Visualize the HadCRUT5 temperature datasets

HadCRUT5 is a gridded dataset of global historical surface temperature anomalies relative to a 1961-1990 reference period. Data are available for each month from January 1850 to December 2018 (updates will be available in time), on a 5 degree grid. The dataset is a collaborative product of the Met Office Hadley Centre and the Climatic Research Unit at the University of East Anglia.

HadCRUT5 data has now been updated to include data to the year 2020 in HadCRUT.5.0.1.0, available from the download page.

— source: HadCRUT5 Index

Stations on land are at different elevations, and different countries calculate average monthly temperatures using different methods and formulae. To avoid biases that could result from these differences, monthly average temperatures are reduced to anomalies from the period with best coverage (1961-90).

— source: HadCRUT5 FAQ-5

Datafiles that are loaded by the Python script:

• HadCRUT.5.0.1.0.analysis.summary_series.global.annual.nc
• HadCRUT.5.0.1.0.analysis.summary_series.northern_hemisphere.annual.nc
• HadCRUT.5.0.1.0.analysis.summary_series.southern_hemisphere.annual.nc

HadCRUT5 data taken from: https://www.metoffice.gov.uk/hadobs/hadcrut5/data/current/download.html

Plot of the temperature anomalies

The following plots have been generated by the Python scripts hadcrut5-plot.py and hadcrut5-bars.py. They require the Python libraries: Matplotlib, netCDF4, NumPy, and Requests.

hadcrut5-plot.py — Script usage

$ ./hadcrut5-plot.py --help
usage: hadcrut5-plot.py [-h] [-f OUTFILE] [-p PERIOD] [-m SMOOTHER] [-g] [-n] [-s] [-a ANNOTATE] [-v]

Parse and plot the HadCRUT5 temperature datasets v.2 (stable)
Copyright (C) 2020-2022 Davide Madrisan <[email protected]>
License: GNU General Public License v3.0

options:
  -h, --help            show this help message and exit
  -a ANNOTATE, --annotate ANNOTATE
                        add temperature annotations (0: no annotations, 1 (default): bottom only, 2: all ones
  -f OUTFILE, --outfile OUTFILE
                        name of the output PNG file
  -g, --global          plot the Global Temperatures
  -m SMOOTHER, --smoother SMOOTHER
                        make the lines smoother by using N-year means
  -n, --northern        Northern Hemisphere Temperatures
  -p PERIOD, --period PERIOD
                        show anomalies related to 1961-1990 (default), 1850-1900, or 1880-1920
  -s, --southern        Southern Hemisphere Temperatures
  -t TIME_SERIES, --time-series TIME_SERIES
                        do plot the "annual" time series (default) or the "monthly" one
  -v, --verbose         make the operation more talkative

examples:
  hadcrut5-plot.py
  hadcrut5-plot.py --global --annotate=2
  hadcrut5-plot.py --period "1850-1900"
  hadcrut5-plot.py --period "1850-1900" --smoother 5
  hadcrut5-plot.py --period "1880-1920" --outfile HadCRUT5-1880-1920.png
  hadcrut5-plot.py --period "1880-1920" --time-series monthly --global

hadcrut5-plot.py select the period 1961-90 by default but supports (see the command-line switch--period) two other base periods found in the literature: 1850-1900, and 1880-1920.

$ ./hadcrut5-plot.py --annotate=2 --outfile plots/HadCRUT5-1961-1990.png

$ ./hadcrut5-plot.py --annotate=2 --period "1850-1900" --outfile plots/HadCRUT5-1850-1900.png

$ ./hadcrut5-plot.py --annotate=2 --period "1880-1920" --outfile plots/HadCRUT5-1880-1920.png

Plots using the N-year mean data

By adding the command-line option --smoother N you can create the same three plots, but using the N-year means data. For instance --smoother 5 will get you a better idea of the trend lines.

Image generated for the anomalies related to the period 1880-1920.

$ ./hadcrut5-plot.py --period "1880-1920" --smoother 5 --outfile plots/HadCRUT5-1880-1920-smoother.png

Plots using the monthly mean data

The command-line option --time-series monthly selects the monthly HadCRUT5 datasets (by default the dataset providing the annual means is selected).

Image displying the monthly anomalies related to the period 1880-1920, for the global temperatures only.

$ ./hadcrut5-plot.py --global --period "1880-1920" --time-series monthly

hadcrut5-bars.py — Script usage

usage: hadcrut5-bars.py [-h] [-f OUTFILE] [-p PERIOD] [-v]

Parse and plot the HadCRUT5 temperature datasets v.2 (stable)
Copyright (C) 2020-2022 Davide Madrisan <[email protected]>
License: GNU General Public License v3.0

options:
  -h, --help            show this help message and exit
  -f OUTFILE, --outfile OUTFILE
                        name of the output PNG file
  -p PERIOD, --period PERIOD
                        show anomalies related to 1961-1990 (default), 1850-1900, or 1880-1920
  -v, --verbose         make the operation more talkative

examples:
  hadcrut5-bars.py
  hadcrut5-bars.py --period "1850-1900"
  hadcrut5-bars.py --period "1880-1920"
  hadcrut5-bars.py --outfile HadCRUT5-global.png

The image for to the anomalies related to the period 1880-1920 follows.

$ ./hadcrut5-bars.py --period "1880-1920" --outfile plots/HadCRUT5-global-1880-1920.png