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Rossby wave breaking (RWB)

Rossby wave breaking (RWB). Definition Detection / Measurement Climatology Dynamics Impact on internal variability (NAO / NAM) Impact on surface turbulent heat flux (PDO). Definition. - Wave amplitude reaches critical level - Irreversible overturning of isentropic potential vorticity.

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Rossby wave breaking (RWB)

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  1. Rossby wave breaking (RWB) • Definition • Detection / Measurement • Climatology • Dynamics • Impact on internal variability (NAO / NAM) • Impact on surface turbulent heat flux (PDO)

  2. 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

  3. Detection / measurement Anticyclonic RWB Cyclonic RWB PVU Centroid of low-P lobe

  4. Climatology: DJF 1958-2006 Antic Cycl contours are relative frequency shading is zonal extent

  5. Climatology 1958-2008 Relative frequency:

  6. Rossby wave breaking (RWB) • Definition • Detection / measurement • Climatology • Dynamics • Impact on internal variability (NAO / NAM) • Impact on surface turbulent heat flux (PDO)

  7. 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

  8. Forcing of background flow Hoskins et al. (1983) • Look at composite divergence of E fields around hundreds of RWB centroids

  9. SLP

  10. Regions where RWB forces NAO Pos. Neg.

  11. 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

  12. Pacific Decadal Oscillation Leading pattern of extratropical Pacific sea surface temperature variability “cool” “warm” Data: NOAA ESRL SST V2

  13. Pacific Decadal Oscillation Anticyclonic and cyclonic RWB Alexander et al. (2002) Journal of Climate

  14. Anticyclonic RWB Composite of 200 randomly Selected winter cases D Negative indicates into the ocean

  15. Cyclonic RWB Composite of 200 randomly selected winter cases U Negative indicates into the ocean

  16. RWB Variability (EOFs) All four patterns are significantly correlated with the current and future PDO (e.g., January) Relative frequency:

  17. Effect of Cyclonic Dec-Jan RWB

  18. Effect of Cyclonic Dec-Jan RWB 200 randomly selected cases

  19. Effect of Cyclonic Dec-Jan RWB 200 randomly selected cases

  20. Effect of Anticyclonic Jul-Aug RWB 200 randomly selected cases

  21. RWB Variability (EOFs) All four patterns are significantly correlated with the current and future PDO (e.g., January) Relative frequency:

  22. Statistical Model of PDO using RWB • Cross validation • Stepwise • bootstrapping • Model any • month

  23. Rossby wave breaking (RWB) • Definition • Detection / Measurement • Climatology • Dynamics • Impact on internal variability (NAO / NAM) • Impact on surface turbulent heat flux (PDO)

  24. Rossby wave breaking - Wave amplitude reaches critical level - Irreversible overturning of isentropic potential vorticity PVU PVU 350 K, July 1998, NCEP / NCAR Reanalysis data

  25. Cyclonic Rossby wave breaking Potential vorticity on the 350-K surface, January 2003 PVU PVU

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