Reader John McLean emails with details of some surprising finds he has made in the Hadley Centre's sea-surface temperature record, HadSST. John is wondering whether others might like to take a look and confirm what he is seeing. Here's what he has found:
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.