Sunday, October 12, 2014

New ideas on TempLS reporting - mesh

For over three years now, I've been running my least squares based GMST index TempLS each month and reporting the results, with a second post comparing with GISS. See here and here for last August. The second has past links. I did a mini-review here recently, and there is a new summary of TempLS here.

I'm planning a change. For some time, I've believed that using mesh based weighting (see here and here, for example) is better than what I call grid-based weighting, where observations are weighted on a cell-based density estimate. I was deterred from changing because the mesh generation took a long time, but I've fixed that. I'll persist with the grid model because as I noted, it has uncanny agreement with NOAA, and also tracks HADCRUT well. But I think that it also has the faults of those, in dealing with empty cells. For TempLS it takes the form that stations in empty areas have a capped weight based on the size on one cell, which in the Arctic can be small.

The data cycle goes like this. ERSST posts a preliminary on about 3rd or 4th of month. It's actually complete, and the numbers are little different when updated in late month. GHCN starts the month with a rush of numbers from places with efficient electronic systems, and then stuff trickles in fairly slowly. Lately GHCN (unadjusted) has had early gyrations too. But notwithstanding, I think it is meaningful to to a mesh baed calc as soon as the SST comes in. Mesh is more robust to missing.

I've now posted an automatic report on the latest data page. It shows the current mesh-based report, with maps of temperatures and of reporting stations. I think I can maintain this, reporting with every new GHCN (most days). It would flip to the new month when the SST is posted. Obviously, early figures would be subject to change.

This would supersede my first monthly report on the grid results. I'd still publish the GISS comparison, and record the grid and mesh TempLS results there.

Update. GISS has produced a map for September, and it says the Sept temperature is 0.78°C, up from 0.70°C in August. This tracks the mesh TempLS rise from 0.628°C to 0.673°C (grid TempLS went down slightly). I expect that mesh TempLS will follow GISS more closely. I'll post the GISS comparison soon. The new number is not yet on their datafile. It's getting warm.


  1. 77.

    1. Thanks. I've been watching with Chrome, and it doesn't show. Damn caching. I'll try to write it up in the new style.

    2. Nick - I did the average through last month, and it was 65.25. The changed some of the past anomalies, so I think it's now ticked down a bit from being a warmest month.