Die gecorrigeerde grafiek die je toont is merkwaardig. De temperatuur voor 1945 (Amerikaanse Marine, machinekamer) vertoonde toch een bias en zou moeten gecorrigeerd?
De gegevens vóór 1945 waren al gecorrigeerd, die erna niet. Er werd namelijk verondersteld dat de Nederlanders, Britten en Japanners al overgegaan waren op de nieuwe techniek, maar dat bleek niet zo.
De uitleg van RealClimate: ,,The Thompson anomaly seems to coincide strongly with the post-war shift back to a mix of US and UK ships, implying that post-war bias corrections are indeed required and significant. This conclusion is not much of a surprise to any of the people working on this since they have been saying it in publications and meetings for years. The issue is of course quantifying and validating the corrections, for which the Thompson analysis might prove useful. The use of canvas buckets by the Dutch, Japanese and some UK ships is most likely to blame, and given the mix of national fleets shown above, this will make a noticeable difference in 1945 up to the early 1960s maybe - the details will depend on the seasonal and areal coverage of those sources compared to the dominant US information.'' (RealClimate)
Verder: ,,Breaking the data up into separate countries' contributions shows that the assumption made in deriving the original bucket corrections—that is, that the use of uninsulated buckets ended in January 1942—is incorrect. In particular, data gathered by ships recruited by Japan and the Netherlands (not shown) are biased in a way that suggests that these nations were still using uninsulated buckets to obtain SST measurements as late as the 1960s. By contrast, it appears that the United States started the switch to using engine room intake measurements as early as 1920. '' (Rayner et al. 2005)
Hieronder de gerefereerde grafiek. Vandaar dus dat alleen na 1945 gecorrigeerd wordt (voor hoofdzakelijk de rode + oranje + donkerblauwe blokjes na 1945).
Gr. Ben
