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COST733 WG4 meeting, Ioannina, 9-10 May 2008. clim.pact – a tool for empirical - statistical downscaling. Monika Cahynová cahynova @ ufa. cas.cz Institute of Atmospheric Physics & Facult y of Science, Charles University Prague, Czech Republic. clim.pact. a package in the R environment
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COST733 WG4 meeting, Ioannina, 9-10 May 2008 clim.pact – a tool for empirical-statistical downscaling Monika Cahynová cahynova@ufa. cas.cz Institute of Atmospheric Physics & Faculty of Science, Charles University Prague, Czech Republic
clim.pact • a package in the R environment • developed by Rasmus Benestad (met.no, Oslo) • freely available online • enables various analyses of climate time series, multivariate methods (CCA, PCA), graphical output • main task: empirical-statistical downscaling of monthly or daily time series
Downscaling (DS) in clim.pact • finding linear relationships between regional predictor and local predictand in the calibration period • extrapolation of the downscaled results to the period when only the predictor is known • input data • predictor: gridded observational or modelled data (ERA40, NCEP/NCAR, GCM output,…), converted into EOFs • EOFs of one variable (e.g. SLP) or mixed-field EOFs (coupled structure of two fields, e.g. SLP and temperature) • predictand: station, gridpoint or spatial mean time series of a climatic or other environmental variable
Downscaling (DS) in clim.pact • what does clim.pact do within the DS function? • stepwise regression between the leading EOFs of the predictor and the time series of the predictand within the calibration period • calibration is by default carried out on detrended data • construction of a downscaled (predicted) local time series for the period of known predictor – hindcast or forecast • output: predicted local time series, spatial pattern of large-scale anomalies associated with it, ANOVA, analysis of residuals
For those interested in clim.pact… • A compendium on empirical-statistical downscaling, with examples on clim.pact use: www.gvc2.gu.se/ngeo/rcg/edu/esd.pdf • Download clim.pact http://cran.r-project.org/web/packages/clim.pact/index.html