Implication of Stratospheric Vortex Intensification on Climate Variability

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Implication of Stratospheric Vortex
Intensification on Climate Variability

• Kumar Jeev
• (kjeev_at_coastal.edu)
• Coastal Carolina University
• Conway, South Carolina
• Faculty Mentor Dr. Var Limpasuvan

• Aim Does the stratosphere affect the
  troposphere ?
• NAO and the Stratosphere Vortex
• Tools Methods
• Stratosphere NAO Index Composites
• Wind and Temperature Anomalies
• Conclusions

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The NAO High Phase

• Stronger subtropical high
• Deeper Icelandic Low
• Increased pressure difference
• Stronger storms move north
• Warm wet winters in Europe
• Cold dry winters in Canada
• Mild wet winters in East US
• Intense vortex (circumpolar winds in
  stratosphere)

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The NAO Low Phase

• Weak subtropical high
• Weak Icelandic low
• Less Pressure difference
• Fewer storms move west
• Mediterranean is moist
• Northern Europe is cold
• US east cost is cold snowy
• Weak stratospheric polar vortex

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Previous Study Stratosphere-Troposphere
Connection

• Limpasuvan Thompson in prep

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Tools Indices
Numerical description of phase/vortex
strengths The NAM Index High Phase gt greater
than 0 Low Phase gt less than 0
The Stratosphere Vortex Index Strong Vortex gt
greater than 0 Weak Vortex gt less than 0
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Tools NCEP Reanalysis Data (daily 1958-2002)
Variables air temperature vwnd meridian
wind uwnd latitudinal wind
NP
air
vwnd
lev
uwnd
Parameters Latitude Longitude Height (Lev) Time
(Date)
SP
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Methods Lead-Lag Composite

• Event Selection (25 events)
• Selecting time intervals
• greater than 10 days
• with stratospheric index gt 1
• ending within that winter (not ending in late
  spring)
• The midday and 30 days before and after it form
  your event
• Zonal Averaging
• Sweeping the globe (average around latitude
  circle)
• Compositing
• Averaging over the 25 events
• Finding Anomaly
• Anomaly (Variable value) (Climatological
  variable value)

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Index Average Comparison over an event
-30 -15
0 15
30
-30 -15
0 15
30
? 60 days ?
? 60 days ?
The Stratosphere Index
The NAO Index
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Temperature Anomalies
Onset Mature
Decay
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Wind Anomalies
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Conclusions and Future Work
uwnd
latitude
time

• Stratospheric vortex intensification leads to the
  NAO High
• Wind and Temperature anomalies descend from upper
  stratosphere to middle troposphere during
  intensification
• We are still looking into wave structure related
  to intense vortex
• Momentum and Heat Fluxes
• Wave forcing
• We intend to use Global Climate Model to study
  the NAO and its relationship with the
  Stratosphere vortex

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Comments ! or Questions ?