CMEMS-LSCE: A global 0.25-degree, monthly reconstruction of the surface ocean carbonate system

• Main Authors: Chau, Thi-Tuyet-Trang, Gehlen, Marion, Metzl, Nicolas, Chevallier, Frédéric
• Format: Text
• Language: English
• Published: 2023
• Subjects: Ocean acidification
• Online Access: https://doi.org/10.5194/essd-2023-146; https://essd.copernicus.org/preprints/essd-2023-146/

Observation-based data reconstructions of global surface ocean carbonate system variables play an essential role in monitoring the recent status of ocean carbon uptake and ocean acidification as well as their impacts on marine organisms and ecosystems. So far ongoing efforts are directed towards exploring new approaches to describe the complete marine carbonate system and to better recover its fine-scale features. In this respect, our research activities within the Copernicus Marine Environment Monitoring Service (CMEMS) aim at developing a sustainable production chain of observation-derived global ocean carbonate system datasets at high space-time resolution. As the start of the long-term objective, this study introduces a new global 0.25° monthly reconstruction, namely CMEMS-LSCE, for the period 1985–2021. The CMEMS-LSCE reconstruction derives datasets of six carbonate system variables including surface ocean partial pressure of CO 2 ( p CO 2 ), total alkalinity (A T ), total dissolved inorganic carbon (DIC), surface ocean p H, and saturation states with respect to aragonite (Ω ar ) and calcite (Ω ca ). Reconstructing p CO 2 relies on an ensemble of neural network models mapping gridded observation-based data provided by the Surface Ocean CO 2 ATlas (SOCAT). Surface ocean A T is estimated with a multiple linear regression approach, and the remaining carbonate variables are resolved by CO 2 system speciation given the reconstructed p CO 2 and A T . 1 σ -uncertainty associated with these estimates is also provided. Here, σ stands for either ensemble standard deviation of p CO 2 estimates or total uncertainty for each of the five other variables propagated through the processing chain with input data uncertainty. We demonstrate that the 0.25°-resolution p CO 2 product outperforms a coarser spatial resolution (1°) thanks to a higher data coverage nearshore and a better description of horizontal and temporal variations in p CO 2 across diverse ocean basins, particularly in the coastal-open-ocean continuum. Product ...