Articles | Volume 20, issue 2
Research article 31 Jan 2020
Research article | 31 Jan 2020
Transport of short-lived halocarbons to the stratosphere over the Pacific Ocean
Michal T. Filus et al.
Richard Newton, Geraint Vaughan, Eric Hintsa, Michal T. Filus, Laura L. Pan, Shawn Honomichl, Elliot Atlas, Stephen J. Andrews, and Lucy J. Carpenter
Atmos. Chem. Phys., 18, 5157–5171,Short summary
We consider the ozone measurements from aircraft during the CAST/CONTRAST/ATTREX campaigns of 2014. Low concentrations of ozone were found in the layer of 10–15 km altitude, which is indicative of uplift of ozone-poor air from near the sea surface to 10–15 km altitude. Chemicals that have origins in the sea were found in greater abundance when ozone concentrations were low compared to when ozone concentrations were high. The lowest ozone concentrations were found in the Southern Hemisphere.
Taku Umezawa, Satoshi Sugawara, Kenji Kawamura, Ikumi Oyabu, Stephen J. Andrews, Takuya Saito, Shuji Aoki, and Takakiyo Nakazawa
Atmos. Chem. Phys. Discuss.,
Preprint under review for ACPShort summary
Atmospheric concentration of methane (CH4), an important greenhouse gas, in the Arctic has not been accurately reported for the period 1900–1980 either by direct observations or ice core reconstructions. Using trace gas data from firn (compacted snow layers above ice sheet) air samples at Greenland sites and a firm-air transport model, we examine reconstruction of the atmospheric CH4 for that period and show that the Arctic CH4 concentration can be reliably estimated only back to the mid 1970s.
Leigh Crilley, Louisa Kramer, Francis Pope, Chris Reed, James Lee, Lucy Carpenter, Lloyd Hollis, Stephen Ball, and William Bloss
Atmos. Chem. Phys. Discuss.,
Preprint under review for ACPShort summary
Nitrous acid (HONO) is a key source of atmospheric oxidants. We evaluate if the ocean surface is a source of HONO into the marine boundary layer, using measurements from two contrasting coastal locations. We observed no evidence for a night-time ocean surface source, in contrast to previous work. This points to significant geographical variation in the predominant HONO formation mechanisms in marine environments, reflecting possible variability in the sea-surface microlayer composition.
Simone T. Andersen, Lucy J. Carpenter, Beth S. Nelson, Luis Neves, Katie A. Read, Chris Reed, Martyn Ward, Matthew J. Rowlinson, and James D. Lee
Atmos. Meas. Tech., 14, 3071–3085,Short summary
NOx has been measured in remote marine air via chemiluminescence detection using two different methods for NO2 to NO photolytic conversion: (a) internal diodes and a reaction chamber made of Teflon-like barium-doped material, which causes a NO2 artefact, and (b) external diodes and a quartz photolysis cell. Once corrections are made for the artefact of (a), the two converters are shown to give comparable NO2 mixing ratios, giving confidence in the quantitative measurement of NOx at low levels.
Sebastian Landwehr, Michele Volpi, F. Alexander Haumann, Charlotte M. Robinson, Iris Thurnherr, Valerio Ferracci, Andrea Baccarini, Jenny Thomas, Irina Gorodetskaya, Christian Tatzelt, Silvia Henning, Rob L. Modini, Heather J. Forrer, Yajuan Lin, Nicolas Cassar, Rafel Simó, Christel Hassler, Alireza Moallemi, Sarah E. Fawcett, Neil Harris, Ruth Airs, Marzieh H. Derkani, Alberto Alberello, Alessandro Toffoli, Gang Chen, Pablo Rodríguez Ros, Marina Zamanillo, Pau Cortés-Greus, Lei Xue, Conor G. Bolas, Katherine C. Leonard, Fernando Perez-Cruz, David Walton, and Julia Schmale
Earth Syst. Dynam. Discuss.,
Revised manuscript accepted for ESDShort summary
The Antarctic Circumnavigation Expedition surveyed a large number of variables describing the dynamic state of ocean and atmosphere, freshwater cycle, atmospheric chemistry, ocean biogeochemistry and microbiology in the Southern Ocean. To reduce the dimensionality of the dataset, we apply a sparse Principal Component Analysis and identify temporal patterns from diurnal to seasonal cycles, as well as geographical gradients and “hotspots” of interaction. Code and data are open-access.
Shona E. Wilde, Pamela A. Dominutti, Grant Allen, Stephen J. Andrews, Prudence Bateson, Stephane J.-B. Bauguitte, Ralph R. Burton, Ioana Colfescu, James France, James R. Hopkins, Langwen Huang, Anna E. Jones, Tom Lachlan-Cope, James D. Lee, Alastair C. Lewis, Stephen D. Mobbs, Alexandra Weiss, Stuart Young, and Ruth M. Purvis
Atmos. Chem. Phys., 21, 3741–3762,Short summary
We use airborne measurements to evaluate the speciation of volatile organic compound (VOC) emissions from offshore oil and gas (O&G) installations in the North Sea. The composition of emissions varied across regions associated with either gas, condensate or oil extraction, demonstrating that VOC emissions are not uniform across the whole O&G sector. We compare our results to VOC source profiles in the UK emissions inventory, showing these emissions are not currently fully characterized.
James L. France, Prudence Bateson, Pamela Dominutti, Grant Allen, Stephen Andrews, Stephane Bauguitte, Max Coleman, Tom Lachlan-Cope, Rebecca E. Fisher, Langwen Huang, Anna E. Jones, James Lee, David Lowry, Joseph Pitt, Ruth Purvis, John Pyle, Jacob Shaw, Nicola Warwick, Alexandra Weiss, Shona Wilde, Jonathan Witherstone, and Stuart Young
Atmos. Meas. Tech., 14, 71–88,Short summary
Measuring emission rates of methane from installations is tricky, and it is even more so when those installations are located offshore. Here, we show the aircraft set-up and demonstrate an effective methodology for surveying emissions from UK and Dutch offshore oil and gas installations. We present example data collected from two campaigns to demonstrate the challenges and solutions encountered during these surveys.
David C. Loades, Mingxi Yang, Thomas G. Bell, Adam R. Vaughan, Ryan J. Pound, Stefan Metzger, James D. Lee, and Lucy J. Carpenter
Atmos. Meas. Tech., 13, 6915–6931,Short summary
The loss of ozone to the sea surface was measured from the south coast of the UK and was found to be more rapid than previous observations over the open ocean. This is likely a consequence of different chemistry and biology in coastal environments. Strong winds appeared to speed up the loss of ozone. A better understanding of what influences ozone loss over the sea will lead to better model estimates of total ozone in the troposphere.
Swaleha Inamdar, Liselotte Tinel, Rosie Chance, Lucy J. Carpenter, Prabhakaran Sabu, Racheal Chacko, Sarat C. Tripathy, Anvita U. Kerkar, Alok K. Sinha, Parli Venkateswaran Bhaskar, Amit Sarkar, Rajdeep Roy, Tomás Sherwen, Carlos Cuevas, Alfonso Saiz-Lopez, Kirpa Ram, and Anoop S. Mahajan
Atmos. Chem. Phys., 20, 12093–12114,Short summary
Iodine chemistry is generating a lot of interest because of its impacts on the oxidising capacity of the marine boundary and depletion of ozone. However, one of the challenges has been predicting the right levels of iodine in the models, which depend on parameterisations for emissions from the sea surface. This paper discusses the different parameterisations available and compares them with observations, showing that our current knowledge is still insufficient, especially on a regional scale.
Manuela van Pinxteren, Khanneh Wadinga Fomba, Nadja Triesch, Christian Stolle, Oliver Wurl, Enno Bahlmann, Xianda Gong, Jens Voigtländer, Heike Wex, Tiera-Brandy Robinson, Stefan Barthel, Sebastian Zeppenfeld, Erik Hans Hoffmann, Marie Roveretto, Chunlin Li, Benoit Grosselin, Veronique Daële, Fabian Senf, Dominik van Pinxteren, Malena Manzi, Nicolás Zabalegui, Sanja Frka, Blaženka Gašparović, Ryan Pereira, Tao Li, Liang Wen, Jiarong Li, Chao Zhu, Hui Chen, Jianmin Chen, Björn Fiedler, Wolf von Tümpling, Katie Alana Read, Shalini Punjabi, Alastair Charles Lewis, James Roland Hopkins, Lucy Jane Carpenter, Ilka Peeken, Tim Rixen, Detlef Schulz-Bull, María Eugenia Monge, Abdelwahid Mellouki, Christian George, Frank Stratmann, and Hartmut Herrmann
Atmos. Chem. Phys., 20, 6921–6951,Short summary
An introduction to a comprehensive field campaign performed at the Cape Verde Atmospheric Observatory regarding ocean–atmosphere interactions is given. Chemical, physical, biological and meteorological techniques were applied, and measurements of bulk water, the sea surface microlayer, cloud water and ambient aerosol particles took place. Oceanic compounds were found to be transferred to atmospheric aerosol and to the cloud level; however, sea spray contributions to CCN and INPs were limited.
Elise S. Droste, Karina E. Adcock, Matthew J. Ashfold, Charles Chou, Zoë Fleming, Paul J. Fraser, Lauren J. Gooch, Andrew J. Hind, Ray L. Langenfelds, Emma Leedham Elvidge, Norfazrin Mohd Hanif, Simon O'Doherty, David E. Oram, Chang-Feng Ou-Yang, Marios Panagi, Claire E. Reeves, William T. Sturges, and Johannes C. Laube
Atmos. Chem. Phys., 20, 4787–4807,Short summary
We update the tropospheric trends and emissions of six perfluorocarbon (PFC) gases, including separate isomers. Trends for these strong greenhouse gases are still increasing, but at slower rates than previously. The lack of natural sinks results in the global accumulation of 833 million metric tonnes of CO2 equivalent for these six PFCs by 2017. Modelling results indicate potential source regions and types in East Asia, but we find that many emissions are unaccounted for in emission reports.
Ryan J. Pound, Tomás Sherwen, Detlev Helmig, Lucy J. Carpenter, and Mat J. Evans
Atmos. Chem. Phys., 20, 4227–4239,Short summary
Ozone is an important pollutant with impacts on health and the environment. Ozone is lost to plants, land and the oceans. Loss to the ocean is slow compared to all other types of land cover and has not received as much attention. We build on previous work to more accurately model ozone loss to the ocean. We find changes in the concentration of ozone over the oceans, notably the Southern Ocean, which improves model performance.
Marios Panagi, Zoë L. Fleming, Paul S. Monks, Matthew J. Ashfold, Oliver Wild, Michael Hollaway, Qiang Zhang, Freya A. Squires, and Joshua D. Vande Hey
Atmos. Chem. Phys., 20, 2825–2838,Short summary
In this paper, using dispersion modelling with emission inventories it was determined that on average 45 % of the total CO pollution that affects Beijing is transported from other areas. About half of the CO comes from beyond the immediate surrounding areas. Finally three classification types of pollution were identified and used to analyse the APHH winter campaign. The results can inform targeted control measures to be implemented in Beijing and the other regions to tackle air quality problems.
Conor G. Bolas, Valerio Ferracci, Andrew D. Robinson, Mohammed I. Mead, Mohd Shahrul Mohd Nadzir, John A. Pyle, Roderic L. Jones, and Neil R. P. Harris
Atmos. Meas. Tech., 13, 821–838,Short summary
Here we present the iDirac, a new instrument capable of making isoprene measurements in remote and challenging environments. The iDirac is a customisable and rugged field instrument for investigating emissions of volatile organic compounds from vegetation. It has been tested here in a series of experiments to ensure a high degree of technical precision, accuracy and repeatability. This new instrument allows us to ask and answer new questions about the influence of vegetation on the atmosphere.
Kuo-Ying Wang, Philippe Nedelec, Hannah Clark, and Neil Harris
Earth Syst. Sci. Data Discuss.,
Revised manuscript not acceptedShort summary
Atmospheric dispersion of radioactive materials following the accidents of the 11 March 2011 Fukushima Nuclear Power Plants contain very distinctive characteristics over the land surface areas and over the oceanic atmosphere. Air dose rates measured over the land surface areas exhibit a combination of the effects from the deposited radioactive materials on the surface and the airborne radioactive materials. Air dose rates measured over the oceanic atmosphere were due to airborne particles.
Tomás Sherwen, Rosie J. Chance, Liselotte Tinel, Daniel Ellis, Mat J. Evans, and Lucy J. Carpenter
Earth Syst. Sci. Data, 11, 1239–1262,Short summary
Iodine plays an important role in the Earth system, as a nutrient to the biosphere and by changing the concentrations of climate and air-quality species. However, there are uncertainties on the magnitude of iodine’s role, and a key uncertainty is our understanding of iodide in the global sea-surface. Here we take a data-driven approach using a machine learning algorithm to convert a sparse set of sea-surface iodide observations into a spatially and temporally resolved dataset for use in models.
Stuart N. Riddick, Denise L. Mauzerall, Michael Celia, Neil R. P. Harris, Grant Allen, Joseph Pitt, John Staunton-Sykes, Grant L. Forster, Mary Kang, David Lowry, Euan G. Nisbet, and Alistair J. Manning
Atmos. Chem. Phys., 19, 9787–9796,Short summary
Currently, bottom-up methods estimate that 0.13 % of methane produced by UK North Sea oil and gas installations is lost. Here we measure emissions from eight platforms in the North Sea and, when considered collectively, the methane loss is estimated at 0.19 % of gas production. As this ambient loss is not explicitly accounted for in the bottom-up approach, these measured emissions represent significant additional emissions above previous estimates.
Leon King, Ieuan J. Roberts, Liselotte Tinel, and Lucy J. Carpenter
Ocean Sci. Discuss.,
Preprint withdrawnShort summary
Recent studies suggest that the sea surface microlayer is ubiquitously enriched in surfactants, even at high wind speeds, which exert a control on air-sea gas exchange. These conclusions are partly based on voltammetry measurements of
surfactant activity(SA). Here, we show that the response of SA-voltammetry varies widely for different surfactants, becomes saturated above total surfactant concentrations of 1–2 mg L-1, and shows a poor correlation in natural waters with surface film pressure.
Alba Badia, Claire E. Reeves, Alex R. Baker, Alfonso Saiz-Lopez, Rainer Volkamer, Theodore K. Koenig, Eric C. Apel, Rebecca S. Hornbrook, Lucy J. Carpenter, Stephen J. Andrews, Tomás Sherwen, and Roland von Glasow
Atmos. Chem. Phys., 19, 3161–3189,Short summary
The oceans have an impact on the composition and reactivity of the troposphere through the emission of gases and particles. Thus, a quantitative understanding of the marine atmosphere is crucial to examine the oxidative capacity and climate forcing. This study investigates the impact of halogens in the tropical troposphere and explores the sensitivity of this to uncertainties in the fluxes and their chemical processing. Our modelled tropospheric Ox loss due to halogens ranges from 20 % to 60 %.
Sarah Connors, Alistair J. Manning, Andrew D. Robinson, Stuart N. Riddick, Grant L. Forster, Anita Ganesan, Aoife Grant, Stephen Humphrey, Simon O'Doherty, Dave E. Oram, Paul I. Palmer, Robert L. Skelton, Kieran Stanley, Ann Stavert, Dickon Young, and Neil R. P. Harris
Atmos. Chem. Phys. Discuss.,
Preprint withdrawnShort summary
Methane is an important greenhouse gas & reducing its emissions is a vital part of climate change mitigation to limit global temperature increase to 1.5 °C or 2.0 °C. This paper explains a way to estimate emitted methane over a sub-national area by combining measurements & computer dispersion modelling in a so-called
inversiontechnique. Compared with the current national inventory, our results show lower emissions for Cambridgeshire, possibly due to waste sector emission differences.
Liang Feng, Paul I. Palmer, Robyn Butler, Stephen J. Andrews, Elliot L. Atlas, Lucy J. Carpenter, Valeria Donets, Neil R. P. Harris, Ross J. Salawitch, Laura L. Pan, and Sue M. Schauffler
Atmos. Chem. Phys., 18, 14787–14798,Short summary
We infer surface fluxes of bromoform (CHBr3) and dibromoform (CH2Br2) from CAST and CONTRAST aircraft observations over the western Pacific, using a tagged version of the GEOS-Chem global 3-D atmospheric chemistry model and a Maximum A Posteriori inverse model. Using the aircraft data, we estimate the regional fluxes about 20–40 % smaller than the prior inventories by Ordóñez et al. (2012). We find no evidence to support a robust linear relationship between CHBr3 and CH2Br2 oceanic emissions.
Tim Arnold, Alistair J. Manning, Jooil Kim, Shanlan Li, Helen Webster, David Thomson, Jens Mühle, Ray F. Weiss, Sunyoung Park, and Simon O'Doherty
Atmos. Chem. Phys., 18, 13305–13320,Short summary
Emissions of carbon tetrafluoride CF4, NF3 and CHF3 in east Asia have been calculated using atmospheric measurements and an atmospheric transport model. We calculate emissions of CF4 to be quite constant between the years 2008 and 2015 for both China and South Korea, with 2015 emissions calculated at 4.33 ± 2.65 Gg yr-1 and 0.36 ± 0.11 Gg yr-1, respectively. Emission estimates of NF3 from South Korea could be made with relatively small uncertainty at 0.6 ± 0.07 Gg yr-1 in 2015.
Robyn Butler, Paul I. Palmer, Liang Feng, Stephen J. Andrews, Elliot L. Atlas, Lucy J. Carpenter, Valeria Donets, Neil R. P. Harris, Stephen A. Montzka, Laura L. Pan, Ross J. Salawitch, and Sue M. Schauffler
Atmos. Chem. Phys., 18, 13135–13153,Short summary
Natural sources of short-lived bromoform and dibromomethane are important for determining the inorganic bromine budget in the stratosphere that drives ozone loss. Two new modelling techniques describe how different geographical source regions influence their atmospheric variability over the western Pacific. We find that it is driven primarily by open ocean sources, and we use atmospheric observations to help estimate their contributions to the upper tropospheric inorganic bromine budget.
Paul I. Palmer, Simon O'Doherty, Grant Allen, Keith Bower, Hartmut Bösch, Martyn P. Chipperfield, Sarah Connors, Sandip Dhomse, Liang Feng, Douglas P. Finch, Martin W. Gallagher, Emanuel Gloor, Siegfried Gonzi, Neil R. P. Harris, Carole Helfter, Neil Humpage, Brian Kerridge, Diane Knappett, Roderic L. Jones, Michael Le Breton, Mark F. Lunt, Alistair J. Manning, Stephan Matthiesen, Jennifer B. A. Muller, Neil Mullinger, Eiko Nemitz, Sebastian O'Shea, Robert J. Parker, Carl J. Percival, Joseph Pitt, Stuart N. Riddick, Matthew Rigby, Harjinder Sembhi, Richard Siddans, Robert L. Skelton, Paul Smith, Hannah Sonderfeld, Kieran Stanley, Ann R. Stavert, Angelina Wenger, Emily White, Christopher Wilson, and Dickon Young
Atmos. Chem. Phys., 18, 11753–11777,Short summary
This paper provides an overview of the Greenhouse gAs Uk and Global Emissions (GAUGE) experiment. GAUGE was designed to quantify nationwide GHG emissions of the UK, bringing together measurements and atmospheric transport models. This novel experiment is the first of its kind. We anticipate it will inform the blueprint for countries that are building a measurement infrastructure in preparation for global stocktakes, which are a key part of the Paris Agreement.
Prasad Kasibhatla, Tomás Sherwen, Mathew J. Evans, Lucy J. Carpenter, Chris Reed, Becky Alexander, Qianjie Chen, Melissa P. Sulprizio, James D. Lee, Katie A. Read, William Bloss, Leigh R. Crilley, William C. Keene, Alexander A. P. Pszenny, and Alma Hodzic
Atmos. Chem. Phys., 18, 11185–11203,Short summary
Recent measurements of NOx and HONO suggest that photolysis of particulate nitrate in sea-salt aerosols is important in terms of marine boundary layer oxidant chemistry. We present the first global-scale assessment of the significance of this new chemical pathway for NOx, O3, and OH in the marine boundary layer. We also present a preliminary assessment of the potential impact of photolysis of particulate nitrate associated with other aerosol types on continental boundary layer chemistry.
James Keeble, Hannah Brown, N. Luke Abraham, Neil R. P. Harris, and John A. Pyle
Atmos. Chem. Phys., 18, 7625–7637,Short summary
2017 marks the 30th anniversary of the Montreal Protocol, which was implemented to protect the stratospheric ozone layer from the harmful effects of synthetic ozone depleting substances. Since the late 1990s atmospheric concentrations of these species have begun to decline, and as a result ozone concentrations are expected to increase. In this study we use an ensemble of chemistry–climate simulations to investigate recent ozone trends and search for early signs of ozone recovery.
Richard Newton, Geraint Vaughan, Eric Hintsa, Michal T. Filus, Laura L. Pan, Shawn Honomichl, Elliot Atlas, Stephen J. Andrews, and Lucy J. Carpenter
Atmos. Chem. Phys., 18, 5157–5171,Short summary
We consider the ozone measurements from aircraft during the CAST/CONTRAST/ATTREX campaigns of 2014. Low concentrations of ozone were found in the layer of 10–15 km altitude, which is indicative of uplift of ozone-poor air from near the sea surface to 10–15 km altitude. Chemicals that have origins in the sea were found in greater abundance when ozone concentrations were low compared to when ozone concentrations were high. The lowest ozone concentrations were found in the Southern Hemisphere.
Karina E. Adcock, Claire E. Reeves, Lauren J. Gooch, Emma C. Leedham Elvidge, Matthew J. Ashfold, Carl A. M. Brenninkmeijer, Charles Chou, Paul J. Fraser, Ray L. Langenfelds, Norfazrin Mohd Hanif, Simon O'Doherty, David E. Oram, Chang-Feng Ou-Yang, Siew Moi Phang, Azizan Abu Samah, Thomas Röckmann, William T. Sturges, and Johannes C. Laube
Atmos. Chem. Phys., 18, 4737–4751,
Jacob T. Shaw, Richard T. Lidster, Danny R. Cryer, Noelia Ramirez, Fiona C. Whiting, Graham A. Boustead, Lisa K. Whalley, Trevor Ingham, Andrew R. Rickard, Rachel E. Dunmore, Dwayne E. Heard, Ally C. Lewis, Lucy J. Carpenter, Jacqui F. Hamilton, and Terry J. Dillon
Atmos. Chem. Phys., 18, 4039–4054,Short summary
The lifetime of a chemical in the atmosphere is largely governed by the rate of its reaction with the hydroxyl radical (OH). Measurements of rates for many of the thousands of identified volatile organic compounds (VOCs) have yet to be determined experimentally. We have developed a new technique for the rapid determination of gas-phase rate coefficients for the simultaneous reactions between multiple VOCs and OH. The method is tasted across a range of scenarios and is used to derive new values.
Daniel Stone, Tomás Sherwen, Mathew J. Evans, Stewart Vaughan, Trevor Ingham, Lisa K. Whalley, Peter M. Edwards, Katie A. Read, James D. Lee, Sarah J. Moller, Lucy J. Carpenter, Alastair C. Lewis, and Dwayne E. Heard
Atmos. Chem. Phys., 18, 3541–3561,Short summary
Halogen chemistry in the troposphere impacts oxidising capacity, but model studies assessing the nature of these impacts can vary according to the model framework used. In this work we present simulations of OH and HO2 radicals using both box and global model frameworks, and compare to observations made at the Cape Verde Atmospheric Observatory. We highlight, and rationalise, differences between the model frameworks.
Natalie J. Harvey, Nathan Huntley, Helen F. Dacre, Michael Goldstein, David Thomson, and Helen Webster
Nat. Hazards Earth Syst. Sci., 18, 41–63,
James Keeble, Ewa M. Bednarz, Antara Banerjee, N. Luke Abraham, Neil R. P. Harris, Amanda C. Maycock, and John A. Pyle
Atmos. Chem. Phys., 17, 13801–13818,Short summary
In this study we explore the chemical and transport processes controlling ozone abundances in different altitude regions in the tropics for the present day and how these processes may change in the future in order to determine when total-column ozone values in the tropics will recover to pre-1980s values following the implementation of the Montreal Protocol and its subsequent amendments, which imposed bans on the use and emissions of CFCs.
Hannah Sonderfeld, Hartmut Bösch, Antoine P. R. Jeanjean, Stuart N. Riddick, Grant Allen, Sébastien Ars, Stewart Davies, Neil Harris, Neil Humpage, Roland Leigh, and Joseph Pitt
Atmos. Meas. Tech., 10, 3931–3946,Short summary
The waste sector is the second largest source of methane in the UK. However, uncertainties of methane emissions from landfill sites still remain. In this study we present a new approach for the estimation of methane emissions from a landfill site by applying a computational fluid dynamics (CFD) model for precise measurements of methane with in situ Fourier-transform infrared (FTIR) spectroscopy. Different source areas could be distinguished with this method and their emissions were assessed.
David E. Oram, Matthew J. Ashfold, Johannes C. Laube, Lauren J. Gooch, Stephen Humphrey, William T. Sturges, Emma Leedham-Elvidge, Grant L. Forster, Neil R. P. Harris, Mohammed Iqbal Mead, Azizan Abu Samah, Siew Moi Phang, Chang-Feng Ou-Yang, Neng-Huei Lin, Jia-Lin Wang, Angela K. Baker, Carl A. M. Brenninkmeijer, and David Sherry
Atmos. Chem. Phys., 17, 11929–11941,Short summary
We have observed large amounts of man-made chlorine compounds in E and SE Asia and in the upper tropical troposphere. These relatively short-lived compounds are not controlled by the Montreal Protocol, but if significant quantities were able to reach the stratosphere, the long-term recovery of stratospheric ozone would be delayed. We have also identified an important atmospheric transport mechanism that can rapidly transport these chemicals from E Asia to the upper troposphere via the tropics.
Wolfgang Steinbrecht, Lucien Froidevaux, Ryan Fuller, Ray Wang, John Anderson, Chris Roth, Adam Bourassa, Doug Degenstein, Robert Damadeo, Joe Zawodny, Stacey Frith, Richard McPeters, Pawan Bhartia, Jeannette Wild, Craig Long, Sean Davis, Karen Rosenlof, Viktoria Sofieva, Kaley Walker, Nabiz Rahpoe, Alexei Rozanov, Mark Weber, Alexandra Laeng, Thomas von Clarmann, Gabriele Stiller, Natalya Kramarova, Sophie Godin-Beekmann, Thierry Leblanc, Richard Querel, Daan Swart, Ian Boyd, Klemens Hocke, Niklaus Kämpfer, Eliane Maillard Barras, Lorena Moreira, Gerald Nedoluha, Corinne Vigouroux, Thomas Blumenstock, Matthias Schneider, Omaira García, Nicholas Jones, Emmanuel Mahieu, Dan Smale, Michael Kotkamp, John Robinson, Irina Petropavlovskikh, Neil Harris, Birgit Hassler, Daan Hubert, and Fiona Tummon
Atmos. Chem. Phys., 17, 10675–10690,Short summary
Thanks to the 1987 Montreal Protocol and its amendments, ozone-depleting chlorine (and bromine) in the stratosphere has declined slowly since the late 1990s. Improved and extended long-term ozone profile observations from satellites and ground-based stations confirm that ozone is responding as expected and has increased by about 2 % per decade since 2000 in the upper stratosphere, around 40 km altitude. At lower altitudes, however, ozone has not changed significantly since 2000.
Maria A. Navarro, Alfonso Saiz-Lopez, Carlos A. Cuevas, Rafael P. Fernandez, Elliot Atlas, Xavier Rodriguez-Lloveras, Douglas Kinnison, Jean-Francois Lamarque, Simone Tilmes, Troy Thornberry, Andrew Rollins, James W. Elkins, Eric J. Hintsa, and Fred L. Moore
Atmos. Chem. Phys., 17, 9917–9930,Short summary
Inorganic bromine (Bry) plays an important role in ozone layer depletion. Based on aircraft observations of organic bromine species and chemistry simulations, we model the Bry abundances over the Pacific tropical tropopause. Our results show BrO and Br as the dominant species during daytime hours, and BrCl and BrONO2 as the nighttime dominant species over the western and eastern Pacific, respectively. The difference in the partitioning is due to changes in the abundance of O3, NO2, and Cly.
Stuart N. Riddick, Sarah Connors, Andrew D. Robinson, Alistair J. Manning, Pippa S. D. Jones, David Lowry, Euan Nisbet, Robert L. Skelton, Grant Allen, Joseph Pitt, and Neil R. P. Harris
Atmos. Chem. Phys., 17, 7839–7851,Short summary
High methane mixing ratios occurred at our long-term measurement site. Isotopic measurements show the source is a landfill 7 km away; the emissions were estimated using three different approaches. The emission estimates made by near-source and middle-distance methods agree well for a period of intense observation. The estimate of the inverse modelling is similar to the labour-intensive middle-distance approach, which shows it can be used to identify point sources within an emission landscape.
Katie A. Read, Luis M. Neves, Lucy J. Carpenter, Alastair C. Lewis, Zoe L. Fleming, and John Kentisbeer
Atmos. Chem. Phys., 17, 5393–5406,Short summary
This paper presents 4 years of total gaseous mercury data obtained from measurements made at the Cape Verde Atmospheric Observatory, a subtropical site in the Atlantic Ocean. The data show a clear decreasing trend in the overall concentrations but in air from sub-Saharan Africa the trend is less significant and the data more variable. We attribute this result to an influence from artisanal small-scale gold mining in this region, a source for which there is uncertain information.
Chris Reed, Mathew J. Evans, Leigh R. Crilley, William J. Bloss, Tomás Sherwen, Katie A. Read, James D. Lee, and Lucy J. Carpenter
Atmos. Chem. Phys., 17, 4081–4092,Short summary
The source of ozone-depleting compounds in the remote troposphere has been thought to be long-range transport of secondary pollutants such as organic nitrates. Processing of organic nitrates to nitric acid and subsequent deposition on surfaces in the atmosphere was thought to remove these nitrates from the ozone–NOx–HOx cycle. We found through observation of NOx in the remote tropical troposphere at the Cape Verde Observatory that surface nitrates can be released back into the atmosphere.
Tomás Sherwen, Mat J. Evans, Lucy J. Carpenter, Johan A. Schmidt, and Loretta J. Mickley
Atmos. Chem. Phys., 17, 1557–1569,Short summary
We model pre-industrial to present day changes using the GEOS-Chem global chemical transport model with halogens (Cl, Br, I). The model better captures pre-industrial O3 observations with halogens included. Halogens buffer the tropospheric forcing of O3 (RFTO3) from pre-industrial to present day, reducing RFTO3 by 0.087 Wm−2. This reduction is greater than that from halogens on stratospheric O3 (−0.05 Wm−2). This suggests that models that do not include halogens will overestimate RFTO3by ~ 25%.
Bodo Werner, Jochen Stutz, Max Spolaor, Lisa Scalone, Rasmus Raecke, James Festa, Santo Fedele Colosimo, Ross Cheung, Catalina Tsai, Ryan Hossaini, Martyn P. Chipperfield, Giorgio S. Taverna, Wuhu Feng, James W. Elkins, David W. Fahey, Ru-Shan Gao, Erik J. Hintsa, Troy D. Thornberry, Free Lee Moore, Maria A. Navarro, Elliot Atlas, Bruce C. Daube, Jasna Pittman, Steve Wofsy, and Klaus Pfeilsticker
Atmos. Chem. Phys., 17, 1161–1186,Short summary
The paper reports on inorganic and organic bromine measured in the tropical tropopause layer (TTL) over the eastern Pacific in early 2013. Bryinorg is found to increase from a mean of 2.63 ± 1.04 ppt for θ in the range of 350–360 K to 5.11 ± 1.57 ppt for θ=390 ± 400 K, whereas in the subtropical lower stratosphere, it reaches 7.66 ± 2.95 ppt for θ in the range of 390–400 K. Within the TTL, total bromine is found to range from 20.3 ppt to 22.3 ppt.
Stephen J. Andrews, Lucy J. Carpenter, Eric C. Apel, Elliot Atlas, Valeria Donets, James R. Hopkins, Rebecca S. Hornbrook, Alastair C. Lewis, Richard T. Lidster, Richard Lueb, Jamie Minaeian, Maria Navarro, Shalini Punjabi, Daniel Riemer, and Sue Schauffler
Atmos. Meas. Tech., 9, 5213–5225,Short summary
We present a comparison of aircraft measurements of important trace gases from a co-ordinated campaign in Jan–Feb 2014 in the tropical west Pacific involving the NASA Global Hawk, NCAR GV and FAAM BAe-146 aircraft. The paper studies the comparability of separate measurements across platforms and demonstrates that aircraft measurements are relevant for characterising the vertical uplift of important gases, such as those with ozone-depleting potential, to the upper troposphere–lower stratosphere.
Tomás Sherwen, Johan A. Schmidt, Mat J. Evans, Lucy J. Carpenter, Katja Großmann, Sebastian D. Eastham, Daniel J. Jacob, Barbara Dix, Theodore K. Koenig, Roman Sinreich, Ivan Ortega, Rainer Volkamer, Alfonso Saiz-Lopez, Cristina Prados-Roman, Anoop S. Mahajan, and Carlos Ordóñez
Atmos. Chem. Phys., 16, 12239–12271,Short summary
We present a simulation of tropospheric Cl, Br, I chemistry within the GEOS-Chem CTM. We find a decrease in tropospheric ozone burden of 18.6 % and a 8.2 % decrease in global mean OH concentrations. Cl oxidation of some VOCs range from 15 to 27 % of the total loss. Bromine plays a small role in oxidising oVOCs. Surface ozone, ozone sondes, and methane lifetime are in general improved by the inclusion of halogens. We argue that simulated bromine and chlorine represent a lower limit.
R. Hossaini, P. K. Patra, A. A. Leeson, G. Krysztofiak, N. L. Abraham, S. J. Andrews, A. T. Archibald, J. Aschmann, E. L. Atlas, D. A. Belikov, H. Bönisch, L. J. Carpenter, S. Dhomse, M. Dorf, A. Engel, W. Feng, S. Fuhlbrügge, P. T. Griffiths, N. R. P. Harris, R. Hommel, T. Keber, K. Krüger, S. T. Lennartz, S. Maksyutov, H. Mantle, G. P. Mills, B. Miller, S. A. Montzka, F. Moore, M. A. Navarro, D. E. Oram, K. Pfeilsticker, J. A. Pyle, B. Quack, A. D. Robinson, E. Saikawa, A. Saiz-Lopez, S. Sala, B.-M. Sinnhuber, S. Taguchi, S. Tegtmeier, R. T. Lidster, C. Wilson, and F. Ziska
Atmos. Chem. Phys., 16, 9163–9187,
M. R. Russo, M. J. Ashfold, N. R. P. Harris, and J. A. Pyle
Atmos. Chem. Phys., 15, 14031–14040,Short summary
We find a strong regional element to the uplift of CHBr3 from the ocean to the upper troposphere and lower stratosphere. The strongest uplift occurs when the largest emission and the most intense convection are co-located which is over the Maritime Continent in northern winter. Estimates of CHBr3 emissions based on aircraft measurements will be sensitive to where the available aircraft campaigns took place.
R. S. Humphries, R. Schofield, M. D. Keywood, J. Ward, J. R. Pierce, C. M. Gionfriddo, M. T. Tate, D. P. Krabbenhoft, I. E. Galbally, S. B. Molloy, A. R. Klekociuk, P. V. Johnston, K. Kreher, A. J. Thomas, A. D. Robinson, N. R. P. Harris, R. Johnson, and S. R. Wilson
Atmos. Chem. Phys., 15, 13339–13364,Short summary
An atmospheric new particle formation event that was observed in the pristine East Antarctic pack ice during a springtime voyage in 2012 is characterised in terms of formation and growth rates. Known nucleation mechanisms (e.g. those involving sulfate, iodine and organics) were unable to explain observations; however, correlations with total gaseous mercury were found, leading to the suggestion of a possible mercury-driven nucleation mechanism not previously described.
N. R. P. Harris, B. Hassler, F. Tummon, G. E. Bodeker, D. Hubert, I. Petropavlovskikh, W. Steinbrecht, J. Anderson, P. K. Bhartia, C. D. Boone, A. Bourassa, S. M. Davis, D. Degenstein, A. Delcloo, S. M. Frith, L. Froidevaux, S. Godin-Beekmann, N. Jones, M. J. Kurylo, E. Kyrölä, M. Laine, S. T. Leblanc, J.-C. Lambert, B. Liley, E. Mahieu, A. Maycock, M. de Mazière, A. Parrish, R. Querel, K. H. Rosenlof, C. Roth, C. Sioris, J. Staehelin, R. S. Stolarski, R. Stübi, J. Tamminen, C. Vigouroux, K. A. Walker, H. J. Wang, J. Wild, and J. M. Zawodny
Atmos. Chem. Phys., 15, 9965–9982,Short summary
Trends in the vertical distribution of ozone are reported for new and recently revised data sets. The amount of ozone-depleting compounds in the stratosphere peaked in the second half of the 1990s. We examine the trends before and after that peak to see if any change in trend is discernible. The previously reported decreases are confirmed. Furthermore, the downward trend in upper stratospheric ozone has not continued. The possible significance of any increase is discussed in detail.
M. J. Ashfold, J. A. Pyle, A. D. Robinson, E. Meneguz, M. S. M. Nadzir, S. M. Phang, A. A. Samah, S. Ong, H. E. Ung, L. K. Peng, S. E. Yong, and N. R. P. Harris
Atmos. Chem. Phys., 15, 3565–3573,Short summary
We use observations and model calculations to show that "cold surges" occurring during Northern Hemisphere winter can rapidly transport East Asian pollution to equatorial Southeast Asia. As well as affecting atmospheric composition near the surface, we argue that strong convection can subsequently lift the polluted air masses to the tropical upper troposphere. This suggests a potentially important connection between midlatitude pollution sources and the lower stratosphere.
F. Tummon, B. Hassler, N. R. P. Harris, J. Staehelin, W. Steinbrecht, J. Anderson, G. E. Bodeker, A. Bourassa, S. M. Davis, D. Degenstein, S. M. Frith, L. Froidevaux, E. Kyrölä, M. Laine, C. Long, A. A. Penckwitt, C. E. Sioris, K. H. Rosenlof, C. Roth, H.-J. Wang, and J. Wild
Atmos. Chem. Phys., 15, 3021–3043,Short summary
Understanding ozone trends in the vertical is vital in terms of assessing the success of the Montreal Protocol. This paper compares and analyses the long-term trends in stratospheric ozone from seven new merged satellite data sets. The data sets largely agree well with each other, particularly for the negative trends seen in the early period 1984-1997. For the 1998-2011 period there is less agreement, but a clear shift from negative to mostly positive trends.
A. D. Robinson, N. R. P. Harris, M. J. Ashfold, B. Gostlow, N. J. Warwick, L. M. O'Brien, E. J. Beardmore, M. S. M. Nadzir, S. M. Phang, A. A. Samah, S. Ong, H. E. Ung, L. K. Peng, S. E. Yong, M. Mohamad, and J. A. Pyle
Atmos. Chem. Phys., 14, 8369–8388,
M. S. Mohd Nadzir, S. M. Phang, M. R. Abas, N. Abdul Rahman, A. Abu Samah, W. T. Sturges, D. E. Oram, G. P. Mills, E. C. Leedham, J. A. Pyle, N. R. P. Harris, A. D. Robinson, M. J. Ashfold, M. I. Mead, M. T. Latif, M. F. Khan, A. M. Amiruddin, N. Banan, and M. M. Hanafiah
Atmos. Chem. Phys., 14, 8137–8148,
M. J. Ashfold, N. R. P. Harris, A. J. Manning, A. D. Robinson, N. J. Warwick, and J. A. Pyle
Atmos. Chem. Phys., 14, 979–994,
S. Tegtmeier, K. Krüger, B. Quack, E. Atlas, D. R. Blake, H. Boenisch, A. Engel, H. Hepach, R. Hossaini, M. A. Navarro, S. Raimund, S. Sala, Q. Shi, and F. Ziska
Atmos. Chem. Phys., 13, 11869–11886,
Related subject area
Subject: Dynamics | Research Activity: Atmospheric Modelling | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)Modelling spatiotemporal variations of the canopy layer urban heat island in Beijing at the neighbourhood scaleDispersion of particulate matter (PM2.5) from wood combustion for residential heating: optimization of mitigation actions based on large-eddy simulationsMeasurement report: Effect of wind shear on PM10 concentration vertical structure in the urban boundary layer in a complex terrainThe effect of forced change and unforced variability in heat waves, temperature extremes, and associated population risk in a CO2-warmed worldConvective self–aggregation in a mean flowThe potential for geostationary remote sensing of NO2 to improve weather predictionRobust winter warming over Eurasia under stratospheric sulfate geoengineering – the role of stratospheric dynamicsParameterizing the vertical downward dispersion of ship exhaust gas in the near fieldAnthropogenic aerosol forcing of the Atlantic meridional overturning circulation and the associated mechanisms in CMIP6 modelsSensitivities of the Madden–Julian oscillation forecasts to configurations of physics in the ECMWF global modelIdentifying source regions of air masses sampled at the tropical high-altitude site of Chacaltaya using WRF-FLEXPART and cluster analysisSensitivity of modeled Indian monsoon to Chinese and Indian aerosol emissionsThe spring transition of the North Pacific jet and its relation to deep stratosphere-to-troposphere mass transport over western North AmericaVery long-period oscillations in the atmosphere (0–110 km)Identification of molecular cluster evaporation rates, cluster formation enthalpies and entropies by Monte Carlo methodThe “urban meteorology island”: a multi-model ensemble analysisValidation of reanalysis Southern Ocean atmosphere trends using sea ice dataRevisiting the trend in the occurrences of the “warm Arctic–cold Eurasian continent” temperature patternA microphysics guide to cirrus – Part 2: Climatologies of clouds and humidity from observationsCeilometers as planetary boundary layer height detectors and a corrective tool for COSMO and IFS modelsUsing a coupled large-eddy simulation–aerosol radiation model to investigate urban haze: sensitivity to aerosol loading and meteorological conditionsConfinement of air in the Asian monsoon anticyclone and pathways of convective air to the stratosphere during the summer seasonOn the climate sensitivity and historical warming evolution in recent coupled model ensemblesSurface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modellingHadley cell expansion in CMIP6 modelsAtmospheric teleconnection processes linking winter air stagnation and haze extremes in China with regional Arctic sea ice declineDehydration and low ozone in the tropopause layer over the Asian monsoon caused by tropical cyclones: Lagrangian transport calculations using ERA-Interim and ERA5 reanalysis dataCharacterization of the air–sea exchange mechanisms during a Mediterranean heavy precipitation event using realistic sea state modellingA very high-resolution assessment and modelling of urban air qualitySurface temperature response to the major volcanic eruptions in multiple reanalysis data setsRole of eyewall and rainband eddy forcing in tropical cyclone intensificationA double ITCZ phenomenology of wind errors in the equatorial Atlantic in seasonal forecasts with ECMWF modelsAnalysis of total column CO2 and CH4 measurements in Berlin with WRF-GHGQuantifying the contribution of anthropogenic influence to the East Asian winter monsoon in 1960–2012Land cover and its transformation in the backward trajectory footprint region of the Amazon Tall Tower ObservatoryLarge-scale dynamics of tropical cyclone formation associated with ITCZ breakdownA numerical process study on the rapid transport of stratospheric air down to the surface over western North America and the Tibetan PlateauGlobal tropopause altitudes in radiosondes and reanalysesHeat transport pathways into the Arctic and their connections to surface air temperaturesTornado-scale vortices in the tropical cyclone boundary layer: numerical simulation with the WRF–LES frameworkDissipation rate of turbulent kinetic energy in stably stratified sheared flowsTwo pathways of how remote SST anomalies drive the interannual variability of autumnal haze days in the Beijing–Tianjin–Hebei region, ChinaLong-term simulation of the boundary layer flow over the double-ridge site during the Perdigão 2017 field campaignAnthropogenic fine particulate matter pollution will be exacerbated in eastern China due to 21st century GHG warmingOn the role of thermal expansion and compression in large-scale atmospheric energy and mass transportsChanges in sea-surface temperature and atmospheric circulation patterns associated with reductions in Arctic sea ice cover in recent decadesA multi-model comparison of meteorological drivers of surface ozone over EuropeMulti-model comparison of urban heat island modelling approachesA statistical examination of the effects of stratospheric sulfate geoengineering on tropical storm genesisCan explicit convection improve modelled dust in summertime West Africa?
Michael Biggart, Jenny Stocker, Ruth M. Doherty, Oliver Wild, David Carruthers, Sue Grimmond, Yiqun Han, Pingqing Fu, and Simone Kotthaus
Atmos. Chem. Phys., 21, 13687–13711,Short summary
Heat-related illnesses are of increasing concern in China given its rapid urbanisation and our ever-warming climate. We examine the relative impacts that land surface properties and anthropogenic heat have on the urban heat island (UHI) in Beijing using ADMS-Urban. Air temperature measurements and satellite-derived land surface temperatures provide valuable means of evaluating modelled spatiotemporal variations. This work provides critical information for urban planners and UHI mitigation.
Tobias Wolf, Lasse H. Pettersson, and Igor Esau
Atmos. Chem. Phys., 21, 12463–12477,Short summary
House heating by wood-burning stoves is cozy and needed in boreal cities, e.g., Bergen, Norway. But smoke (aerosols) from stoves may reduce urban air quality. It can be transported over long distance excessively polluting some neighborhoods. Who will suffer the most? Our modelling study looks at urban pollution in unprecedented meter-sized details tracing smoke pathways and turbulent dispersion in a typical city. We prototype effective policy scenarios to mitigate urban air quality problems.
Piotr Sekuła, Anita Bokwa, Jakub Bartyzel, Bogdan Bochenek, Łukasz Chmura, Michał Gałkowski, and Mirosław Zimnoch
Atmos. Chem. Phys., 21, 12113–12139,Short summary
The wind shear generated on a local scale by the diversified relief’s impact can be a factor which significantly modifies the spatial pattern of PM10 concentration. The vertical profile of PM10 over a city located in a large valley during the events with high surface-level PM10 concentrations may show a sudden decrease with height not only due to the increase in wind speed, but also due to the change in wind direction alone. Vertical aerosanitary urban zones can be distinguished.
Jangho Lee, Jeffrey C. Mast, and Andrew E. Dessler
Atmos. Chem. Phys., 21, 11889–11904,Short summary
This paper investigates the impact of global warming on heat and humidity extremes. There are three major findings in this study. We quantify how unforced variability in the climate impacts can lead to large variations where heat waves occur, we find that all heat extremes increase as the climate warms, especially between 1.5 and 2.0 °C of the average global warming, and we show that the economic inequity of facing extreme heat will worsen in a warmer world.
Hyunju Jung, Ann Kristin Naumann, and Bjorn Stevens
Atmos. Chem. Phys., 21, 10337–10345,Short summary
We analyze the behavior of organized convection in a large-scale flow by imposing a mean flow to idealized simulations. In the mean flow, organized convection initially propagates slower than the mean wind speed and becomes stationary. The initial upstream and downstream difference in surface fluxes becomes symmetric as the surface momentum flux acts as a drag, resulting in the stationarity. Meanwhile, the surface enthalpy flux has a minor role in the propagation of the convection.
Xueling Liu, Arthur P. Mizzi, Jeffrey L. Anderson, Inez Fung, and Ronald C. Cohen
Atmos. Chem. Phys., 21, 9573–9583,Short summary
Observations of winds in the planetary boundary layer remain sparse, making it challenging to simulate and predict the atmospheric conditions that are most important for describing and predicting urban air quality. Here we investigate the application of data assimilation of NO2 columns as will be observed from geostationary orbit to improve predictions and retrospective analysis of wind fields in the boundary layer.
Antara Banerjee, Amy H. Butler, Lorenzo M. Polvani, Alan Robock, Isla R. Simpson, and Lantao Sun
Atmos. Chem. Phys., 21, 6985–6997,Short summary
We find that simulated stratospheric sulfate geoengineering could lead to warmer Eurasian winters alongside a drier Mediterranean and wetting to the north. These effects occur due to the strengthening of the Northern Hemisphere stratospheric polar vortex, which shifts the North Atlantic Oscillation to a more positive phase. We find the effects in our simulations to be much more significant than the wintertime effects of large tropical volcanic eruptions which inject much less sulfate aerosol.
Ronny Badeke, Volker Matthias, and David Grawe
Atmos. Chem. Phys., 21, 5935–5951,Short summary
This work aims to describe the physical distribution of ship exhaust gases in the near field, e.g., inside of a harbor. Results were calculated with a mathematical model for different meteorological and technical conditions. It has been shown that large vessels like cruise ships have a significant effect of up to 55 % downward movement of exhaust gas, as they can disturb the ground near wind circulation. This needs to be considered in urban air pollution studies.
Taufiq Hassan, Robert J. Allen, Wei Liu, and Cynthia A. Randles
Atmos. Chem. Phys., 21, 5821–5846,Short summary
State-of-the-art climate models yield robust, externally forced changes in the Atlantic meridional overturning circulation (AMOC), the bulk of which are due to anthropogenic aerosol perturbations to net surface shortwave radiation and sea surface temperature. AMOC-related feedbacks act to reinforce this aerosol-forced response, largely due to changes in sea surface salinity (and hence sea surface density), with temperature- and cloud-related feedbacks acting to mute the initial response.
Jun-Ichi Yano and Nils P. Wedi
Atmos. Chem. Phys., 21, 4759–4778,Short summary
Sensitivities of forecasts of the Madden–Julian oscillation (MJO) to various different configurations of the physics are examined with the global model of ECMWF's Integrated Forecasting System (IFS). The motivation for the study was to simulate the MJO as a nonlinear free wave. To emulate free dynamics in the IFS, various momentum dissipation terms (
friction) as well as diabatic heating were selectively turned off over the tropics for the range of the latitudes from 20° S to 20° N.
Diego Aliaga, Victoria A. Sinclair, Marcos Andrade, Paulo Artaxo, Samara Carbone, Evgeny Kadantsev, Paolo Laj, Alfred Wiedensohler, Radovan Krejci, and Federico Bianchi
Atmos. Chem. Phys. Discuss.,
Revised manuscript accepted for ACPShort summary
We investigate the origin of air masses sampled at mount Chacaltaya, Bolivia. Three quarters of the measured air has not been influenced by the surface in the previous four days. However, it is rare that, at any given time, the sampled air has not been influenced at all by the surface and often the sampled air has multiple origins. The influence of the surface is more prevalent during day than night. Furthermore, during the 6-month study, one third of the air masses originated from Amazonia.
Peter Sherman, Meng Gao, Shaojie Song, Alex T. Archibald, Nathan Luke Abraham, Jean-François Lamarque, Drew Shindell, Gregory Faluvegi, and Michael B. McElroy
Atmos. Chem. Phys., 21, 3593–3605,Short summary
The aims here are to assess the role of aerosols in India's monsoon precipitation and to determine the relative contributions from Chinese and Indian emissions using CMIP6 models. We find that increased sulfur emissions reduce precipitation, which is primarily dynamically driven due to spatial shifts in convection over the region. A significant increase in precipitation (up to ~ 20 %) is found only when both Indian and Chinese sulfate emissions are regulated.
Melissa L. Breeden, Amy H. Butler, John R. Albers, Michael Sprenger, and Andrew O'Neil Langford
Atmos. Chem. Phys., 21, 2781–2794,Short summary
Prior research has found a maximum in deep stratosphere-to-troposphere mass/ozone transport over the western United States in boreal spring, which can enhance surface ozone concentrations, reducing air quality. We find that the winter-to-summer evolution of the north Pacific jet increases the frequency of stratospheric intrusions that drive transport, helping explain the observed maximum. The El Niño–Southern Oscillation affects the timing of the spring jet transition and therefore transport.
Dirk Offermann, Christoph Kalicinsky, Ralf Koppmann, and Johannes Wintel
Atmos. Chem. Phys., 21, 1593–1611,Short summary
Atmospheric oscillations with periods of up to several 100 years exist at altitudes up to 110 km. They are also seen in computer models (GCMs) of the atmospheric. They are often attributed to external influences from the sun, from the oceans, or from atmospheric constituents. This is difficult to verify as the atmosphere cannot be manipulated in an experiment. However, a GCM can be changed arbitrarily. Doing so, we find that long-period oscillations may be excited internally in the atmosphere.
Anna Shcherbacheva, Tracey Balehowsky, Jakub Kubečka, Tinja Olenius, Tapio Helin, Heikki Haario, Marko Laine, Theo Kurtén, and Hanna Vehkamäki
Atmos. Chem. Phys., 20, 15867–15906,Short summary
Atmospheric new particle formation and cluster growth to aerosol particles is an important field of research, in particular due to the climate change phenomenon. Evaporation rates are very difficult to account for but they are important to explain the formation and growth of particles. Different quantum chemistry (QC) methods produce substantially different values for the evaporation rates. We propose a novel approach for inferring evaporation rates of clusters from available measurements.
Jan Karlický, Peter Huszár, Tereza Nováková, Michal Belda, Filip Švábik, Jana Ďoubalová, and Tomáš Halenka
Atmos. Chem. Phys., 20, 15061–15077,Short summary
Cities are characterized by their impact on various meteorological variables. Our study aims to generalize these modifications into a single phenomenon – the urban meteorology island (UMI). A wide ensemble of Weather Research and Forecasting (WRF) and Regional Climate Model (RegCM) simulations investigated urban-induced modifications as individual UMI components. Significant changes are found in most of the discussed meteorological variables with a strong impact of specific model simulations.
William R. Hobbs, Andrew R. Klekociuk, and Yuhang Pan
Atmos. Chem. Phys., 20, 14757–14768,Short summary
Reanalysis products are an invaluable tool for representing variability and long-term trends in regions with limited in situ data. However, validation of these products is difficult because of that lack of station data. Here we present a novel assessment of eight reanalyses over the polar Southern Ocean, leveraging the close relationship between trends in sea ice cover and surface air temperature, that provides clear guidance on the most reliable product for Antarctic research.
Lejiang Yu, Shiyuan Zhong, Cuijuan Sui, and Bo Sun
Atmos. Chem. Phys., 20, 13753–13770,Short summary
The recent increasing trend of "warm Arctic, cold continents" has attracted much attention, but it remains debatable as to what forces are behind this phenomenon. Sea surface temperature (SST) over the central North Pacific and the North Atlantic oceans influences the trend. On an interdecadal timescale, the recent increase in the occurrences of the warm Arctic–cold Eurasia pattern is a fragment of the interdecadal variability of SST over the Atlantic Ocean and over the central Pacific Ocean.
Martina Krämer, Christian Rolf, Nicole Spelten, Armin Afchine, David Fahey, Eric Jensen, Sergey Khaykin, Thomas Kuhn, Paul Lawson, Alexey Lykov, Laura L. Pan, Martin Riese, Andrew Rollins, Fred Stroh, Troy Thornberry, Veronika Wolf, Sarah Woods, Peter Spichtinger, Johannes Quaas, and Odran Sourdeval
Atmos. Chem. Phys., 20, 12569–12608,Short summary
To improve the representations of cirrus clouds in climate predictions, extended knowledge of their properties and geographical distribution is required. This study presents extensive airborne in situ and satellite remote sensing climatologies of cirrus and humidity, which serve as a guide to cirrus clouds. Further, exemplary radiative characteristics of cirrus types and also in situ observations of tropical tropopause layer cirrus and humidity in the Asian monsoon anticyclone are shown.
Leenes Uzan, Smadar Egert, Pavel Khain, Yoav Levi, Elyakom Vadislavsky, and Pinhas Alpert
Atmos. Chem. Phys., 20, 12177–12192,Short summary
Detection of the planetary boundary layer (PBL) height is crucial to various fields, from air pollution assessment to weather prediction. We examined the diurnal summer PBL height by eight ceilometers in Israel, radiosonde profiles, the global IFS, and regional COSMO models. Our analysis utilized the bulk Richardson number method, the parcel method, and the wavelet covariance transform method. A novel correction tool to improve model results against in-situ ceilometer measurements is introduced.
Jessica Slater, Juha Tonttila, Gordon McFiggans, Paul Connolly, Sami Romakkaniemi, Thomas Kühn, and Hugh Coe
Atmos. Chem. Phys., 20, 11893–11906,Short summary
The feedback effect between aerosol particles, radiation and meteorology reduces turbulent motion and results in increased surface aerosol concentrations during Beijing haze. Observational analysis and regional modelling studies have examined the feedback effect but these studies are limited. In this work, we set up a high-resolution model for the Beijing environment to examine the sensitivity of the aerosol feedback effect to initial meteorological conditions and aerosol loading.
Bernard Legras and Silvia Bucci
Atmos. Chem. Phys., 20, 11045–11064,Short summary
The Asian monsoon is the most active region bringing surface compounds by convection to the stratosphere during summer. We study the transport pathways and the trapping within the upper-layer anticyclonic circulation. Above 15 km, the confinement can be represented by a uniform ascent over continental Asia of about 200 m per day and a uniform loss to other regions with a characteristic time of 2 weeks. We rule out the presence of a
chimneyproposed in previous studies over the Tibetan Plateau.
Clare Marie Flynn and Thorsten Mauritsen
Atmos. Chem. Phys., 20, 7829–7842,Short summary
The range of climate sensitivity of models participating in CMIP6 has increased relative to models participating in CMIP5 due to decreases in the total feedback parameter. This is caused by increases in the shortwave all-sky and clear-sky feedbacks, particularly over the Southern Ocean. These shifts between CMIP6 and CMIP5 did not arise by chance. Both CMIP5 and CMIP6 models are found to exhibit aerosol forcing that is too strong, causing too much cooling relative to observations.
Marie-Noëlle Bouin and Cindy Lebeaupin Brossier
Atmos. Chem. Phys., 20, 6861–6881,Short summary
A coupled, kilometre-scale simulation of a medicane is used to assess the impact of the ocean feedback and role of surface fluxes. Sea surface temperature (SST) drop is much weaker than for tropical cyclones, resulting in no impact on the cyclone. Surface fluxes depend mainly on wind and SST for evaporation and on air temperature for sensible heat. Processes in the Mediterranean, like advection of continental air, rain evaporation and dry air intrusion, play a role in cyclone development.
Kevin M. Grise and Sean M. Davis
Atmos. Chem. Phys., 20, 5249–5268,Short summary
As Earth's climate warms, the tropical overturning circulation (Hadley circulation) is projected to expand, potentially pushing subtropical dry zones further poleward. This study examines projections of the Hadley circulation from the latest generation of computer models and finds several notable differences from older models. For example, the Northern Hemisphere circulation has expanded northward at a greater rate in recent decades than would be expected from increasing greenhouse gases alone.
Yufei Zou, Yuhang Wang, Zuowei Xie, Hailong Wang, and Philip J. Rasch
Atmos. Chem. Phys., 20, 4999–5017,Short summary
We analyze the relationship between winter air stagnation and pollution extremes over eastern China and preceding Arctic sea ice loss based on climate modeling and dynamic diagnoses. We find significant increases in both the probability and intensity of air stagnation extremes in the modeling result driven by regional sea ice and sea surface temperature changes over the Pacific sector of the Arctic. We reveal the considerable impact of the Arctic climate change on mid-latitude weather extremes.
Dan Li, Bärbel Vogel, Rolf Müller, Jianchun Bian, Gebhard Günther, Felix Ploeger, Qian Li, Jinqiang Zhang, Zhixuan Bai, Holger Vömel, and Martin Riese
Atmos. Chem. Phys., 20, 4133–4152,Short summary
Low ozone and low water vapour signatures in the UTLS were investigated using balloon-borne measurements and trajectory calculations. The results show that deep convection in tropical cyclones over the western Pacific transports boundary air parcels with low ozone into the tropopause region. Subsequently, these air parcels are dehydrated when passing the lowest temperature region (< 190 K) during quasi-horizontal advection.
César Sauvage, Cindy Lebeaupin Brossier, Marie-Noëlle Bouin, and Véronique Ducrocq
Atmos. Chem. Phys., 20, 1675–1699,Short summary
Air–sea exchanges during Mediterranean heavy precipitation events are key and their representation must be improved for high-resolution weather forecasts. This study investigates the mechanisms acting at the air–sea interface during a case that occurred in southern France. To focus on the impact of sea state, we developed and used an original coupled air–wave model. Results show modifications of the forecast for the air–sea fluxes, the near-surface wind and the location of precipitation.
Tobias Wolf, Lasse H. Pettersson, and Igor Esau
Atmos. Chem. Phys., 20, 625–647,Short summary
Exceedances of legal thresholds for urban air pollution are of wide concern. We demonstrate the usefulness of very high-resolution modelling for the assessment of air pollution in the urban space on the example of Bergen, Norway. Vulnerability maps highlight areas with high pollutant loading and pathways for pollutant dispersion. This supports the understanding of urban air pollution beyond existing, scarce monitoring networks and possibly the mitigation of impacts on the local population.
Masatomo Fujiwara, Patrick Martineau, and Jonathon S. Wright
Atmos. Chem. Phys., 20, 345–374,Short summary
The global response of surface air temperature (SST) to the eruptions of Mount Agung in 1963, El Chichón in 1982, and Mount Pinatubo in 1991 is investigated using 11 global atmospheric reanalysis data sets. Multiple linear regression is applied, with a set of climatic indices orthogonalized, and the residuals are investigated. It is found that careful treatment of tropical SST variability is necessary to evaluate the surface response to volcanic eruptions in observations and reanalyses.
Ping Zhu, Bryce Tyner, Jun A. Zhang, Eric Aligo, Sundararaman Gopalakrishnan, Frank D. Marks, Avichal Mehra, and Vijay Tallapragada
Atmos. Chem. Phys., 19, 14289–14310,Short summary
Producing timely and accurate intensity forecasts of tropical cyclones (TCs) continues to be one of the most difficult challenges in numerical weather prediction. The difficulty stems from the fact that TC intensification is not only modulated by environmental conditions but also largely depends on TC internal dynamics. The study shows that asymmetric eyewall and rainband eddy forcing above the boundary layer plays an important role in spinning up a TC vortex including rapid intensification.
Jonathan K. P. Shonk, Teferi D. Demissie, and Thomas Toniazzo
Atmos. Chem. Phys., 19, 11383–11399,Short summary
Modern climate models are affected by systematic biases that harm their ability to produce reliable seasonal forecasts and climate projections. In this study, we investigate causes of biases in wind patterns over the tropical Atlantic during northern spring in three related models. We find that the wind biases are associated with an increase in excess rainfall and convergence in the tropical western Atlantic at the start of April, leading to the redirection of trade winds away from the Equator.
Xinxu Zhao, Julia Marshall, Stephan Hachinger, Christoph Gerbig, Matthias Frey, Frank Hase, and Jia Chen
Atmos. Chem. Phys., 19, 11279–11302,Short summary
The Weather Research and Forecasting model (WRF), coupled with greenhouse gas (GHG) modules (WRF-GHG), is considered to be a suitable basis for precise GHG transport analysis in urban areas, especially when combined with differential column methodology (DCM). DCM is an effective method not only for comparing models to observations independently of biases caused, for example, by initial conditions, but also for detecting and understanding sources of GHG emissions quantitatively in urban areas.
Xin Hao, Shengping He, Huijun Wang, and Tingting Han
Atmos. Chem. Phys., 19, 9903–9911,Short summary
The East Asian winter monsoon (EAWM) can be greatly influenced by many factors that can be classified as anthropogenic forcing and natural forcing. Our results show that the increasing anthropogenic emissions in the past decades may have contributed to the weakening of the EAWM, the frequency of occurrence of strong EAWM may have decreased by 45 % due to the anthropogenic forcing, and the anthropogenic forcing is a dominant contributor to the occurrence of a weak EAWM.
Christopher Pöhlker, David Walter, Hauke Paulsen, Tobias Könemann, Emilio Rodríguez-Caballero, Daniel Moran-Zuloaga, Joel Brito, Samara Carbone, Céline Degrendele, Viviane R. Després, Florian Ditas, Bruna A. Holanda, Johannes W. Kaiser, Gerhard Lammel, Jošt V. Lavrič, Jing Ming, Daniel Pickersgill, Mira L. Pöhlker, Maria Praß, Nina Löbs, Jorge Saturno, Matthias Sörgel, Qiaoqiao Wang, Bettina Weber, Stefan Wolff, Paulo Artaxo, Ulrich Pöschl, and Meinrat O. Andreae
Atmos. Chem. Phys., 19, 8425–8470,Short summary
The Amazon Tall Tower Observatory (ATTO) has been established to monitor the rain forest's biosphere–atmosphere exchange, which experiences the combined pressures from human-made deforestation and progressing climate change. This work is meant to be a reference study, which characterizes various geospatial properties of the ATTO footprint region and shows how the human-made transformation of Amazonia may impact future atmospheric observations at ATTO.
Quan Wang, Chanh Kieu, and The-Anh Vu
Atmos. Chem. Phys., 19, 8383–8397,Short summary
This study presents an analytical model to study large-scale tropical cyclone (TC) formation that can help us understand the maximum capacity of the Earth's atmosphere to produce TCs. Using a barotropic model for the intertropical convergence zone and recent advances in nonlinear dynamical transition, it is found that the Earth's atmosphere can support a limited number of TCs at any given time (<12) in the current climate, thus providing new theoretical insights into the TC formation process.
Bojan Škerlak, Stephan Pfahl, Michael Sprenger, and Heini Wernli
Atmos. Chem. Phys., 19, 6535–6549,Short summary
Upper-level fronts are often associated with the rapid transport of stratospheric air to the lower troposphere, leading to significantly enhanced ozone concentrations. This paper considers the multi-scale nature that is needed to bring stratospheric air down to the surface. The final transport step to the surface can be related to frontal zones and the associated vertical winds or to near-horizontal tracer transport followed by entrainment into a growing planetary boundary layer.
Tao Xian and Cameron R. Homeyer
Atmos. Chem. Phys., 19, 5661–5678,Short summary
Global characteristics and trends in the tropopause (the boundary between troposphere and stratosphere) over a 35-year period (1981–2015) are evaluated using both observations and models. The use of two coordinate systems reveals previously undiagnosed changes in the tropopause altitude within the tropics and extratropics and these results have important implications for studies of climate and atmospheric composition (especially that related to stratosphere–troposphere exchange).
Daniel Mewes and Christoph Jacobi
Atmos. Chem. Phys., 19, 3927–3937,Short summary
Horizontal moist static energy (MSE) transport patterns were extracted from reanalysis data using an artificial neuronal network for the winter months. The results show that during the last 30 years transport pathways that favour MSE transport through the North Atlantic are getting more frequent. This North Atlantic pathway is connected to positive temperature anomalies over the central Arctic, which implies a connection between Arctic amplification and the change in horizontal heat transport.
Liguang Wu, Qingyuan Liu, and Yubin Li
Atmos. Chem. Phys., 19, 2477–2487,Short summary
The tornado-scale vortex in the tropical cyclone boundary layer has been speculated in intense hurricanes. A numerical experiment is conducted using the Advanced Weather Research and Forecast model by incorporating the large-eddy simulation technique. The simulated tornado-scale vortex shows the similar features as revealed with the limited observational data. The presence of the tornado-scale vortex also leads to significant gradients in the near surface wind speed and wind gusts.
Sergej Zilitinkevich, Oleg Druzhinin, Andrey Glazunov, Evgeny Kadantsev, Evgeny Mortikov, Iryna Repina, and Yulia Troitskaya
Atmos. Chem. Phys., 19, 2489–2496,Short summary
We consider the budget of turbulent kinetic energy (TKE) in stably stratified flows. TKE is generated by velocity shear, then partially converted to potential energy, but basically cascades towards very small eddies and dissipates into heat. The TKE dissipation rate is vital for comprehending and modelling turbulent flows in geophysics, astrophysics, and engineering. Until now its dependence on static stability remained unclear. We define it theoretically and validate against experimental data.
Jing Wang, Zhiwei Zhu, Li Qi, Qiaohua Zhao, Jinhai He, and Julian X. L. Wang
Atmos. Chem. Phys., 19, 1521–1535,Short summary
Less attention has been paid to haze weather during the autumn season. Here, we unravel the mechanism of how SST anomalies over the subtropical North Atlantic and western North Pacific drive the interannual variability of the autumnal haze days in the Beijing–Tianjin–Hebei region. The two pathways of SST anomaly forcings can result in an anticyclonic (cyclonic) anomaly over Northeast Asia, leading to a lower-level southerly (northerly) anomaly and in turn more (fewer) haze days in this region.
Johannes Wagner, Thomas Gerz, Norman Wildmann, and Kira Gramitzky
Atmos. Chem. Phys., 19, 1129–1146,Short summary
Long-term WRF-LES simulations were performed with a horizontal resolution of 200 m for a period of 49 days during the Perdigão campaign. Simulation results were used to characterize the meteorological conditions and to analyse characteristic flow patterns. It could be shown that thermally driven flows including low-level jets frequently occurred during the observation period. Model results were in very good agreement with observations in spite of the long simulation time.
Huopo Chen, Huijun Wang, Jianqi Sun, Yangyang Xu, and Zhicong Yin
Atmos. Chem. Phys., 19, 233–243,Short summary
Our results show that the anthropogenic air pollution over eastern China will increase considerably at the end of 21st century, even though we keep the aerosol emission constant throughout the experiment. Furthermore, estimation shows that the effect of climate change induced by the GHG warming can account for 11%–28% of the changes of anthropogenic air pollution days over this region.
Melville E. Nicholls and Roger A. Pielke Sr.
Atmos. Chem. Phys., 18, 15975–16003,Short summary
The current understanding of atmospheric energy and mass transports is that the general circulation moves energy and mass from place to place in a relatively slow manner at the speed of the winds. This study challenges this view and provides evidence that considerable transfer can occur at the speed of sound. This transport mechanism is probably not adequately represented in current global models, which potentially could be a source of error that has yet to be evaluated.
Lejiang Yu and Shiyuan Zhong
Atmos. Chem. Phys., 18, 14149–14159,Short summary
The Arctic sea ice has been declining at a rapid pace in recent decades, which has been attributed largely to global warming. Using a relatively novel statistical method called self-organizing maps (SOM), we show that a large portion of the autumn Arctic sea ice decline in the past four decades may be explained by atmospheric circulation anomalies associated with anomalous sea-surface temperature patterns over the North Pacific and North Atlantic through ocean–atmosphere interactions.
Noelia Otero, Jana Sillmann, Kathleen A. Mar, Henning W. Rust, Sverre Solberg, Camilla Andersson, Magnuz Engardt, Robert Bergström, Bertrand Bessagnet, Augustin Colette, Florian Couvidat, Cournelius Cuvelier, Svetlana Tsyro, Hilde Fagerli, Martijn Schaap, Astrid Manders, Mihaela Mircea, Gino Briganti, Andrea Cappelletti, Mario Adani, Massimo D'Isidoro, María-Teresa Pay, Mark Theobald, Marta G. Vivanco, Peter Wind, Narendra Ojha, Valentin Raffort, and Tim Butler
Atmos. Chem. Phys., 18, 12269–12288,Short summary
This paper evaluates the capability of air-quality models to capture the observed relationship between surface ozone concentrations and meteorology over Europe. The air-quality models tended to overestimate the influence of maximum temperature and surface solar radiation. None of the air-quality models captured the strength of the observed relationship between ozone and relative humidity appropriately, underestimating the effect of relative humidity, a key factor in the ozone removal processes.
Jan Karlický, Peter Huszár, Tomáš Halenka, Michal Belda, Michal Žák, Petr Pišoft, and Jiří Mikšovský
Atmos. Chem. Phys., 18, 10655–10674,Short summary
Our work presents a comparison of modelled and observed urban-induced meteorological changes in long-term perspective using 10-year simulations. It contains an evaluation of models' urban parameterizations, investigations of the benefits of more sophisticated urban parameterizations with respect to simple approaches and evaluation of urban-induced meteorological changes from the perspective of pollutant dispersion.
Qin Wang, John C. Moore, and Duoying Ji
Atmos. Chem. Phys., 18, 9173–9188,Short summary
(1) Genesis potential and ventilation indices are assessed in 6 ESMs running RCP4.5 and G4, in 6 tropical cyclone genesis basins. (2) Genesis potential is reasonably well parameterized by simple surface temperature, but other factors are important in different basins and models such as relative humidity and wind shear. (3) The Northern Hemisphere basins behave rather differently from the southern ones, and these dominate TC statistics. G4 leads to significantly fewer TCs globally than RCP4.5.
Alexander J. Roberts, Margaret J. Woodage, John H. Marsham, Ellie J. Highwood, Claire L. Ryder, Willie McGinty, Simon Wilson, and Julia Crook
Atmos. Chem. Phys., 18, 9025–9048,Short summary
The summer Saharan dust hotspot is seasonally tied to the occurrence of convective storms. Global weather and climate models parameterise convection and so are unable to represent their associated dust uplift (haboobs). However, this work shows that even when simulations represent convection explicitly: (1) dust fields are not strongly affected, (2) convective storms are too small, (3) haboobs are too weak and (4) the land surface (bare soil and soil moisture) is dominant in controlling dust.
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The effectiveness of transport of short-lived halocarbons to the upper troposphere and lower stratosphere remains an important unknown in quantifying the supply of ozone-depleting substances to the stratosphere. In early 2014, a major field campaign in Guam in the western Pacific, involving UK and US research aircraft, sampled the tropical troposphere and lower stratosphere. The resulting measurements of CH3I, CHBr3 and CH2Br2 are compared here with calculations from a Lagrangian model.
The effectiveness of transport of short-lived halocarbons to the upper troposphere and lower...