Evaluation of subseasonal impacts of the MJO/BSISO in the East Asian extended summer     

Chang  Chueh-Hsin  Johnson  Nathaniel C.  Yoo  Changhyun 《Climate Dynamics》2021,56(11):3553-3568

The Madden–Julian Oscillation (MJO)/Boreal Summer Intraseasonal Oscillation (BSISO) has been considered an important climate mode of variability on subseasonal timescales for East Asian summer. However, it is unclear how well the MJO/BSISO indices would serve as guidance for subseasonal forecasts. Using a probabilistic forecast model determined through multiple linear regression (MLR) with MJO, ENSO, and long-term trend as predictors, we examine lagged impacts of each predictor on East Asia extended summer (May–October) climate from 1982 to 2015. The forecast skills of surface air temperature (T2m) contributed by each predictor is evaluated for lead times out to five weeks. We also provide a systematic evaluation of three commonly used, real-time MJO/BSISO indices in the context of lagged temperature impacts over East Asia. It is found that the influence of the trend provides substantial summertime skill over broad regions of East Asia on subseasonal timescales. In contrast, the MJO influence shows regional as well as phase dependence outside the tropical band of the main action centers of the MJO convective anomalies. All three MJO/BSISO indices generate forecasts that yield high skill scores for week 1 forecasts. For some initial phases of the MJO/BSISO, skill reemerges over some regions for lead times of 3–5 weeks. This emergence indicates the existence of windows of opportunity for skillful subseasonal forecasts over East Asia in summer. We also explore the dynamics that contribute to the elevated skills at long lead times over Tibet and Taiwan–Philippine regions following the initial state of phases 7 and 5, respectively. The elevated skill is rooted in a wave train forced by the MJO convective heating over the Arabian Sea and feedbacks between MJO convection and SSTs in Taiwan–Philippine region. Two out of the three commonly used MJO/BSISO indices tend to identify MJO events that evolve consistently in time, allowing them to serve as reliable predictors for subseasonal forecasts for up to 5 weeks.

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SPARC Local Workshop on “WCRP Grand Challenges and Regional Climate Change”     

Joowan KIM  Seok-Woo SON  Hye-Jin KIM  Baek-Min KIM  Changhyun YOO 《大气科学进展》2018,35(6):624-627

正1.Overview SPARC(Stratosphere-Troposphere Processes and their Role in Climate)is one of the core projects of the World Climate Research Program(WCRP),coordinating international efforts to address relevant issues in climate and climate prediction via better understanding of the stratosphere-troposphere system.SPARC is a broad umbrella body that  相似文献