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 350 K Potential Vorticity, 1-8 July 1998 - Wave amplitude reaches critical level - Irreversible overturning of isentropic potential vorticity PVU Data: NCEP / NCAR Reanalysis

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

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

6. Climatology 1958-2008 Relative frequency:

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

8. 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

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

10. SLP

11. Regions where RWB forces NAO Pos. Neg.

13. 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

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

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

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

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

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

19. Effect of Cyclonic Dec-Jan RWB

20. 200 randomly selected cases

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

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

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

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

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

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

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