Investigation of methods for hydroclimatic data homogenization

E. Steirou, and D. Koutsoyiannis, Investigation of methods for hydroclimatic data homogenization, European Geosciences Union General Assembly 2012, Geophysical Research Abstracts, Vol. 14, Vienna, 956-1, doi:10.13140/RG.2.2.23854.31046, European Geosciences Union, 2012.

[doc_id=1212]

[English]

We investigate the methods used for the adjustment of inhomogeneities of temperature time series covering the last 100 years. Based on a systematic study of scientific literature, we classify and evaluate the observed inhomogeneities in historical and modern time series, as well as their adjustment methods. It turns out that these methods are mainly statistical, not well justified by experiments and are rarely supported by metadata. In many of the cases studied the proposed corrections are not even statistically significant.

From the global database GHCN-Monthly Version 2, we examine all stations containing both raw and adjusted data that satisfy certain criteria of continuity and distribution over the globe. In the United States of America, because of the large number of available stations, stations were chosen after a suitable sampling. In total we analyzed 181 stations globally. For these stations we calculated the differences between the adjusted and non-adjusted linear 100-year trends. It was found that in the two thirds of the cases, the homogenization procedure increased the positive or decreased the negative temperature trends.

One of the most common homogenization methods, ‘SNHT for single shifts’, was applied to synthetic time series with selected statistical characteristics, occasionally with offsets. The method was satisfactory when applied to independent data normally distributed, but not in data with long-term persistence.

The above results cast some doubts in the use of homogenization procedures and tend to indicate that the global temperature increase during the last century is between 0.4°C and 0.7°C, where these two values are the estimates derived from raw and adjusted data, respectively.

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See also: http://dx.doi.org/10.13140/RG.2.2.23854.31046

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Weblogs and forums that discussed this article during July-September 2012

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  7. Proof that Global Warming is man-made (Daily Pundit)
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Other reactions in weblogs, forums and Internet resources during July-September 2012:

ScientificAmerican * Radio 4 Science Boards * Watts Up With That? (#1) * (#2) * (#3) * topix * Baltimore Sun talk forum * weatherzone (*1) * (*2) * (*3) * Australian Climate Madness * Otago Daily Times * Digital Spy Forums * Musings from the Chiefio * abcforums * faster louder * The Motley Fool * Climate etc. * Catallaxy Files * U.S. News on nbcnews.com * robertstavinsblog * Astromart Forums * f88me.com * Post Bulletin * The Hook * Tulsa World *

Other works that reference this work (this list might be obsolete):

1. #Stockwell, D. R.B., Is temperature or the temperature record rising?, Australian Environment Foundation Conference, Sydney, Australia, 2012.
2. Fleming, S. W., A non-uniqueness problem in the identification of power-law spectral scaling for hydroclimatic time series, Hydrological Sciences Journal, 59 (1), 73–84, 2014.

Tagged under: Climate stochastics, Works discussed in weblogs, Students' works