Met Office, HadSST3, CRUTEM3, HadCRUT3, questions over gridded coverage
[update: I used an incorrect mix of datasets, see Talkshop thread here. Corrected PDF and now expanded to include HadCRUT4.
The UK Met Office / Hadley Centre (Met Office) / Climatic Research Unit (UEA) construct and publish global time series for temperature based on published 5 degree gridded. How this is derived from land meteorological station readings and ship board for sea surface temperature is unclear. The gridded to eg. global is a simple (cosine) weighted average which takes into account the variable area of a linear grid representing a sphere.
I have put together maps showing the data counts for decades over a world shore outline. These are provided as vector plots (master work), PDF, or for casual looks, PNG. The results are disturbing and particularly in the light of the Met Office producing 100 different versions of HadSST3. “Each of the following files is a zip archive containing ten realisations of the HadSST3 data set. There are 100 realisations in total.”
Do I detect obfuscation, flapping for distraction?
Image left is the cell over the majority of France, dates 1950..1959. Black squiggle is coastline, red squiggle national border. HadSST3 has 60 months of data. How exactly is the sea temperature used?
Here is another, majority of area is land, not sea.
The situation has improved with time, earlier on there is what looks like highly questionable instances.
I have a database here containing gridded datasets in a common format. An extract from any grid cell can be done, time series. Given the amount of code involved in this whole work treat me as unreliable.
An area of Europe was selected for time series extraction where this includes an abnormal weather event. See http://tallbloke.wordpress.com/2014/09/16/the-snowfall-of-1956/comment-page-1
Plots of grid counts
Master file is the PDF, PNG is only for those who need to use an image, less legible, use save to file. File sizes have been minimised: PDF about 600kB, PNG (3175 x 2246) about 500kB. Full sheet will just print legibly on A3 paper.
With PDF you are expected to use magnify as required.
The last decade is short, 2010..2013, see notes.
There isn’t one. This work is informational where I hope others will step in.
Within reason I can extract data and make it available. The sheer size of data should be kept in mind. there are >2,500 grid cells.
The cutoff at the end of 2013 is pragmatic. At the time of writing the three underlying datasets finish at slightly different dates during 2014. Omission is the easy option, has no material effect on the result.
HadCRUT3:- Met Office
HadSST3:- Met Office
CRUTEM3:- Met Office
Climatic Reserch Unit page on temperature datasets
Images are marked copyright to enable copying, otherwise the situation is in legal limbo which stops strict usage.
Coastal vector data from NOAA GEODAS
The resolution and colour usage in the plots is a compromise. I don’t like visually hitting people in the face, technical work where function comes first. The figures are low key so the shore outline shows through. If one is not legible for PDF magnify more.
Post by Tim