Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements
Autor(a) principal: | |
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Data de Publicação: | 2017 |
Outros Autores: | , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UNIFESP |
Texto Completo: | https://repositorio.unifesp.br/handle/11600/54924 http://dx.doi.org/10.5194/acp-17-3619-2017 |
Resumo: | Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Uppertropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88% during the wet season and not lower than 50% during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 +/- 1.9 (SD) km, 12.9 +/- 2.2 km, 1.4 +/- 1.1 km, and 0.25 +/- 0.46, respectively. Cirrus clouds were found at tem-peratures down to 90 degrees C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 +/- 8.0 sr. However, for subvisible cirrus clouds a bimodal distribution with a secondary peak at about 44 sr was found suggesting a mixed composition. A dependence of the lidar ratio with cloud temperature (altitude) was not found, indicating that the clouds are vertically well mixed. The frequency of occurrence of cirrus clouds classified as subvisible (tau < 0 : 03) were 41.6 %, whilst 37.8% were thin cirrus (0 : 03 < tau < 0 : 3) and 20.5% opaque cirrus (tau > 0 : 3). Hence, in central Amazonia not only a high frequency of cirrus clouds occurs, but also a large fraction of subvisible cirrus clouds. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun photometers and satellite sensors to an unknown extent. |
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Gouveia, Diego A.Barja, BorisBarbosa, Henrique M. J.Seifert, PatricBaars, HolgerPauliquevis, Theotonio [UNIFESP]Artaxo, Paulo2020-07-17T14:02:39Z2020-07-17T14:02:39Z2017Atmospheric Chemistry And Physics. Gottingen, v. 17, n. 5, p. 3619-3636, 2017.1680-7316https://repositorio.unifesp.br/handle/11600/54924http://dx.doi.org/10.5194/acp-17-3619-2017WOS000397928200001.pdf10.5194/acp-17-3619-2017WOS:000397928200001Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Uppertropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88% during the wet season and not lower than 50% during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 +/- 1.9 (SD) km, 12.9 +/- 2.2 km, 1.4 +/- 1.1 km, and 0.25 +/- 0.46, respectively. Cirrus clouds were found at tem-peratures down to 90 degrees C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 +/- 8.0 sr. However, for subvisible cirrus clouds a bimodal distribution with a secondary peak at about 44 sr was found suggesting a mixed composition. A dependence of the lidar ratio with cloud temperature (altitude) was not found, indicating that the clouds are vertically well mixed. The frequency of occurrence of cirrus clouds classified as subvisible (tau < 0 : 03) were 41.6 %, whilst 37.8% were thin cirrus (0 : 03 < tau < 0 : 3) and 20.5% opaque cirrus (tau > 0 : 3). Hence, in central Amazonia not only a high frequency of cirrus clouds occurs, but also a large fraction of subvisible cirrus clouds. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun photometers and satellite sensors to an unknown extent.CNPq fellowship programCAPES project on the program Science without FrontiersSAVERNET projectFAPESP Research Program on Global Climate ChangeUniv Sao Paulo, Inst Phys, Dept Appl Phys, Sao Paulo, SP, BrazilMeteorol Inst Cuba, Atmospher Opt Grp Camaguey, Camaguey, CubaUniv Magallanes, Atmospher Res Lab, Punta Arenas, ChileLeibniz Inst Tropospher Res TROPOS, Leipzig, GermanyUniv Fed Sao Paulo, Dept Environm Sci, Diadema, SP, BrazilUniv Fed Sao Paulo, Dept Environm Sci, Diadema, SP, BrazilCAPES: A016_2013FAPESP Research Program on Global Climate Change: 2008/58100-1FAPESP Research Program on Global Climate Change: 2009/15235-8FAPESP Research Program on Global Climate Change: 2012/16100-1FAPESP Research Program on Global Climate Change: 2013/50510-5FAPESP Research Program on Global Climate Change: 2013/05014-0Web of Science3619-3636engCopernicus Gesellschaft MbhAtmospheric Chemistry And PhysicsOptical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurementsinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleGottingen175info:eu-repo/semantics/openAccessreponame:Repositório Institucional da UNIFESPinstname:Universidade Federal de São Paulo (UNIFESP)instacron:UNIFESPORIGINALWOS000397928200001.pdfapplication/pdf3868128${dspace.ui.url}/bitstream/11600/54924/1/WOS000397928200001.pdfc8d6a169431059922c3e96eafdb9978eMD51open accessTEXTWOS000397928200001.pdf.txtWOS000397928200001.pdf.txtExtracted texttext/plain83337${dspace.ui.url}/bitstream/11600/54924/8/WOS000397928200001.pdf.txt745e69c135cd226a82c1530b1fc4e96cMD58open accessTHUMBNAILWOS000397928200001.pdf.jpgWOS000397928200001.pdf.jpgIM Thumbnailimage/jpeg6681${dspace.ui.url}/bitstream/11600/54924/10/WOS000397928200001.pdf.jpgca9184053ec5438c27afd7c5fc903534MD510open access11600/549242023-06-05 19:22:23.695open accessoai:repositorio.unifesp.br:11600/54924Repositório InstitucionalPUBhttp://www.repositorio.unifesp.br/oai/requestopendoar:34652023-06-05T22:22:23Repositório Institucional da UNIFESP - Universidade Federal de São Paulo (UNIFESP)false |
dc.title.en.fl_str_mv |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
title |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
spellingShingle |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements Gouveia, Diego A. |
title_short |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
title_full |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
title_fullStr |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
title_full_unstemmed |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
title_sort |
Optical and geometrical properties of cirrus clouds in Amazonia derived from 1 year of ground-based lidar measurements |
author |
Gouveia, Diego A. |
author_facet |
Gouveia, Diego A. Barja, Boris Barbosa, Henrique M. J. Seifert, Patric Baars, Holger Pauliquevis, Theotonio [UNIFESP] Artaxo, Paulo |
author_role |
author |
author2 |
Barja, Boris Barbosa, Henrique M. J. Seifert, Patric Baars, Holger Pauliquevis, Theotonio [UNIFESP] Artaxo, Paulo |
author2_role |
author author author author author author |
dc.contributor.author.fl_str_mv |
Gouveia, Diego A. Barja, Boris Barbosa, Henrique M. J. Seifert, Patric Baars, Holger Pauliquevis, Theotonio [UNIFESP] Artaxo, Paulo |
description |
Cirrus clouds cover a large fraction of tropical latitudes and play an important role in Earth's radiation budget. Their optical properties, altitude, vertical and horizontal coverage control their radiative forcing, and hence detailed cirrus measurements at different geographical locations are of utmost importance. Studies reporting cirrus properties over tropical rain forests like the Amazon, however, are scarce. Studies with satellite profilers do not give information on the diurnal cycle, and the satellite imagers do not report on the cloud vertical structure. At the same time, ground-based lidar studies are restricted to a few case studies. In this paper, we derive the first comprehensive statistics of optical and geometrical properties of upper-tropospheric cirrus clouds in Amazonia. We used 1 year (July 2011 to June 2012) of ground-based lidar atmospheric observations north of Manaus, Brazil. This dataset was processed by an automatic cloud detection and optical properties retrieval algorithm. Uppertropospheric cirrus clouds were observed more frequently than reported previously for tropical regions. The frequency of occurrence was found to be as high as 88% during the wet season and not lower than 50% during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle of precipitation. The mean values of cirrus cloud top and base heights, cloud thickness, and cloud optical depth were 14.3 +/- 1.9 (SD) km, 12.9 +/- 2.2 km, 1.4 +/- 1.1 km, and 0.25 +/- 0.46, respectively. Cirrus clouds were found at tem-peratures down to 90 degrees C. Frequently cirrus were observed within the tropical tropopause layer (TTL), which are likely associated to slow mesoscale uplifting or to the remnants of overshooting convection. The vertical distribution was not uniform, and thin and subvisible cirrus occurred more frequently closer to the tropopause. The mean lidar ratio was 23.3 +/- 8.0 sr. However, for subvisible cirrus clouds a bimodal distribution with a secondary peak at about 44 sr was found suggesting a mixed composition. A dependence of the lidar ratio with cloud temperature (altitude) was not found, indicating that the clouds are vertically well mixed. The frequency of occurrence of cirrus clouds classified as subvisible (tau < 0 : 03) were 41.6 %, whilst 37.8% were thin cirrus (0 : 03 < tau < 0 : 3) and 20.5% opaque cirrus (tau > 0 : 3). Hence, in central Amazonia not only a high frequency of cirrus clouds occurs, but also a large fraction of subvisible cirrus clouds. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun photometers and satellite sensors to an unknown extent. |
publishDate |
2017 |
dc.date.issued.fl_str_mv |
2017 |
dc.date.accessioned.fl_str_mv |
2020-07-17T14:02:39Z |
dc.date.available.fl_str_mv |
2020-07-17T14:02:39Z |
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info:eu-repo/semantics/publishedVersion |
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info:eu-repo/semantics/article |
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publishedVersion |
dc.identifier.citation.fl_str_mv |
Atmospheric Chemistry And Physics. Gottingen, v. 17, n. 5, p. 3619-3636, 2017. |
dc.identifier.uri.fl_str_mv |
https://repositorio.unifesp.br/handle/11600/54924 http://dx.doi.org/10.5194/acp-17-3619-2017 |
dc.identifier.issn.none.fl_str_mv |
1680-7316 |
dc.identifier.file.none.fl_str_mv |
WOS000397928200001.pdf |
dc.identifier.doi.none.fl_str_mv |
10.5194/acp-17-3619-2017 |
dc.identifier.wos.none.fl_str_mv |
WOS:000397928200001 |
identifier_str_mv |
Atmospheric Chemistry And Physics. Gottingen, v. 17, n. 5, p. 3619-3636, 2017. 1680-7316 WOS000397928200001.pdf 10.5194/acp-17-3619-2017 WOS:000397928200001 |
url |
https://repositorio.unifesp.br/handle/11600/54924 http://dx.doi.org/10.5194/acp-17-3619-2017 |
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eng |
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Atmospheric Chemistry And Physics |
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openAccess |
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Copernicus Gesellschaft Mbh |
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Copernicus Gesellschaft Mbh |
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