Atmospheric Chemistry of Perfluoroaldehydes (CxF2x+1CHO) and Fluorotelomer Aldehydes (CxF2x+1CH2CHO):  Quantification of the Important Role of Photolysis

2006 ◽  
Vol 110 (43) ◽  
pp. 11944-11953 ◽  
Author(s):  
Malisa S. Chiappero ◽  
Fabio E. Malanca ◽  
Gustavo A. Argüello ◽  
Steven T. Wooldridge ◽  
Michael D. Hurley ◽  
...  
Keyword(s):  
Atmospheric Chemistry

scholarly journals Central role of carbonyl compounds in atmospheric chemistry

2000 ◽  
Vol 105 (D15) ◽  
pp. 19771-19778 ◽  
Author(s):  
D. J. Lary ◽  
D. E. Shallcross
Keyword(s):  
Atmospheric Chemistry ◽  
Carbonyl Compounds

Atmospheric impacts of short-lived chlorinated species over the recent past: a chemistry-climate perspective

2021 ◽  
Author(s):  
Ewa Bednarz ◽  
Ryan Hossaini ◽  
Luke Abraham ◽  
Peter Braesicke ◽  
Martyn Chipperfield
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Lower Boundary ◽  
Montreal Protocol ◽  
Recent Past ◽  
Substantial Impact ◽  
Ozone Depleting Substances ◽  
The Impact

<p>The emissions of most long-lived halogenated ozone-depleting substances (ODSs) are now decreasing, owing to controls on their production introduced by Montreal Protocol and its amendments. However, short-lived halogenated compounds can also have substantial impact on atmospheric chemistry, including stratospheric ozone, particularly if emitted near climatological uplift regions. It has recently become evident that emissions of some chlorinated very short-lived species (VSLSs), such as chloroform (CHCl<sub>3</sub>) and dichloromethane (CH<sub>2</sub>Cl<sub>2</sub>), could be larger than previously believed and increasing, particularly in Asia. While these may exert a significant influence on atmospheric chemistry and climate, their impacts remain poorly characterised. </p><p> </p><p>We address this issue using the UM-UKCA chemistry-climate model (CCM). While not only the first, to our knowledge, model study addressing this problem using a CCM, it is also the first such study employing a whole atmosphere model, thereby simulating the tropospheric Cl-VSLSs emissions and the resulting stratospheric impacts in a fully consistent manner. We use a newly developed Double-Extended Stratospheric-Tropospheric (DEST) chemistry scheme, which includes emissions of all major chlorinated and brominated VSLSs alongside an extended treatment of long-lived ODSs.</p><p> </p><p>We examine the impacts of rising Cl-VSLSs emissions on atmospheric chlorine tracers and ozone, including their long-term trends. We pay particular attention to the role of ‘nudging’, as opposed to the free-running model set up, for the simulated Cl-VSLSs impacts, thereby demostrating the role of atmospheric dynamics in modulating the atmospheric responses to Cl-VSLSs. In addition, we employ novel estimates of Cl-VSLS emissions over the recent past and compare the results with the simulations that prescribe Cl-VSLSs using simple lower boundary conditions. This allows us to demonstrate the impact such choice has on the dominant location and seasonality of the Cl-VSLSs transport into the stratosphere.</p>

Local modes

2002 ◽  
Vol 80 (12) ◽  
pp. 1635-1642 ◽  
Author(s):  
Bryan R Henry ◽  
Henrik G Kjaergaard
Keyword(s):  
Atmospheric Chemistry ◽  
Molecular Conformation ◽  
Critical Role ◽  
Historical Background ◽  
Local Mode ◽  
Local Modes ◽  
Band Profile ◽  
Methyl Rotation ◽  
Insight Into

The historical background for the development of the local mode approach is reviewed, including the critical role of the radiation field. The harmonically coupled anharmonic oscillator model is described. Local modes have been used in the interpretation of XH stretching overtone spectra. These spectra can be used as sensitive probes of molecular properties such as bond length and molecular conformation. Examples of these spectral features are discussed. An intensity theory has been developed that permits the accurate calculation of relative and absolute overtone intensities. In molecules with low barriers to methyl rotation, torsional states contribute to the XH stretching band profile. A successful theoretical approach is presented that accounts for these effects and provides insight into the vibrational dynamics. The application of calculated local mode overtone spectra to atmospheric chemistry is discussed.Key words: local mode, overtone, vibrational intensity.

scholarly journals Characterization of a boreal convective boundary layer and its impact on atmospheric chemistry during HUMPPA-COPEC-2010

2012 ◽  
Vol 12 (19) ◽  
pp. 9335-9353 ◽  
Author(s):  
H. G. Ouwersloot ◽  
J. Vilà-Guerau de Arellano ◽  
A. C. Nölscher ◽  
M. C. Krol ◽  
L. N. Ganzeveld ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Convective Boundary Layer ◽  
Large Scale ◽  
Spatial Scales ◽  
Potential Temperature ◽  
Chemical Species ◽  
Convective Boundary ◽  
The Impact

Abstract. We studied the atmospheric boundary layer (ABL) dynamics and the impact on atmospheric chemistry during the HUMPPA-COPEC-2010 campaign. We used vertical profiles of potential temperature and specific moisture, obtained from 132 radio soundings, to determine the main boundary layer characteristics during the campaign. We propose a classification according to several main ABL prototypes. Further, we performed a case study of a single day, focusing on the convective boundary layer, to analyse the influence of the dynamics on the chemical evolution of the ABL. We used a mixed layer model, initialized and constrained by observations. In particular, we investigated the role of large scale atmospheric dynamics (subsidence and advection) on the ABL development and the evolution of chemical species concentrations. We find that, if the large scale forcings are taken into account, the ABL dynamics are represented satisfactorily. Subsequently, we studied the impact of mixing with a residual layer aloft during the morning transition on atmospheric chemistry. The time evolution of NOx and O3 concentrations, including morning peaks, can be explained and accurately simulated by incorporating the transition of the ABL dynamics from night to day. We demonstrate the importance of the ABL height evolution for the representation of atmospheric chemistry. Our findings underscore the need to couple the dynamics and chemistry at different spatial scales (from turbulence to mesoscale) in chemistry-transport models and in the interpretation of observational data.

scholarly journals Seasonal variability of tropical wetland CH<sub>4</sub> emissions: the role of the methanogen-available carbon pool

2012 ◽  
Vol 9 (8) ◽  
pp. 2821-2830 ◽  
Author(s):  
A. A. Bloom ◽  
P. I. Palmer ◽  
A. Fraser ◽  
D. S. Reay
Keyword(s):  
Atmospheric Chemistry ◽  
Seasonal Variability ◽  
Transport Model ◽  
Global Scale ◽  
Plant Litter ◽  
Carbon Pool ◽  
Spatial And Temporal Variability ◽  
Ch4 Emissions ◽  
Available Carbon

Abstract. We develop a dynamic methanogen-available carbon model (DMCM) to quantify the role of the methanogen-available carbon pool in determining the spatial and temporal variability of tropical wetland CH4 emissions over seasonal timescales. We fit DMCM parameters to satellite observations of CH4 columns from SCIAMACHY CH4 and equivalent water height (EWH) from GRACE. Over the Amazon River basin we found substantial seasonal variability of this carbon pool (coefficient of variation = 28 ± 22%) and a rapid decay constant (φ = 0.017 day−1), in agreement with available laboratory measurements, suggesting that plant litter is likely the prominent methanogen carbon source over this region. Using the DMCM we derived global CH4 emissions for 2003–2009, and determined the resulting seasonal variability of atmospheric CH4 on a global scale using the GEOS-Chem atmospheric chemistry and transport model. First, we estimated that tropical emissions amounted to 111.1 Tg CH4 yr−1, of which 24% was emitted from Amazon wetlands. We estimated that annual tropical wetland emissions increased by 3.4 Tg CH4 yr−1 between 2003 and 2009. Second, we found that the model was able to reproduce the observed seasonal lag of CH4 concentrations peaking 1–3 months before peak EWH values. We also found that our estimates of CH4 emissions substantially improved the comparison between the model and observed CH4 surface concentrations (r = 0.9). We anticipate that these new insights from the DMCM represent a fundamental step in parameterising tropical wetland CH4 emissions and quantifying the seasonal variability and future trends of tropical CH4 emissions.

Air Chemistry

1959 ◽  
Vol 40 (10) ◽  
pp. 493-498 ◽  
Author(s):  
Christian E. Junge
Keyword(s):  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Trace Gases ◽  
Special Importance ◽  
Physical Processes ◽  
Industrial Activities ◽  
Cent Increase ◽  
Air Chemistry

The field of atmospheric chemistry, which is defined as the chemistry of trace substances in the troposphere, is reviewed. Trace substances can be present as aerosols or as gases. Major sources of aerosols are the ocean and industrial activities. The chemical composition of the aerosol particles is not only determined by their source but also by various processes in the atmosphere—notably, reactions with gas traces. Only little is known about trace gases like SO2, H2S, NH3 or NO2. Of special importance for meteorology is CO2 and its long-term fluctuations. The facts and possible reasons for its 10 per cent increase during this century are discussed. The last part of the discussion is concerned with the physical processes by which the trace substances are removed from the atmosphere, primarily the role of precipitation.

The role of photochemistry in Titan’s atmospheric chemistry

2005 ◽  
Vol 36 (2) ◽  
pp. 251-257 ◽  
Author(s):  
James Ferris ◽  
Buu Tran ◽  
Jeffrey Joseph ◽  
Veronique Vuitton ◽  
Robert Briggs ◽  
...  
Keyword(s):  
Atmospheric Chemistry

scholarly journals Brominated VSLS and their influence on ozone under a changing climate

2017 ◽  
Vol 17 (18) ◽  
pp. 11313-11329 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber ◽  
Gisèle Krysztofiak ◽  
Patrick Jöckel ◽  
Phoebe Graf ◽  
...  
Keyword(s):  
21St Century ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Atmospheric Transport ◽  
Stratospheric Ozone ◽  
Chemical Transformations ◽  
Mixing Ratios ◽  
Ocean Atmosphere ◽  
The Impact

Abstract. Very short-lived substances (VSLS) contribute as source gases significantly to the tropospheric and stratospheric bromine loading. At present, an estimated 25 % of stratospheric bromine is of oceanic origin. In this study, we investigate how climate change may impact the ocean–atmosphere flux of brominated VSLS, their atmospheric transport, and chemical transformations and evaluate how these changes will affect stratospheric ozone over the 21st century. Under the assumption of fixed ocean water concentrations and RCP6.0 scenario, we find an increase of the ocean–atmosphere flux of brominated VSLS of about 8–10 % by the end of the 21st century compared to present day. A decrease in the tropospheric mixing ratios of VSLS and an increase in the lower stratosphere are attributed to changes in atmospheric chemistry and transport. Our model simulations reveal that this increase is counteracted by a corresponding reduction of inorganic bromine. Therefore the total amount of bromine from VSLS in the stratosphere will not be changed by an increase in upwelling. Part of the increase of VSLS in the tropical lower stratosphere results from an increase in the corresponding tropopause height. As the depletion of stratospheric ozone due to bromine depends also on the availability of chlorine, we find the impact of bromine on stratospheric ozone at the end of the 21st century reduced compared to present day. Thus, these studies highlight the different factors influencing the role of brominated VSLS in a future climate.

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