Analysis of the Moberg et al. (2005) hemispheric temperature reconstruction
2008 (English)In: Climate Dynamics, Vol. 31, no 7-8, 957-971 p.Article in journal (Refereed) Published
The Moberg et al. (Nature 433(7026):613–617, 2005. doi:10.1038/nature03265; M05) reconstruction of northern hemisphere temperature variations from proxy data has been criticised; the M05 method may artificially inflate low-frequency variance relative to reality. We test this assertion by undertaking several pseudoproxy experiments in three climate model simulations—one control run and two forced simulations that include several time-varying radiative forcings. The pseudoproxy series are designed to have the same variance spectra as the real M05 proxies, primarily to mimic the low-resolution character of several series. A simple composite-plus-scale (CPS) method is also analysed. In the CPS case all input data behave like annually resolved proxies. The spectral domain performance of both M05 and CPS is found to be dependent on the noise type and noise level in pseudoproxies, on the variance spectrum of the climate model simulation, and on the degree of data smoothing. CPS performs better than M05 in most investigated cases with the control run, but leads to deflated lowfrequency variance in some cases. With M05, low-frequency variance tend to be inflated for the control run but not for one of the forced runs and only very slightly with the other forced simulation. Hence, the M05 approach does not routinely
inflate low-frequency variance. In our experiment, the M05 approach performs better in the spectral domain than CPS when applied to forced climate model simulations. The results underscore the importance of evaluating the variance spectrum of climate reconstructions.
Place, publisher, year, edition, pages
2008. Vol. 31, no 7-8, 957-971 p.
Paleoclimatology, temperature reconstruction, pseudoproxies, northern hemisphere, variance spectrum
IdentifiersURN: urn:nbn:se:su:diva-13596DOI: doi:10.1007/s00382-008-0392-8ISI: 000260370300014OAI: oai:DiVA.org:su-13596DiVA: diva2:180116