Monday, October 5, 2020

September global surface TempLS up 0.095°C from August.

The TempLS mesh anomaly (1961-90 base) was 0.837deg;C in September vs 0.742°C in August. This rise was less than the rise in the NCEP/NCAR reanalysis base index, which was 0.203°C. The UAH satellite data for the lower troposphere also rose more, by 0.14°C.

It was the warmest September in the TempLS record; next was 2016 at 0.781°C.

Again N Siberia and the adjacent Arctic Ocean was very warm. There was also warmth in the Near East, including E Mediterranean, and in Antarctica. There was a cool region in Central Asia; N America was split between a warm West and cool central and East. S America was warm.

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


  1. Thank you for the new report, Nick.
    I wonder if you have noted and can comment on the the contrast between the recent monthly anomalies from NCEP/NCAR and other surface based series (like NOAA), and UAH as regards the difference between the northern and southern henisphere? While UAH reports almost identical anomalies for NH and SH, the surface series report the NH about 0,5-1,0 C warmer than the SH.
    Simarly, if you plot a 3 month period (ie. june, july, august) for NOAA, land and ocean, the northern hemisphere for 2020 comes out as the warmest, at 1.17 C, while the southern hemisphere is only 0.67 C and at place.
    Could this be a 'nartural' phenomenon, that temepratures in the troposphere are more mixed and anomalies more venly distributed, or it is an artefact for example related to the reference values? Best regards T.Klemsdal, Oslo, Norway.

    1. As I have been occasionally mentioning, Karsten has been warning of recent aberrant behaviour of the NCEP/NCAR data. It seems to me to be more settled in Aug/Sep.

      I give a regional breakdown of anomalies and their contribution to global anomaly here. I have now added NH and SH as regions. The plot shown is not so meaningful here, but if you click through (bottom arrows) two places, it shows the anomalies for the last seven months for NH, SH, land, sea and globe. Alternatively, that plot is here.

      It shows that earlier in the year, the NH anomaly was much higher than SH, but the gap has closed more recently. It widened to about 0.16°C in September (NH warmer). Generally warmer months reflect mainly warmer land, and so warmer NH.

      I think the difference between UAH and surface based measures like TempLS and GISS/NOAA etc may be that the latter use SST, where satellites not only measure air temperature, but air at considerable altitude, so they don't have the stabilising effect of SST.

    2. Thank you for interesting comments. I realize there may be special issues regarding NCEP/NCAR and the SH, but the much more pronounced warming is also present for other series, like GISS (se for instance this graph ), where the gap really starts around 2000.
      Perhaps UAH has an issue here in the opposite direction, RSS anomalies for the last 4 months reports around 0,2 to 0,3 degrees lower temperatures in the southern hemsiphere compared to the northern.
      RSS TLT SH
      2020 5 0.6291
      2020 6 0.6766
      2020 7 0.5851
      2020 8 0.5920
      2020 9 0.7307

      RSS TLT NH
      2020 5 0.9873
      2020 6 0.8485
      2020 7 0.8907
      2020 8 0.9426
      2020 9 0.9981

      T. Klemsdal