ATM525Summary - University at Albany
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Transcript ATM525Summary - University at Albany
Stratosphere-Troposphere
Coupling and Links with
Eurasian Land Surface
Variability
Cohen 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
Method
Uses three metrics to diagnose relationship:
1. Wave Activity Flux:
2. October Eurasian snowcover extent
Uses 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
2013
2013 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
2013
As 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 0.816
Where does this rank vs other years?
2013
Once again, this is still very new research and the firstever 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
[email protected]
630.337.1999