 11 %. This additional deposition reduces the magnitude of the CMAQ low-bias in nitrate wet deposition with respect to National Atmospheric Deposition monitors to near zero. In order to obtain an upper bound on the contribution of uncertainties in chemistry to upper tropospheric NOx low biases, sensitivity calculations with updated chemistry were run for the time period of the Intercontinental Chemical Transport Experiment (INTEX-A) field campaign (summer 2004). After adjusting for possible interferences in NO2 measurements and averaging over the entire campaign, these updates reduced 7–9 km biases from 32 to 17 % and 9–12 km biases from 57 to 46 %. While these changes lead to better agreement, a considerable NO2 low-bias remains in the uppermost troposphere.

scholarly journals The role of aerosol–radiation–cloud interactions in linking anthropogenic pollution over southern west Africa and dust emission over the Sahara

2019 ◽  
Vol 19 (23) ◽  
pp. 14657-14676 ◽  
Author(s):  
Laurent Menut ◽  
Paolo Tuccella ◽  
Cyrille Flamant ◽  
Adrien Deroubaix ◽  
Marco Gaetani
Keyword(s):  
West Africa ◽  
Mineral Dust ◽  
Surface Wind ◽  
Dust Emission ◽  
Longwave Radiation ◽  
Atmospheric Composition ◽  
Anthropogenic Emissions ◽  
Dust Emissions ◽  
Aerosol Cloud ◽  
The Impact

Abstract. The aerosol direct and indirect effects are studied over west Africa in the summer of 2016 using the coupled WRF-CHIMERE regional model including aerosol–cloud interaction parameterization. First, a reference simulation is performed and compared with observations acquired during the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) field campaign which took place in June and July 2016. Sensitivity experiments are also designed to gain insights into the impact of the aerosols dominating the atmospheric composition in southern west Africa (one simulation with halved anthropogenic emissions and one with halved mineral dust emissions). The most important effect of aerosol–cloud interactions is found for the mineral dust scenario, and it is shown that halving the emissions of mineral dust decreases the 2 m temperature by 0.5 K and the boundary layer height by 25 m on a monthly average (July 2016) and over the Saharan region. The presence of dust aerosols also increases (decreases) the shortwave (longwave) radiation at the surface by 25 W m−2. It is also shown that the decrease of anthropogenic emissions along the coast has an impact on the mineral dust load over west Africa by increasing their emissions in the Saharan region. It is due to a mechanism where particulate matter concentrations are decreased along the coast, imposing a latitudinal shift of the monsoonal precipitation and, in turn, an increase of the surface wind speed over arid areas, inducing more mineral dust emissions.

scholarly journals The Weather Research and Forecasting Model with Aerosol–Cloud Interactions (WRF-ACI): Development, Evaluation, and Initial Application

2019 ◽  
Vol 147 (5) ◽  
pp. 1491-1511 ◽  
Author(s):  
Timothy Glotfelty ◽  
Kiran Alapaty ◽  
Jian He ◽  
Patrick Hawbecker ◽  
Xiaoliang Song ◽  
...  
Keyword(s):  
Cloud Microphysics ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Subgrid Scale ◽  
Liquid Water Path ◽  
Modeling Framework ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions ◽  
The Impact ◽  
Weather Research

Abstract The Weather Research and Forecasting Model with Aerosol–Cloud Interactions (WRF-ACI) is developed for studying aerosol effects on gridscale and subgrid-scale clouds using common aerosol activation and ice nucleation formulations and double-moment cloud microphysics in a scale-aware subgrid-scale parameterization scheme. Comparisons of both the standard WRF and WRF-ACI models’ results for a summer season against satellite and reanalysis estimates show that the WRF-ACI system improves the simulation of cloud liquid and ice water paths. Correlation coefficients for nearly all evaluated parameters are improved, while other variables show slight degradation. Results indicate a strong cloud lifetime effect from current climatological aerosols increasing domain average cloud liquid water path and reducing domain average precipitation as compared to a simulation with aerosols reduced by 90%. Increased cloud-top heights indicate a thermodynamic invigoration effect, but the impact of thermodynamic invigoration on precipitation is overwhelmed by the cloud lifetime effect. A combination of cloud lifetime and cloud albedo effects increases domain average shortwave cloud forcing by ~3.0 W m−2. Subgrid-scale clouds experience a stronger response to aerosol levels, while gridscale clouds are subject to thermodynamic feedbacks because of the design of the WRF modeling framework. The magnitude of aerosol indirect effects is shown to be sensitive to the choice of autoconversion parameterization used in both the gridscale and subgrid-scale cloud microphysics, but spatial patterns remain qualitatively similar. These results indicate that the WRF-ACI model provides the community with a computationally efficient tool for exploring aerosol–cloud interactions.

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