MJO Influence on Subseasonal-to-Seasonal Prediction in the Northern Hemisphere Extratropics

• Published in: Journal of Climate
• Main Authors: Kim, Hera, Son, Seok-Woo, Kim, Hyemi, Seo, Kyong-Hwan, Kang, Min-Jee
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Meteorological Society 2023
• Subjects: MADDEN-JULIAN OSCILLATION; FORECAST ERRORS; PART I; TELECONNECTIONS; MECHANISMS; SKILL; PNA; PROPAGATION; PERFORMANCE; MODELS; Hindcasts; Operational forecasting; Subseasonal variability; North Atlantic
• Online Access: https://hdl.handle.net/10371/204968; https://doi.org/10.1175/JCLI-D-23-0139.1

The impacts of the Madden-Julian oscillation (MJO) on the subseasonal-to-seasonal (S2S) prediction in the Northern Hemisphere extratropics are examined using the reforecasts from the S2S Project and Subseasonal Experi-ment Project (SubX). When forecasts are initialized during an active MJO, extratropical prediction skill becomes signifi- cantly higher at 3-4-week windows compared to inactive MJO. Such prediction skill improvement is evident in the 500-hPa geopotential height over the Pacific-North America region and the North Atlantic and in surface temperature over North America, especially when the model is initialized during the MJO phases 6-7 and 8-1. However, the extratropical predic-tion skill is not modulated by the MJO phases 2-3 and 4-5. This phase dependency is likely determined by the arrival time of the MJO at the Maritime Continent (MC) barrier that substantially enhances the MJO amplitude error. This result sug-gests that only MJO phases whose convection lies east of the MC are a source of wintertime S2S predictability in the extratropics. N 1