*Masami Nonaka1
(1.Application Laboratory, Japan Agency for Marine-Earth Science and Technology)
Keywords:mid-latitude, air-sea interaction, extreme events, observation, high-resolution modeling
Frequency of extreme rainfalls and snowfalls has been increasing these years, and those events severely affect human lives and properties. It has been considered that tropical ocean and atmosphere variability as well as the warming climate, remotely influences mid-latitude extreme weather/climate, while the mid-latitude ocean is passive to atmospheric variability. Recent high-resolution ocean/atmospheric data analyses, however, have revealed that mid-latitude ocean also influences atmospheric circulations and their variability. Rediscovering strong warm current and associated strong ocean frontal zones as “climate hotspot”, we have elucidated mechanisms of ocean-atmosphere interactions. The research progress has prompted a new crucial task: application of such new knowledge to predictions of extreme rainfalls/snowfalls and climate variability. For the new task, a research project called “Climatic Hotspot2” with about 70 collaborators has been developed in Japan. In this project, we have conducted studies to further our understandings of mid-latitude ocean-atmosphere interaction processes that span multiple spatio-temporal scales and interplay among them. Also, based on the improved understandings, we investigate predictability of extreme weather (such as typhoons and bomb cyclones), of persistent atmospheric circulation anomalies that induce those extremes, projection of climate changes, and active roles of mid-latitude oceans in those phenomena. In the project, several observation campaigns and also oceanic and atmospheric high-resolution numerical modeling studies have been/will be conducted. In this presentation, we introduce results of the projects in the first two years of its five-year period.