NOVEL— assessing meridional vis-à-vis zonal mechanisms of the Atlantic Niño

• Applicant: Hyacinth Nnamchi, Ph.D.
• Subject Area: Atmospheric Science ; Oceanography
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456490637

• Final Report Year: 2025

Final Report Abstract

The NOVEL has produced a new understanding of the coupling between the migrations of the Atlantic ITCZ and thermocline feedback associated with the EM (Nnamchi and Latif, 2025), as well as their roles in Atlantic-scale decadal climate variability (Nnamchi et al., 2023) and teleconnections to the tropical Indo-Pacific Ocans (Ding et al., 2023; Nnamchi and Diallo, 2024). Our results close a key knowledge-gap by linking the impacts of ocean circulation on the climate variability across the entire Atlantic basin. The NOVEL framework shows that the EM’s internannual variability exhibits robust seasonal predictability of 5-6 months. For a comparison, using the conventional Atlantic Nino index gives only 2-3 predictable variability. These advances support internationally-coordinated high profile review of the tropical and South Atlantic (Rodriguez-Fonseca et al., 2025) as well as review of oceanic impacts on African climate (Cai et al., 2025). Thanks to the scientific contributions produced by the NOVEL project, the project PI Hyacinth Nnamchi was recently invited as a member of the Climate and Ocean Variability and Predictability (CLIVAR) Atlantic Regional Panel.

Publications

• Leading patterns of the satellite-era summer precipitation over West Africa and associated global teleconnections. Atmospheric Research, 259, 105677.
  Nnamchi, Hyacinth C.; Dike, Victor N.; Akinsanola, Akintomide A. & Okoro, Ugochukwu K.
  
• Dynamics of tropical Atlantic variability. CLIVAR Exchanges. 82, 9-14.
  Lübbecke, J., I. Richter & H. C. Nnamchi
  
• North Atlantic oscillation controls multidecadal changes in the North Tropical Atlantic−Pacific connection. Nature Communications, 14(1).
  Ding, Ruiqiang; Nnamchi, Hyacinth C.; Yu, Jin-Yi; Li, Tim; Sun, Cheng; Li, Jianping; Tseng, Yu‐Heng; Li, Xichen; Xie, Fei; Feng, Juan; Ji, Kai & Li, Xumin
  
• Pan-Atlantic decadal climate oscillation linked to ocean circulation. Communications Earth & Environment, 4(1).
  Nnamchi, Hyacinth C.; Farneti, Riccardo; Keenlyside, Noel S.; Kucharski, Fred; Latif, Mojib; Reintges, Annika & Martin, Thomas
  
• Strengthening atmospheric circulation and trade winds slowed tropical Pacific surface warming. Communications Earth & Environment, 4(1).
  Latif, Mojib; Bayr, Tobias; Kjellsson, Joakim; Lübbecke, Joke F.; Martin, Thomas; Nnamchi, Hyacinth C.; Park, Wonsun; Savita, Abhishek; Sun, Jing & Dommenget, Dietmar
  
• Divergent future change in South Atlantic Ocean Dipole impacts on regional rainfall in CMIP6 models. Environmental Research: Climate, 3(3), 035002.
  Nworgu, Uzoma C.; Nnamchi, Hyacinth C. & Rosário, Nilton E.
  
• Inconsistent Atlantic Links to Precipitation Extremes over the Humid Tropics. Earth Systems and Environment, 8(2), 347-368.
  Nnamchi, Hyacinth C. & Diallo, Ismaila