Ah...

Ah yes. GISTEMP.

Jovial Monk wrote on Aug 16^th, 2017 at 12:12pm:



Yup. And all based on reconstructions performed in the 1990's that are apparently accurate to 2 decimal places all the way back. Absolutely too funny. They probably used climate models which don't hindcast all that well.

Jovial Monk wrote on Aug 16^th, 2017 at 12:27pm:



All what agree?

The models? - Nope.
The "data" sets? - Nope

Just pulling statements out you arse again.

Jovial Monk wrote on Aug 16^th, 2017 at 12:43pm:


And have you ever wondered why?

There is really only ONE reconstructed "data" set. And then HADCRU, GISS etc add there own little algorithms which then gives a little "wriggle" in the "data".

You really do need to study some.

"Astute readers then ask a deeper question: why do different institutions come up with slightly different numbers for the same planet? Although all four science institutions have strong similarities in how they track and analyze temperatures, there are subtle differences. As shown in the chart above, the NASA record tends to run slightly higher than the Japanese record, while the Met Office and NOAA records are usually in the middle.

There are good reasons for these differences, small as they are. Getting an accurate measurement of air temperature across the entire planet is not simple. Ideally, scientists would like to have thousands of standardized weather stations spaced evenly all around Earth’s surface. The trouble is that while there are plenty of weather stations on land, there are some pretty big gaps over the oceans, the polar regions, and even parts of Africa and South America.

The four research groups mentioned above deal with those gaps in slightly different ways. The Japanese group leaves areas without plenty of temperature stations out of their analysis, so its analysis covers about 85 percent of the globe. The Met Office makes similar choices, meaning its record covers about 86 percent of Earth’s surface. NOAA takes a different approach to the gaps, using nearby stations to interpolate temperatures in some areas that lack stations, giving the NOAA analysis 93 percent coverage of the globe. The group at NASA interpolates even more aggressively—areas with gaps are interpolated from the nearest station up to 1,200 kilometers away—and offers 99 percent coverage."

https://www.giss.nasa.gov/research/features/201501_gistemp/

Astute? You?

Jovial Monk wrote on Aug 16^th, 2017 at 1:54pm:


"The third point is how this product differs from similar efforts at GISTEMP, NCDC, and (though not mentioned) the Berkeley Earth project. The basis for GISTEMP and NCDC is GHCN for the majority of their records, so there is a lot of overlap (95% or so), but there are big differences in how they deal with grid-boxes with missing data. GISTEMP interpolates anomalies from nearby grid points, Berkeley uses kriging, while NCDC and CRUTEM estimate global means only using grid boxes with data. Since many missing data points in CRUTEM3 were in the high latitudes, which have been warming substantially faster than the global mean, this was a source of a low bias in CRUTEM3 (and HadCRUT3), when these data products were used to estimate global mean temperature trends. The increase in source data in CRUTEM4, goes some way to remove this bias, but it will likely still remain (to some extent) in HadCRUT4 (because of the sea ice covered areas of the Arctic which are still not included). Another improvement is in how the error bars are being estimated – due to data sparsity, autocorrelation, structural uncertainty, and assumptions in the synthesis. "


http://www.realclimate.org/index.php/archives/2012/03/updating-the-cru-and-hadcr...

You really think there are multiple datasets for Australia etc?

The lack of readings in polar regions means the temperature series seriously understate the global temperature.