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. 2007 Sep 19;104(39):15248–15253. doi: 10.1073/pnas.0702872104

Fig. 4.

Fig. 4.

Simulated and observed spatial patterns of changes in Wo and estimation of detection time (10). Multimodel averages of the 20th century changes in Wo were used to calculate the ALL (A) and ANTHRO (B) fingerprints we search for in the observations. Also shown are the leading noise modes of the concatenated ALL (C) and ANTHRO (D) model control runs and the observed pattern of total linear changes in Wo over 1998–2006 (E). All calculations were performed on the common 10° × 10° latitude/longitude grid used for the fingerprint analysis. The method used for estimation of detection time (F) is illustrated for one specific example, in which Wo changes from both SSM/I data and the concatenated ANTHRO model control runs were projected onto the ANTHRO model fingerprint patterns. We fit trends of increasing length L to the resulting “signal” and “noise” projection time series, Z(t) and N(t), respectively; form a trend S/N as described in SI Text; and then determine the time at which this ratio exceeds and remains above a stipulated 5% significance threshold. This is the detection time. The dashed vertical lines denote the detection times for the raw and optimized fingerprints (1999 and 2002, respectively). In this example, data from the concatenated ALL model control runs were used for fingerprint optimization.