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Tuesday, April 12, 2016

The HadSST error was an error and has been fixed

Sou | 2:13 PM Go to the first of 10 comments. Add a comment
A couple of weeks ago I wrote about how John McLean thought he found an error in HadSST data, and how no-one else who looked could find the same error (except for some "missing data" notations that Zeke Hausfather noticed). Well it turns out there were some errors - in the files (not the data - see below). I found out from WUWT that there's an update on the HadSST website:
08/04/2016: An error in the format of some of the ascii files was brought to our attention by John McLean. Maps of numbers of observations and measurement and sampling uncertainties provided in ascii format ran from south to north rather than north to south as described in the data format. This has now been fixed. In some cases, the number of observations in a grid cell exceeded 9999 and were replaced by a series of asterisks in the ascii files. This too has been fixed with numbers of observations now represented as integers between 0, indicating no data, and 9,999,999, indicating lots of data.
So if you've been using HadSST lately, you might want to check the data.


Update


After someone said that Nick Stokes and Zeke Hausfather should apologise, Nick Stokes points out why no apology is warranted and has clarified what the error was and what in the original claim was wrong:
April 11, 2016 at 11:31 pm
So lets see if Nick and Zeke would like to apologize and say they were wrong

No, we were not wrong. The original claim of John McLean, on which Josh’s cartoon was based, was:

“1 – Files HadSST3-nh.dat and HadSST3-sh.dat are the wrong way around.
About 35% down web page https://crudata.uea.ac.uk/cru/data/temperature/ there’s a section for HadSST3. Click on the ‘NH’ label and you go to https://crudata.uea.ac.uk/cru/data/temperature/HadSST3-nh.dat, which has ‘nh’ in the file name. But based on the complete gridded dataset that data file is for the Southern Hemisphere, not the Northern. The two sets are swapped. The links to named files are correct but the content of those files is wrong, likely due to errors in the program that created these summary files from the SST3 gridded data.”

We both checked it. That claim was wrong. The two sets were not swapped. The contents of
https://crudata.uea.ac.uk/cru/data/temperature/HadSST3-nh.dat
and the SH version were correct, and have not been changed. The key link is
But based on the complete gridded dataset…
JM did a calc based on the ascii gridded set, interpreting the format as per the guide, got something different, and asserted that the .dat files were wrong. But they aren’t. His calc went wrong, not through his fault. The latitudes were listed in the opposite order to what was stated in the guide. HAD has corrected what made it go wrong.

The thing is that people commenting here mostly not only did not check themselves, but don’t know what the files being talked about are. The ascii grid output files which contained the error are obsolete. Hadley now produce a netCDF version which do not have these format issues, and are what serious researchers use. So JM’s claim
the content of those files is wrong, likely due to errors in the program that created these summary files from the SST3 gridded data
is wrong on two counts. The file content was not wrong, and there was no way that it would have been generated by someone reading the ascii files.

The issues (2 and 3) on observation counts (order and format overflow) were not disputed at any stage, and Hadley has corrected them. As JM said:
The HadSST3 observation count problems won’t be used by many people, maybe I’m even the first if no-one else has hit the problems.”
Added by Sou at 5:07 pm AEST  12 April 2016

10 comments:

Chris Philips said...

AGW is clearly "settled" science. Can you prove it?

Sou said...

Can you be more specific Chris? Are you asking about the greenhouse effect?

About the only people who talk in blanket terms about "settled science" are the fake sceptics. Some science is settled, some is not, otherwise there'd not be any scientific research in any field.

In climate science, the greenhouse effect was demonstrated more than 150 years ago and published in 1861. Modern thermodynamic theories evolved over time from the late 1700s. Fluid dynamics has a long history. The Navier-Stokes equations were formulated in the 1800s.

The proof of climate science is in the evidence. The world is getting hotter, as expected.

For comparison: In biology, genetic inheritance was documented shortly after Tyndall's 1861 paper on CO2. In regard to evolution, Darwin's On the Origin of Species was published in 1859. Almost 40 years later, in 1897 the electron was discovered, which led to a proposed model of the atom.

So which part of "AGW" are you asking is "settled science"?

DavidR said...

As it happens March 2016 HadSST3 figures have just been published: http://www.metoffice.gov.uk/hadobs/hadsst3/

At 0.687, it's a new record warmest March. Temperatures were also up compared to February.

I download these data most months and the only change this month from last is a slight increase in the February figure, up from 0.604 to 0.611. (It's not unusual for the previous month or couple of months' values to be changed slightly in any of the HadCRU data sets.)

So while we have to credit John McClean for his hawk-eyed attention to detail, it appears that the error did not in any way affect the global picture in HadSST3.

Sou said...

Thanks, DavidR.

I've added an update which is a comment by Nick Stokes. He points out what was corrected, as well as what was wrong with the original claim.

Nick Stokes said...

I've added some clarifications. Apparently the temperatures were OK at all times. The numbers for coverage were listed in the opposite order in the grid, and this was reflected in the hemisphere files. Coverage numbers aren't used for any common purpose.

John McLean added his own clarification here:
"Try looking at the coverage from (a) the HadSST3-nh.dat file and (b) calculated from the gridded data. (I didn’t make it clear enough that coverage was the issue when I emailed Bishop Hill.)"
The parenthesis is an understatement.

Sou said...

Thanks, Nick.

Harry Twinotter said...

Why does Chris Philips handle point back to the Pacific Maritime Magazine website?

Probably just another shill making up their monthly quota of posts.

Millicent said...

If climate change deniers want any claim they make to be taken seriously by the larger community then they need to cut all the crap that represents their daily activity. Thing is, that means they would all have been silent for the past five years or more.

metzomagic said...

Millicent is right. There's always one niggly little point or another they have issue with, and then when they have been proven to be wrong on that point, they just move on to their next niggly little point. There's no accountability, no ownership taken about being wrong/trying to improve their... um... so-called skeptical abilities.

Hank Roberts said...

> Why does Chris Philips handle point back
> to the Pacific Maritime Magazine website?
Look at the caption on the video -- they have a "Dynamic Under Keel Clearance Project" working on making more navigable water between the bottom of their boats and the ocean floor.

Bet they're counting on sea level rising?