Hilbert analysis of air temperature dynamics
The dynamics of the climate system plays a crucial role in the sustainability of life on Earth, and this motivates research to understand and characterise our climate and predict its evolution. In this thesis we focus on the dynamics of atmospheric temperature and analyse time series of surface air...
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Universitat Politècnica de Catalunya
2019
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ftupcatalunya:oai:www.tdx.cat:10803/666715 2023-11-12T04:13:54+01:00 Hilbert analysis of air temperature dynamics Zappalà, Dario Masoller, Cristina Universitat Politècnica de Catalunya. Departament de Física 2019-04-25T10:34:25Z 109 p. application/pdf http://hdl.handle.net/10803/666715 eng eng Universitat Politècnica de Catalunya http://hdl.handle.net/10803/666715 ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs. info:eu-repo/semantics/openAccess TDX (Tesis Doctorals en Xarxa) Àrees temàtiques de la UPC::Física 531/534 55 info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion 2019 ftupcatalunya 2023-10-16T17:17:11Z The dynamics of the climate system plays a crucial role in the sustainability of life on Earth, and this motivates research to understand and characterise our climate and predict its evolution. In this thesis we focus on the dynamics of atmospheric temperature and analyse time series of surface air temperature using the Hilbert transform. This allows us to characterise the dynamics of temperature with time series of instantaneous amplitude, phase and frequency. Using these series as the basis of our analysis, we extract meaningful information about global patterns of temperature dynamics. Firstly, we calculate maps of time-averaged frequency and of its standard deviation and uncover patterns that correspond to well-known climatic conditions: different amplitudes of the annual temperature cycle and regions of high precipitation. In addition, we study the dynamics of instantaneous frequency and phase in three geographical sites. The results reflect the main features of different climates, in particular the difference between the tropical and the extratropical climate. Then, we use the Hilbert time series to quantify inter-decadal changes in temperature dynamics (specifically, in the last 35 years). We find high changes of amplitude in the Arctic and in Amazonia, which are interpreted respectively as due to ice melting and precipitation decrease. We also uncover frequency changes in the Pacific Ocean that suggest a shift towards north and a widening of the atmospheric convection pattern known as the intertropical convergence zone. Thirdly, we uncover temporal regularities in phase dynamics. We smooth (by doing a temporal average on a moving window) the temperature series, then we apply the Hilbert analysis and study how the mean rotation period of the Hilbert phase depends on the length of the averaging window. In this way, we discover different types of atmospheric dynamics and classify geographical regions according to the results of our analysis. Finally, we analyse correlations between the phase, amplitude and ... Doctoral or Postdoctoral Thesis Arctic Universitat Politècnica de Catalunya (UPC): Theses and Dissertations Online (TDX) Arctic Pacific |
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Open Polar |
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Universitat Politècnica de Catalunya (UPC): Theses and Dissertations Online (TDX) |
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ftupcatalunya |
language |
English |
topic |
Àrees temàtiques de la UPC::Física 531/534 55 |
spellingShingle |
Àrees temàtiques de la UPC::Física 531/534 55 Zappalà, Dario Hilbert analysis of air temperature dynamics |
topic_facet |
Àrees temàtiques de la UPC::Física 531/534 55 |
description |
The dynamics of the climate system plays a crucial role in the sustainability of life on Earth, and this motivates research to understand and characterise our climate and predict its evolution. In this thesis we focus on the dynamics of atmospheric temperature and analyse time series of surface air temperature using the Hilbert transform. This allows us to characterise the dynamics of temperature with time series of instantaneous amplitude, phase and frequency. Using these series as the basis of our analysis, we extract meaningful information about global patterns of temperature dynamics. Firstly, we calculate maps of time-averaged frequency and of its standard deviation and uncover patterns that correspond to well-known climatic conditions: different amplitudes of the annual temperature cycle and regions of high precipitation. In addition, we study the dynamics of instantaneous frequency and phase in three geographical sites. The results reflect the main features of different climates, in particular the difference between the tropical and the extratropical climate. Then, we use the Hilbert time series to quantify inter-decadal changes in temperature dynamics (specifically, in the last 35 years). We find high changes of amplitude in the Arctic and in Amazonia, which are interpreted respectively as due to ice melting and precipitation decrease. We also uncover frequency changes in the Pacific Ocean that suggest a shift towards north and a widening of the atmospheric convection pattern known as the intertropical convergence zone. Thirdly, we uncover temporal regularities in phase dynamics. We smooth (by doing a temporal average on a moving window) the temperature series, then we apply the Hilbert analysis and study how the mean rotation period of the Hilbert phase depends on the length of the averaging window. In this way, we discover different types of atmospheric dynamics and classify geographical regions according to the results of our analysis. Finally, we analyse correlations between the phase, amplitude and ... |
author2 |
Masoller, Cristina Universitat Politècnica de Catalunya. Departament de Física |
format |
Doctoral or Postdoctoral Thesis |
author |
Zappalà, Dario |
author_facet |
Zappalà, Dario |
author_sort |
Zappalà, Dario |
title |
Hilbert analysis of air temperature dynamics |
title_short |
Hilbert analysis of air temperature dynamics |
title_full |
Hilbert analysis of air temperature dynamics |
title_fullStr |
Hilbert analysis of air temperature dynamics |
title_full_unstemmed |
Hilbert analysis of air temperature dynamics |
title_sort |
hilbert analysis of air temperature dynamics |
publisher |
Universitat Politècnica de Catalunya |
publishDate |
2019 |
url |
http://hdl.handle.net/10803/666715 |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
TDX (Tesis Doctorals en Xarxa) |
op_relation |
http://hdl.handle.net/10803/666715 |
op_rights |
ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs. info:eu-repo/semantics/openAccess |
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1782331685768003584 |