1. The impact of tropical convection and interference on the extratropical circulation Steven Feldstein and Michael Goss The Pennsylvania State University IUGG, Prague, June 25, 2015

2. Questions: 1. What is the relationship between interference, Arctic sea ice, and tropical convection and how does it impact the extratropical circulation? 2. What is the relative impact of different centers of tropical convection on the extratropical circulation? Methods: Self-Organizing Map (SOM) analysis, Composites, Idealized Numerical Model Data: ERA-Interim Reanalysis, NOAA OLR, NSICD sea ice

3. SOM patterns, trend, and frequency of occurrence Tropical convection Sea Ice 6.5-7.5 day timescale for patterns

4. Poleward Jet Shift in the Northern Hemisphere

5. Lagged-correlations between Arctic sea ice and SOM frequency positive sea ice anomaly leads SOM1 negative sea ice anomaly leads SOM3 positive sea ice anomaly leads AO

6. Zonal-mean zonal wind SOM1SOM3

7. SOM1 (preceded by positive sea ice anomaly) EP Fluxes Zonal wave 1 and 2Zonal wave 3 and above

8. Negative Interference occurs in SOM1 Positive Interference occurs in SOM3 -60 to -45 days-45 to -30 days -30 to -10 days-10 to 0days -60 to -45 days-45 to -30 days -30 to -10 days-10 to 0days

9. Sea-ice concentration anomalies Days -60 to -45 prior to SOM1Days -10 to 0 prior to SOM3 Anomalously high sea ice concentrationAnomalously low sea ice concentration

10. Summary of impact of sea ice

11. Question: What is the relationship between interference, tropical convection, and surface air temperature, sea ice, the stratospheric polar vortex, and the Arctic Oscillation? Stationary wave index (SWI): Defined as the projection of the daily 300-hPa streamfunction onto the 300-hPa climatological stationary eddies.

12. Evolution of 300-hPa streamfunction Positive SWI daysNegative SWI days

13. Evolution of outgoing longwave radiation Positive SWI daysNegative SWI days Enhanced convection

14. Evolution of 2-m temperature Positive SWI daysNegative SWI days

15. Arctic Sea-Ice Concentration evolution Positive SWI daysNegative SWI days Reduced Sea ice

16. Time evolution: OLR  SWI  sea ice  stratospheric polar vortex  AO (for k=1,2)

17. Surface Air Temperature: Constructive interference with and without Warm Pool convection Western Pacific OLR < -0.5 Western Pacific -0.5 < OLR < 0.5 Western Pacific OLR > 0.5

18. Question: What is the extratropical response to individual tropical convection anomalies?

19. -> PNA- -> PNA+ -> PNA- Convective Precipitation

20. Convective heating anomalies

21. Anomalous 0.3σ Geopotential Height (7-10 days) MJO Phase 1El Nino

22. Anomalous 0.3σ Geopotential Height (7-10 days) MJO Phase 5La Nina

23. CONCLUSIONS Interference and changes in Arctic sea ice: Reduced sea ice  constructive interference  enhanced vertical wave activity propagation into stratosphere  deceleration of stratospheric polar vortex  excitation of negative AO. Interference and changes in Warm Pool (WP) tropical convection: Enhanced convection  constructive interference  warming of the Arctic & melting of sea ice  deceleration of the stratospheric polar vortex  excitation of the negative AO MJO phase 1 and El Nino have a similar pattern in tropical convection yet they excite the opposite phases of the PNA (also, between MJO phase 5 and La Nina). Possible Explanation: Competing influences of warm pool (WP) and central Pacific (CP) convection.

24. Implications For medium-range and climate models, if a single tropical convection anomaly is wrong, the extratropical response could be rather inaccurate.

29. MJO Phase 1 Anomalous Convective Precipitation

30. MJO Phase 5 Anomalous Convective Precipitation

31. Correlation between sea-ice area (Barents and Kara Seas) and SOM frequencies

32. Composites of AO index

33. Composite eddy-momentum flux convergence & zonal wind SOM1 synoptic waves planetary-scale waves SOM2 synoptic waves planetary-scale waves SOM3 synoptic waves planetary-scale waves SOM4 synoptic waves planetary-scale waves

34. CONCLUSIONS Four distinct teleconnection (SOM) patterns in the Northern Hemisphere, associated with GHG driving/ENSO and Arctic sea ice (time scale 6.5-7.5 days, driven by storm track eddies) Poleward shift of subtropical jet associated with GHG driving and Arctic sea ice decline GHG driving contributes to poleward shift of eddy-driven jet and Arctic sea ice decline to an equatorward eddy-driven jet shift (implications for AO trend) Up-to 12 month predictability based upon Arctic sea ice Our understanding of inter-decadal variability hinges in part on (1) the dynamics of intraseasonal time scale processes (2) the mechanism by which external forcing (GHG, sea ice) alter the frequency of intraseasonal time scale teleconnection patterns. Impact of SOMs manifested through change in tropical convection.