Coupled and Uncoupled Model Simulation of the Global ENSO-TC Teleconnection Ray Bell With thanks to Kevin Hodges, Pier Luigi Vidale, Jane Strachan and Malcolm Introduction Motivation It is important to evaluate the ability of GCMs to simulate realistic ENSO associated TC teleconnections for seasonal forecasting and before predictions are made for TCs and climate change using GCMs (Mori et al. 2013). Lack of studies on simulated ENSO-TC teleconnection worldwide. Research Objectives What are the advantages and shortcomings of the simulated ENSO-TC teleconnection? Are the key mechanisms well represented in the simulation? Previous work Observations The influence ENSO on TC activity has long been observed (NATL, Gray 1984; WPAC, Chan 1985; AUS, Nicholls 1975) Reanalysis NCEP (50-05) GPI. Camargo (2007) Previous work GCMs First research by Wu and Lau (1992) at resolution R15. Understanding simulation of the ENSO-TC teleconnection in the NATL Shaman and Maloney, 2011: CMIP3 GCMs coarse resolution (~2 o x 2 o ) Impacts of ENSO on Caribbean vertical wind shear were the most poorly simulated Murakami and Wang, 2010: AGCM 20 km Captured the broad tropical cyclone response to ENSO in the North Atlantic Recent AOGCM students: Iizuka and Matsuura (2008; 2009) ; Kim et al (2013); Wang et al (2013) Idealised GCM simulation HiGEM UKs High-Resolution Global Environmental Model (Shaffrey et al, 2009) HiGAM: AMIP (atmospheric model forced with observed SST and sea ice) (Strachan et al, 2013) HiGAM with HiGEM SST: atmosphere component forced with coupled SST 1.25 o x0.83 o, x 50N = 90 km 1/3 o ocean model HiGEM 1.1 Present-day integration 150 yrs N144 High-resolution climate models: Improved representation of ENSO (Guilyardi et al. 2009) Improved mean-state TC climatology (Strachan et al. 2013) Improved ENSO-teleconnections (Dawson et al. 2012) Tracking Algorithm (TRACK) A 20 year time-slice of GCM simulated tropical storms Bengstton et al (2007); Strachan et al (2013) 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 Genesis through to Lysis ENSO Composites Nio-3.4 normalised SST anomaly for DJF >1 El Nio; DJF