Climate model data

A simple procedure has been developed to remove unphysical temporal discontinuities in ERA-Interim temperature data in the upper stratosphere that have arisen due to changes in satellite radiance data used in the assimilation ^{Footnote 1} . This procedure is applied to the jump in August 1998 discussed in Dee and Uppala (2008) ^{Footnote 2} and also to another large jump in March 1985, which was outside of their analysis period. A set of equations and a tabulated set of coefficients that can be easily used to generate the global-mean temperature adjustments are presented in McLandress et al. (2013) ^{Footnote 1} . Here, the specific 365-day calendar ERA-Interim adjustments used for CMAM30 are available as a time series of global-mean adjustments to the 1, 2, 3, and 5hPa temperature field of the ERA-Interim dataset (NetCDF file and ASCII file). The standard calendar versions with leap years are also available (NetCDF file and ASCII file). The data files extend from 00Z January 1, 1979 to 18Z December 31, 1998 at 6 hour intervals. Note that the temperature adjustments after 1998 are not provided since they are identically zero. Note also that the values of the adjustments provided in these files are not identically equal to the values generated using the set of equations in McLandress et al (2013) ^{Footnote 1} , since the tabulated coefficients provided in that paper were rounded off. These global-mean temperature adjustments are suitable for use in models like CMAM30 that are nudged (i.e. relaxed) to 6-hourly winds and temperatures from ERA-Interim.

For reference, plots of the time series of global-mean temperature adjustments contained in the ERA-interim adjustments files on the four pressure levels are presented in panel (a) below. Time series of the ERA-interim global-mean temperature anomalies on these levels with and without the adjustments are presented in panel (b). In both panels the curves at 2, 3, and 5 hPa are shifted by 10 K with respect to the curve above.