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  • RAOBCORE/RICH
    Version 1.5.1

    January 2012

    • New visualization utility for RAOBCORE and RICH adjusted global radiosonde dataset now available:

    RAOBCORE-Visualization

    RAOBCORE and RICH homogeneity adjustments for upper air temperatures from the global radiosonde network. The homogeneity adjustments are required for serious analysis of the upper air climate of the past decades and may be used also for improving the data input for climate data assimilation efforts (often called reanalyses) such as ERA-40 or ERA-Interim.

    The adjustment process has two steps:
    1) Detection of shifts in existing radiosonde observation time series
    2) Estimation of the size of the shifts through comparison with suitable reference series.

    Breakpoints in observed radiosonde temperature time series are detected through time series analysis of innovation statistics from ERA-40 (1958-2001) and of the operational data assimilation process (2002 onwards). This means that background forecast time series have been used as reference for break detection. The rationale for this approach is documented in an ERA-40 project report Haimberger (2005) and in Haimberger (2007) (J. Climate). An update employing ERA-Interim analysis feedback data has recently been submitted to J. Climate [pdf].

    The background forecast time series serve well as a reference for break detection but once the breakpoints are known, there are several options for breaksize estimation. We have implemented two options so far:

    RAOBCORE

    One is to use again the background forecasts as reference. This has been done in the RAOBCORE homogenization method.

    The current version of radiosonde temperature adjustments is v1.5.1 It basically consists of a single ASCII-file containing the stationIDs and all the adjustments and adjustment dates on 16 pressure levels for 00GMT and 12GMT. The adjustments can be added to the original datasets to yield homogenized time series.

    A RAOBCORE- v1.5 adjusted temperature anomaly dataset with 10x5 degree resolution can be downloaded as ftp://srvx7.img.univie.ac.at/pub/v1.5.1/raobcore15_gridded_2011.nc
    It covers the period 1958-2011. For some users it may be of interest to have also the raw gridded radiosonde data, which are available as ftp://srvx7.img.univie.ac.at/pub/v1.5.1/raobcore_raw_gridded_2011.nc


    RICH

    Using the background forecasts as reference has the disadvantage that the forecasts themselves may be influenced by biases in the radiosonde temperatuers. They may also be influenced by biases from other observing systems, most notably satellites. This problem can be avoided by creating reference series from neighboring radiosonde stations for breakpoint adjustment. This works well as long as the radiosonde network is not too sparse and as long one takes care that only homogeneous pieces of the neighboring time series are used. RICH is superficially documented in Haimberger, Tavolato and Sperka (2008). A more detailed documentation has been submitted to J. Climate in Nov 2011 and is available on request [pdf].

    A gridded NetCDF formatted RICH-adjusted radiosondet dataset based on RAOBCORE v1.5 can be downloaded as
    ftp://srvx7.img.univie.ac.at/pub/v1.5.1/rich15obs_mean_gridded_2011.nc This file is based on RICH-obs, which uses composites of neighboring observations for break adjustments.

    The mean of RICH-tau (v1.5) that uses composites of innovations can be found at ftp://srvx7.img.univie.ac.at/pub/v1.5.1/ens/rich15tau_mean_gridded_2011.nc.

    Other formats of RAOBCORE- and RICH adjusted data

    The RICH datasets above are means of 32 realizations of RICH based on one realization of RAOBCORE. One can download individual ensemble members of RICH-obs and RICH-tau from ftp://srvx7.img.univie.ac.at/pub/v1.5.1/ens/

    Station time series with monthly and daily resolution are available on request from leopold.haimberger(at)univie.ac.at

    Acknowledgements

    The development of RAOBCORE and RICH has been financially supported by Austrian Science Funds (FWF) projects P18120-N10, P21772-N10 and by the 5th and 7th EU framework program, notably research project "ERA-CLIM" (2011-2013).

    Selected Publications

    Department of Meteorology and Geophysics
    University of Vienna

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