Thursday, 29 June 2017
Salon A-E (Marriott Portland Downtown Waterfront)
In recent years, the winter circumglobal teleconnection pattern (CTP), a stationary zonal wavenumber 5 pattern which dominates the subseasonal monthly mean meridional wind variability (Branstator, 2002), was found to be closely linked to various weather and climate phenomena, including North American cold spells and droughts, as well as winter precipitation anomalies over the Eastern Mediterranean (Harnik et al., 2016; Feldstein & Dayan, 2008). A trend reminiscent of the CTP also appears to be a large-scale response of the upper tropospheric wind to GHG forcing in CMIP3 and CMIP5 model projections (Brandefelt & Kornich, 2008; Simpson et al., 2015), however with considerable model spread in magnitude. In this study, we explicitly examine the CTP dynamics by comparing different CMIP5 models, in both historical and future runs. Models are categorized into distinct groups based on the spatial patterns of variability produced and their likeliness to the observational CTP internal mode. Accordingly, we relate model differences to the temporal behavior and frequency of these stationary wave patterns and to the spread of projected circulation trends in the ensemble.
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