August 2017, G. Gollan (ggollan@geomar.de)

This directory contains files, data and links to data to reproduce Gollan and Greatbatch (2017), "The relationship between northern hemisphere winter blocking and tropical modes of variability".

This directory contains:

1) The model output used in the paper for the experiment CLIM-TROPICS (CT), where the tropical atmosphere is relaxed towards ERA-Interim data in the ECMWF IFS model, cycle 40r1 (see link below). The variable given in the NetCDF files is daily mean potential temperature on the PVU=2 level that is needed to compute the daily binary blocking index as described in the paper. This variable is a standard output from the ECMWF model.
Furthermore there are 9 ensemble members, differing in their initial conditions by taking initial conditions from ERA-Interim in 6-hourly intervals from the beginning of November.

2) The MATLAB function blocking_frequency_theta.m, written by the first author, to compute the 2D binary blocking index, following the methodology of Woollings et al (2008), the methodolgy being described in the manuscript in detail.

Links:

ERA-Interim Reanalysis data on PVU=2 level can be found under:
http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=pv/

ERA-Interim on pressure levels, to compute the U150 index (zonal mean zonal wind at the 150hPa level):
http://apps.ecmwf.int/datasets/data/interim-full-daily/levtype=pl/

Documentation of the ECMWF model, cycle 40r1, can be found under:
https://www.ecmwf.int/en/forecasts/documentation-and-support/changes-ecmwf-model/cycle-40r1/cycle-40r1

MJO RMM index (by Wheeler and Hendon, 2004):
http://www.bom.gov.au/climate/mjo/graphics/rmm.74toRealtime.txt

SST data (used to compute the NINO3.4 index):
https://www.ncdc.noaa.gov/data-access/marineocean-data/extended-reconstructed-sea-surface-temperature-ersst-v3b