reference : Forced and internal components of winter air temperature trends over North America during the past 50 years: Mechanisms and implications

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/reference/3ed9cb1b-ca7f-40f7-be2d-74dd5f2ca113
Bibliographic fields
reftype Journal Article
Abstract This study elucidates the physical mechanisms underlying internal and forced components of winter surface air temperature (SAT) trends over North America during the past 50 years (1963–2012) using a combined observational and modeling framework. The modeling framework consists of 30 simulations with the Community Earth System Model (CESM) at 1° latitude–longitude resolution, each of which is subject to an identical scenario of historical radiative forcing but starts from a slightly different atmospheric state. Hence, any spread within the ensemble results from unpredictable internal variability superimposed upon the forced climate change signal. Constructed atmospheric circulation analogs are used to estimate the dynamical contribution to forced and internal components of SAT trends: thermodynamic contributions are obtained as a residual. Internal circulation trends are estimated to account for approximately one-third of the observed wintertime warming trend over North America and more than half locally over parts of Canada and the United States. Removing the effects of internal atmospheric circulation variability narrows the spread of SAT trends within the CESM ensemble and brings the observed trends closer to the model’s radiatively forced response. In addition, removing internal dynamics approximately doubles the signal-to-noise ratio of the simulated SAT trends and substantially advances the “time of emergence” of the forced component of SAT anomalies. The methodological framework proposed here provides a general template for improving physical understanding and interpretation of observed and simulated climate trends worldwide and may help to reconcile the diversity of SAT trends across the models from phase 5 of the Coupled Model Intercomparison Project (CMIP5).
Author Clara Deser; Laurent Terray; Adam S. Phillips
DOI 10.1175/JCLI-D-15-0304.1
Issue 6
Journal Journal of Climate
Keywords Circulation/ Dynamics,Atmospheric circulation,Atm/Ocean Structure/ Phenomena,Pacific-North American pattern/oscillation,Physical Meteorology and Climatology,Anthropogenic effects,Models and modeling,Climate models,Variability,Climate variability,Trends
Pages 2237-2258
Title Forced and internal components of winter air temperature trends over North America during the past 50 years: Mechanisms and implications
Volume 29
Year 2016
Bibliographic identifiers
.reference_type 0
_record_number 19609
_uuid 3ed9cb1b-ca7f-40f7-be2d-74dd5f2ca113