著者

HUANG Huei-Ping RAGHUNATHAN Girish Nigamanth

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2022-012, (Released:2021-11-02)

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Retrograde long waves in the higher latitudes of Northern Hemisphere can episodically attain large amplitudes and sustain coherent phase propagation for 2-3 weeks. The potential influence of such waves on extended-range weather forecast has been conjectured but not systematically quantified. Using a set of ensemble reforecast data, this study examines the predictability associated with an extraordinary retrograde-wave episode in the 1979-80 winter. Quantified by the anomaly correlation of 500 hPa geopotential height in the 40°N-70°N latitudinal band, increased week-2 predictability is found within the sub-period with the presence of coherent retrograde waves. Some individual forecasts made within the retrograde-wave event exhibit the behavior of “return of skills”. The results suggest a future investigation into the relation between the uptick of anomaly correlation in week-2 and detailed dynamics of the retrograde waves.