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Reanalyses – A sharing of juicy tidbits * and gory details**

Reanalyses – A sharing of juicy tidbits * and gory details**. Andrew Klekociuk, Australian Antarctic Division * a choice or pleasing bit of anything, as gossip. ** to tell all the small details about something that is unpleasant or interesting in a shocking way. Outline.

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Reanalyses – A sharing of juicy tidbits * and gory details**

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  1. Reanalyses – A sharing of juicy tidbits* and gory details** Andrew Klekociuk, Australian Antarctic Division * a choice or pleasing bit of anything, as gossip.** to tell all the small details about something that is unpleasant or interesting in a shocking way.

  2. Outline • A Brief Introduction to Reanalyses • Uses • Potential Issues • Resources

  3. Reanalysis = Retrospective Analysis • Observations taken over a long time period are combined objectively with a model forecast to form time-series of fields representing the state of the system. • Observations: • Atmosphere: pressure, temperature, wind humidity. • Ocean: pressure, temperature, currents, salinity.

  4. Reanalysis = Retrospective Analysis • Model is kept constant over entire time period (though quality, density and type of observations can change). • Differs from ‘operation analysis’ where the model may change. • Data assimilation fills gaps. • The best resource – http://reanalyses.org/

  5. Key Reanalyses • Atmosphere – http://reanalysis.org/atmosphere/overview-current-reanalyses • ECMWF(European Centre for Medium-Range Weather Forecasts) • NCEP/NCAR(National Centers for Environmental Prediction, National Center for Atmospheric Research) • Oceans – http://reanalysis.org/ocean/overview-current-reanalyses • NCEP CFSR (Climate Forecast System Reanalysis)

  6. Applications • Climate Model Intercomparisons Bias with respect to ERA-40, averaged over 1980-2000 ACCESS = Australian Community Climate and Earth System Simulator

  7. Potential Issues • Data Assimilation/Filtering/Interpolation Methods: 4-dimensional variational analysis (4D-var) vs other approaches. • Treatment of uncertainties (Gaussian) • http://earth.esa.int/dragon/D5_L1_Elbern.pdf

  8. Potential Issues • What observational data are used? ERA-Interim: Dee et al., QJRMS 2011, Fig 10

  9. ERA-Interim Ozone Measurements ERA-Interim: Dee et al., QJRMS 2011, Fig 15

  10. Total Column Ozone

  11. ERA-Interim Surface Pressure Surface Pressure ERA-Interim: Dee et al., QJRMS 2011, Fig 17

  12. Other Reanalyses of Interest • MACC (Monitoring Atmospheric Composition and Climate) http://www.gmes-atmosphere.eu/d/services/gac/reanalysis/macc • 20th Century Reanalysishttp://www.esrl.noaa.gov/psd/data/20thC_Rean

  13. Useful Resources • Downloading data – local servers (e.g. NCI) vs remote servers (e.g. http://apps.ecmwf.int/datasets) • Data viewers (e.g. Panopoly for HDF, GRIB, NetCDF - http://www.giss.nasa.gov/tools/panoply) • Web-based Reanalysis Intercomparison Tools (WRIT) - http://reanalyses.org/atmosphere/writ • NCO Tools http://nco.sourceforge.net

  14. Useful Resources • Climate Atlases – e.g. MERRA (Modern Era Retrospective-analyses for Research Applications) http://gmao.gsfc.nasa.gov/ref/merra/atlas/menu.php • Climate Explorer http://climexp.knmi.nl • Climate Data Library http://iridl.ldeo.columbia.edu • Climate Reanalyserhttp://cci-reanalyzer.org • Local Resources

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