Tuesday, May 3, 2016

April global NCEP/NCAR down by 0.15°C; still fourth warmest month

The NCEP/NCAR index that I calculate from their reanalysis was down by 0.147°C in April, from 0.783°C to 0.636 (anomaly base 1994-2013). That is then down 0.2°C from February, and coolest for 2016, but it still warmer than any month before 2016.

Temperatures have been stable near that average level since about March 10, after some very high earlier peaks. There was this time less warmth in the Arctic (except Greenland), but a broad band of warmth through Siberia, Eastern Europe, into Africa. Cold in NE Canada; patchy in Antarctica.

Among other reports, Karsten has GFS surface down from 0.794°C to 0.706°C. Roy Spencer has UAH 6 lower troposphere down slightly, from 0.73 to 0.71°C. ENSO numbers are down, and if you watch the ENSO movie of recent weeks, you can see the equatorial jet turning to cool.

Friday, April 29, 2016

GWPF inquiry anniversary.

Just over a year ago, the GWPF announced an inquiry into global temperature adjustments. There would be a panel of experts, chaired by Professor Terence Kealey. It was exuberantly promoted in the Telegraph - "Top Scientists Start To Examine Fiddled Global Warming Figures". Terms of reference were promulgated, and submissions called for, deadline June 30th. I made a submission, and wrote more about the process here.

As said there, the GWPF did mount a news page here. About three weeks after the submissions deadline, the panel said that they would not write a report, but would aim to write papers etc. The last update here was Sept 29, 2015.

So after a year, what has happened? Nothing more to report. The inquiry web pages are still up; submissions have not been published. No further news.

I have been reporting occasionally on progress; maybe I'll report again on the next anniversary, unless there is news in the meantime. But it sure doesn't sound like they have found those "Fiddled Global Warming Figures".

Friday, April 22, 2016

Averaging temperature data improves accuracy.

I've been arguing again at WUWT. It's a bizarre but quite interesting thread. There is a contrarian meme that asks how global averages can be quoted to maybe two-decimal accuracy, when many of the thermometers might have resolved to just one degree. I tried to deal with that here, showing that adding noise of 1°C amplitude to monthly averages made very little difference to the global average.

But the meme persists, and metrology handbooks get quoted - here a JGCM guide. But the theory quoted is for a single measurement, where repeated measurements can't overcome lack of resolution. But that isn't what is happening in climate. Instead a whole lot of different measurements are averaged.

Of course, averaging does improve accuracy. That's why people incur cost to obtain large samples. In this post, I'll follow my comment at WUWT by taking 13 months of recent daily max in Melbourne, given by BoM to 1 decimal place, and show that if you round off that decimal, emulating a thermometer reading to nearest degree, the difference to the monthly average is only of order 0.05°C; far less than the reduction in resolution. But first, I'll outline some of the theory.

Wednesday, April 20, 2016

NOAA Global index still rising - new record.

Most indices dropped slightly from record February values. But as expected, the global NOAA index held up, and was even slightly warner, at 1.22°C vs 1.19 in Feb. That is the highest anomaly in the record for any month.

I'll show my now usual comparison with 1997/8::

There is a maintained collection of these plots that you can flick through here. In 1998, March fell back from the Feb peak, but here it has risen. HADsst3 is out too, with a rise, which is interesting. February SST dropped, causing some chatter about rapid El Nino decline, but this was premature. I'll show the comparison below the fold.

Saturday, April 16, 2016

March GISS down 0.06°C - hottest March in record.

GISS in March is out. The global average anomaly was 1.28°C; down 0.06°C from Feb, but by a long way the warmest March in the record (Sou has details, note the YTD map). The result is very close to TempLS mesh, which now shows a 0.04°C drop. TempLS rose quite a lot since announced; commenter Olof thinks that Sudan data pushed it up. The NCEP/NCAR index also dropped by 0.057°C.

Here is a plot of the comparison with 1998. In that year, March dropped a lot from the February peak, but then recovered somewhat.

I'll show the world GISS map below the fold. It shows the same general pattern as TempLS; a band of warmth from Europe through Russia to the East, and another through Alaska to central Canada, plus Arctic. General warmth in Africa, Australia and Brazil. Colder spots in Labrador, Argentina, Antarctica and the N Pacific.

Friday, April 8, 2016

Surface TempLS down 0.086°C in March, still second hottest

TempLS mesh, reported here (as of 8 April, 4359 stations), was down from 1.074°C in Feb to 0.988 in March (base 1961-90). This is comparable to the drop in the TLT satellite indices, and greater than the NCEP/NCAR index (0.057). TempLS grid dropped by only 0.037°C, which is similar to NCEP/NCAR. The TempLS anomaly is the second highest in the record, after February.

The spherical harmonics map is here:

Again unusually warm in Russia and most of N America (except Labrador strait region). Not so warm in Arctic, cold in Antarctica, and also cool in N Pacific.

The reason for the grid-mesh discrepancy is again the different coverage of the events at the poles. Both cooled, and the mesh algorithm covers that better. So GISS may well drop more than NOAA and HADCRUT.

Wednesday, April 6, 2016

Checking my NCEP/NCAR integration

Following my report of my integration of the NCEP/NCAR V1 reanalysis during March, commenter Steven D perceptively noticed a discrepancy with the ESRL PSD corresponding numbers. I'll talk more about these, as I hadn't been systematically using hem for checking, and they are useful. Anyway, the discrepancy wasn't huge - 0.782°C instead of 0.755, but it wasn't just integration error. It was natural to suspect a leap year problem.