I promised a list of what scares me (beyond spiders and ice climbing) when homogenizing temperature time series. As our focus is limited to temperatures, I will not worry with changes in variances, extremes, etc. The list:
1) Multiple changepoints
2) Seasonal features, especially those typically present in daily data
3) Autocorrelation
4) Missing and/or erroneous data
5) Mean misspecification, e.g., not accounting for a trend
6) Multiple reference series
Missing data is usually just a programming hassle, so maybe it shouldn't make this list. All of these issues have been tackled in the changepoint/homogenization literature to some degree, but I do not know of a reference where all issues are considered in tandem.
Purpose - To facilitate use of a robust, independent and global common benchmarking and assessment system for temperature data-product creation methodologies to aid product intercomparison and uncertainty quantification:
http://www.surfacetemperatures.org/benchmarking-and-assessment-working-group
Posting and comments are open for constructive advice and ideas.
Thursday, 27 January 2011
Kate's Pseudo-worlds work
I've uploaded a document describing the pseudo-worlds onto our website. I have created these as part of some work with Lisa Alexander, her post-doc Marcus and Peter Thorne to help us design/choose a suit of homogenisation algorithms for creating daily global datasets. I'm happy to provide this data to anyone that is interested and the 'solutions'. It could certainly be improved but may be a useful example/starting point for the benchmarks we're designing here. Hopefully, as it is used, its strengths/weaknesses will become apparent. I've started this thread as a place for people to comment their thoughts/advice on this work.
Tuesday, 18 January 2011
Benchmarking and Assessment Open Comment - January
Welcome to the Benchmarking and Assessment Working Group's work space. This post is open to everyone to comment freely about anything relating to benchmarking and assessment. Full details of who we are, our aims and our progress to date can be found here: http://www.surfacetemperatures.org/benchmarking-and-assessment-working-group.