Sunday, February 14, 2016

January GISS warmer by 0.02°C

As noted by Olof, GISS reported a small rise in January, from 1.11°C in December, to 1.13°C. As in my previous post, indications for January had been mixed. Satellite indices rose quite strongly. The local NCEP/NCAR index rose by a small amount, but others, such as Karsten's, which are GFS based, showed large reductions. Then TempLS also showed reductions, and also quite inconsistent - TempLS grid down 0.07°C and grid down 0.18°C

For GISS this month, I'll show their polar projection, because as Olof suggests, I think this is the key to the variability.

There are three main features. A big very warm region around the Arctic, but a large cool region around the Antarctic. In the context of present warmth, that cool Antarctic is cold indeed, and probably does more to bring down the temperature than the more intense cold in a band from Europe to China. So the end result depends on how the various indices add up these competing effects, two in regions lacking good coverage. GISS interpolates to give good weighting to the poles, and this boosts the Arctic effect. Normally I would expect TempLS mesh to match that, but apparently this time, it didn't quite. Or maybe it gave more weight to the Antarctic. TempLS grid definitely underweights the poles, and so the Europe cold effect dominates.

On this basis, I think it is likely that NOAA and HADCRUT will show a reduction for January.

To remark on where this stands with El Nino - on past experience the next four months or so are likely to be the peak. So the January rise is rather small. On the other hand, December (and October) had risen quite a lot, so it may just be a broadening of he peak.

Below the fold, I'll show the usual comparison between the GISS flat map and TempLS grid.

Thursday, February 11, 2016

January TempLS surface temperature down 0.07°C

The GHCN data for January is now fairly complete. The TempLS report is here. Unusually, the holdup this time was US data, which is usually first to appear. The headline result is that TempLS mesh is down from 0.97°C (1961-90 base) in December to 0.899°C in January, almost the same as November. TempLS grid showed a greater drop of 0.18°C.

The lead up indicators were mixed. The satellite measures rose quite strongly. The satellite measures rose quite strongly. The Moyhu NCEP/NCAR index showed a small rise of about 0.04°C, as I believe did Weatherbell. But Karsten, based on GFS, had a very large drop of 0.25°C, and for NCEP/NCAR 0.15°C. There is support for a significant drop. I would expect falls in GISS and NOAA, though possibly not quite as large.

The daily NCEP/NCAR helps understand what happened. The first half of Jan was very warm, and then a sudden cooling. Back to very warm in February. It seems qite likely that different measures might get variable results there.

I'll focus this time on the breakdown, which is, as shown in the regular report, here:

It shows the actual area-weighted contributions of each region to the monthly anomaly. Interestingly, SST rose, after a dip in December. But Europe, Australia and Antarctica were well down relative to earlier months, and other regions somewhat more subdued, except Arctic, which was warmer. The Spherical Harmonics map and the stations reporting are in the report. Notable features are a warm Canada and a fairly narrow band of cold stretching from Scandinavia to China, with hot spots either side. Also, of course, El Nino.

Thursday, February 4, 2016

Satellites, surface temperatures up in January

The satellite temperatures for January are out now, and also the Mohyu NCEP/NCAR index. All increased, quite significantly. UAH Ver 6 beta was up by 0.09°C, to 0.54°C. RSS-MSU was up from 0.543 to 0.663°C. In both indices, Jan 2016 was the highest ever, making four such months in a row. However, the jump from Dec to Jan was rather smaller than in 1997/8. I have an eye here on the implications for the RSS "pause". February will have to be a lot warmer (0.88) to erase the pause in that month. OTOH, the January warmth, if sustained, will ensure there are only positive trends after March data.

The NCEP/NCAR index rose from 0.621 to 0.665°C. Again, very warm, but not as big a rise as might have been expected. In fact, the first half of January was very warm indeed, but then came a relatively cool period. February is starting warm again.

Monday, February 1, 2016

Any news on the GWPF International Temperature Data Review?

I mentioned the revised state of this project in September. The project was announced in April. The news page hasn't updated since September. And the submissions seem to remain unpublished.

I'll check back around the anniversary of the announcement in April.

Wednesday, January 27, 2016

The fleeting pause

At WUWT, there is a monthly post (latest here recording the duration of the Pause, which Lord Monckton defines as the maximum time back that a satellite index, RSS, can be found to have trend less than zero. The choice of that index, which measures an average of troposphere temperature by a complex analysis of data from several satellites, is necessary because all of the better known surface temperature indices have rising trends for all recent periods.

So there is lots of cherry picking. You can see what is actually going on in this calculation in the following back trend graph (from this active plotter).

The graph shows, for various indices, the trend from the year on the x axis to present (Dec 2015). You can see the cherry picking in the choice of index. RSS is the lowest green curve. It now has UAH V6 beta for company, but only recently; V5.6, still being published, was up with the surface indices. The Pause starts from the first crossing of the x-axis, which I've marked with a red circle. But you'll see that even so, most of the curve is positive. The excursions below the axis are brief and shallow, and about to come to an end. In fact the shape is not too far from an inverted image of the time series itself. The big temperature peak in 1998 shows as a dip, while the following trough shows as a local peak in trend. That is why the "pause" has persisted - because of the very big 1998 peak which depresses subsequent trends.

I'll show later how the troposphere measures respond strongly but late to an El Nino. So much higher readings are expected in the coming months. But already those curves are rising rapidly, and I expect them to clear the axis within two or three months. In fact, I'll show a fairly easy way of measuring this, in terms of temperatures to come. Specifically:
  • If the January anomaly exceeds about 1.3°C, the Pause is gone. This is unlikely.
  • If the Jan and Feb anomalies exceed on average about 0.77°C, the curve will be above the axis. For reference, the Dec anomaly was 0.543°C. I think this is quite likely.
  • If the first three months exceed 0.59°C on average, that would suffice to extinguish the pause. That is barely above the December value, and I think very likely indeed.
  • If Jan-April exceed 0.5°C, that will also suffice.
I'll explain the arithmetic below the fold.

Saturday, January 23, 2016

History of record warm years.

Last year, I posted plots of the progress of the record warmest year for various datasets. This year, I'll show an update for the three main surface sets. The jump from 2014 to 2015 is among the largest record jumps in at least a century. Here is GISS:

And below the fold, NOAA and HADCRUT:

Thursday, January 21, 2016

GISS and TempLS compared, in December and in 2015.

In my previous post, I noted the record levels reached in both the NOAA and GISS indices in December, and for 2015. In the NOAA report they note that December 2015 exceeded any earlier December by 0.29°C.

In this post, I'll present my usual map comparison between GISS and TempLS mesh in December. But I'll also expand on the continued close association between GISS and TempLS mesh, on one hand, and NOAA and TempLS grid on the other. The plot below shows those timeseries for 2015:

There is a deviation in the first three months, where both GISS and NOAA drifted away. I wonder if it is a concidence that these were the last months before introduction of ERSST4. But otherwise, the pairing, and close tracking of the pairs is very evident.