Saturday, April 6, 2019

March global surface TempLS (with GHCN V4) up 0.208°C from February.

This is the first month of full use of the new GHCN V4 land temperature data (unadjusted). It's also using the new version V4 of TempLS, which I will post and describe shortly. The usual report is here, showing the map, the breakdown in regions, and the stations reporting. The detailed WebGL plot is here, and it is a good way of capturing the extra detail available in GHCN V4. It also shows the greater patchiness of the stations, which is partly countered by the greater numbers. It is particularly bad in the US, with so many volunteer stations.

I'm still getting a feel for when is the best time to post. I used to wait until the main countries reported, but with V4 it isn't done by country, and even after four or five days there are a lot of stations with apparently good coverage. But there are still many more stations to come, so there is still the possibility of a late drift. We'll see.

The TempLS mesh anomaly (1961-90 base) was 0.964deg;C in March vs 0.756°C in February. As with the NCEP/NCAR reanalysis index, that makes it a very warm month, especially as February was already warmer than January, and even more so than last November. It was the warmest month since March 2017 (which was just 0.01°C warmer), and the third warmest March in the record.

As with the reanalysis the main features were big warmer areas in Siberia and Alaska/NW Canada, joining up over the adjacent Arctic ice layer. The warmth extended into Europe, especially the East. It was generally cool in the US, and in a belt from Tibet to Egypt.
Here is the temperature map. Southern Africa and Australia were quite warm.

And here is the map of 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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