Abstract
Results of previous studies support the existence of a spatially coherent, secularly varying climate signal, propagating through a network of synchronized climate indices across the Northern Hemisphere during the 20th century. The signal was identified in both instrumental and proxy data sets. In this present study, we seek to detect this same low-frequency signal propagating hemispherically through networks of model-simulated climate indices. These simulated climate indices were reconstructed from a data set generated by models of the third Coupled Model Intercomparison Project (CMIP3). Methods used in the earlier studies on climate-signal propagation guide the strategy for this companion study, for which 60 network analyses were performed. Most analyses focused on 20th century behavior, several on pre-industrial conditions. None succeeded in reproducing a hemispherically propagating signal. In light of previous results, we offer possible reasons for this finding. Among them is speculation on whether mechanisms relevant to signal propagation might be missing from this suite of general circulation models.
Highlights
Recent work using instrumental data of the 20th century suggests that a spatially coherent, low-frequency climate signal propagates across the Northern Hemisphere (Wyatt et al 2011)
Authors of this 2011 paper analyzed a lagged covariance structure of a network of eight climate indices. Their results detailed the transmission of a multidecadal-scale climate signal propagating throughout the Northern Hemisphere through a sequence of synchronizeda atmospheric and lagged oceanic teleconnections. The authors termed this signal propagation the ‘stadium wave’ - a term alluding to the behavior often seen in a sports arena, where successive groups of spectators stand with arms raised, and sit, giving the visual impression of a wave passing through the crowd
We show plots of reconstructed components (RCs) of the indices for each of seven modes of variability
Summary
Recent work using instrumental data of the 20th century suggests that a spatially coherent, low-frequency climate signal propagates across the Northern Hemisphere (Wyatt et al 2011) Authors of this 2011 paper analyzed a lagged covariance structure of a network of eight climate indices. Their results detailed the transmission of a multidecadal-scale climate signal propagating throughout the Northern Hemisphere through a sequence of synchronizeda atmospheric and lagged oceanic teleconnections. Proxy data sets, while longer, are inherently noisy, thereby adding challenge to statistical significance assessment These points made, it is hard to ignore the pervasiveness of multidecadal (~50 to 70-year) fluctuations identified in records of diverse, and perhaps indirectly related indices: from numerous and varied climate-related parameters These points made, it is hard to ignore the pervasiveness of multidecadal (~50 to 70-year) fluctuations identified in records of diverse, and perhaps indirectly related indices: from numerous and varied climate-related parameters (e.g. Kushnir 1994; Minobe 1997, Minobe 1999; Klyashtorin and Lyubushin 2007; Frolov et al 2009 and references therein; Nowak et al 2011; Chambers Don et al 2012) to cadenced variations in commercial-fish populations (Beamish and Bouillon 1993; Beamish et al 1997, 1999; Chavez et al 2003; Klyashtorin 1998; Klyashtorin and Lyubushin 2007; Klyashtorin et al 2009), cosmogenic nuclide accumulations (Ogurtsov et al 2002; Patterson et al 2004), geomagneticfield intensity (Courtillot et al 2007, Roberts et al 2007), Earth’s rotational-rate anomalies (Beamish et al 1999; Sidorenkov et al 2005; Sidorenkov 2005, Sidorenkov 2009), and solar-related aurora records of the mid-latitudes (Scafetta 2011)
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