A new nudging scheme for the current operational climate prediction system of the National Marine Environmental Forecasting Center of China

• Published in: Acta oceanologica Sinica Vol. 41; no. 2; pp. 51 - 64
• Main Authors: Song, Xunshu, Li, Xiaojing, Zhang, Shouwen, Li, Yi, Chen, Xinrong, Tang, Youmin, Chen, Dake
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2022; Springer Nature B.V; State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China; Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China%National Marine Environmental Forecasting Center,Beijing 100081,China; Key Laboratory of Marine Hazards Forecasting of Ministry of Natural Resources,Hohai University,Nanjing 210098,China%Environmental Science and Engineering,University of Northern British Columbia,Prince George V2N 4Z9,Canada; Key Laboratory of Marine Hazards Forecasting of Ministry of Natural Resources,Hohai University,Nanjing 210098,China%College of Oceanography,Hohai University,Nanjing 210098,China; State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China%State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China
• Subjects: Atmospheric models; Climate prediction; Climate system; Climatology; Components; Dipoles; Earth and Environmental Science; Earth Sciences; Ecology; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; Engineering Fluid Dynamics; Environmental Chemistry; Forecasting; General circulation models; Lead time; Marine & Freshwater Sciences; Marine environment; Oceanography; Oceans; Original Article; Simulation; Skills; Southern Oscillation; Spring; Spring (season); Weight; Wind; China; initialization; climate prediction system; ENSO; prediction skill; IOD
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-021-1857-4

A new nudging scheme is proposed for the operational prediction system of the National Marine Environmental Forecasting Center (NMEFC) of China, mainly aimed at improving El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) predictions. Compared with the origin nudging scheme of NMEFC, the new scheme adds a nudge assimilation for wind components, and increases the nudging weight at the subsurface. Increasing the nudging weight at the subsurface directly improved the simulation performance of the ocean component, while assimilating low-level wind components not only affected the atmospheric component but also benefited the oceanic simulation. Hindcast experiments showed that the new scheme remarkably improved both ENSO and IOD prediction skills. The skillful prediction lead time of ENSO was up to 11 months, 1 month longer than a hindcast using the original nudging scheme. Skillful prediction of IOD could be made 4–5 months ahead by the new scheme, with a 0.2 higher correlation at a 3-month lead time. These prediction skills approach the level of some of the best state-of-the-art coupled general circulation models. Improved ENSO and IOD predictions occurred across all seasons, but mainly for target months in the boreal spring for the ENSO and the boreal spring and summer for the IOD.