Trends in Northern Hemisphere storm tracks and teleconnections and their linkage to Greenhouse-gas increase, tropical convection and sea ice Steven Feldstein and Sukyoung Lee The.
Download ReportTranscript Trends in Northern Hemisphere storm tracks and teleconnections and their linkage to Greenhouse-gas increase, tropical convection and sea ice Steven Feldstein and Sukyoung Lee The.
Trends in Northern Hemisphere storm tracks and teleconnections and their linkage to Greenhouse-gas increase, tropical convection and sea ice Steven Feldstein and Sukyoung Lee The Pennsylvania State University December 6, 2012 Poleward Jet Shift in the Northern Hemisphere Sea Ice/Global Mean Temp (GHG) Global Mean Temp (GHG) Sea Ice 6.5-7.5 day timescale for patterns SOM patterns, trend, and frequency of occurrence 6.5-7.5 day time sclae Composites of AO index Correlations between SOM frequencies and global-mean temperature (high- and low-frequency) and Nino3.4 index Negative (positive) lags: sea-ice leading (lagging) SOM frequency Lagged-correlations between Arctic sea ice and SOM frequency Global-mean temperature, SOM1 & SOM4 frequency, Nino3.4 index Unfiltered and low-frequency 7-year cutoff High-frequency Red: global-mean temp, Blue SOM2 freq, Green SOM4 freq, Black Nino 3.4 index Anomalous zonal wind associated with SOM patterns SOM1 SOM2 SOM3 SOM4 Anomalous OLR associated with SOM Patterns SOM1 SOM2 SOM3 SOM4 Composite eddy-momentum flux convergence & zonal wind SOM1 synoptic waves planetary-scale waves SOM2 synoptic waves SOM3 synoptic waves planetary-scale waves planetary-scale waves SOM4 synoptic waves planetary-scale waves Storm Track Climatology and Trend CONCLUSIONS • Four distinct teleconnection (SOM) patterns in the Northern Hemisphere, associated with GHG driving/ENSO and Arctic sea ice (time scale 6.5-7.5 days, driven by storm track eddies) • Poleward shift of subtropical jet associated with GHG driving and Arctic sea ice decline • GHG driving contributes to poleward shift of eddy-driven jet and Arctic sea ice decline to an equatorward eddy-driven jet shift (implications for AO trend) • Up-to 12 month predictability based upon Arctic sea ice • Our understanding of inter-decadal variability hinges in part on (1) the dynamics of intraseasonal time scale processes (2) the mechanism by which external forcing (GHG, sea ice) alter the frequency of intraseasonal time scale teleconnection patterns. • Impact of SOMs manifested through change in tropical convection.