Stratosphere-Troposphere Coupling and Links with Eurasian Land Surface

VariabilityCohen et. al, 2007: Journal of Climate, 20, 5335-5343

Adam Turchioe 2 Dec 2013 ATM 525

Introduction• Stratosphere-Troposphere annular-mode events

are always preceded by an anomalous lower-stratospheric planetary wave activity flux, but lower-tropospheric wave activity signatures of these events are more difficult to find• Difficulty is due to the variability of the

troposphere in relation to the variability to the stratosphere

• Goal to use these precursors to improve long-term forecasts

MethodUses three metrics to diagnose

relationship:

1. Wave Activity Flux:

2. October Eurasian snowcover extentUses the Robinson/NSIDC dataset

3. January SLP NCEP/NCAR Reanalysis Data

Conclusion•December WAF has a strong center of action over a sector extending from eastern Europe to eastern Asia•This corresponds to the climatologically greatest variance in October snow extent

•The January SLP strongly resembles the Arctic Oscillation (AO)

•The strong relationship (R=0.79, 0.77) between the WAF/SLP and Oct Snow/SLP shows tropospheric conditions can be used to predict stratospheric tropospheric interactions weeks to months in advance

2013

20132013 has had a phenomenally fast start to

snowfall growth.

Total Eurasian snow cover extent is well above the 30-year climatological norm

Results with AO correlation have shown there is a MUCH greater importance with snow growth east of 70°E than west.

Notice how the last 3 weeks of October Asian snow cover anomaly tailed off dramatically, as seen in the weekly 2013 snow anomaly maps:

Week 38 2013 vs 10-Year Avg

Sept 23

Week 39 2013 vs 10-Year Avg

Sept 30

Week 40 2013 vs 10-Year Avg

Oct 07

Week 41 2013 vs 10-Year Avg

Oct 14

Week 42 2013 vs 10-Year Avg

Oct 21

Week 43 2013 vs 10-Year Avg

Oct 28

Week 44 2013 vs 10-Year Avg

Nov 04

2013As a result, any early snowfall positive anomaly

was greatly offset by a very benign rate of increase of snowfall

Also, in order to finalize the remaining slope, used the current 2-week snowfall projection and visually identified the year that most closely matched the expected snowfall pattern (which turned out to be 2002)

Thus, the 2013 Snow Growth Parameter Index number is 0.816Where does this rank vs other years?

2013Once again, this is still very new research and

the first-ever use of this index as a predictor

However, with statistically significant correlation values, this year’s winter appears to be headed towards a positive AO state

Will continue to monitor daily snowfall and verify that 2002 is a good analog year for the next two weeks

Will continue working on getting this index to use the daily snowfall data

Thank you!

Adam Turchioe

University at Albany

1600 Washington Ave Albany, New York 12203

aturchioe@albany.edu

630.337.1999