Articles | Volume 36, issue 2
https://doi.org/10.5194/angeo-36-301-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Special issue:
https://doi.org/10.5194/angeo-36-301-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Regular paper
| 
05 Mar 2018
Regular paper |
| 05 Mar 2018
| 05 Mar 2018
Mesopause region temperature variability and its trend in southern Brazil
Mateus S. Venturini
CORRESPONDING AUTHOR
Aerospace Engineering, Federal University of Santa Maria, Av. Roraima,
Santa Maria, Brazil
José V. Bageston
Southern Regional Space Research Center, National Institute for Space
Research, Av. Roraima, Santa Maria, Brazil
Nattan R. Caetano
Aerospace Engineering, Federal University of Santa Maria, Av. Roraima,
Santa Maria, Brazil
Lucas V. Peres
Federal University of Western Pará, Rua Vera Paz, Santarém,
Pará, Brazil
Hassan Bencherif
Université de La Réunion, LACy, UMR 8105, Réunion Island,
France
Nelson J. Schuch
Southern Regional Space Research Center, National Institute for Space
Research, Av. Roraima, Santa Maria, Brazil
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Gabriela Dornelles Bittencourt, Hassan Bencherif, Damaris Kirsch Pinheiro, Nelson Begue, Lucas Vaz Peres, José Valentin Bageston, Douglas Lima de Bem, Francisco Raimundo da Silva, and Tristan Millet
Atmos. Meas. Tech., 17, 5201–5220, https://doi.org/10.5194/amt-17-5201-2024, https://doi.org/10.5194/amt-17-5201-2024, 2024
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The study examines the behavior of ozone at equatorial and subtropical latitudes in South America, in a multi-instrumental analysis. The methodology applied used ozonesondes (SHADOZ/NASA) and satellite data (TIMED/SABER), as well as analysis with ground-based and satellite instruments, allowing a more in-depth study at both latitudes. The main motivation is to understand how latitudinal differences in the observation of ozone content can interfere with the behavior of this trace gas.
Tristan Millet, Hassan Bencherif, Thierry Portafaix, Nelson Bègue, Alexandre Baron, Valentin Duflot, Cathy Clerbaux, Pierre-François Coheur, Andrea Pazmino, Michaël Sicard, Jean-Marc Metzger, Guillaume Payen, Nicolas Marquestaut, and Sophie Godin-Beekmann
EGUsphere, https://doi.org/10.5194/egusphere-2024-2350, https://doi.org/10.5194/egusphere-2024-2350, 2024
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On 15 January 2022, the Hunga volcano erupted, releasing aerosols, sulfur dioxide, and water vapor into the stratosphere, impacting ozone levels over the Indian Ocean. MLS and IASI data show that the volcanic plume decreased ozone levels within the stratospheric ozone layer, shaping a structure similar to an ozone mini-hole. A stable stratosphere, free of dynamical barriers, enabled the volcanic plume's transport over the Indian Ocean.
Nelson Bègue, Alexandre Baron, Gisèle Krysztofiak, Gwenaël Berthet, Corinna Kloss, Fabrice Jégou, Sergey Khaykin, Marion Ranaivombola, Tristan Millet, Thierry Portafaix, Valentin Duflot, Philippe Keckhut, Hélène Vérèmes, Guillaume Payen, Mahesh Kumar Sha, Pierre-François Coheur, Cathy Clerbaux, Michaël Sicard, Tetsu Sakai, Richard Querel, Ben Liley, Dan Smale, Isamu Morino, Osamu Uchino, Tomohiro Nagai, Penny Smale, John Robinson, and Hassan Bencherif
Atmos. Chem. Phys., 24, 8031–8048, https://doi.org/10.5194/acp-24-8031-2024, https://doi.org/10.5194/acp-24-8031-2024, 2024
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During the 2020 austral summer, the pristine atmosphere of the southwest Indian Ocean basin experienced significant perturbations. Numerical models indicated that the lower-stratospheric aerosol content was influenced by the intense and persistent stratospheric aerosol layer generated during the 2019–2020 extreme Australian bushfire events. Ground-based observations at Réunion confirmed the simultaneous presence of African and Australian aerosol layers.
Jean-Marcel Rivonirina, Thierry Portafaix, Solofoarisoa Rakotoniaina, Béatrice Morel, Chao Tang, Kévin Lamy, Marie Lothon, Tom Toulouse, Olivier Liandrat, Solofo Rakotondraompiana, and Hassan Bencherif
EGUsphere, https://doi.org/10.5194/egusphere-2024-1827, https://doi.org/10.5194/egusphere-2024-1827, 2024
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The lack of ground observation instruments and the vast ocean coverage make the Southwest Indian Ocean (SWIO) region difficult to access and poorly studied. For gathering ground-based camera information, satellite measurements have been used with the primary goal of characterizing both sites Saint-Denis of Reunion Island and Antananarivo Madagascar in terms of cloudiness. This study shows the particularity of each site and enhances our understanding of cloud properties, particularly in the SWIO.
Michael Sicard, Alexandre Baron, Marion Ranaivombola, Dominique Gantois, Tristan Millet, Pasquale Sellitto, Nelson Bègue, Hassan Bencherif, Guillaume Payen, Nicolas Marquestaut, and Valentin Duflot
EGUsphere, https://doi.org/10.22541/essoar.170231679.99186200/v1, https://doi.org/10.22541/essoar.170231679.99186200/v1, 2024
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This study quantifies the radiative impact over Reunion Island (21° S, 55° E) of the aerosols and water vapor injected in the stratosphere by the Hunga Tonga-Hunga Ha'apai volcano in the South Pacific. The overall aerosol and water vapor impact on the Earth’s radiation budget for the whole period is negative (cooling, -0.54 ± 0.29 W m-2) and dominated by the aerosols. At the Earth’s surface, aerosols are the main driver and produce a negative (cooling, -1.19 ± 0.40 W m-2) radiative impact.
Marion Ranaivombola, Nelson Bègue, Farahnaz Fazel-Rastgar, Venkataraman Sivakumar, Gisèle Krysztofiak, Gwenaël Berthet, Fabrice Jegou, Stuart Piketh, and Hassan Bencherif
EGUsphere, https://doi.org/10.5194/egusphere-2024-921, https://doi.org/10.5194/egusphere-2024-921, 2024
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From September to October 2022, the Biomass Burning Aerosol Campaign (BiBAC) in Kruger National Park revealed a significant aerosol loading linked to biomass burning activity, with a southeastward transport over Southern Africa and the southwestern of Indian Ocean (SWIO) basin. The "river of smoke" phenomenon drove the plume during September toward the SWIO. One discusses the long-range transport of biomass burning from South America to Southern Africa is likely driven by climate forcings.
Tristan Millet, Hassan Bencherif, Thierry Portafaix, Nelson Bègue, Alexandre Baron, Valentin Duflot, Michaël Sicard, Jean-Marc Metzger, Guillaume Payen, Nicolas Marquestaut, and Sophie Godin-Beekmann
EGUsphere, https://doi.org/10.5194/egusphere-2023-2645, https://doi.org/10.5194/egusphere-2023-2645, 2023
Preprint withdrawn
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The eruption of the Hunga Tonga volcano in January 2022 released substantial amounts of aerosols, sulfur dioxide, and water vapor into the stratosphere. Satellite and ground instruments followed the displacement of the volcanic aerosol plume and its impact on ozone levels over the Indian Ocean. Ozone data reveal the presence of a persistent ozone mini-hole structure from 17 January to 22 January, with most ozone depletion occurring within the ozone layer at the location of the aerosol plume.
Bibiana Lopes, Damaris Kirsch Pinheiro, Hassan Bencherif, Gabriela Dornelles Bittencourt, Lucas Vaz Peres, Jean-Maurice Cadet, Thierry Portafaix, and Nathalie Tissot Boiaski
EGUsphere, https://doi.org/10.5194/egusphere-2023-1474, https://doi.org/10.5194/egusphere-2023-1474, 2023
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This is a study of the climatology and behavior of UV radiation on the surface during events of secondary effects of the Antarctic ozone hole over south of Brazil. Considering all implications of excess exposure to UV radiation on the surface on human health it is important to know how much radiation the population is being exposed to during those events. Results showed that for each 1 % decrease in the ozone total column, the UV index tends to increase by 4 % in the region of study.
Gabriela Dornelles Bittencourt, Damaris Kirsch Pinheiro, Hassan Bencherif, Lucas Vaz Peres, Nelson Begue, José Valentin Bageston, Douglas Lima de Bem, Vagner Anabor, and Luiz Angelo Steffenel
EGUsphere, https://doi.org/10.5194/egusphere-2023-1471, https://doi.org/10.5194/egusphere-2023-1471, 2023
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The study examines ozone depletions at mid-latitudes in Brazil during austral spring Antarctic Ozone Hole influence events. The methodology applied used data from the total column ozone, vertical profile of the atmosphere, and reanalysis data to analyze the atmospheric dynamics. The main motivation of this work is to show how this important trace gas dynamically behaves in the atmosphere in the active period of the Antarctic Ozone Hole in regions of medium latitudes.
Prosper K. Nyassor, Cristiano M. Wrasse, Igo Paulino, Eliah F. M. T. São Sabbas, José V. Bageston, Kleber P. Naccarato, Delano Gobbi, Cosme A. O. B. Figueiredo, Toyese T. Ayorinde, Hisao Takahashi, and Diego Barros
Atmos. Chem. Phys., 22, 15153–15177, https://doi.org/10.5194/acp-22-15153-2022, https://doi.org/10.5194/acp-22-15153-2022, 2022
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This work investigates the sources of concentric gravity waves (CGWs) excited by a moving system of clouds with several overshooting regions on 1–2 October 2019 at São Martinho da Serra. The parameters of these waves were estimated using 2D spectral analysis and their source locations identified using backward ray tracing. Furthermore, the sources of these waves were properly identified by tracking the individual overshooting regions in space and time since the system of clouds was moving.
Olivier Delage, Thierry Portafaix, Hassan Bencherif, Alain Bourdier, and Emma Lagracie
Nonlin. Processes Geophys., 29, 265–277, https://doi.org/10.5194/npg-29-265-2022, https://doi.org/10.5194/npg-29-265-2022, 2022
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The complexity of geophysics systems results in time series with fluctuations at all timescales. The analysis of their variability then consists in decomposing them into a set of basis signals. We developed here a new adaptive filtering method called empirical adaptive wavelet decomposition that optimizes the empirical-mode decomposition existing technique, overcoming its drawbacks using the rigour of wavelets as defined in the recently published empirical wavelet transform method.
Juliano Moro, Jiyao Xu, Clezio Marcos Denardini, Laysa Cristina Araújo Resende, Régia Pereira Silva, Sony Su Chen, Giorgio Arlan da Silva Picanço, Liu Zhengkuan, Hui Li, Chunxiao Yan, Chi Wang, and Nelson Jorge Schuch
Ann. Geophys., 38, 457–466, https://doi.org/10.5194/angeo-38-457-2020, https://doi.org/10.5194/angeo-38-457-2020, 2020
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The monthly averages of the F2 critical frequency (foF2), its peak height (hmF2), and the E-region critical frequency (foE) acquired by the DPS4-D installed in Santa Maria, Brazil, is compared to the International Reference Ionosphere (IRI-2016) model predictions. It is important to test the performance of the IRI over Santa Maria because it is located in the SAMA, which is a region particularly important for high-frequency (HF) ground-to-satellite navigation signals.
Nelson Bègue, Lerato Shikwambana, Hassan Bencherif, Juan Pallotta, Venkataraman Sivakumar, Elian Wolfram, Nkanyiso Mbatha, Facundo Orte, David Jean Du Preez, Marion Ranaivombola, Stuart Piketh, and Paola Formenti
Ann. Geophys., 38, 395–420, https://doi.org/10.5194/angeo-38-395-2020, https://doi.org/10.5194/angeo-38-395-2020, 2020
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This study investigates the influence of the 2015 Calbuco eruption (41.2°S, 72.4°W; Chile) on the total columnar aerosol optical properties in the Southern Hemisphere. The well-known technique of sun photometry was applied to the investigation of the transport and the spatio-temporal evolution of the optical properties of the volcanic plume. The CIMEL sun photometer measurements performed over six South American and three African sites were statistically analyzed.
Emilia Correia, Luis Tiago Medeiros Raunheitte, José Valentin Bageston, and Dino Enrico D'Amico
Ann. Geophys., 38, 385–394, https://doi.org/10.5194/angeo-38-385-2020, https://doi.org/10.5194/angeo-38-385-2020, 2020
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Here the investigation of gravity wave (GW) properties in the low ionosphere using very low frequency (VLF) radio signals is presented. The VLF technique is a powerful tool to obtain the wave period and duration of GW events in the low ionosphere. It can be used independent of sky conditions, during daytime and year-round, which is an advantage in comparison with airglow all-sky imagers.
Gabriela Dornelles Bittencourt, Damaris Kirsch Pinheiro, José Valentin Bageston, Hassan Bencherif, Luis Angelo Steffenel, and Lucas Vaz Peres
Ann. Geophys., 37, 1049–1061, https://doi.org/10.5194/angeo-37-1049-2019, https://doi.org/10.5194/angeo-37-1049-2019, 2019
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The Antarctic ozone hole (AOH) directly influences the Antarctic region, where its levels can reach values below 220 DU. The temporary depletion of ozone in Antarctica generally occurs between the beginning and middle of August, during the austral spring, and extends to November, when a temporary reduction in ozone content is observed in a large region over Antarctica. However, masses of ozone-depleted air can break away from the ozone hole and reach mid-latitude regions.
Kévin Lamy, Thierry Portafaix, Béatrice Josse, Colette Brogniez, Sophie Godin-Beekmann, Hassan Bencherif, Laura Revell, Hideharu Akiyoshi, Slimane Bekki, Michaela I. Hegglin, Patrick Jöckel, Oliver Kirner, Ben Liley, Virginie Marecal, Olaf Morgenstern, Andrea Stenke, Guang Zeng, N. Luke Abraham, Alexander T. Archibald, Neil Butchart, Martyn P. Chipperfield, Glauco Di Genova, Makoto Deushi, Sandip S. Dhomse, Rong-Ming Hu, Douglas Kinnison, Michael Kotkamp, Richard McKenzie, Martine Michou, Fiona M. O'Connor, Luke D. Oman, Giovanni Pitari, David A. Plummer, John A. Pyle, Eugene Rozanov, David Saint-Martin, Kengo Sudo, Taichu Y. Tanaka, Daniele Visioni, and Kohei Yoshida
Atmos. Chem. Phys., 19, 10087–10110, https://doi.org/10.5194/acp-19-10087-2019, https://doi.org/10.5194/acp-19-10087-2019, 2019
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In this study, we simulate the ultraviolet radiation evolution during the 21st century on Earth's surface using the output from several numerical models which participated in the Chemistry-Climate Model Initiative. We present four possible futures which depend on greenhouse gases emissions. The role of ozone-depleting substances, greenhouse gases and aerosols are investigated. Our results emphasize the important role of aerosols for future ultraviolet radiation in the Northern Hemisphere.
Pablo Facundo Orte, Elian Wolfram, Jacobo Salvador, Akira Mizuno, Nelson Bègue, Hassan Bencherif, Juan Lucas Bali, Raúl D'Elia, Andrea Pazmiño, Sophie Godin-Beekmann, Hirofumi Ohyama, and Jonathan Quiroga
Ann. Geophys., 37, 613–629, https://doi.org/10.5194/angeo-37-613-2019, https://doi.org/10.5194/angeo-37-613-2019, 2019
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We analysed an event of short-term ozone variability due to the passage of the polar vortex over Río Gallegos (southern Argentina) with the aim of highlighting the capability of a millimetre-wave radiometer to observe ozone in the stratosphere and the low mesosphere with a high temporal resolution. It is particularly important in this subpolar region due to the high variation that this gas can suffer as a consequence of the passage of the polar vortex and the ozone hole during spring.
Nelson J. Schuch, Rodrigo P. Marques, Otávio S. C. Durão, Marlos R. da Silva, Odim Mendes, Fátima Mattiello-Francisco, Andrei P. Legg, André L. da Silva, Fernando S. Pedroso, and Eduardo E. Bürger
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2019-58, https://doi.org/10.5194/angeo-2019-58, 2019
Preprint withdrawn
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The Brazilian INPE-UFSM NANOSATC-BR CubeSats Development Program consists of two CubeSats, NANOSATC-BR1 (1U) & NANOSATC-BR2 (2U). NANOSATC-BR2 is expected to operate in orbit for at least 12 months, while NANOSATC-BR1 this year has completed more than four years in orbit operation. This paper focuses on the future development of NANOSATC-BR3 & NANOSATC-BR4, in a partnership with the UFSM's Aerospace Engineering Course and on the launching of NANOSATC-BR2.
David J. du Preez, Jelena V. Ajtić, Hassan Bencherif, Nelson Bègue, Jean-Maurice Cadet, and Caradee Y. Wright
Ann. Geophys., 37, 129–141, https://doi.org/10.5194/angeo-37-129-2019, https://doi.org/10.5194/angeo-37-129-2019, 2019
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Reduced atmospheric ozone results in increased solar ultraviolet radiation (UVR) at the surface which may potentially negative impact public health. We aimed to assess whether or not the break-up of the Antarctic ozone hole had an impact on ozone and UVR at Cape Point (South Africa). We found a moderate inverse relationship between ozone and UVR at midday on clear-sky days. The Antarctic ozone hole had a limited effect on ozone levels while tropical air masses more frequently affected the site.
Abdoulwahab Mohamed Toihir, Thierry Portafaix, Venkataraman Sivakumar, Hassan Bencherif, Andréa Pazmiño, and Nelson Bègue
Ann. Geophys., 36, 381–404, https://doi.org/10.5194/angeo-36-381-2018, https://doi.org/10.5194/angeo-36-381-2018, 2018
Gabriela Dornelles Bittencourt, Caroline Bresciani, Damaris Kirsch Pinheiro, José Valentin Bageston, Nelson Jorge Schuch, Hassan Bencherif, Neusa Paes Leme, and Lucas Vaz Peres
Ann. Geophys., 36, 415–424, https://doi.org/10.5194/angeo-36-415-2018, https://doi.org/10.5194/angeo-36-415-2018, 2018
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Ozone-poor air mass can be released and leave through the Antarctic ozone hole, thus reaching midlatitude regions. The objective of this study is to show how tropospheric and stratospheric dynamics behaved during the event. The ozone-poor air mass began to operate in the region on 20 October 2016. A reduction of ozone content of approximately 23 % was observed in relation to the climatology average. The advance of the ozone-poor air mass caused intense reductions in total ozone content.
Caroline Bresciani, Gabriela Dornelles Bittencourt, José Valentin Bageston, Damaris Kirsch Pinheiro, Nelson Jorge Schuch, Hassan Bencherif, Neusa Paes Leme, and Lucas Vaz Peres
Ann. Geophys., 36, 405–413, https://doi.org/10.5194/angeo-36-405-2018, https://doi.org/10.5194/angeo-36-405-2018, 2018
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This paper investigates the passage of the ozone secondary effect (OSE) over southern Brazil and Uruguay in October 2016 by using multi-instrumental data, i.e. ozonesonde, satellites and ground-based instruments, and the large OSE influence on the ozone concentration and on the temperature was shown.
Amauri Fragoso Medeiros, Igo Paulino, Cristiano Max Wrasse, Joaquim Fechine, Hisao Takahashi, José Valentin Bageston, Ana Roberta Paulino, and Ricardo Arlen Buriti
Ann. Geophys., 36, 311–319, https://doi.org/10.5194/angeo-36-311-2018, https://doi.org/10.5194/angeo-36-311-2018, 2018
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On 3 October 2005, a mesospheric front was observed over São João do Cariri (7.4° S, 36.5° W) propagating to the northeast in the OH airglow images. One and a half hours later, it disappeared completely and ripples were observed in the eastern part of the images. After studying the background atmosphere, the main conclusion of this work was that the instability in the airglow layer did not allow the propagation of the front to the other side of the local zenith.
Gabriel Augusto Giongo, José Valentin Bageston, Paulo Prado Batista, Cristiano Max Wrasse, Gabriela Dornelles Bittencourt, Igo Paulino, Neusa Maria Paes Leme, David C. Fritts, Diego Janches, Wayne Hocking, and Nelson Jorge Schuch
Ann. Geophys., 36, 253–264, https://doi.org/10.5194/angeo-36-253-2018, https://doi.org/10.5194/angeo-36-253-2018, 2018
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This work presents four events of mesosphere fronts observed on King George Island, Antarctic Peninsula, in the year 2011. The atmospheric background environment was analyzed to investigate the propagation conditions for all cases. To investigate the sources for such cases, satellite images were used. In two cases, we found that strong tropospheric instabilities were potential sources, and in the other two cases, it was not possible to associate them with tropospheric sources.
Kévin Lamy, Thierry Portafaix, Colette Brogniez, Sophie Godin-Beekmann, Hassan Bencherif, Béatrice Morel, Andrea Pazmino, Jean Marc Metzger, Frédérique Auriol, Christine Deroo, Valentin Duflot, Philippe Goloub, and Charles N. Long
Atmos. Chem. Phys., 18, 227–246, https://doi.org/10.5194/acp-18-227-2018, https://doi.org/10.5194/acp-18-227-2018, 2018
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This work focuses on solar radiation in the tropics, more specifically on ultraviolet radiation. From ground-based and satellite observations of the chemical state of the atmosphere, we were able to model the ultraviolet measurements measured in the southern tropics with a very small error. This is a first step to modelling and predicting future ultraviolet levels in the tropics from chemistry-climate projections.
Nelson Bègue, Damien Vignelles, Gwenaël Berthet, Thierry Portafaix, Guillaume Payen, Fabrice Jégou, Hassan Benchérif, Julien Jumelet, Jean-Paul Vernier, Thibaut Lurton, Jean-Baptiste Renard, Lieven Clarisse, Vincent Duverger, Françoise Posny, Jean-Marc Metzger, and Sophie Godin-Beekmann
Atmos. Chem. Phys., 17, 15019–15036, https://doi.org/10.5194/acp-17-15019-2017, https://doi.org/10.5194/acp-17-15019-2017, 2017
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The space–time evolutions of the Calbuco plume are investigated by combining satellite, in situ aerosol counting and lidar observations, and a numerical model. All the data at Reunion Island reveal a twofold increase in the amount of aerosol with respect to the values observed before the eruption. The dynamic context has favored the spread of the plume exclusively in the Southern Hemisphere. This study highlights the role played by dynamical barriers in the transport of atmospheric species.
Nelson Bègue, Nkanyiso Mbatha, Hassan Bencherif, René Tato Loua, Venkataraman Sivakumar, and Thierry Leblanc
Ann. Geophys., 35, 1177–1194, https://doi.org/10.5194/angeo-35-1177-2017, https://doi.org/10.5194/angeo-35-1177-2017, 2017
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In this investigation a statistical analysis of the characteristics of mesospheric inversion layers (MILs) over tropical regions is presented. This study involves the analysis of 16 years of lidar observations recorded at Reunion (20.8° S, 55.5° E) and 21 years of lidar observations recorded at Mauna Loa (19.5° N, 155.6° W) together with SABER observations at these two locations. Results presented in this study confirm that SAO contributes to the formation of MILs over the tropical region.
Lucas Vaz Peres, Hassan Bencherif, Nkanyiso Mbatha, André Passaglia Schuch, Abdoulwahab Mohamed Toihir, Nelson Bègue, Thierry Portafaix, Vagner Anabor, Damaris Kirsch Pinheiro, Neusa Maria Paes Leme, José Valentin Bageston, and Nelson Jorge Schuch
Ann. Geophys., 35, 25–37, https://doi.org/10.5194/angeo-35-25-2017, https://doi.org/10.5194/angeo-35-25-2017, 2017
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In this paper, we analyze the total ozone column over the Southern Space Observatory, Brazil, between 1992 and 2014 by Brewer spectrometer and TOMS and OMI satellite instruments, finding good agreement between the two. In addition, the seasonal TOC variation is dominated by an annual cycle, and the Quasi-Biennial Oscillation modulation was the main mode of interannual variability and in opposite phase to the total ozone column anomaly time series.
I. Paulino, A. F. Medeiros, S. L. Vadas, C. M. Wrasse, H. Takahashi, R. A. Buriti, D. Leite, S. Filgueira, J. V. Bageston, J. H. A. Sobral, and D. Gobbi
Ann. Geophys., 34, 293–301, https://doi.org/10.5194/angeo-34-293-2016, https://doi.org/10.5194/angeo-34-293-2016, 2016
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Periodic waves have been observed over São João do Cariri during almost one solar cycle. Similarities between the characteristics of these events with observations at other places around the world were noted, primarily the spectral parameters. Most observed waves have appeared during magnetically quiet nights, and the occurrence of those waves followed the solar activity. Due to their characteristics, most of them must have had different generation mechanisms from the Perkins instability.
A. M. Toihir, H. Bencherif, V. Sivakumar, L. El Amraoui, T. Portafaix, and N. Mbatha
Ann. Geophys., 33, 1135–1146, https://doi.org/10.5194/angeo-33-1135-2015, https://doi.org/10.5194/angeo-33-1135-2015, 2015
N. Mbatha, V. Sivakumar, H. Bencherif, and S. Malinga
Ann. Geophys., 31, 1709–1719, https://doi.org/10.5194/angeo-31-1709-2013, https://doi.org/10.5194/angeo-31-1709-2013, 2013
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In the past years, the study of the temperature trend and its variability in the upper atmosphere has increased. However, most works were conducted in regions of medium and high latitude. Therefore, we aim to analyze a low-latitude region, the south of Brazil and surrounding areas. Using data from the TIMED/SABER instrument and applying the Trend-Run model for temperature trend analyses, no substantial temperature trend was found in the MLT region (80–100 km) from the years 2003 to 2014.
In the past years, the study of the temperature trend and its variability in the upper...
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