Global Temperature falls 0.15C in October

The global average temperature anomaly for October was 0.706C, which is a fall of 0.15C from September. This reduces the annual average so far to 0.9C  leaving 2020 still slightly higher than 2016. However the uncorrected data (without pair-wise homogenisation) leave 2020 just below 2016. My calculation of the global temperature anomaly is based on GHCN V4 and HadSST3 using a 3D spherical triangulation method and a baseline of 1961-1990.

Global average temperatures (anomalies) where 2020 is averaged over 10 months. The green points are the uncorrected temperature data

The monthly data below shows a large drop in temperatures  for October

Monthly average temperatures V4U is the uncorrected GHCN V4 data and V4C the corrected version using pair-wise homogenisation.

The spatial distribution below shows lower than average temperatures across North America., Central Asia and Western Europe. Blue colours show temperatures below the 1961-1990 average for October.

Spatial temperatures in the Northern Hemisphere

There were also cooler ocean temperatures in the Southern Hemisphere.

I have noticed an interesting effect of the pair-wise homogenisation process. Recent months seems to show a large divergence between the corrected and uncorrected GHCN V4 results. However this difference slowly decays with time so that past differences reduce. This is because the corrected data from previous months and years also slowly change as the homogenisation algorithm is rerun each month. This seems to produce a self correcting process tending to reduce strong discrepancies. over time.

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4 Responses to Global Temperature falls 0.15C in October

  1. Ron Clutz says:

    Clive, thanks for the update. I noticed the same thing in the HadSST report:

  2. Euan Mearns says:

    Hi Clive, shortly after lockdown began I have been observing a significant change to cloud cover here in Aberdeen (and also in Zurich this summer). Virtually every day when it is not raining I see beautiful formations of high alto cirrus and / or alto stratus clouds. They seem to be close to the tropopause. My wife says its my imagination. I was wondering if you or any of your readers may have made similar observations?

    • Clive Best says:

      Hi Euan,
      We also have had a string of clear days down here in Cambridgeshire. There is indeed always some high level cirrus cloud with low sunshine
      I can’t really say whether that is unusual or not.

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