Geert Jan van Oldenburgh of KNMI develops and, in his part time, maintains excellent KNMI’s Climate Explorer. I recommend that Curt Covey of PCMDI examine whether they should abandon their own much less satisfactory access points.
Hadley Center as well.
The other day, I was interested in deriving a HadISST monthly tropical average. The data of interest to me was ultimately only a few hundred KB if I were able to download the monthly average – which isn’t available in a pre-calculated form. I started logically enough with the Hadley Center HadISST page, which led me to the download page.
The data of interest sits in a gzipped netcdf file (212 MB). I’m fairly handle with NetCDF and downloaded the file, which expanded to over 400 MB. Unfortunately, the file was too big to read into R in my computer and my R session crashed. I was really only interested in data after 1979 and smaller decadal files were available. These were sizes that I could manage. I wrote a little program to read the files, extract the tropical cells and take a tropical average. So far so good. However, the data proved to be in deg C, rather than anomalies. To get an anomaly, I needed to do it all over again, this time concatenating all the decadal files in order to calculate benchmark averages for each cell.
There was nothing conceptually complicated about it, but it would take another couple of hours to do. In taking these sorts of averages, you have to be careful with your array handling to ensure that you don’t make a mistake.
I remembered that Bob Tisdale had plotted some HadISST results and I was 100% certain that he hadn’t gone through this sort of elaborate exercise. Sure enough he’d used KNMI – which I’d used for extracting model data, but hadn’t thought of for HadISST.
Off to the KNMI Climate Explorer webpage. I quickly located the HadISST series, set the radio buttons to extract the TRP data and got the required anomaly series about 40 seconds later. The data handling was done on KNMI’s big computer using tested programs and only the data of interest was sent over the internet.
Another bouquet for Geert Jan’s excellent program.
And if anyone from Hadley Center or PCMDI reads this thread, suck it in and link to KNMI.