Preface: Third ENSO Conference: findings and key messages

The anomalous warming (cooling) of the surface waters of the tropical Pacific known as El Niño (La Niña) phenomena, with the atmospheric response called Southern Oscillation (ENSO), induces a prominent signal in the inter-annual climate variability in different regions of planet. Therefore, a great attention is paid to the understanding of the processes involved in the genesis and development of these phenomena, as well to the monitoring for supporting climate forecasting and warning systems of the countries. The International Center for Research on El Niño (CIIFEN, acronym broadly used by its name in Spanish language) socializes the scientific knowledge related to ENSO and disseminates information on monitoring and forecasting of tropical Pacific processes, particularly in the Eastern Pacific, in order to support climate prediction in the tropical America. For disseminating the knowledge on ENSO, CIIFEN promotes various initiatives; one of them is the ENSO Conference that has as objective to synthesize the progress of the knowledge on the ENSO, and to socialize it for benefit of the society. In this context, CIIFEN organized the Third International ENSO Conference in November 2014 in Guayaquil (Ecuador). The Third International ENSO Conference was devoted to the main theme “Bridging the gaps between global ENSO science and regional processes: extremes and impacts” and was supported by the World Meteorological Organization (WMO), the World Climate Research Program (WCRP), the Secretariat of Risk Management of Ecuador and the National Institute of Meteorology and Hydrology (INAMHI) of Ecuador. The conference was attended by leading scientists in the study of the dynamics of the tropical Pacific Ocean associated with El Niño and La Niña and the effects and impacts that these phenomena have in different regions of the planet. During the three days of the Third Conference, six sessions (dynamics, climate variability, modeling, regional processes, impacts, and information services), 12 central conferences, 30 oral presentations and 50 posters were presented, with the participation of 20 world-renowned scientists and experts on ENSO, more than 150 attendees, most of them women young scientists, of 20 countries. The progress of specialized knowledge on ENSO was exposed during this Conference and several novel findings were presented. The different presented themes confirmed the complexity and diversity of expressions of oceanic-atmospheric processes associated with ENSO. It was showed, for example, that the zone where El Niño is generated (the sector where the impulse mechanism appears), longitudinally oscillates through the Pacific in an inter-decadal cycle. Using data for the 1950–2010 period, the differences in the evolution and impacts of the “canonical” and “modoki” types of El Niño events were showed, pointing out the difficulties for distinguishing different La Niña types. Mention was made about the fact that the Central Pacific (modoki El Niño) events have occurred frequently over the last three decades, compared to the Eastern Pacific (canonical) events. It was pointed out a relationship between the period of the year when the weakening of the winds happens in the tropical Pacific and the development (or not development) of a specific type of El Niño (modoki or canonical), with particular intensity and climate effects in regions. (As it is broadly known, in the relaxation of the easterlies, the intra-seasonal variability of the ocean-atmosphere system plays a crucial role, but the results presented in the Conference outstand the importance of the moment of the year when it occurs). Another advance presented was the role of the inter-decadal variability as a modulator of the more frequent oscillations (the intra-seasonal waves) involved in the genesis of El Niño and La Niña. The diversity of the processes in eastern Pacific woke special interest of participants. The findings about the effect of climate change on frequency and intensity of ENSO phases presented were subject of special attention as well.