Newly digitised marine obs for the WW2 period
In January 2006, Defra and NCDC funded the imaging of 250,000 pages of Royal Navy log-books in the National Archives. Second world war logbooks were taken as there are few observations for this period in ICOADS. The imaging was completed in March and the images shipped to NCDC for digitising. We plan to use the new obs. to make updated versions of HadSST2 and eventually HadISST.Over the year following the imaging, NCDC digitised the observations (through their CDMP project). They produced 270 files of observations in a plain-text format. A total of about 1,550,000 obs. The obs cover 1938-9 and 1941-7 (not 1940).
I've processed the obs. through four steps:
- Conversion to IMMA format,
- Ship by ship inspection,
- SST QC and gridding as for HadSST2,
- Simple comparison with previous data: SST, NAT, DAT and SLP.
The results are very promising. The vast majority of the obs. are easily usable, they provide a considerable increase in coverage, and there are some interesting indications of measurement bias, notably for NAT and SST.
The final IMMA files are available here. The scanned images are now available on WSSRD (you will need a WSSRD account to access them).
This work has been written up as Marine observations of old weather, BAMS, 90, 2, 219-230 (February 2009). Further digitisation projects, looking at East-India company observations from 1785-1830 and Royal Navy data from the First World War, are being run over 2007-9 under the auspices of the the ACRE project.