Articles | Volume 14, issue 8
https://doi.org/10.5194/acp-14-3883-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-14-3883-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
17 Apr 2014
Research article |
| 17 Apr 2014
Surface response to rain events throughout the West African monsoon
Laboratoire d'Aérologie, UMR5560, Université de Toulouse and CNRS, Toulouse, France
L. Kergoat
GET (CNRS/UPS/IRD), Toulouse, France
F. Guichard
CNRM-GAME (CNRS and Météo-France), Toulouse, France
A. Boone
CNRM-GAME (CNRS and Météo-France), Toulouse, France
B. Cappelaere
IRD, Hydrosciences, Montpellier, France
J.-M. Cohard
LTHE (UJF), Grenoble, France
J. Demarty
IRD, Hydrosciences, Montpellier, France
LTHE (UJF), Grenoble, France
M. Grippa
GET (CNRS/UPS/IRD), Toulouse, France
C. Peugeot
IRD, Hydrosciences, Montpellier, France
D. Ramier
CETE Ile de France, Trappes, France
C. M. Taylor
CEH, Wallingford, UK
F. Timouk
GET (CNRS/UPS/IRD), Toulouse, France
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Extended low-level stratus clouds (LLC) form frequently in southern West Africa during the night-time and persist long into the next day. They affect the radiation budget, atmospheric boundary-layer (BL) evolution and regional climate. The relevant processes governing their formation and dissolution are not fully understood. Thus, a field campaign was conducted in summer 2016, which provided a comprehensive data set for process studies, specifically of interactions between LLC and BL conditions.
Joan Cuxart, Burkhard Wrenger, Daniel Martínez-Villagrasa, Joachim Reuder, Marius O. Jonassen, Maria A. Jiménez, Marie Lothon, Fabienne Lohou, Oscar Hartogensis, Jens Dünnermann, Laura Conangla, and Anirban Garai
Atmos. Chem. Phys., 16, 9489–9504, https://doi.org/10.5194/acp-16-9489-2016, https://doi.org/10.5194/acp-16-9489-2016, 2016
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Estimations of the effect of thermal advection in the surface energy budget are provided. Data from the experimental campaign BLLAST, held in Southern France in summer 2011, are used, including airborne data by drones and surface-based instrumentation. Model data outputs and satellite information are also inspected. Surface heterogeneities of the order of the kilometer or larger seem to have little effect on the budget, whereas hectometer-scale structures may contribute significantly to it.
Fleur Couvreux, Eric Bazile, Guylaine Canut, Yann Seity, Marie Lothon, Fabienne Lohou, Françoise Guichard, and Erik Nilsson
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Erik Nilsson, Fabienne Lohou, Marie Lothon, Eric Pardyjak, Larry Mahrt, and Clara Darbieu
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Erik Nilsson, Marie Lothon, Fabienne Lohou, Eric Pardyjak, Oscar Hartogensis, and Clara Darbieu
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C. Darbieu, F. Lohou, M. Lothon, J. Vilà-Guerau de Arellano, F. Couvreux, P. Durand, D. Pino, E. G. Patton, E. Nilsson, E. Blay-Carreras, and B. Gioli
Atmos. Chem. Phys., 15, 10071–10086, https://doi.org/10.5194/acp-15-10071-2015, https://doi.org/10.5194/acp-15-10071-2015, 2015
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H. P. Pietersen, J. Vilà-Guerau de Arellano, P. Augustin, A. van de Boer, O. de Coster, H. Delbarre, P. Durand, M. Fourmentin, B. Gioli, O. Hartogensis, F. Lohou, M. Lothon, H. G. Ouwersloot, D. Pino, and J. Reuder
Atmos. Chem. Phys., 15, 4241–4257, https://doi.org/10.5194/acp-15-4241-2015, https://doi.org/10.5194/acp-15-4241-2015, 2015
M. Lothon, F. Lohou, D. Pino, F. Couvreux, E. R. Pardyjak, J. Reuder, J. Vilà-Guerau de Arellano, P Durand, O. Hartogensis, D. Legain, P. Augustin, B. Gioli, D. H. Lenschow, I. Faloona, C. Yagüe, D. C. Alexander, W. M. Angevine, E Bargain, J. Barrié, E. Bazile, Y. Bezombes, E. Blay-Carreras, A. van de Boer, J. L. Boichard, A. Bourdon, A. Butet, B. Campistron, O. de Coster, J. Cuxart, A. Dabas, C. Darbieu, K. Deboudt, H. Delbarre, S. Derrien, P. Flament, M. Fourmentin, A. Garai, F. Gibert, A. Graf, J. Groebner, F. Guichard, M. A. Jiménez, M. Jonassen, A. van den Kroonenberg, V. Magliulo, S. Martin, D. Martinez, L. Mastrorillo, A. F. Moene, F. Molinos, E. Moulin, H. P. Pietersen, B. Piguet, E. Pique, C. Román-Cascón, C. Rufin-Soler, F. Saïd, M. Sastre-Marugán, Y. Seity, G. J. Steeneveld, P. Toscano, O. Traullé, D. Tzanos, S. Wacker, N. Wildmann, and A. Zaldei
Atmos. Chem. Phys., 14, 10931–10960, https://doi.org/10.5194/acp-14-10931-2014, https://doi.org/10.5194/acp-14-10931-2014, 2014
E. Blay-Carreras, E. R. Pardyjak, D. Pino, D. C. Alexander, F. Lohou, and M. Lothon
Atmos. Chem. Phys., 14, 9077–9085, https://doi.org/10.5194/acp-14-9077-2014, https://doi.org/10.5194/acp-14-9077-2014, 2014
E. Blay-Carreras, D. Pino, J. Vilà-Guerau de Arellano, A. van de Boer, O. De Coster, C. Darbieu, O. Hartogensis, F. Lohou, M. Lothon, and H. Pietersen
Atmos. Chem. Phys., 14, 4515–4530, https://doi.org/10.5194/acp-14-4515-2014, https://doi.org/10.5194/acp-14-4515-2014, 2014
Marie Lothon, François Gheusi, Fabienne Lohou, Véronique Pont, Serge Soula, Corinne Jambert, Solène Derrien, Yannick Bezombes, Emmanuel Leclerc, Gilles Athier, Antoine Vial, Alban Philibert, Bernard Campistron, Frédérique Saïd, Jeroen Sonke, Julien Amestoy, Erwan Bargain, Pierre Bosser, Damien Boulanger, Guillaume Bret, Renaud Bodichon, Laurent Cabanas, Guylaine Canut, Jean-Bernard Estrampes, Eric Gardrat, Zaida Gomez Kuri, Jérémy Gueffier, Fabienne Guesdon, Morgan Lopez, Olivier Masson, Pierre-Yves Meslin, Yves Meyerfeld, Nicolas Pascal, Eric Pique, Michel Ramonet, Felix Starck, and Romain Vidal
Atmos. Meas. Tech., 17, 6265–6300, https://doi.org/10.5194/amt-17-6265-2024, https://doi.org/10.5194/amt-17-6265-2024, 2024
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The Pyrenean Platform for Observation of the Atmosphere (P2OA) is a coupled plain–mountain instrumented platform in southwestern France for the monitoring of climate variables and the study of meteorological processes in a mountainous region. A comprehensive description of this platform is presented for the first time: its instrumentation, the associated dataset, and a meteorological characterization the site. The potential of the P2OA is illustrated through several examples of process studies.
Bethan L. Harris, Tristan Quaife, Christopher M. Taylor, and Phil P. Harris
Earth Syst. Dynam., 15, 1019–1035, https://doi.org/10.5194/esd-15-1019-2024, https://doi.org/10.5194/esd-15-1019-2024, 2024
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The response of vegetation productivity to rainfall is a crucial process linking the water and carbon cycles and influencing the evolution of the climate system. However, there are many uncertainties in its representation in Earth system models. We show that the vegetation productivity responses to short-term rainfall events are very different between models due to their differing sensitivities to water availability. We also evaluate the models against a range of observational products.
Maurin Zouzoua, Sophie Bastin, Marjolaine Chiriaco, Fabienne Lohou, Marie Lothon, Mathilde Jome, Cécile Mallet, Laurent Barthes, and Guylaine Canut
EGUsphere, https://doi.org/10.5194/egusphere-2024-568, https://doi.org/10.5194/egusphere-2024-568, 2024
Short summary
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This study proposes using a statistical model to freeze errors due to differences in environmental forcing when evaluating the surface turbulent heat fluxes from numerical simulations with observations. The statistical model is first built with observation and then applied to the simulated environment to generate possibly observed fluxes. This novel method provides insight into differently evaluating the numerical formulation of turbulent heat fluxes with a long period of observational data.
Alban Philibert, Marie Lothon, Julien Amestoy, Pierre-Yves Meslin, Solène Derrien, Yannick Bezombes, Bernard Campistron, Fabienne Lohou, Antoine Vial, Guylaine Canut-Rocafort, Joachim Reuder, and Jennifer K. Brooke
Atmos. Meas. Tech., 17, 1679–1701, https://doi.org/10.5194/amt-17-1679-2024, https://doi.org/10.5194/amt-17-1679-2024, 2024
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We present a new algorithm, CALOTRITON, for the retrieval of the convective boundary layer depth with ultra-high-frequency radar measurements. CALOTRITON is partly based on the principle that the top of the convective boundary layer is associated with an inversion and a decrease in turbulence. It is evaluated using ceilometer and radiosonde data. It is able to qualify the complexity of the vertical structure of the low troposphere and detect internal or residual layers.
Jérémy Gueffier, François Gheusi, Marie Lothon, Véronique Pont, Alban Philibert, Fabienne Lohou, Solène Derrien, Yannick Bezombes, Gilles Athier, Yves Meyerfeld, Antoine Vial, and Emmanuel Leclerc
Atmos. Chem. Phys., 24, 287–316, https://doi.org/10.5194/acp-24-287-2024, https://doi.org/10.5194/acp-24-287-2024, 2024
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This study investigates the link between weather regime and atmospheric composition at a Pyrenean observatory. Five years of meteorological data were synchronized on a daily basis and then, using a clustering method, separated into six groups of observation days, with most showing marked characteristics of different weather regimes (fair and disturbed weather, winter windstorms, foehn). Statistical differences in gas and particle concentrations appeared between the groups and are discussed.
Mathilde de Fleury, Laurent Kergoat, and Manuela Grippa
Hydrol. Earth Syst. Sci., 27, 2189–2204, https://doi.org/10.5194/hess-27-2189-2023, https://doi.org/10.5194/hess-27-2189-2023, 2023
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This study surveys small lakes and reservoirs, which are vital resources in the Sahel, through a multi-sensor satellite approach. Water height changes compared to evaporation losses in dry seasons highlight anthropogenic withdrawals and water supplies due to river and groundwater connections. Some reservoirs display weak withdrawals, suggesting low usage may be due to security issues. The
satellite-derived water balance thus proved effective in estimating water resources in semi-arid areas.
Julia Crook, Cornelia Klein, Sonja Folwell, Christopher M. Taylor, Douglas J. Parker, Adama Bamba, and Kouakou Kouadio
Weather Clim. Dynam., 4, 229–248, https://doi.org/10.5194/wcd-4-229-2023, https://doi.org/10.5194/wcd-4-229-2023, 2023
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We estimate recent deforestation in West Africa and use a climate model allowing explicit convection to determine impacts on early season rainfall. We find enhanced rainfall over deforestation, in line with recent observational results, due to changes in circulation rather than humidity, showing potential for future studies. Local changes depend on initial soil moisture, deforestation extent, and ocean proximity, with sea breezes shifting inland where surface friction decreased.
Rebecca J. Oliver, Lina M. Mercado, Doug B. Clark, Chris Huntingford, Christopher M. Taylor, Pier Luigi Vidale, Patrick C. McGuire, Markus Todt, Sonja Folwell, Valiyaveetil Shamsudheen Semeena, and Belinda E. Medlyn
Geosci. Model Dev., 15, 5567–5592, https://doi.org/10.5194/gmd-15-5567-2022, https://doi.org/10.5194/gmd-15-5567-2022, 2022
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We introduce new representations of plant physiological processes into a land surface model. Including new biological understanding improves modelled carbon and water fluxes for the present in tropical and northern-latitude forests. Future climate simulations demonstrate the sensitivity of photosynthesis to temperature is important for modelling carbon cycle dynamics in a warming world. Accurate representation of these processes in models is necessary for robust predictions of climate change.
Adrien Deroubaix, Laurent Menut, Cyrille Flamant, Peter Knippertz, Andreas H. Fink, Anneke Batenburg, Joel Brito, Cyrielle Denjean, Cheikh Dione, Régis Dupuy, Valerian Hahn, Norbert Kalthoff, Fabienne Lohou, Alfons Schwarzenboeck, Guillaume Siour, Paolo Tuccella, and Christiane Voigt
Atmos. Chem. Phys., 22, 3251–3273, https://doi.org/10.5194/acp-22-3251-2022, https://doi.org/10.5194/acp-22-3251-2022, 2022
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During the summer monsoon in West Africa, pollutants emitted in urbanized areas modify cloud cover and precipitation patterns. We analyze these patterns with the WRF-CHIMERE model, integrating the effects of aerosols on meteorology, based on the numerous observations provided by the Dynamics-Aerosol-Climate-Interactions campaign. This study adds evidence to recent findings that increased pollution levels in West Africa delay the breakup time of low-level clouds and reduce precipitation.
Clément Outrequin, Anne Alexandre, Christine Vallet-Coulomb, Clément Piel, Sébastien Devidal, Amaelle Landais, Martine Couapel, Jean-Charles Mazur, Christophe Peugeot, Monique Pierre, Frédéric Prié, Jacques Roy, Corinne Sonzogni, and Claudia Voigt
Clim. Past, 17, 1881–1902, https://doi.org/10.5194/cp-17-1881-2021, https://doi.org/10.5194/cp-17-1881-2021, 2021
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Continental atmospheric humidity is a key climate parameter poorly captured by global climate models. Model–data comparison approaches that are applicable beyond the instrumental period are essential to progress on this issue but face a lack of quantitative relative humidity proxies. Here, we calibrate the triple oxygen isotope composition of phytoliths as a new quantitative proxy of continental relative humidity suitable for past climate reconstructions.
Carlos Román-Cascón, Marie Lothon, Fabienne Lohou, Oscar Hartogensis, Jordi Vila-Guerau de Arellano, David Pino, Carlos Yagüe, and Eric R. Pardyjak
Geosci. Model Dev., 14, 3939–3967, https://doi.org/10.5194/gmd-14-3939-2021, https://doi.org/10.5194/gmd-14-3939-2021, 2021
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The type of vegetation (or land cover) and its status influence the heat and water transfers between the surface and the air, affecting the processes that develop in the atmosphere at different (but connected) spatiotemporal scales. In this work, we investigate how these transfers are affected by the way the surface is represented in a widely used weather model. The results encourage including realistic high-resolution and updated land cover databases in models to improve their predictions.
Yves Tramblay, Nathalie Rouché, Jean-Emmanuel Paturel, Gil Mahé, Jean-François Boyer, Ernest Amoussou, Ansoumana Bodian, Honoré Dacosta, Hamouda Dakhlaoui, Alain Dezetter, Denis Hughes, Lahoucine Hanich, Christophe Peugeot, Raphael Tshimanga, and Patrick Lachassagne
Earth Syst. Sci. Data, 13, 1547–1560, https://doi.org/10.5194/essd-13-1547-2021, https://doi.org/10.5194/essd-13-1547-2021, 2021
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This dataset provides a set of hydrometric indices for about 1500 stations across Africa with daily discharge data. These indices represent mean flow characteristics and extremes (low flows and floods), allowing us to study the long-term evolution of hydrology in Africa and support the modeling efforts that aim at reducing the vulnerability of African countries to hydro-climatic variability.
Maurin Zouzoua, Fabienne Lohou, Paul Assamoi, Marie Lothon, Véronique Yoboue, Cheikh Dione, Norbert Kalthoff, Bianca Adler, Karmen Babić, Xabier Pedruzo-Bagazgoitia, and Solène Derrien
Atmos. Chem. Phys., 21, 2027–2051, https://doi.org/10.5194/acp-21-2027-2021, https://doi.org/10.5194/acp-21-2027-2021, 2021
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Based on a field experiment conducted in June and July 2016, we analyzed the daytime breakup of continental low-level stratiform clouds over southern West Africa in order to provide complementary guidance for model evaluation during the monsoon season. Those clouds exhibit weaker temperature and moisture jumps at the top compared to marine stratiform clouds. Their lifetime and the transition towards shallow convective clouds during daytime hours depend on their coupling with the surface.
Wim Verbruggen, Guy Schurgers, Stéphanie Horion, Jonas Ardö, Paulo N. Bernardino, Bernard Cappelaere, Jérôme Demarty, Rasmus Fensholt, Laurent Kergoat, Thomas Sibret, Torbern Tagesson, and Hans Verbeeck
Biogeosciences, 18, 77–93, https://doi.org/10.5194/bg-18-77-2021, https://doi.org/10.5194/bg-18-77-2021, 2021
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A large part of Earth's land surface is covered by dryland ecosystems, which are subject to climate extremes that are projected to increase under future climate scenarios. By using a mathematical vegetation model, we studied the impact of single years of extreme rainfall on the vegetation in the Sahel. We found a contrasting response of grasses and trees to these extremes, strongly dependent on the way precipitation is spread over the rainy season, as well as a long-term impact on CO2 uptake.
Barbara Altstädter, Konrad Deetz, Bernhard Vogel, Karmen Babić, Cheikh Dione, Federica Pacifico, Corinne Jambert, Friederike Ebus, Konrad Bärfuss, Falk Pätzold, Astrid Lampert, Bianca Adler, Norbert Kalthoff, and Fabienne Lohou
Atmos. Chem. Phys., 20, 7911–7928, https://doi.org/10.5194/acp-20-7911-2020, https://doi.org/10.5194/acp-20-7911-2020, 2020
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We present the high vertical variability of the black carbon (BC) mass concentration measured with the unmanned aerial system ALADINA during the field experiment of DACCIWA. The COSMO-ART model output was applied for the campaign period and is compared with the observational BC data during a case study on 14–15 July 2016. Enhanced BC concentrations were related to transport processes to the measurement site by maritime inflow and not to local emissions as initially expected.
Xabier Pedruzo-Bagazgoitia, Stephan R. de Roode, Bianca Adler, Karmen Babić, Cheikh Dione, Norbert Kalthoff, Fabienne Lohou, Marie Lothon, and Jordi Vilà-Guerau de Arellano
Atmos. Chem. Phys., 20, 2735–2754, https://doi.org/10.5194/acp-20-2735-2020, https://doi.org/10.5194/acp-20-2735-2020, 2020
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Using a high-resolution model we simulate the transition from night to day clouds on southern West Africa using observations from the DACCIWA project. We find that the radiative effects of clouds help mantain a thick cloud layer in the night, while the mixing of cloud air with air above during the day, aided by moisture and heat fluxes at the surface, thins this layer and promotes its transition to other clouds. The effect of changing wind with height accelerates the transition.
Fabienne Lohou, Norbert Kalthoff, Bianca Adler, Karmen Babić, Cheikh Dione, Marie Lothon, Xabier Pedruzo-Bagazgoitia, and Maurin Zouzoua
Atmos. Chem. Phys., 20, 2263–2275, https://doi.org/10.5194/acp-20-2263-2020, https://doi.org/10.5194/acp-20-2263-2020, 2020
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A conceptual model of the low-level stratiform clouds (LLSCs), which develop almost every night in southern West Africa, is built with the dataset acquired during the DACCIWA (Dynamics Aerosol Chemistry Cloud Interactions in West Africa) ground-based field experiment. Several processes occur during the four phases composing this diurnal cycle: the cooling of the air until saturation (stable and jet phases), LLSC and low-level jet interactions (stratus phase), and LLSC breakup (convective phase).
Mark F. Lunt, Paul I. Palmer, Liang Feng, Christopher M. Taylor, Hartmut Boesch, and Robert J. Parker
Atmos. Chem. Phys., 19, 14721–14740, https://doi.org/10.5194/acp-19-14721-2019, https://doi.org/10.5194/acp-19-14721-2019, 2019
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Using data from the GOSAT satellite between 2010 and 2016 and a Bayesian inversion approach, we estimate monthly emissions of methane from tropical Africa. We find an increase in methane emissions during this period, driven in part by rising emissions from South Sudan. Using ancillary data we attribute this short-term emissions rise to an increase in the extent of the Sudd wetlands driven by increased outflow from the East African lakes.
Karmen Babić, Norbert Kalthoff, Bianca Adler, Julian F. Quinting, Fabienne Lohou, Cheikh Dione, and Marie Lothon
Atmos. Chem. Phys., 19, 13489–13506, https://doi.org/10.5194/acp-19-13489-2019, https://doi.org/10.5194/acp-19-13489-2019, 2019
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This study investigates differences in atmospheric conditions between nights with and without low-level stratus clouds (LLCs) over southern West Africa. We use high-quality observations collected during 2016 summer monsoon season and the ERA5 reanalysis data set. Our results show that the formation of LLCs depends on the interplay between the onset time and strength of the nocturnal low-level jet, horizontal cold-air advection, and the overall moisture level in the whole region.
Marie Lothon, Paul Barnéoud, Omar Gabella, Fabienne Lohou, Solène Derrien, Sylvain Rondi, Marjolaine Chiriaco, Sophie Bastin, Jean-Charles Dupont, Martial Haeffelin, Jordi Badosa, Nicolas Pascal, and Nadège Montoux
Atmos. Meas. Tech., 12, 5519–5534, https://doi.org/10.5194/amt-12-5519-2019, https://doi.org/10.5194/amt-12-5519-2019, 2019
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In the context of an atmospheric network of instrumented sites equipped with sky cameras for cloud monitoring, we present an algorithm named ELIFAN, which aims to estimate the cloud cover amount from full-sky visible daytime images. ELIFAN is based on red-to-blue ratio thresholding applied on the image pixels and on the use of a blue-sky library. We present its principle and its performance and highlight the interest of combining several complementary instruments.
Samuel Nahmani, Olivier Bock, and Françoise Guichard
Atmos. Chem. Phys., 19, 9541–9561, https://doi.org/10.5194/acp-19-9541-2019, https://doi.org/10.5194/acp-19-9541-2019, 2019
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A mesoscale convective system (MCS) is a cloud system that occurs in connection with an ensemble of thunderstorms and produces a contiguous precipitation area of the order of 100 km or more. Numerous questions related to MCSs remain poorly answered (e.g., their life cycle, and interactions between physical processes and atmospheric circulations). This work shows how a GPS technique can provide relevant and complementary information on MCSs passing over or in the vicinity of observation stations.
Cheikh Dione, Fabienne Lohou, Marie Lothon, Bianca Adler, Karmen Babić, Norbert Kalthoff, Xabier Pedruzo-Bagazgoitia, Yannick Bezombes, and Omar Gabella
Atmos. Chem. Phys., 19, 8979–8997, https://doi.org/10.5194/acp-19-8979-2019, https://doi.org/10.5194/acp-19-8979-2019, 2019
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Low atmospheric dynamics and low-level cloud (LLC) macrophysical properties are analyzed using in situ and remote sensing data collected from 20 June to 30 July at Savè, Benin, during the DACCIWA field campaign in 2016. We find that the low-level jet (LLJ), LLCs, monsoon flow, and maritime inflow reveal a day-to-day variability. LLCs form at the same level as the jet core height. The cloud base height is stationary at night and remains below the jet. The cloud top height is found above the jet.
Federica Pacifico, Claire Delon, Corinne Jambert, Pierre Durand, Eleanor Morris, Mat J. Evans, Fabienne Lohou, Solène Derrien, Venance H. E. Donnou, Arnaud V. Houeto, Irene Reinares Martínez, and Pierre-Etienne Brilouet
Atmos. Chem. Phys., 19, 2299–2325, https://doi.org/10.5194/acp-19-2299-2019, https://doi.org/10.5194/acp-19-2299-2019, 2019
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Biogenic fluxes from soil at a local and regional scale are crucial to study air pollution and climate. Here we present field measurements of soil fluxes of nitric oxide (NO) and ammonia (NH3) observed over four different land cover types, i.e. bare soil, grassland, maize field, and forest, at an inland rural site in Benin, West Africa, during the DACCIWA field campaign in
June and July 2016.
Sophie L. Haslett, Jonathan W. Taylor, Konrad Deetz, Bernhard Vogel, Karmen Babić, Norbert Kalthoff, Andreas Wieser, Cheikh Dione, Fabienne Lohou, Joel Brito, Régis Dupuy, Alfons Schwarzenboeck, Paul Zieger, and Hugh Coe
Atmos. Chem. Phys., 19, 1505–1520, https://doi.org/10.5194/acp-19-1505-2019, https://doi.org/10.5194/acp-19-1505-2019, 2019
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As the population in West Africa grows and air pollution increases, it is becoming ever more important to understand the effects of this pollution on the climate and on health. Aerosol particles can grow by absorbing water from the air around them. This paper shows that during the monsoon season, aerosol particles in the region are likely to grow significantly because of the high moisture in the air. This means that climate effects from increasing pollution will be enhanced.
Karmen Babić, Bianca Adler, Norbert Kalthoff, Hendrik Andersen, Cheikh Dione, Fabienne Lohou, Marie Lothon, and Xabier Pedruzo-Bagazgoitia
Atmos. Chem. Phys., 19, 1281–1299, https://doi.org/10.5194/acp-19-1281-2019, https://doi.org/10.5194/acp-19-1281-2019, 2019
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The first detailed observational analysis of the complete diurnal cycle of low-level clouds (LLC) and associated atmospheric processes over southern West Africa is performed using the data gathered within the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa) ground-based campaign. We find cooling related to the horizontal advection, which occurs in connection with the inflow of cool maritime air mass and a prominent low-level jet, to have the dominant role in LLC formation.
Bianca Adler, Karmen Babić, Norbert Kalthoff, Fabienne Lohou, Marie Lothon, Cheikh Dione, Xabier Pedruzo-Bagazgoitia, and Hendrik Andersen
Atmos. Chem. Phys., 19, 663–681, https://doi.org/10.5194/acp-19-663-2019, https://doi.org/10.5194/acp-19-663-2019, 2019
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This study deals with nocturnal stratiform low-level clouds that frequently form in the atmospheric boundary layer over southern West Africa. We use observational data from 11 nights to characterize the clouds and intranight variability of boundary layer conditions as well as to assess the physical processes relevant for cloud formation. We find that cooling is crucial to reach saturation and a large part of the cooling is related to horizontal advection of cool air from the Gulf of Guinea.
Basile Hector, Jean-Martial Cohard, Luc Séguis, Sylvie Galle, and Christophe Peugeot
Hydrol. Earth Syst. Sci., 22, 5867–5888, https://doi.org/10.5194/hess-22-5867-2018, https://doi.org/10.5194/hess-22-5867-2018, 2018
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The hydrological functioning of western African headwater wetlands remains poorly understood, despite their potential for small-scale farming and their role in streamflow production. We found that land cover changes significantly affect water budgets, and pedo-geological features control dry season baseflow. These are the results of virtual experiments with a physically based critical zone model evaluated against streamflow, evapotranspiration, soil moisture, water table and water storage data.
Hervé Petetin, Bastien Sauvage, Herman G. J. Smit, François Gheusi, Fabienne Lohou, Romain Blot, Hannah Clark, Gilles Athier, Damien Boulanger, Jean-Marc Cousin, Philippe Nedelec, Patrick Neis, Susanne Rohs, and Valérie Thouret
Atmos. Chem. Phys., 18, 9561–9581, https://doi.org/10.5194/acp-18-9561-2018, https://doi.org/10.5194/acp-18-9561-2018, 2018
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Based on the numerous profiles available since 1994, this paper investigates the vertical stratification of ozone, carbon monoxide and relative humidity in the lower part of the troposphere (planetary boundary layer, lower free troposphere). Such a characterization of the vertical distribution of pollution is notably important for better understanding vertical exchanges and evaluating models on the vertical dimension.
Norbert Kalthoff, Fabienne Lohou, Barbara Brooks, Gbenga Jegede, Bianca Adler, Karmen Babić, Cheikh Dione, Adewale Ajao, Leonard K. Amekudzi, Jeffrey N. A. Aryee, Muritala Ayoola, Geoffrey Bessardon, Sylvester K. Danuor, Jan Handwerker, Martin Kohler, Marie Lothon, Xabier Pedruzo-Bagazgoitia, Victoria Smith, Lukman Sunmonu, Andreas Wieser, Andreas H. Fink, and Peter Knippertz
Atmos. Chem. Phys., 18, 2913–2928, https://doi.org/10.5194/acp-18-2913-2018, https://doi.org/10.5194/acp-18-2913-2018, 2018
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Extended low-level stratus clouds (LLC) form frequently in southern West Africa during the night-time and persist long into the next day. They affect the radiation budget, atmospheric boundary-layer (BL) evolution and regional climate. The relevant processes governing their formation and dissolution are not fully understood. Thus, a field campaign was conducted in summer 2016, which provided a comprehensive data set for process studies, specifically of interactions between LLC and BL conditions.
Laetitia Gal, Manuela Grippa, Pierre Hiernaux, Léa Pons, and Laurent Kergoat
Hydrol. Earth Syst. Sci., 21, 4591–4613, https://doi.org/10.5194/hess-21-4591-2017, https://doi.org/10.5194/hess-21-4591-2017, 2017
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The intense, prolonged Sahel drought has caused a widespread increase in surface runoff and surface waters like lakes or rivers, against all expectations. Using long-term observations and the Kineros2 hydrological model, we show that the runoff coefficient of the Agoufou watershed increased from ~ 0 to 5.5 % in 1950–2011. We attribute this phenomenon to a change in vegetation and soil surface properties, in response to the drought, rather than land–use change or rainfall regime intensification.
Torbern Tagesson, Jonas Ardö, Bernard Cappelaere, Laurent Kergoat, Abdulhakim Abdi, Stéphanie Horion, and Rasmus Fensholt
Biogeosciences, 14, 1333–1348, https://doi.org/10.5194/bg-14-1333-2017, https://doi.org/10.5194/bg-14-1333-2017, 2017
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Vegetation growth in semi-arid regions is an important sink for human-induced fossil fuel emissions of CO2 and this study addresses the strong need for improved understanding and spatially explicit estimates of CO2 uptake by semi-arid ecosystems. We show that a model incorporating photosynthetic parameters upscaled using satellite-based earth observation simulates CO2 uptake well for the Sahel, one of the largest semi-arid regions in the world.
Joan Cuxart, Burkhard Wrenger, Daniel Martínez-Villagrasa, Joachim Reuder, Marius O. Jonassen, Maria A. Jiménez, Marie Lothon, Fabienne Lohou, Oscar Hartogensis, Jens Dünnermann, Laura Conangla, and Anirban Garai
Atmos. Chem. Phys., 16, 9489–9504, https://doi.org/10.5194/acp-16-9489-2016, https://doi.org/10.5194/acp-16-9489-2016, 2016
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Estimations of the effect of thermal advection in the surface energy budget are provided. Data from the experimental campaign BLLAST, held in Southern France in summer 2011, are used, including airborne data by drones and surface-based instrumentation. Model data outputs and satellite information are also inspected. Surface heterogeneities of the order of the kilometer or larger seem to have little effect on the budget, whereas hectometer-scale structures may contribute significantly to it.
Fleur Couvreux, Eric Bazile, Guylaine Canut, Yann Seity, Marie Lothon, Fabienne Lohou, Françoise Guichard, and Erik Nilsson
Atmos. Chem. Phys., 16, 8983–9002, https://doi.org/10.5194/acp-16-8983-2016, https://doi.org/10.5194/acp-16-8983-2016, 2016
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This study evaluates the ability of operational models to predict the boundary-layer turbulent processes and mesoscale variability observed during the Boundary Layer Late-Afternoon and Sunset Turbulence field campaign. The models succeed in reproducing the variability from one day to another in terms of cloud cover, temperature and boundary-layer depth. However, they exhibit some systematic biases. The high-resolution model reproduces the vertical structures better.
Erik Nilsson, Fabienne Lohou, Marie Lothon, Eric Pardyjak, Larry Mahrt, and Clara Darbieu
Atmos. Chem. Phys., 16, 8849–8872, https://doi.org/10.5194/acp-16-8849-2016, https://doi.org/10.5194/acp-16-8849-2016, 2016
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The evolution of near-surface turbulence kinetic energy (TKE) and its budget in the afternoon transition has been studied based on field measurements. The study shows that TKE transport is an important budget term that needs to be taken into account in modeling of TKE. A non-local parametrization of dissipation using a TKE–length scale model which takes into account of boundary layer depth also gave improved results compared to a local parametrization.
Erik Nilsson, Marie Lothon, Fabienne Lohou, Eric Pardyjak, Oscar Hartogensis, and Clara Darbieu
Atmos. Chem. Phys., 16, 8873–8898, https://doi.org/10.5194/acp-16-8873-2016, https://doi.org/10.5194/acp-16-8873-2016, 2016
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A new simple model for turbulence kinetic energy (TKE) and its budget is presented for the sheared convective atmospheric boundary layer. It is used to study effects of buoyancy and shear on TKE evolution during the afternoon transition, especially near the surface. We also find a region of weak turbulence during unstable afternoon conditions below the inversion top, which we refer to as a "pre-residual layer".
Delphine J. Leroux, Thierry Pellarin, Théo Vischel, Jean-Martial Cohard, Tania Gascon, François Gibon, Arnaud Mialon, Sylvie Galle, Christophe Peugeot, and Luc Seguis
Hydrol. Earth Syst. Sci., 20, 2827–2840, https://doi.org/10.5194/hess-20-2827-2016, https://doi.org/10.5194/hess-20-2827-2016, 2016
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Water is one of the most valuable resources and has an undeniable influence on every aspect of life. Being a very good indicator of the water cycle, the soil water content can be monitored by satellites from space. The region studied here is located in Benin, West Africa, where people have to face major water-related risks every year during the monsoon season. By adjusting the model simulations with satellite observations, river discharge and water table levels have greatly been improved.
C. Darbieu, F. Lohou, M. Lothon, J. Vilà-Guerau de Arellano, F. Couvreux, P. Durand, D. Pino, E. G. Patton, E. Nilsson, E. Blay-Carreras, and B. Gioli
Atmos. Chem. Phys., 15, 10071–10086, https://doi.org/10.5194/acp-15-10071-2015, https://doi.org/10.5194/acp-15-10071-2015, 2015
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A case study of the BLLAST experiment is considered to explore the decay of turbulence that occurs in the convective boundary layer over land during the afternoon. Based on observations and on a large-eddy simulation, the analysis reveals two phases in the afternoon: a first quasi-stationary phase when the turbulent kinetic energy slowly decays without significant change in the turbulence structure and a second phase of more rapid decay with a change in spectral turbulence characteristics.
F. Hourdin, M. Gueye, B. Diallo, J.-L. Dufresne, J. Escribano, L. Menut, B. Marticoréna, G. Siour, and F. Guichard
Atmos. Chem. Phys., 15, 6775–6788, https://doi.org/10.5194/acp-15-6775-2015, https://doi.org/10.5194/acp-15-6775-2015, 2015
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New parameterizations of the convective boundary layer are used to better represent the diurnal cycle of near-surface wind over Sahara and Sahel in a climate model and the associated emission of dust.
C. Leauthaud, J. Demarty, B. Cappelaere, M. Grippa, L. Kergoat, C. Velluet, F. Guichard, E. Mougin, S. Chelbi, and B. Sultan
Proc. IAHS, 371, 195–201, https://doi.org/10.5194/piahs-371-195-2015, https://doi.org/10.5194/piahs-371-195-2015, 2015
C. Delon, E. Mougin, D. Serça, M. Grippa, P. Hiernaux, M. Diawara, C. Galy-Lacaux, and L. Kergoat
Biogeosciences, 12, 3253–3272, https://doi.org/10.5194/bg-12-3253-2015, https://doi.org/10.5194/bg-12-3253-2015, 2015
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This study provides seasonal and interannual variation of simulated biogenic NO emission fluxes in a Sahelian rangeland in Mali, a region where intense NO emissions occur during the wet season. Emissions are related to their biogeochemical origin, to the quantity of biomass, and to the quantity of livestock, which drive the N pool and N turnover in the soil, using a coupled vegetation–litter decomposition–emission model.
H. P. Pietersen, J. Vilà-Guerau de Arellano, P. Augustin, A. van de Boer, O. de Coster, H. Delbarre, P. Durand, M. Fourmentin, B. Gioli, O. Hartogensis, F. Lohou, M. Lothon, H. G. Ouwersloot, D. Pino, and J. Reuder
Atmos. Chem. Phys., 15, 4241–4257, https://doi.org/10.5194/acp-15-4241-2015, https://doi.org/10.5194/acp-15-4241-2015, 2015
C. Velluet, J. Demarty, B. Cappelaere, I. Braud, H. B.-A. Issoufou, N. Boulain, D. Ramier, I. Mainassara, G. Charvet, M. Boucher, J.-P. Chazarin, M. Oï, H. Yahou, B. Maidaji, F. Arpin-Pont, N. Benarrosh, A. Mahamane, Y. Nazoumou, G. Favreau, and J. Seghieri
Hydrol. Earth Syst. Sci., 18, 5001–5024, https://doi.org/10.5194/hess-18-5001-2014, https://doi.org/10.5194/hess-18-5001-2014, 2014
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Long-term average water and energy cycles are described for two main land cover types in the cultivated Sahel (millet crop and fallow bush). Mean seasonal cycles and annual budgets for all component variables were estimated from detailed field and model analysis. Evapotranspiration totals over 80% of rainfall for both covers, but with different time distribution and soil/plant contributions. The remainder is shared between runoff and deep drainage for the crop, but is only runoff for the fallow.
M. Lothon, F. Lohou, D. Pino, F. Couvreux, E. R. Pardyjak, J. Reuder, J. Vilà-Guerau de Arellano, P Durand, O. Hartogensis, D. Legain, P. Augustin, B. Gioli, D. H. Lenschow, I. Faloona, C. Yagüe, D. C. Alexander, W. M. Angevine, E Bargain, J. Barrié, E. Bazile, Y. Bezombes, E. Blay-Carreras, A. van de Boer, J. L. Boichard, A. Bourdon, A. Butet, B. Campistron, O. de Coster, J. Cuxart, A. Dabas, C. Darbieu, K. Deboudt, H. Delbarre, S. Derrien, P. Flament, M. Fourmentin, A. Garai, F. Gibert, A. Graf, J. Groebner, F. Guichard, M. A. Jiménez, M. Jonassen, A. van den Kroonenberg, V. Magliulo, S. Martin, D. Martinez, L. Mastrorillo, A. F. Moene, F. Molinos, E. Moulin, H. P. Pietersen, B. Piguet, E. Pique, C. Román-Cascón, C. Rufin-Soler, F. Saïd, M. Sastre-Marugán, Y. Seity, G. J. Steeneveld, P. Toscano, O. Traullé, D. Tzanos, S. Wacker, N. Wildmann, and A. Zaldei
Atmos. Chem. Phys., 14, 10931–10960, https://doi.org/10.5194/acp-14-10931-2014, https://doi.org/10.5194/acp-14-10931-2014, 2014
E. Blay-Carreras, E. R. Pardyjak, D. Pino, D. C. Alexander, F. Lohou, and M. Lothon
Atmos. Chem. Phys., 14, 9077–9085, https://doi.org/10.5194/acp-14-9077-2014, https://doi.org/10.5194/acp-14-9077-2014, 2014
C. Delon, E. Mougin, D. Serça, M. Grippa, P. Hiernaux, M. Diawara, C. Galy-Lacaux, and L. Kergoat
Biogeosciences Discuss., https://doi.org/10.5194/bgd-11-11785-2014, https://doi.org/10.5194/bgd-11-11785-2014, 2014
Revised manuscript not accepted
E. Blay-Carreras, D. Pino, J. Vilà-Guerau de Arellano, A. van de Boer, O. De Coster, C. Darbieu, O. Hartogensis, F. Lohou, M. Lothon, and H. Pietersen
Atmos. Chem. Phys., 14, 4515–4530, https://doi.org/10.5194/acp-14-4515-2014, https://doi.org/10.5194/acp-14-4515-2014, 2014
O. Mamadou, J. M. Cohard, S. Galle, C. N. Awanou, A. Diedhiou, B. Kounouhewa, and C. Peugeot
Hydrol. Earth Syst. Sci., 18, 893–914, https://doi.org/10.5194/hess-18-893-2014, https://doi.org/10.5194/hess-18-893-2014, 2014
A. Richard, S. Galle, M. Descloitres, J.-M. Cohard, J.-P. Vandervaere, L. Séguis, and C. Peugeot
Hydrol. Earth Syst. Sci., 17, 5079–5096, https://doi.org/10.5194/hess-17-5079-2013, https://doi.org/10.5194/hess-17-5079-2013, 2013
A. McNally, C. Funk, G. J. Husak, J. Michaelsen, B. Cappelaere, J. Demarty, T. Pellarin, T. P. Young, K. K. Caylor, C. Riginos, and K. E. Veblen
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hessd-10-7963-2013, https://doi.org/10.5194/hessd-10-7963-2013, 2013
Revised manuscript not accepted
Related subject area
Subject: Biosphere Interactions | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Physics (physical properties and processes)
Dynamics of aerosol, humidity, and clouds in air masses travelling over Fennoscandian boreal forests
Residence times of air in a mature forest: observational evidence from a free-air CO2 enrichment experiment
Energy and mass exchange at an urban site in mountainous terrain – the Alpine city of Innsbruck
Observations of aerosol–vapor pressure deficit–evaporative fraction coupling over India
Biogeochemical and biophysical responses to episodes of wildfire smoke from natural ecosystems in southwestern British Columbia, Canada
Traces of urban forest in temperature and CO2 signals in monsoon East Asia
Technical note: Uncertainties in eddy covariance CO2 fluxes in a semiarid sagebrush ecosystem caused by gap-filling approaches
Simulating the spatiotemporal variations in aboveground biomass in Inner Mongolian grasslands under environmental changes
Concentrations and biosphere–atmosphere fluxes of inorganic trace gases and associated ionic aerosol counterparts over the Amazon rainforest
Characterization of the radiative impact of aerosols on CO2 and energy fluxes in the Amazon deforestation arch using artificial neural networks
New particle formation events observed at the King Sejong Station, Antarctic Peninsula – Part 2: Link with the oceanic biological activities
Vertical observations of the atmospheric boundary layer structure over Beijing urban area during air pollution episodes
Characterisation of short-term extreme methane fluxes related to non-turbulent mixing above an Arctic permafrost ecosystem
Characterization of ozone deposition to a mixed oak–hornbeam forest – flux measurements at five levels above and inside the canopy and their interactions with nitric oxide
Direct effect of aerosols on solar radiation and gross primary production in boreal and hemiboreal forests
The monsoon effect on energy and carbon exchange processes over a highland lake in the southwest of China
Turbulent transport of energy across a forest and a semiarid shrubland
Study of the daily and seasonal atmospheric CH4 mixing ratio variability in a rural Spanish region using 222Rn tracer
Nighttime wind and scalar variability within and above an Amazonian canopy
Estimating regional-scale methane flux and budgets using CARVE aircraft measurements over Alaska
Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest
Net ecosystem exchange and energy fluxes measured with the eddy covariance technique in a western Siberian bog
Biophysical effects on the interannual variation in carbon dioxide exchange of an alpine meadow on the Tibetan Plateau
Quantifying the contribution of land use change to surface temperature in the lower reaches of the Yangtze River
Overview of mercury dry deposition, litterfall, and throughfall studies
Scalar turbulent behavior in the roughness sublayer of an Amazonian forest
Surface–atmosphere exchange of ammonia over peatland using QCL-based eddy-covariance measurements and inferential modeling
Characterization of total ecosystem-scale biogenic VOC exchange at a Mediterranean oak–hornbeam forest
Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season
Step changes in persistent organic pollutants over the Arctic and their implications
Estimating surface fluxes using eddy covariance and numerical ogive optimization
Nitrous oxide emissions from a commercial cornfield (Zea mays) measured using the eddy covariance technique
Observations of the scale-dependent turbulence and evaluation of the flux–gradient relationship for sensible heat for a closed Douglas-fir canopy in very weak wind conditions
The effect of atmospheric aerosol particles and clouds on net ecosystem exchange in the Amazon
Acetaldehyde exchange above a managed temperate mountain grassland
The role of vegetation in the CO2 flux from a tropical urban neighbourhood
Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia
Four-year (2006–2009) eddy covariance measurements of CO2 flux over an urban area in Beijing
Momentum and scalar transport within a vegetation canopy following atmospheric stability and seasonal canopy changes: the CHATS experiment
Coupling processes and exchange of energy and reactive and non-reactive trace gases at a forest site – results of the EGER experiment
Abiotic and biotic control of methanol exchanges in a temperate mixed forest
Analysis of coherent structures and atmosphere-canopy coupling strength during the CABINEX field campaign
Methane flux, vertical gradient and mixing ratio measurements in a tropical forest
The effects of clouds and aerosols on net ecosystem CO2 exchange over semi-arid Loess Plateau of Northwest China
Size-dependent aerosol deposition velocities during BEARPEX'07
Day-time concentrations of biogenic volatile organic compounds in a boreal forest canopy and their relation to environmental and biological factors
Meri Räty, Larisa Sogacheva, Helmi-Marja Keskinen, Veli-Matti Kerminen, Tuomo Nieminen, Tuukka Petäjä, Ekaterina Ezhova, and Markku Kulmala
Atmos. Chem. Phys., 23, 3779–3798, https://doi.org/10.5194/acp-23-3779-2023, https://doi.org/10.5194/acp-23-3779-2023, 2023
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We utilised back trajectories to identify the source region of air masses arriving in Hyytiälä, Finland, and their travel time over forests. Combined with atmospheric observations, they revealed how air mass transport over the Fennoscandian boreal forest during the growing season produced an accumulation of cloud condensation nuclei and humidity, promoting cloudiness and precipitation. By 55 h of transport, air masses appeared to reach a balanced state with the forest environment.
Edward J. Bannister, Mike Jesson, Nicholas J. Harper, Kris M. Hart, Giulio Curioni, Xiaoming Cai, and A. Rob MacKenzie
Atmos. Chem. Phys., 23, 2145–2165, https://doi.org/10.5194/acp-23-2145-2023, https://doi.org/10.5194/acp-23-2145-2023, 2023
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In forests, the residence time of air influences canopy chemistry and atmospheric exchange. However, there have been few field observations. We use long-term open-air CO2 enrichment measurements to show median daytime residence times are twice as long when the trees are in leaf versus when they are not. Residence times increase with increasing atmospheric stability and scale inversely with turbulence. Robust parametrisations for large-scale models are available using common distributions.
Helen Claire Ward, Mathias Walter Rotach, Alexander Gohm, Martin Graus, Thomas Karl, Maren Haid, Lukas Umek, and Thomas Muschinski
Atmos. Chem. Phys., 22, 6559–6593, https://doi.org/10.5194/acp-22-6559-2022, https://doi.org/10.5194/acp-22-6559-2022, 2022
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This study examines how cities and their surroundings influence turbulent exchange processes responsible for weather and climate. Analysis of a 4-year observational dataset for the Alpine city of Innsbruck reveals several similarities with other (flat) city centre sites. However, the mountain setting leads to characteristic daily and seasonal flow patterns (valley winds) and downslope windstorms that have a marked effect on temperature, wind speed, turbulence and pollutant concentration.
Chandan Sarangi, TC Chakraborty, Sachchidanand Tripathi, Mithun Krishnan, Ross Morrison, Jonathan Evans, and Lina M. Mercado
Atmos. Chem. Phys., 22, 3615–3629, https://doi.org/10.5194/acp-22-3615-2022, https://doi.org/10.5194/acp-22-3615-2022, 2022
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Transpiration fluxes by vegetation are reduced under heat stress to conserve water. However, in situ observations over northern India show that the strength of the inverse association between transpiration and atmospheric vapor pressure deficit is weakening in the presence of heavy aerosol loading. This finding not only implicates the significant role of aerosols in modifying the evaporative fraction (EF) but also warrants an in-depth analysis of the aerosol–plant–temperature–EF continuum.
Sung-Ching Lee, Sara H. Knox, Ian McKendry, and T. Andrew Black
Atmos. Chem. Phys., 22, 2333–2349, https://doi.org/10.5194/acp-22-2333-2022, https://doi.org/10.5194/acp-22-2333-2022, 2022
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Wildfire smoke alters land–atmosphere exchange. Here, measurements in a forest and a wetland during four smoke episodes over four summers showed that impacts on radiation and heat budget were the greatest when smoke arrived in late summer. Both sites sequestered more CO2 under smoky days, partly due to diffuse light, but emitted CO2 when smoke was dense. This kind of field study is important for validating predictions of smoke–productivity feedbacks and has climate change implications.
Keunmin Lee, Je-Woo Hong, Jeongwon Kim, Sungsoo Jo, and Jinkyu Hong
Atmos. Chem. Phys., 21, 17833–17853, https://doi.org/10.5194/acp-21-17833-2021, https://doi.org/10.5194/acp-21-17833-2021, 2021
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This study examine two benefits of urban forest, thermal mitigation and carbon uptake. Our analysis indicates that the urban forest reduces both the warming trend and urban heat island intensity. Urban forest is a net CO2 source despite larger photosynthetic carbon uptake because of strong contribution of ecosystem respiration, which can be attributed to the substantial amount of soil organic carbon by intensive historical soil use and warm temperature in a city.
Jingyu Yao, Zhongming Gao, Jianping Huang, Heping Liu, and Guoyin Wang
Atmos. Chem. Phys., 21, 15589–15603, https://doi.org/10.5194/acp-21-15589-2021, https://doi.org/10.5194/acp-21-15589-2021, 2021
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Gap-filling usually accounts for a large source of uncertainties in the annual CO2 fluxes, though gap-filling CO2 fluxes is challenging at dryland sites due to small fluxes. Using data collected from a semiarid site, four machine learning methods are evaluated with different lengths of artificial gaps. The artificial neural network and random forest methods outperform the other methods. With these methods, uncertainties in the annual CO2 flux at this site are estimated to be within 16 g C m−2.
Guocheng Wang, Zhongkui Luo, Yao Huang, Wenjuan Sun, Yurong Wei, Liujun Xiao, Xi Deng, Jinhuan Zhu, Tingting Li, and Wen Zhang
Atmos. Chem. Phys., 21, 3059–3071, https://doi.org/10.5194/acp-21-3059-2021, https://doi.org/10.5194/acp-21-3059-2021, 2021
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We simulate the spatiotemporal dynamics of aboveground biomass (AGB) in Inner Mongolian grasslands using a machine-learning-based approach. Under climate change, on average, compared with the historical AGB (average of 1981–2019), the AGB at the end of this century (average of 2080–2100) would decrease by 14 % under RCP4.5 and 28 % under RCP8.5. The decrease in AGB might be mitigated or even reversed by positive carbon dioxide enrichment effects on plant growth.
Robbie Ramsay, Chiara F. Di Marco, Matthias Sörgel, Mathew R. Heal, Samara Carbone, Paulo Artaxo, Alessandro C. de Araùjo, Marta Sá, Christopher Pöhlker, Jost Lavric, Meinrat O. Andreae, and Eiko Nemitz
Atmos. Chem. Phys., 20, 15551–15584, https://doi.org/10.5194/acp-20-15551-2020, https://doi.org/10.5194/acp-20-15551-2020, 2020
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The Amazon rainforest is a unique
laboratoryto study the processes which govern the exchange of gases and aerosols to and from the atmosphere. This study investigated these processes by measuring the atmospheric concentrations of trace gases and particles at the Amazon Tall Tower Observatory. We found that the long-range transport of pollutants can affect the atmospheric composition above the Amazon rainforest and that the gases ammonia and nitrous acid can be emitted from the rainforest.
Renato Kerches Braghiere, Marcia Akemi Yamasoe, Nilton Manuel Évora do Rosário, Humberto Ribeiro da Rocha, José de Souza Nogueira, and Alessandro Carioca de Araújo
Atmos. Chem. Phys., 20, 3439–3458, https://doi.org/10.5194/acp-20-3439-2020, https://doi.org/10.5194/acp-20-3439-2020, 2020
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We evaluate how the interaction of smoke with sun light impacts the exchange of energy and mass between vegetation and the atmosphere using a machine learning technique. We found an effect of the smoke on CO2, energy, and water fluxes, linking the effects of smoke with temperature, humidity, and winds. CO2 exchange increased by up to 55 % in the presence of smoke. A decrease of 12 % was observed for a site with simpler vegetation. Energy fluxes were negatively impacted for all study sites.
Eunho Jang, Ki-Tae Park, Young Jun Yoon, Tae-Wook Kim, Sang-Bum Hong, Silvia Becagli, Rita Traversi, Jaeseok Kim, and Yeontae Gim
Atmos. Chem. Phys., 19, 7595–7608, https://doi.org/10.5194/acp-19-7595-2019, https://doi.org/10.5194/acp-19-7595-2019, 2019
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We reported long-term observations (from 2009 to 2016) of the nanoparticles measured at the Antarctic Peninsula (62.2° S, 58.8° W), and satellite-derived estimates of the biological characteristics were analyzed to identify the link between new particle formation and marine biota. The key finding from this research is that the formation of nanoparticles was strongly associated not only with the biomass of phytoplankton but, more importantly, also its taxonomic composition in the Antarctic Ocean.
Linlin Wang, Junkai Liu, Zhiqiu Gao, Yubin Li, Meng Huang, Sihui Fan, Xiaoye Zhang, Yuanjian Yang, Shiguang Miao, Han Zou, Yele Sun, Yong Chen, and Ting Yang
Atmos. Chem. Phys., 19, 6949–6967, https://doi.org/10.5194/acp-19-6949-2019, https://doi.org/10.5194/acp-19-6949-2019, 2019
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Urban boundary layer (UBL) affects the physical and chemical processes of the pollutants, and UBL structure can also be altered by pollutants. This paper presents the interactions between air pollution and the UBL structure by using the field data mainly collected from a 325 m meteorology tower, as well as from a Doppler wind lidar, during a severe heavy pollution event that occurred during 1–4 December 2016 in Beijing.
Carsten Schaller, Fanny Kittler, Thomas Foken, and Mathias Göckede
Atmos. Chem. Phys., 19, 4041–4059, https://doi.org/10.5194/acp-19-4041-2019, https://doi.org/10.5194/acp-19-4041-2019, 2019
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Methane emissions from biogenic sources, e.g. Arctic permafrost ecosystems, are associated with uncertainties due to the high variability of fluxes in both space and time. Besides the traditional eddy covariance method, we evaluated a method based on wavelet analysis, which does not require a stationary time series, to calculate fluxes. The occurrence of extreme methane flux events was strongly correlated with the soil temperature. They were triggered by atmospheric non-turbulent mixing.
Angelo Finco, Mhairi Coyle, Eiko Nemitz, Riccardo Marzuoli, Maria Chiesa, Benjamin Loubet, Silvano Fares, Eugenio Diaz-Pines, Rainer Gasche, and Giacomo Gerosa
Atmos. Chem. Phys., 18, 17945–17961, https://doi.org/10.5194/acp-18-17945-2018, https://doi.org/10.5194/acp-18-17945-2018, 2018
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A 1-month field campaign of ozone (O3) flux measurements along a five-level vertical profile of a mature broadleaf forest highlighted that the biosphere–atmosphere exchange of this pollutant is modulated by complex diel dynamics occurring within and below the canopy. The canopy removed nearly 80 % of the O3 deposited to the forest; only a minor part was removed by the soil and the understorey (2 %), while the remaining 18.2 % was removed by chemical reactions with NO mostly emitted from soil.
Ekaterina Ezhova, Ilona Ylivinkka, Joel Kuusk, Kaupo Komsaare, Marko Vana, Alisa Krasnova, Steffen Noe, Mikhail Arshinov, Boris Belan, Sung-Bin Park, Jošt Valentin Lavrič, Martin Heimann, Tuukka Petäjä, Timo Vesala, Ivan Mammarella, Pasi Kolari, Jaana Bäck, Üllar Rannik, Veli-Matti Kerminen, and Markku Kulmala
Atmos. Chem. Phys., 18, 17863–17881, https://doi.org/10.5194/acp-18-17863-2018, https://doi.org/10.5194/acp-18-17863-2018, 2018
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Understanding the connections between aerosols, solar radiation and photosynthesis in terrestrial ecosystems is important for estimates of the CO2 balance in the atmosphere. Atmospheric aerosols and clouds influence solar radiation. In this study, we quantify the aerosol effect on solar radiation in boreal forests and study forest ecosystems response to this change in the radiation conditions. The analysis is based on atmospheric observations from several remote stations in Eurasian forests.
Qun Du, Huizhi Liu, Lujun Xu, Yang Liu, and Lei Wang
Atmos. Chem. Phys., 18, 15087–15104, https://doi.org/10.5194/acp-18-15087-2018, https://doi.org/10.5194/acp-18-15087-2018, 2018
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Erhai Lake is a subtropical highland shallow lake on the southeast margin of the Tibetan Plateau, which is influenced by both South Asian and East Asian summer monsoons. The substantial difference in atmospheric properties during monsoon and non-monsoon periods has a large effect in regulating turbulent heat and carbon dioxide exchange processes over Erhai Lake. Large difference are found for the factors controlling sensible heat and carbon dioxide flux during monsoon and non-monsoon periods.
Tirtha Banerjee, Peter Brugger, Frederik De Roo, Konstantin Kröniger, Dan Yakir, Eyal Rotenberg, and Matthias Mauder
Atmos. Chem. Phys., 18, 10025–10038, https://doi.org/10.5194/acp-18-10025-2018, https://doi.org/10.5194/acp-18-10025-2018, 2018
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We studied the nature of turbulent transport over a well-defined surface heterogeneity (approximate scale 7 km) comprising a shrubland and a forest in the Yatir semiarid area in Israel. Using eddy covariance and Doppler lidar measurements, we studied the variations in the turbulent kinetic energy budget and turbulent fluxes, focusing especially on transport terms. We also confirmed the role of large-scale secondary circulations that transport energy between the shrubland and the forest.
Claudia Grossi, Felix R. Vogel, Roger Curcoll, Alba Àgueda, Arturo Vargas, Xavier Rodó, and Josep-Anton Morguí
Atmos. Chem. Phys., 18, 5847–5860, https://doi.org/10.5194/acp-18-5847-2018, https://doi.org/10.5194/acp-18-5847-2018, 2018
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To gain a full picture of the Spanish (and European) GHG balance, understanding of CH4 emissions in different regions is a critical challenge, as is the improvement of bottom-up inventories for all European regions. This study uses, among other elements, GHG, meteorological and 222Rn tracer data from a Spanish region to understand the main causes of temporal variability of GHG mixing ratios. The study can offer new insights into regional emissions by identifying the impacts of changing sources.
Pablo E. S. Oliveira, Otávio C. Acevedo, Matthias Sörgel, Anywhere Tsokankunku, Stefan Wolff, Alessandro C. Araújo, Rodrigo A. F. Souza, Marta O. Sá, Antônio O. Manzi, and Meinrat O. Andreae
Atmos. Chem. Phys., 18, 3083–3099, https://doi.org/10.5194/acp-18-3083-2018, https://doi.org/10.5194/acp-18-3083-2018, 2018
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Carbon dioxide and latent heat fluxes within the canopy are dominated by low-frequency (nonturbulent) processes. There is a striking contrast between fully turbulent and intermittent nights, such that turbulent processes dominate the total nighttime exchange during the former, while nonturbulent processes are more relevant in the latter. In very stable nights, during which intermittent exchange prevails, the stable boundary layer may be shallower than the highest observational level at 80 m.
Sean Hartery, Róisín Commane, Jakob Lindaas, Colm Sweeney, John Henderson, Marikate Mountain, Nicholas Steiner, Kyle McDonald, Steven J. Dinardo, Charles E. Miller, Steven C. Wofsy, and Rachel Y.-W. Chang
Atmos. Chem. Phys., 18, 185–202, https://doi.org/10.5194/acp-18-185-2018, https://doi.org/10.5194/acp-18-185-2018, 2018
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Methane is the second most important greenhouse gas but its emissions from northern regions are still poorly constrained. This study uses aircraft measurements of methane from Alaska to estimate surface emissions. We found that methane emission rates depend on the soil temperature at depths where its production was taking place, and that total emissions were similar between tundra and boreal regions. These results provide a simple way to predict methane emissions in this region.
Linda M. J. Kooijmans, Kadmiel Maseyk, Ulli Seibt, Wu Sun, Timo Vesala, Ivan Mammarella, Pasi Kolari, Juho Aalto, Alessandro Franchin, Roberta Vecchi, Gianluigi Valli, and Huilin Chen
Atmos. Chem. Phys., 17, 11453–11465, https://doi.org/10.5194/acp-17-11453-2017, https://doi.org/10.5194/acp-17-11453-2017, 2017
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Carbon cycle studies rely on the accuracy of models to estimate the amount of CO2 being taken up by vegetation. The gas carbonyl sulfide (COS) can serve as a tool to estimate the vegetative CO2 uptake by scaling the ecosystem uptake of COS to that of CO2. Here we investigate the nighttime fluxes of COS. The relationships found in this study will aid in implementing nighttime COS uptake in models, which is key to obtain accurate estimates of vegetative CO2 uptake with the use of COS.
Pavel Alekseychik, Ivan Mammarella, Dmitry Karpov, Sigrid Dengel, Irina Terentieva, Alexander Sabrekov, Mikhail Glagolev, and Elena Lapshina
Atmos. Chem. Phys., 17, 9333–9345, https://doi.org/10.5194/acp-17-9333-2017, https://doi.org/10.5194/acp-17-9333-2017, 2017
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West Siberian peatlands occupy a large fraction of land area in the region, and yet little is known about their interaction with the atmosphere. We took the first measurements of CO2 and energy surface balances over a typical bog of West Siberian middle taiga, in the vicinity of the Mukhrino field station (Khanty–Mansiysk). The May–August study in a wet year (2015) revealed a relatively large photosynthetic sink of CO2 that was close to the high end of estimates at bog sites elsewhere.
Lei Wang, Huizhi Liu, Jihua Sun, and Yaping Shao
Atmos. Chem. Phys., 17, 5119–5129, https://doi.org/10.5194/acp-17-5119-2017, https://doi.org/10.5194/acp-17-5119-2017, 2017
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This study found that the seasonal variation in CO2 exchange over an alpine meadow on the Tibetan Plateau was primarily affected by the seasonal pattern of air temperature, especially in spring and autumn. The annual net ecosystem exchange decreased with mean annual temperature, and then increased when the gross primary production became saturated. This study contributes to the response of the alpine meadow ecosystem to global warming.
Xueqian Wang, Weidong Guo, Bo Qiu, Ye Liu, Jianning Sun, and Aijun Ding
Atmos. Chem. Phys., 17, 4989–4996, https://doi.org/10.5194/acp-17-4989-2017, https://doi.org/10.5194/acp-17-4989-2017, 2017
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Land use or cover change is a fundamental anthropogenic forcing for climate change. Based on field observations, we quantified the contributions of different factors to surface temperature change and deepened the understanding of its mechanisms. We found evaporative cooling plays the most important role in the temperature change, while radiative forcing, which is traditionally emphasized, is not significant. This study provided firsthand evidence to verify the model results in IPCC AR5.
L. Paige Wright, Leiming Zhang, and Frank J. Marsik
Atmos. Chem. Phys., 16, 13399–13416, https://doi.org/10.5194/acp-16-13399-2016, https://doi.org/10.5194/acp-16-13399-2016, 2016
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The current knowledge concerning mercury dry deposition is reviewed, including dry deposition algorithms used in chemical transport models and at monitoring sites, measurement methods and studies for quantifying dry deposition of oxidized mercury, and measurement studies of litterfall and throughfall mercury. Over all the regions, dry deposition, estimated as the sum of litterfall and throughfall minus open-field wet deposition, is more dominant than wet deposition for Hg deposition.
Einara Zahn, Nelson L. Dias, Alessandro Araújo, Leonardo D. A. Sá, Matthias Sörgel, Ivonne Trebs, Stefan Wolff, and Antônio Manzi
Atmos. Chem. Phys., 16, 11349–11366, https://doi.org/10.5194/acp-16-11349-2016, https://doi.org/10.5194/acp-16-11349-2016, 2016
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Preliminary data from the ATTO project were analyzed to characterize the exchange of heat, water vapor, and CO2 between the Amazon forest and the atmosphere. The forest roughness makes estimation of their fluxes difficult, and even measurements at 42 m above the canopy show a lot of scatter. Still, measurements made around noon showed much better conformity with standard theories for the exchange of these quantities, opening the possibility of good flux estimates when the sun is high.
Undine Zöll, Christian Brümmer, Frederik Schrader, Christof Ammann, Andreas Ibrom, Christophe R. Flechard, David D. Nelson, Mark Zahniser, and Werner L. Kutsch
Atmos. Chem. Phys., 16, 11283–11299, https://doi.org/10.5194/acp-16-11283-2016, https://doi.org/10.5194/acp-16-11283-2016, 2016
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Accurate quantification of atmospheric ammonia concentration and exchange fluxes with the land surface has been a major metrological challenge. We demonstrate the applicability of a novel laser device to identify concentration and flux patterns over a peatland ecosystem influenced by nearby agricultural practices. Results help to strengthen air quality monitoring networks, lead to better understanding of ecosystem functionality and improve parameterizations in air chemistry and transport models.
Simon Schallhart, Pekka Rantala, Eiko Nemitz, Ditte Taipale, Ralf Tillmann, Thomas F. Mentel, Benjamin Loubet, Giacomo Gerosa, Angelo Finco, Janne Rinne, and Taina M. Ruuskanen
Atmos. Chem. Phys., 16, 7171–7194, https://doi.org/10.5194/acp-16-7171-2016, https://doi.org/10.5194/acp-16-7171-2016, 2016
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We present ecosystem exchange fluxes from a mixed oak–hornbeam forest in the Po Valley, Italy. Detectable fluxes were observed for 29 compounds, dominated by isoprene, which comprised over 60 % of the upward flux. Methanol seemed to be deposited to dew, as the deposition happened in the early morning. We estimated that up to 30 % of the upward flux of methyl vinyl ketone and methacrolein originated from atmospheric oxidation of isoprene.
Aurélie Bachy, Marc Aubinet, Niels Schoon, Crist Amelynck, Bernard Bodson, Christine Moureaux, and Bernard Heinesch
Atmos. Chem. Phys., 16, 5343–5356, https://doi.org/10.5194/acp-16-5343-2016, https://doi.org/10.5194/acp-16-5343-2016, 2016
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This research focuses on Biogenic Volatile Organic Compounds (BVOC) exchanges between a maize field and the atmosphere. Indeed, few BVOC studies have already investigated agricultural ecosystems. We found that the maize field emitted mainly methanol, that both soil and plants contributed to the net exchange, that exchanges were lower than in other studies and than considered by models. Our work tends thus to lower the impact of maize on terrestrial BVOC exchanges.
Y. Zhao, T. Huang, L. Wang, H. Gao, and J. Ma
Atmos. Chem. Phys., 15, 3479–3495, https://doi.org/10.5194/acp-15-3479-2015, https://doi.org/10.5194/acp-15-3479-2015, 2015
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After several decades of declining persistent organic pollutants in the arctic environment due to their global use restriction, some of these toxic chemicals increased in the mid-2000s and undertook statistically significant step changes which coincided with arctic sea ice melting. Results provide statistical evidence for the releasing of toxic chemicals from their reservoirs in the Arctic due to the rapid change in the arctic environment.
J. Sievers, T. Papakyriakou, S. E. Larsen, M. M. Jammet, S. Rysgaard, M. K. Sejr, and L. L. Sørensen
Atmos. Chem. Phys., 15, 2081–2103, https://doi.org/10.5194/acp-15-2081-2015, https://doi.org/10.5194/acp-15-2081-2015, 2015
H. Huang, J. Wang, D. Hui, D. R. Miller, S. Bhattarai, S. Dennis, D. Smart, T. Sammis, and K. C. Reddy
Atmos. Chem. Phys., 14, 12839–12854, https://doi.org/10.5194/acp-14-12839-2014, https://doi.org/10.5194/acp-14-12839-2014, 2014
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An EC system was assembled with a sonic anemometer and a new fast-response N2O analyzer and applied in a cornfield during a growing season. This N2O EC system provided reliable N2O flux measurements. The average flux was about 63% higher during the daytime than during the nighttime. Seasonal fluxes were highly dependent on soil moisture rather than soil temperature.
D. Vickers and C. K. Thomas
Atmos. Chem. Phys., 14, 9665–9676, https://doi.org/10.5194/acp-14-9665-2014, https://doi.org/10.5194/acp-14-9665-2014, 2014
G. G. Cirino, R. A. F. Souza, D. K. Adams, and P. Artaxo
Atmos. Chem. Phys., 14, 6523–6543, https://doi.org/10.5194/acp-14-6523-2014, https://doi.org/10.5194/acp-14-6523-2014, 2014
L. Hörtnagl, I. Bamberger, M. Graus, T. M. Ruuskanen, R. Schnitzhofer, M. Walser, A. Unterberger, A. Hansel, and G. Wohlfahrt
Atmos. Chem. Phys., 14, 5369–5391, https://doi.org/10.5194/acp-14-5369-2014, https://doi.org/10.5194/acp-14-5369-2014, 2014
E. Velasco, M. Roth, S. H. Tan, M. Quak, S. D. A. Nabarro, and L. Norford
Atmos. Chem. Phys., 13, 10185–10202, https://doi.org/10.5194/acp-13-10185-2013, https://doi.org/10.5194/acp-13-10185-2013, 2013
G. C. Edwards and D. A. Howard
Atmos. Chem. Phys., 13, 5325–5336, https://doi.org/10.5194/acp-13-5325-2013, https://doi.org/10.5194/acp-13-5325-2013, 2013
H. Z. Liu, J. W. Feng, L. Järvi, and T. Vesala
Atmos. Chem. Phys., 12, 7881–7892, https://doi.org/10.5194/acp-12-7881-2012, https://doi.org/10.5194/acp-12-7881-2012, 2012
S. Dupont and E. G. Patton
Atmos. Chem. Phys., 12, 5913–5935, https://doi.org/10.5194/acp-12-5913-2012, https://doi.org/10.5194/acp-12-5913-2012, 2012
T. Foken, F. X. Meixner, E. Falge, C. Zetzsch, A. Serafimovich, A. Bargsten, T. Behrendt, T. Biermann, C. Breuninger, S. Dix, T. Gerken, M. Hunner, L. Lehmann-Pape, K. Hens, G. Jocher, J. Kesselmeier, J. Lüers, J.-C. Mayer, A. Moravek, D. Plake, M. Riederer, F. Rütz, M. Scheibe, L. Siebicke, M. Sörgel, K. Staudt, I. Trebs, A. Tsokankunku, M. Welling, V. Wolff, and Z. Zhu
Atmos. Chem. Phys., 12, 1923–1950, https://doi.org/10.5194/acp-12-1923-2012, https://doi.org/10.5194/acp-12-1923-2012, 2012
Q. Laffineur, M. Aubinet, N. Schoon, C. Amelynck, J.-F. Müller, J. Dewulf, H. Van Langenhove, K. Steppe, and B. Heinesch
Atmos. Chem. Phys., 12, 577–590, https://doi.org/10.5194/acp-12-577-2012, https://doi.org/10.5194/acp-12-577-2012, 2012
A. L. Steiner, S. N. Pressley, A. Botros, E. Jones, S. H. Chung, and S. L. Edburg
Atmos. Chem. Phys., 11, 11921–11936, https://doi.org/10.5194/acp-11-11921-2011, https://doi.org/10.5194/acp-11-11921-2011, 2011
C. A. S. Querino, C. J. P. P. Smeets, I. Vigano, R. Holzinger, V. Moura, L. V. Gatti, A. Martinewski, A. O. Manzi, A. C. de Araújo, and T. Röckmann
Atmos. Chem. Phys., 11, 7943–7953, https://doi.org/10.5194/acp-11-7943-2011, https://doi.org/10.5194/acp-11-7943-2011, 2011
X. Jing, J. Huang, G. Wang, K. Higuchi, J. Bi, Y. Sun, H. Yu, and T. Wang
Atmos. Chem. Phys., 10, 8205–8218, https://doi.org/10.5194/acp-10-8205-2010, https://doi.org/10.5194/acp-10-8205-2010, 2010
R. J. Vong, I. J. Vong, D. Vickers, and D. S. Covert
Atmos. Chem. Phys., 10, 5749–5758, https://doi.org/10.5194/acp-10-5749-2010, https://doi.org/10.5194/acp-10-5749-2010, 2010
H. K. Lappalainen, S. Sevanto, J. Bäck, T. M. Ruuskanen, P. Kolari, R. Taipale, J. Rinne, M. Kulmala, and P. Hari
Atmos. Chem. Phys., 9, 5447–5459, https://doi.org/10.5194/acp-9-5447-2009, https://doi.org/10.5194/acp-9-5447-2009, 2009
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