This repository contains python- and R-scripts to calculate Arctic amplification metrics and figures presented in Rantanen et al. (2022) manuscript "The Arctic has warmed nearly four times faster than the globe since 1979"
The dataset for producing the charts and graphs of the manuscript is reposited in public repository at http://doi.org/10.23728/fmi-b2share.5d81ded56e984072a5f7162a18b60cb9. The instructions to produce the data are below.
With these instructions you can post-process the observational datasets to calculate the Arctic amplification diagnostics. You need CDO software (https://code.mpimet.mpg.de/projects/cdo) and python version 3+. You can calculate the datasets by yourself by following these steps, or just download them from links given below.
BEST: http://berkeleyearth.lbl.gov/auto/Global/Gridded/Land_and_Ocean_LatLong1.nc
HadCRUT5: https://www.metoffice.gov.uk/hadobs/hadcrut5/data/current/analysis/HadCRUT.5.0.1.0.analysis.anomalies.ensemble_mean.nc
GISTEMP: https://data.giss.nasa.gov/pub/gistemp/gistemp1200_GHCNv4_ERSSTv5.nc.gz
ERA5 1950-1978: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels-monthly-means-preliminary-back-extension?tab=overview
ERA5 1979-2021: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels-monthly-means?tab=overview \
cdo -mergetime input1 input2 output
3. Regrid the datasets into 0.5° horizontal resolution (this will take couple of hours for all the datasets!):
cdo -remapcon,r720x360 input output
a. Calculate climatology
cdo -ymonmean -selyear,1981/2010 input input-clim
b. Subtract the climatology to get the departures
cdo -sub input test-clim test-anom
python fix_berkeley_earth_timeaxis.py
cdo -L -b F32 -ensmean -selyear,1950/2021 -selvar,temperature BEST-regridded-retimed-anom.nc -selyear,1950/2021 -selvar,tas_mean hadcrut5-regridded-anom.nc -selyear,1950/2021 -selvar,tempanomaly GISTEMP-regridded-anom.nc -selyear,1950/2021 -selvar,t2m ERA5-regridded-anom.nc OBSAVE.nc
Run calculate_observed_aa_trends.py
Run calc_bootstrapCI_temps_obs.R.
Inputs arctic_temps_obs.csv and reference_temps_obs.csv,
output bootstrapCI_temps_obs.csv.
Run merge_hist_scen_cmip6.py
Run calculate_temps_cmip6.py
Run calculate_trends_and_aa_cmip6.py