Contrasting interannual atmospheric CO2 variabilities and their terrestrial mechanisms for two types of El Niños

Jun Wang (1) , Ning Zeng (2) , Meirong Wang (3) , Fei Jiang (1) , Jingming Chen (1) , Pierre Friedlingstein (4) , Atul Jain (5) , Ziqiang Jiang (1) , Weimin Ju (1) , Sebastian Lienert (6) , Julia Nabel (7) , Stephen Sitch (8) , Nicolas Viovy (9, 10) , Hengmao Wang (1) , Andrew Wiltshire (11)

1 NJU - Nanjing University
2 IAP - Institute of Atmospheric Physics [Beijing]
3 NUIST - Nanjing University of Information Science and Technology
4 EMPS - College of Engineering, Mathematics and Physical Sciences [Exeter]
5 UIUC - University of Illinois at Urbana-Champaign [Urbana]
6 UNIBE - Universität Bern / University of Bern
7 MPI-M - Max Planck Institute for Meteorology
8 College of Life and Environmental Sciences [Exeter]
9 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
10 MOSAIC - Modélisation des Surfaces et Interfaces Continentales
11 MOHC - Met Office Hadley Centre

El Niño has two different flavors, eastern Pacific (EP) and central Pacific (CP) El Niños, with different global teleconnections. However, their different impacts on the interannual carbon cycle variability remain unclear. Here we compared the behaviors of interannual atmospheric CO 2 variability and analyzed their terrestrial mechanisms during these two types of El Niños, based on the Mauna Loa (MLO) CO 2 growth rate (CGR) and the Dynamic Global Vegetation Model's (DGVM) historical simulations. The composite analysis showed that evolution of the MLO CGR anomaly during EP and CP El Niños had three clear differences: (1) negative or neutral precursors in the boreal spring during an El Niño developing year (denoted as "yr0"), (2) strong or weak amplitudes, and (3) durations of the peak from Decem-ber (yr0) to April during an El Niño decaying year (denoted as "yr1") compared to October (yr0) to January (yr1) for a CP El Niño, respectively. The global land-atmosphere carbon flux (F TA) simulated by multi-models was able to capture the essentials of these characteristics. We further found that the gross primary productivity (GPP) over the tropics and the extratropical Southern Hemisphere (Trop + SH) generally dominated the global F TA variations during both El Niño types. Regional analysis showed that during EP El Niño events significant anomalous carbon uptake caused by increased precipitation and colder temperatures, corresponding to the negative precursor, occurred between 30 • S and 20 •

Domaines: Océan, Atmosphère; Climatologie

Jun Wang, Ning Zeng, Meirong Wang, Fei Jiang, Jingming Chen, et al.. Contrasting interannual atmospheric CO2 variabilities and their terrestrial mechanisms for two types of El Niños. Atmospheric Chemistry and Physics, 2018, 18 (14), pp.10333-10345. ⟨10.5194/acp-18-10333-2018⟩. ⟨hal-02976230⟩