Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study

Gravity waves (GWs) and convective systems play a fundamental role in atmospheric circulation, weather, and climate. Two usual main sources of GWs are orographic effects triggering mountain waves and convective activity. In addition, GW generation by fronts and geostrophic adjustment must also be co...

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Publicado:	2018
Materias:	atmospheric circulation GPS gravity wave instrumentation mountain region orography radio stratosphere subtropical region weather forecasting Alps Andes
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18671381_v11_n6_p3523_Hierro http://hdl.handle.net/20.500.12110/paper_18671381_v11_n6_p3523_Hierro
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_18671381_v11_n6_p3523_Hierro
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spelling	paper:paper_18671381_v11_n6_p3523_Hierro2025-07-30T19:05:26Z Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study atmospheric circulation GPS gravity wave instrumentation mountain region orography radio stratosphere subtropical region weather forecasting Alps Andes Gravity waves (GWs) and convective systems play a fundamental role in atmospheric circulation, weather, and climate. Two usual main sources of GWs are orographic effects triggering mountain waves and convective activity. In addition, GW generation by fronts and geostrophic adjustment must also be considered. The utility of Global Positioning System (GPS) radio occultation (RO) observations for the detection of convective systems is tested. A collocation database between RO events and convective systems over subtropical to midlatitude mountain regions close to the Alps and Andes is built. From the observation of large-amplitude GW structures in the absence of jets and fronts, subsets of RO profiles are sampled. A representative case study among those considered at each region is selected and analyzed. The case studies are investigated using mesoscale Weather Research and Forecasting (WRF) simulations, ERA-Interim reanalysis data, and measured RO temperature profiles. The absence of fronts or jets during both case studies reveals similar relevant GW features (main parameters, generation, and propagation). Orographic and convective activity generates the observed GWs. Mountain waves above the Alps reach higher altitudes than close to the Andes. In the Andes case, a critical layer prevents the propagation of GW packets up to stratospheric heights. The case studies are selected also because they illustrate how the observational window for GW observations through RO profiles admits a misleading interpretation of structures at different altitude ranges. From recent results, the distortion introduced in the measured atmospheric vertical wavelengths by one of the RO events is discussed as an illustration. In the analysis, both the elevation angle of the sounding path (line of tangent points) and the gravity wave aspect ratio estimated from the simulations and the line of sight are taken into account. In both case studies, a considerable distortion, over- and underestimation of the vertical wavelengths measured by RO, may be expected. © Author(s) 2018. 2018 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18671381_v11_n6_p3523_Hierro http://hdl.handle.net/20.500.12110/paper_18671381_v11_n6_p3523_Hierro
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	atmospheric circulation GPS gravity wave instrumentation mountain region orography radio stratosphere subtropical region weather forecasting Alps Andes
spellingShingle	atmospheric circulation GPS gravity wave instrumentation mountain region orography radio stratosphere subtropical region weather forecasting Alps Andes Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
topic_facet	atmospheric circulation GPS gravity wave instrumentation mountain region orography radio stratosphere subtropical region weather forecasting Alps Andes
description	Gravity waves (GWs) and convective systems play a fundamental role in atmospheric circulation, weather, and climate. Two usual main sources of GWs are orographic effects triggering mountain waves and convective activity. In addition, GW generation by fronts and geostrophic adjustment must also be considered. The utility of Global Positioning System (GPS) radio occultation (RO) observations for the detection of convective systems is tested. A collocation database between RO events and convective systems over subtropical to midlatitude mountain regions close to the Alps and Andes is built. From the observation of large-amplitude GW structures in the absence of jets and fronts, subsets of RO profiles are sampled. A representative case study among those considered at each region is selected and analyzed. The case studies are investigated using mesoscale Weather Research and Forecasting (WRF) simulations, ERA-Interim reanalysis data, and measured RO temperature profiles. The absence of fronts or jets during both case studies reveals similar relevant GW features (main parameters, generation, and propagation). Orographic and convective activity generates the observed GWs. Mountain waves above the Alps reach higher altitudes than close to the Andes. In the Andes case, a critical layer prevents the propagation of GW packets up to stratospheric heights. The case studies are selected also because they illustrate how the observational window for GW observations through RO profiles admits a misleading interpretation of structures at different altitude ranges. From recent results, the distortion introduced in the measured atmospheric vertical wavelengths by one of the RO events is discussed as an illustration. In the analysis, both the elevation angle of the sounding path (line of tangent points) and the gravity wave aspect ratio estimated from the simulations and the line of sight are taken into account. In both case studies, a considerable distortion, over- and underestimation of the vertical wavelengths measured by RO, may be expected. © Author(s) 2018.
title	Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
title_short	Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
title_full	Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
title_fullStr	Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
title_full_unstemmed	Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study
title_sort	orographic and convective gravity waves above the alps and andes mountains during gps radio occultation events - a case study
publishDate	2018
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18671381_v11_n6_p3523_Hierro http://hdl.handle.net/20.500.12110/paper_18671381_v11_n6_p3523_Hierro
_version_	1840321724771467264

Orographic and convective gravity waves above the Alps and Andes Mountains during GPS radio occultation events - A case study

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