>Here is the methane concentration graph the from the Soywa flask. Missing data is indicated by -999.99.

Yes. It seems they had updated the file. 1987 is missing and 1988 had too -999.99 It took me a little longer but I basically get the same results as you:


The mean temperatures at Syowa are very stable at around -10 degrees. So now it would be interesting to see the water temps in Syowa's vicinity.