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報告題目：A Theory for Seasonal Predictability Barrier

報告人：劉征宇 教授（俄亥俄州立大學）

報告人簡介：

劉征宇，1982年畢業(yè)于南京氣象學院獲學士學位，1985年獲中國科學院大氣物理研究所碩士學位，1991年獲美國麻省理工學院和Woods Hole海洋研究所聯(lián)合博士學位。現(xiàn)任美國俄亥俄州立大學地理系氣候動力學Thomas教授，主要從事海-地-氣系統(tǒng)相互作用與氣候動力學、大洋環(huán)流動力學、古氣候模擬及地球系統(tǒng)模擬等方面的研究，其領(lǐng)銜的研究團隊多次在Science、Nature、PNAS等頂級學術(shù)刊物上發(fā)表研究成果。Google Scholar Citation顯示(截止到2021年1月14日)，劉征宇教授有超過17000次引，h指數(shù)為68, i10指數(shù)為249。劉征宇教授同時是美國科學促進會(AAAS)會士、美國氣象學會(AMS)會士和美國地球物理學會(AGU)會士。他曾長期擔任威斯康辛大學麥迪遜分校氣候研究中心主任職務(wù)，擔任美國國家科學基金(NSF)古時研究組成員、CCSM古氣候模擬工作組聯(lián)合主席、氣候變率與可預(yù)測性計劃(CLIVAR)科學指導(dǎo)委員會成員等學術(shù)團體職務(wù)。

Abstract

A theory is developed in stochastic climate models for understanding the general features of seasonal predictability barrier (PB), which is characterized by a band of maximum decline in autocorrelation function phase-locked to a particular season. The theory is first developed in the damped persistence model. Our theory determines the forcing threshold, timing and intensity of the seasonal PB as a function of the damping rate and seasonal forcing. A seasonal PB is found to be an intrinsic feature of a stochastic climate system forced by either seasonal growth rate or seasonal noise forcing. A PB is generated when the seasonal forcing, relative to the damping rate, exceeds a modest threshold. Once generated, all the PBs occur on the same calendar month, forming a seasonal PB. The PB season is determined by the decline of the seasonal forcing as well as the delayed response associated with damping. The intensity of the PB is determined mainly by the amplitude of the seasonal forcing. The theory is able to explain the general features of the seasonal PB of the observed SST variability over the world. The PB theory is further developed in a recharge oscillator model with the application to ENSO seasonal PB in both SST and heat content. Our theory provides a general framework for the understanding of the seasonal PB of climate variability.

時間：2021年04月30日（周五）21:00-23:00

報告方式：騰訊會議，會議號：790 531 659

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