Sunday, March 10, 2019

February global surface TempLS (with GHCN V4) up 0.033°C from January.

TempLS is in transition from using GHCN V3 (which it has used for the last eight years) to the new GHCN V4. I'll report the V4 mesh results here, but for now, the Moyhu posted data is based on V3. I've been delayed a little because it is timely to also bring out a new version of TempLS (V4). Apart from anything else, the code needs reorganising to handle the bigger datasets smoothly. The Moyhu data page is still reporting values based on V3, as are the various pages with globe maps.

I worried about whether GHCN V4 would report as punctually as V3. But it seems to do better. Their version of 9 March showed 8779 stations reporting, compared with 10653 in January. But unlike V3, where countries report en bloc, here the reporting is spread, so no region is completely missing. I'll show a station map below.

TempLS mesh with V3 GHCN showed a larger rise, from 0.686°C to 0.779°C in February. This was more in line with the rise calculated with NCEP reanalysis. However, the V3 based infilled grid method was in agreement with V4 mesh, as was V4 infilled.

I'll write a post soon with a comparison of the whole V4-based history compared with V3. I'll also post a new version of TempLS which I have been using - I'll call that V4 too. It's mainly a restructuring to deal with the greater memory demands of GHCN V4, and also to include my new approach to handling spherical harmonics enhancement.

The TempLS mesh anomaly (1961-90 base) was 0.746deg;C in February vs 0.708°C in January. That makes it the third warmest February in the (V4-based) record.

The main feature of the month was rather severe cold over western Canada and adjacent US, but with warmth just a little to the North in the Arctic and Alaska. Europe was also very warm. There were patches of cool in the Sahara and western China.
Here is the temperature map.

And here is the map of land and sea stations reporting:

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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