Is time a variable like the others in multivariate statistical downscaling and bias correction?

<p>Bias correction and statistical downscaling are now regularly applied to climate simulations to make then more usable for impact models and studies. Over the last few years, various methods were developed to account for multivariate – inter-site or inter-variable – properties in addition to...

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Autores principales:	Y. Robin, M. Vrac
Formato:	article
Lenguaje:	EN
Publicado:	Copernicus Publications 2021
Materias:	Science Q Geology QE1-996.5 Dynamic and structural geology QE500-639.5
Acceso en línea:	https://doaj.org/article/069405e5f91c4ed8b299b73e3007f028
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spelling	oai:doaj.org-article:069405e5f91c4ed8b299b73e3007f0282021-11-25T07:07:07ZIs time a variable like the others in multivariate statistical downscaling and bias correction?10.5194/esd-12-1253-20212190-49792190-4987https://doaj.org/article/069405e5f91c4ed8b299b73e3007f0282021-11-01T00:00:00Zhttps://esd.copernicus.org/articles/12/1253/2021/esd-12-1253-2021.pdfhttps://doaj.org/toc/2190-4979https://doaj.org/toc/2190-4987<p>Bias correction and statistical downscaling are now regularly applied to climate simulations to make then more usable for impact models and studies. Over the last few years, various methods were developed to account for multivariate – inter-site or inter-variable – properties in addition to more usual univariate ones. Among such methods, temporal properties are either neglected or specifically accounted for, i.e. differently from the other properties. In this study, we propose a new multivariate approach called “time-shifted multivariate bias correction” (TSMBC), which aims to correct the temporal dependency in addition to the other marginal and multivariate aspects. TSMBC relies on considering the initial variables at various times (i.e. lags) as additional variables to be corrected. Hence, temporal dependencies (e.g. auto-correlations) to be corrected are viewed as inter-variable dependencies to be adjusted and an existing multivariate bias correction (MBC) method can then be used to answer this need. This approach is first applied and evaluated on synthetic data from a vector auto-regressive (VAR) process. In a second evaluation, we work in a “perfect model” context where a regional climate model (RCM) plays the role of the (pseudo-)observations, and where its forcing global climate model (GCM) is the model to be downscaled or bias corrected. For both evaluations, the results show a large reduction of the biases in the temporal properties, while inter-variable and spatial dependence structures are still correctly adjusted. However, increasing the number of lags too much does not necessarily improve the temporal properties, and an overly strong increase in the number of dimensions of the dataset to be corrected can even imply some potential instability in the adjusted and/or downscaled results, calling for a reasoned use of this approach for large datasets.</p>Y. RobinM. VracCopernicus PublicationsarticleScienceQGeologyQE1-996.5Dynamic and structural geologyQE500-639.5ENEarth System Dynamics, Vol 12, Pp 1253-1273 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Science Q Geology QE1-996.5 Dynamic and structural geology QE500-639.5
spellingShingle	Science Q Geology QE1-996.5 Dynamic and structural geology QE500-639.5 Y. Robin M. Vrac Is time a variable like the others in multivariate statistical downscaling and bias correction?
description	<p>Bias correction and statistical downscaling are now regularly applied to climate simulations to make then more usable for impact models and studies. Over the last few years, various methods were developed to account for multivariate – inter-site or inter-variable – properties in addition to more usual univariate ones. Among such methods, temporal properties are either neglected or specifically accounted for, i.e. differently from the other properties. In this study, we propose a new multivariate approach called “time-shifted multivariate bias correction” (TSMBC), which aims to correct the temporal dependency in addition to the other marginal and multivariate aspects. TSMBC relies on considering the initial variables at various times (i.e. lags) as additional variables to be corrected. Hence, temporal dependencies (e.g. auto-correlations) to be corrected are viewed as inter-variable dependencies to be adjusted and an existing multivariate bias correction (MBC) method can then be used to answer this need. This approach is first applied and evaluated on synthetic data from a vector auto-regressive (VAR) process. In a second evaluation, we work in a “perfect model” context where a regional climate model (RCM) plays the role of the (pseudo-)observations, and where its forcing global climate model (GCM) is the model to be downscaled or bias corrected. For both evaluations, the results show a large reduction of the biases in the temporal properties, while inter-variable and spatial dependence structures are still correctly adjusted. However, increasing the number of lags too much does not necessarily improve the temporal properties, and an overly strong increase in the number of dimensions of the dataset to be corrected can even imply some potential instability in the adjusted and/or downscaled results, calling for a reasoned use of this approach for large datasets.</p>
format	article
author	Y. Robin M. Vrac
author_facet	Y. Robin M. Vrac
author_sort	Y. Robin
title	Is time a variable like the others in multivariate statistical downscaling and bias correction?
title_short	Is time a variable like the others in multivariate statistical downscaling and bias correction?
title_full	Is time a variable like the others in multivariate statistical downscaling and bias correction?
title_fullStr	Is time a variable like the others in multivariate statistical downscaling and bias correction?
title_full_unstemmed	Is time a variable like the others in multivariate statistical downscaling and bias correction?
title_sort	is time a variable like the others in multivariate statistical downscaling and bias correction?
publisher	Copernicus Publications
publishDate	2021
url	https://doaj.org/article/069405e5f91c4ed8b299b73e3007f028
work_keys_str_mv	AT yrobin istimeavariableliketheothersinmultivariatestatisticaldownscalingandbiascorrection AT mvrac istimeavariableliketheothersinmultivariatestatisticaldownscalingandbiascorrection
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Is time a variable like the others in multivariate statistical downscaling and bias correction?

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