This document describes the data used for the paper "The weakening of summer circulation in the Northern Hemisphere mid-latitudes", Science, 2015 (in review) by Dim Coumou, Jascha Lehmann, and Johanna Beckmann.
CMIP5 data
The CMIP5 data was downloaded from the official Earth System Grid Federation (ESGF) data nodes. For each model EKE is calculated from daily windfield data (u-wind and v-wind) using a 2.5-6 day bandpass filter. This outputs netCDF files containing monthly u2syn and v2syn, where u2syn and v2syn denote the squared synoptic component of the zonal and meridional wind, respectively. Monthly EKE is defined as 0.5 * (u2syn + v2syn).
The output from the bandpass filter is not available online due to its large amount of required disc space, but can be supplied upon request. Please see contact information below.
The spatial resolution of this output is equivalent to the model’s original longitude-latitue grid. For further processing all model results were interpolated onto the same 2.5° x 2.5° grid using cdo commands.
Similarly, cdo commands were also used to create monthly averages of daily zonal winds and to interpolate these monthly zonal winds onto a unique 2.5° x 2.5° grid for direct analyses of the zonal wind.
To derive the trend and corresponding p-values of linear regression analyses applied in this study, we used the standard lm()-function in the programming language R.
ERA-Interim
The ERA-Interim data (daily u-wind and v-wind) was downloaded from the official ECMWF website on 01-24-2014. We downloaded the version with resolution of 1.5° x 1.5°.
Further data processing was conducted equivalently to the CMIP5 data.
The output from the bandpass filter can be found here.
NCEP-NCAR
The NCEP-NCAR data (daily u-wind and v-wind) was downloaded from the ESRL website on 05-06-2014. The resolution of the data is 2.5° x 2.5°.
Further data processing was conducted equivalently to the CMIP5 data.
The output from the bandpass filter can be found here.
For further questions regarding the data or data processing please contact Dim Comou or Jascha Lehmann.
