El Nino triggering mechanism: High-resolution climate model study focusing on coastal upwelling and high mountains

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We conducted numerical model experiments to confirm a hypothesis that coastal upwelling along New Guinea (NG) coast can strengthen westerly wind burst, which is important for trigger of El Nino. Using a high resolution global ocean-atmosphere coupled climate model (SINTEX-F2), we confirmed that El Nino that coast upwelling preceded (NG coastal upwelling preceding type El Nino) was found in 150-year output. Furthermore, we conducted regional atmosphere model (iRAM) experiment in the western Pacific as a case study in boreal winter of 2001/2002, which is just before the 2002/03 El Nino event. The results show contribution of sea surface temperature horizontal gradient due to NG coastal upwelling for the enhancement of westerly wind.