Wednesday, January 6, 2021

TempLS global surface 2020 just cooler than 2016 (virtual tie).

TempLS December 2020 results are in, and that makes a complete average for 2020. I had calculated that a December average anomaly (1961-90) of over 0.681°C would be enough to make 2020 the hottest year, which seemed quite likely, given the November average was 0.891°C and the lowest month of 2020 to date was 0.704°C. However, December was very cool, at 0.628°C, a drop of 0.263°C. That meant that 2020 averaged 0.852°C, whereas 2016 was 0.857°C. Here is a table of those TempLS anomaly averages:
Nov 20200.891Ave 20160.857
Dec 20200.628Ave 20200.852

The TempLS result is based on 8603 land stations of GHCN V4 which have reported to date, along with ERSST. More (about 800) land stations will post results during January, and this will alter the result a little. An increase of 0.054°C needed to put 2020 ahead is possible, but not very likely. TempLS usually matches GISS NASA fairly well, but given the closeness, whether GISS 2020 comes out ahead is not predictable from this.

The cool December was foreshadowed in the NCEP/NCAR reanalysis tracking, which also showed a drop of 0.263°C. The first part of the month was warm, but after about ten days there was a drop of about 0.4°C, and no recovery.

The main very cool region was over Kazakhstan and parts of Russia nearby, with an extension over Mongolia and into China. The ENSO region of the Pacific coast, and also SE, was cool (La Nina). Elsewhere it was mostly (relatively) warm, especially around the Arctic, extending into Canada and Scandinavia. Most of Europe was warm, and also the Sahara.

Here is the temperature map, using the LOESS-based map of anomalies.

As always, the 3D globe map gives better detail.

This post is part of a series that has now run since 2011. The TempLS mesh data is reported here, and the recent history of monthly readings is here. Unadjusted GHCN is normally used, but if you click the TempLS button there, it will show data with adjusted, and also with different integration methods. There is an interactive graph using 1981-2010 base period here which you can use to show different periods, or compare with other indices. There is a general guide to TempLS here.

The reporting cycle starts with a report of the daily reanalysis index on about the 4th of the month. The next post is this, the TempLS report, usually about the 8th. Then when the GISS result comes out, usually about the 15th, I discuss it and compare with TempLS. The TempLS graph uses a spherical harmonics to the TempLS mesh residuals; the residuals are displayed more directly using a triangular grid in a better resolved WebGL plot here.

A list of earlier monthly reports of each series in date order is here:

  1. NCEP/NCAR Reanalysis report
  2. TempLS report
  3. GISS report and comparison with TempLS


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