Rossby wave breaking RWB

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Rossby wave breaking (RWB)

• Definition
• Detection / Measurement
• Climatology
• Dynamics
• Impact on internal variability (NAO / NAM)
• Impact on surface turbulent heat flux (PDO)

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Definition
- Wave amplitude reaches critical level -
Irreversible overturning of isentropic potential
vorticity
350 K Potential Vorticity, 1-8 July 1998
PVU
Data NCEP / NCAR Reanalysis
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Detection / measurement
Anticyclonic RWB
Cyclonic RWB
PVU
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Climatology DJF 1958-2006
Antic Cycl
contours are relative frequency shading is zonal
extent
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Climatology 1958-2008
Relative frequency
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Rossby wave breaking (RWB)

• Definition
• Detection / measurement
• Climatology
• Dynamics
• Impact on internal variability (NAO / NAM)
• Impact on surface turbulent heat flux (PDO)

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Dynamics

• Impact on internal variability (NAO / NAM)
• Forces the background flow via, primarily, eddy
  momentum flux convergence
• Generates surface pressure anomalies
• Impact on surface turbulent heat flux (PDO)
• Generates coherent, 3D circulations associated
  with temperature and moisture anomalies

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Forcing of background flow
Hoskins et al. (1983)

• Look at composite divergence of E fields around
  hundreds of RWB centroids

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SLP
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Regions where RWB forces NAO
Pos. Neg.
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Dynamics

• Impact on internal variability (NAO / NAM)
• Forces the background flow via, primarily, eddy
  momentum flux convergence
• Generates surface pressure anomalies
• Impact on surface turbulent heat flux (PDO)
• Generates coherent, 3D circulations associated
  with temperature and moisture anomalies

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Pacific Decadal Oscillation
Leading pattern of extratropical Pacific sea
surface temperature variability
cool
warm
Data NOAA ESRL SST V2
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Pacific Decadal Oscillation
Anticyclonic and cyclonic RWB
Alexander et al. (2002) Journal of Climate
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Anticyclonic RWB Composite of 200 randomly
Selected winter cases
Negative indicates into the ocean
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Cyclonic RWB Composite of 200 randomly
selected winter cases
Negative indicates into the ocean
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RWB Variability (EOFs)
All four patterns are significantly correlated
with the current and future PDO (e.g., January)
Relative frequency
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Effect of Cyclonic Dec-Jan RWB
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Effect of Cyclonic Dec-Jan RWB
200 randomly selected cases
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Effect of Cyclonic Dec-Jan RWB
200 randomly selected cases
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Effect of Anticyclonic Jul-Aug RWB
200 randomly selected cases
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RWB Variability (EOFs)
All four patterns are significantly correlated
with the current and future PDO (e.g., January)
Relative frequency
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Statistical Model of PDO using RWB

• Cross validation
• Stepwise
• bootstrapping
• Model any
• month

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Rossby wave breaking (RWB)

• Definition
• Detection / Measurement
• Climatology
• Dynamics
• Impact on internal variability (NAO / NAM)
• Impact on surface turbulent heat flux (PDO)

www.ess.uci.edu/cstrong
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Rossby wave breaking
- Wave amplitude reaches critical level -
Irreversible overturning of isentropic potential
vorticity
PVU
PVU
350 K, July 1998, NCEP / NCAR Reanalysis data
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Cyclonic Rossby wave breaking
Potential vorticity on the 350-K surface, January
2003
PVU
PVU