Time series analysis and identification of trends in a Mediterranean urban area
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| Title: | Time series analysis and identification of trends in a Mediterranean urban area |
|---|---|
| Authors: | Capilla, C.1 ccapilla@eio.upv.es |
| Source: | Global & Planetary Change. Sep2008, Vol. 63 Issue 2/3, p275-281. 7p. |
| Subjects: | Time series analysis, Temperature, Regression analysis |
| Geographic Terms: | Mediterranean Region |
| Abstract: | Abstract: During the last decade there has been considerable interest in the stochastic analysis of temperature trends. This attention usually focuses upon global and hemispheric time series. Analyses of global temperatures are of obvious importance but it is equally of interest to analyse questions of warming at a more ‘micro’ level. The objective of the paper is to illustrate that the appropriate estimation of a local record trend component necessitates the use of flexible methods. A long time series of temperature data from a Mediterranean urban area is analysed. The data comprise a series on monthly mean surface temperatures for Valencia (Spain), a Mediterranean city in terms of its urban structure and climatology. Trends are extracted from the temperature data available from 1938, using both annual and seasonal averages. Attention is focused on applying non-parametric methods which allow the analysis of non stationary trends in comparison to other methods. A local polynomial regression fitting and wavelet thresholding indicate that there is an upward trend in the annual series. The bandwidth in the local regression model selected by cross-validation follows short-term cycles rather than tracing out the long-term component. Therefore to extract the long-term trend a higher smoothing parameter is selected. The trend visualization plots show that the increase in the mean temperature per year is non-stationary. A change-point detection test indicates a trend change in the series around the year 1968. There is compelling evidence of a trend increase after this year, which is probably due to increase urbanization. The analysis of monthly observations is also discussed. Seasonal differences in trend patterns are more clearly observed when the monthly data are averaged across seasons. There have been upward shifts in the trends of spring and summer temperatures. [Copyright &y& Elsevier] |
| Copyright of Global & Planetary Change is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 34440501 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Time series analysis and identification of trends in a Mediterranean urban area – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Capilla%2C+C%2E%22">Capilla, C.</searchLink><relatesTo>1</relatesTo><i> ccapilla@eio.upv.es</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Global+%26+Planetary+Change%22">Global & Planetary Change</searchLink>. Sep2008, Vol. 63 Issue 2/3, p275-281. 7p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Time+series+analysis%22">Time series analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Temperature%22">Temperature</searchLink><br /><searchLink fieldCode="DE" term="%22Regression+analysis%22">Regression analysis</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Mediterranean+Region%22">Mediterranean Region</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Abstract: During the last decade there has been considerable interest in the stochastic analysis of temperature trends. This attention usually focuses upon global and hemispheric time series. Analyses of global temperatures are of obvious importance but it is equally of interest to analyse questions of warming at a more ‘micro’ level. The objective of the paper is to illustrate that the appropriate estimation of a local record trend component necessitates the use of flexible methods. A long time series of temperature data from a Mediterranean urban area is analysed. The data comprise a series on monthly mean surface temperatures for Valencia (Spain), a Mediterranean city in terms of its urban structure and climatology. Trends are extracted from the temperature data available from 1938, using both annual and seasonal averages. Attention is focused on applying non-parametric methods which allow the analysis of non stationary trends in comparison to other methods. A local polynomial regression fitting and wavelet thresholding indicate that there is an upward trend in the annual series. The bandwidth in the local regression model selected by cross-validation follows short-term cycles rather than tracing out the long-term component. Therefore to extract the long-term trend a higher smoothing parameter is selected. The trend visualization plots show that the increase in the mean temperature per year is non-stationary. A change-point detection test indicates a trend change in the series around the year 1968. There is compelling evidence of a trend increase after this year, which is probably due to increase urbanization. The analysis of monthly observations is also discussed. Seasonal differences in trend patterns are more clearly observed when the monthly data are averaged across seasons. There have been upward shifts in the trends of spring and summer temperatures. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Global & Planetary Change is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.gloplacha.2007.10.001 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 7 StartPage: 275 Subjects: – SubjectFull: Time series analysis Type: general – SubjectFull: Temperature Type: general – SubjectFull: Regression analysis Type: general – SubjectFull: Mediterranean Region Type: general Titles: – TitleFull: Time series analysis and identification of trends in a Mediterranean urban area Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Capilla, C. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 09 Text: Sep2008 Type: published Y: 2008 Identifiers: – Type: issn-print Value: 09218181 Numbering: – Type: volume Value: 63 – Type: issue Value: 2/3 Titles: – TitleFull: Global & Planetary Change Type: main |
| ResultId | 1 |
