1. The role of the eastern tropical Pacific on typhoon activity associated with different types of El Niño Ray Bell Supervisors: Prof. P.L. Vidale, Dr. Kevin Hodges, Dr. Jane Strachan Thanks to Hillary Weller and Eric Guilyardi

2. PhD 1)How does the El Niño Southern Oscillation (ENSO) influence global tropical cyclone activity? 2)What is the role of the eastern tropical Pacific on typhoon activity associated with different types of El Niño. 3)What is the response of tropical cyclones to climate change?

3. Different types of El Niño Ashok et al 2007 Wang el 2007 1951, 1957, 1965, 1972, 1976, 1982, 1987, 1997 1969, 1991, 1994, 2002, 2004

4. Different types of El Niño Various definitions: e.g. Kug et al (2009) EP-EN NINO3 > NINO3std & CP-EN NINO4 > NINO4std Kao and Yu (2009) combined regression–EOF Ren and Jin (2011) new Niño indices, piecewise linear combination of the Niño3 and Niño4 indices Kug and Ham (2011) EP-EN DJF SSTa norm NINO3 > 1 & NINO3>NINO4 CP-EN DJF SSTa norm NINO4 > 1 & NINO4>NINO3 (& _20W) Distinctly different types of ENSO, or whether there is one type of ENSO with variability in its location?

5. Typhoon activity associated with different types of El Niño Kim et al 2011 Pradhan (2011) Jin (2013)

6. Drivers of Typhoon activity associated with different types of El Niño Wang et al (2013) Kim et al (2011)

7. Drivers of Typhoon activity associated with different types of El Niño Chen and Tam (2011) Baroclinic model (dynamic core of the Geophysical Fluid Dynamics Laboratory AGCM, T42) Heating anomaly experiments Day 30 are shown as the steady responses. heating profiles imposed at σ = 0.5 and the 850-hPa anomalous winds CP-EN EP-EN

8. Modelling typhoon activity associated with different types of El Niño Jin et al (2013) Hong et al (2012) CP-EN minus EP-EN ECHAM5, T42 6-member ensemble Global-exp and WNP-exp, observed global monthly SSTA pattern (CP-EN minus EP- EN) and local SSTA pattern in WNP Local SST is important WRF RCM with 50-km horizontal Remote SST is important

9. Idealised GCM simulation HiGEM UK’s High-Resolution Global Environmental Model (Shaffrey et al, 2009) HiGAM: AMIP (atmospheric model forced with observed SST and sea ice) 1979-2002 (Strachan et al, 2011) 1.25 o x0.83 o, ∆x 50N = 90 km 1/3 o ocean model HiGEM 1.1 CTRL 150 yrs HiGEM CTRL ~5x30 yrs N144

10. 1) Locate and track all centres of high relative vorticity  35000/yr 2) Apply a 2-day filter to the tracks  8000 storms / yr 3) Analyse vertical structure of storm for evidence of warm-core (tropical storm structure)  120 storms / yr Tracking algorithm (TRACK; Bengstton et al, 2007) A 20 year time-slice of GCM simulated tropical storms

11. Different types of El Niño in HiGEM EP-EN DJF SSTa norm NINO3 > 1 & NINO3>NINO4 CP-EN DJF SSTa norm NINO4 > 1 & NINO4>NINO3 (& _20W) Kug and Ham (2011)

12. Ideas for experiments Hill et al (2011) Spencer et al (2003)

13. El Niño experiments Tukey filter

14. Tropical cyclone density

15. Tropical cyclone genesis

16. Walker circulation Kim (2011)

17. Upper-level circulation

18. Precipitation

19. OLR Pradhan (2011)

20. Vertical wind shear Kim (2011)

21. Steering flow and GPH Jin (2013)

22. Relative humidity Kim (2011)

23. Discussion and conclusion HiGEM-HiGAM simulates TCs moving towards SE Asia in CP-EN, similar to previous studies For the CP-EN, TC activity is dominated by SST in the tropical eastern Pacific. The pattern strengthens in the case of the tCP-EN experiment. The influence is mainly through strengthening the anomalous cyclonic response in the Philippine sea. For the EP-EN local SST is (most/just?) as important as the warm SSTs in the tropical eastern Pacific. SSTs are cooler in the WPAC during EP-EN compared to CP-EN. The influence is through a change in local thermodynamic parameters (RH); Steering flow is mostly unchanged