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Correlation properties of global satellite and model ozone time series Viktória Homonnai, Imre M. Jánosi Eötvös Loránd University, Hungary Data: LATMOS/CNRS
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RECONCILE Reconciliation of essential process parameters for an enhanced predictability of arctic stratospheric ozone loss and its climate interactions 17 partners from 9 countries
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Activities Aircraft campaign Match campaign Laboratory experiments Modelling activities https://www.fp7-reconcile.eu/reconcileaircraft.html
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Activities Aircraft campaign Match campaign Laboratory experiments Modelling activities https://www.fp7-reconcile.eu/reconcilematch.html https://www.fp7-reconcile.eu/reconcilelabexp.html
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Activities Aircraft campaign Match campaign Laboratory experiments Modelling activities Chemistry-Transport Model Chemistry-Climate Model our task: model validation for correlation properties A CLaMS simulation of vortex evolution over the 2009/10 winter https://www.fp7- reconcile.eu/reconcilemodel. html
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Methods Spectral analysis semi-annual annual QBO Spectral weight determination :
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Quasi-biennial oscillation quasi-periodic oscillation of the equatorial zonal wind in the stratosphere mean period: 28-29 months red: westerly winds blue: easterly winds http://ugamp.nerc.ac.uk/hot/ajh/qboanim.movie Baldwin, M. P., et al. (2001), The quasi-biennial oscillation, Rev. Geophys., 39(2), 179–229
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Methods Detrended fluctuation analysis (DFA) integrated time series : y(k) local trend: y n (k) root-mean-square fluctuation: slope of the linear fit on log-log scale scaling exponent: α α >0.5 long-term correlation same information as autocorrelation function and Fourier spectrum advantage: treat weak stationarity well
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Empirical data Previous studies: spectral and detrended fluctuation analysis (DFA) of TOMS total column ozone (TO) data in 1978-1993 periods (Nimbus-7 satellite) Present studies: spectral analysis and DFA of NIWA TO database between 1978 and 2011 NIWA: global, daily, satellite- based data with spatial and temporal interpolation (vs. TOMS); offsets and drifts are corrected with ground-based measurements
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Comparison of the two empirical datasets Spectral analysis TOMS Nimbus-7NIWA QBO peak annual peak semi-annual peak
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Comparison of the two empirical datasets Detrended fluctuation analysis NIWA TOMS Nimbus-7
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Model data LMDz-REPROBUS Chemistry-Climate Model Spatial resolution: 2.5° in latitude, 3.75° in longitude, 31 vertical levels (pressure coordinate) Temporal resolution: monthly mean data from 1960-2006 volume mixing ratio (vmr) data of ozone It was calculated total column ozone (TCO) from vmr:
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Monthly data vs. Daily data Fourier-spectrum: in daily data there is a long tail → normalization! semi-annual annual QBO
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Monthly data vs. Daily data DFA: offset because of the different window sizes (x-axis) and the different average fluctuations (y-axis), but after shift is the same
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Comparison of the empirical and model datasets Spectral analysis Spectral weight of the semi-annual peak Shifted and stronger peak over the Indian ocean Strong peak in Tibet NIWA monthly CCM
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Comparison of the empirical and model datasets Spectral analysis Spectral weight of the annual peak Equatorial area is different NIWA monthlyCCM
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Comparison of the empirical and model datasets Spectral analysis Spectral weight of the QBO peak No QBO peak in the CCM NIWA monthly CCM
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Quasi-biennial oscillation Big challenge we need large spatial resolution, tropical convection, effects of gravity waves Baldwin, M. P., et al. (2001), The quasi-biennial oscillation, Rev. Geophys., 39(2), 179–229
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QBO in the CCMs Spontaneous QBO QBO nudging SPARC Report on the Evaluation of Chemistry Climate Models, June 2010
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Comparison of the empirical and model datasets Detrended fluctuation analysis 1 grid point tropics vs. extratropics tropics CCM NIWA monthly NIWA daily extratropics CCM NIWA monthly NIWA daily
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Comparison of the empirical and model datasets Detrended fluctuation analysis Global map of the α exponent values NIWA monthlyCCM
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Summary Comparisons: two empirical datasets empirical vs. model output QBO: not simple to build into a global climate model Annual peak is stronger over the Equator in the CCM DFA might be related to nonlinearity good agreement next step in validation
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Thank you for your attention!
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