Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor

We investigate convective storms over the Sabana de Bogotá, a high-altitude and densely populated area in the Colombian tropical Andes. Convective events are identified using infrared satellite images and in-situ precipitation data. As expected, convection shows a strong early-afternoon peak during...

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Detalles Bibliográficos
Autores: Casallas-García, Alejandro, Hernández-Deckers, Daniel, Mora-Páez, Héctor
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2023
País:México
Institución:UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO
Repositorio:Atmósfera
Idioma:inglés
OAI Identifier:oai:ojs.pkp.sfu.ca:article/53051
Acceso en línea:https://www.revistascca.unam.mx/atm/index.php/atm/article/view/53051
Access Level:acceso abierto
Palabra clave:Tropical convection
GNSS meteorology
mountain meteorology
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spelling Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vaporCasallas-García, AlejandroHernández-Deckers, DanielMora-Páez, HéctorTropical convectionGNSS meteorologymountain meteorologyWe investigate convective storms over the Sabana de Bogotá, a high-altitude and densely populated area in the Colombian tropical Andes. Convective events are identified using infrared satellite images and in-situ precipitation data. As expected, convection shows a strong early-afternoon peak during the two rainy seasons. Previous studies hypothesize that early-afternoon westerly winds and their moisture advection from the warmer Magdalena valley are the main explanatory mechanism for intense storms. We find that early-afternoon westerlies are present in 78% of rainy season days, but convective events develop in only 26% of them. Thus, although westerlies seem necessary for convection due to the convergence they generate, they only occasionally generate storms and are therefore not a good predictor. Furthermore, reanalysis data indicate that precipitable water vapor (PWV) at the Magdalena valley is anomalously low during convective days, suggesting that moisture converges locally instead of being advected from the west. Based on composites of surface wind speed, air temperature, surface pressure, and GPS-derived PWV, we identify the most prominent signals associated with deep convection: a weaker than average wind speed throughout the morning, higher than normal values of surface air temperature towards noon, followed by an anomalous steep increase of PWV and wind speed. These features indicate that convection results from a strong diurnal forcing facilitated by convergence of westerly winds, combined with sufficient water vapor convergence, with a timescale of about 3 h. This highlights the relevance of high temporal resolution monitoring of PWV offered by Global Navigational Satellite System stations.Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México2023-01-17info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://www.revistascca.unam.mx/atm/index.php/atm/article/view/5305110.20937/ATM.53051Atmósfera; Vol. 36 Núm. 2 (2023); 225-238Atmósfera; Vol. 36 No. 2 (2023); 225-2382395-88120187-6236reponame:Atmósferainstname:UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICOinstacron:UNAMenghttps://www.revistascca.unam.mx/atm/index.php/atm/article/view/53051/46907Copyright (c) 2021 Atmósferahttp://creativecommons.org/licenses/by-nc/4.0info:eu-repo/semantics/openAccessoai:ojs.pkp.sfu.ca:article/530512024-08-16T16:52:41Z
dc.title.none.fl_str_mv Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
title Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
spellingShingle Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
Casallas-García, Alejandro
Tropical convection
GNSS meteorology
mountain meteorology
title_short Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
title_full Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
title_fullStr Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
title_full_unstemmed Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
title_sort Understanding convective storms in a tropical, high-altitude location with in-situ meteorological observations and GPS-derived water vapor
dc.creator.none.fl_str_mv Casallas-García, Alejandro
Hernández-Deckers, Daniel
Mora-Páez, Héctor
author Casallas-García, Alejandro
author_facet Casallas-García, Alejandro
Hernández-Deckers, Daniel
Mora-Páez, Héctor
author_role author
author2 Hernández-Deckers, Daniel
Mora-Páez, Héctor
author2_role author
author
dc.subject.none.fl_str_mv Tropical convection
GNSS meteorology
mountain meteorology
topic Tropical convection
GNSS meteorology
mountain meteorology
description We investigate convective storms over the Sabana de Bogotá, a high-altitude and densely populated area in the Colombian tropical Andes. Convective events are identified using infrared satellite images and in-situ precipitation data. As expected, convection shows a strong early-afternoon peak during the two rainy seasons. Previous studies hypothesize that early-afternoon westerly winds and their moisture advection from the warmer Magdalena valley are the main explanatory mechanism for intense storms. We find that early-afternoon westerlies are present in 78% of rainy season days, but convective events develop in only 26% of them. Thus, although westerlies seem necessary for convection due to the convergence they generate, they only occasionally generate storms and are therefore not a good predictor. Furthermore, reanalysis data indicate that precipitable water vapor (PWV) at the Magdalena valley is anomalously low during convective days, suggesting that moisture converges locally instead of being advected from the west. Based on composites of surface wind speed, air temperature, surface pressure, and GPS-derived PWV, we identify the most prominent signals associated with deep convection: a weaker than average wind speed throughout the morning, higher than normal values of surface air temperature towards noon, followed by an anomalous steep increase of PWV and wind speed. These features indicate that convection results from a strong diurnal forcing facilitated by convergence of westerly winds, combined with sufficient water vapor convergence, with a timescale of about 3 h. This highlights the relevance of high temporal resolution monitoring of PWV offered by Global Navigational Satellite System stations.
publishDate 2023
dc.date.none.fl_str_mv 2023-01-17
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://www.revistascca.unam.mx/atm/index.php/atm/article/view/53051
10.20937/ATM.53051
url https://www.revistascca.unam.mx/atm/index.php/atm/article/view/53051
identifier_str_mv 10.20937/ATM.53051
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv https://www.revistascca.unam.mx/atm/index.php/atm/article/view/53051/46907
dc.rights.none.fl_str_mv Copyright (c) 2021 Atmósfera
http://creativecommons.org/licenses/by-nc/4.0
info:eu-repo/semantics/openAccess
rights_invalid_str_mv Copyright (c) 2021 Atmósfera
http://creativecommons.org/licenses/by-nc/4.0
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México
publisher.none.fl_str_mv Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México
dc.source.none.fl_str_mv Atmósfera; Vol. 36 Núm. 2 (2023); 225-238
Atmósfera; Vol. 36 No. 2 (2023); 225-238
2395-8812
0187-6236
reponame:Atmósfera
instname:UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO
instacron:UNAM
instname_str UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO
instacron_str UNAM
institution UNAM
reponame_str Atmósfera
collection Atmósfera
repository.name.fl_str_mv
repository.mail.fl_str_mv
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