日本地球惑星科学連合2014年大会

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ポスター発表

セッション記号 A (大気海洋・環境科学) » A-AS 大気科学・気象学・大気環境

[A-AS21_30PO1] 成層圏過程とその気候への影響

2014年4月30日(水) 18:15 〜 19:30 3階ポスター会場 (3F)

コンビーナ:*宮崎 和幸(独立行政法人 海洋研究開発機構 地球環境変動領域)、田口 正和(愛知教育大学)、河谷 芳雄(独立行政法人海洋研究開発機構)、佐藤 薫(東京大学 大学院理学系研究科 地球惑星科学専攻)

18:15 〜 19:30

[AAS21-P06] 気象庁1ヶ月ハインドキャスト実験における予報スキル変動の基本特性

*田口 正和1 (1.愛知教育大学)

This study investigates basic characteristics of stratospheric predictability in the Northern Hemisphere using 1-month hindcast (HC) experiment data of the Japan Meteorological Agency for 1979-2009. We describe characteristics of forecast properties of spread, error (root mean square error), and anomaly correlation, contrasting the stratosphere and troposphere for different seasons, as well as explore the so-called spread-skill relationship for the winter stratosphere. We also examine the role of stratospheric sudden warmings (SSWs) in variations in the forecast skills. Our results show that for lead times shorter than about 10 to 15 days, the forecast skills of the HC data are higher on average and more variable in the stratosphere than in the troposphere especially for Northern winter. This is reflected in larger average and variability in predictable time limit, or characteristic time scale of useful predictions, for the winter stratosphere. We also reveal that the spread-skill relationship for the Northern winter stratosphere is characterized by the existence of notable outliers from their expected linear distribution; the outliers have markedly large errors, or low skills, for given spreads. Most of the outliers are contributed by HC sets initialized before observed major SSWs. Such HC data fail to reproduce the strength and/or shape of the stratospheric polar vortex including both onset and recovery phases of SSWs. The HC data tend to yield too strong vortex and shorter-than-average predictable limit.