The sensitivity of p CO 2 reconstructions to sampling scales across a Southern Ocean sub-domain: a semi-idealized ocean sampling simulation approach

• Published in: Biogeosciences
• Main Authors: L. M. Djeutchouang, N. Chang, L. Gregor, M. Vichi, P. M. S. Monteiro
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Antarctic; Southern Ocean; Antarc*
• Online Access: https://doi.org/10.5194/bg-19-4171-2022; https://doaj.org/article/2c99341eaafe4e46b0bac103b125b0a3

The Southern Ocean is a complex system yet is sparsely sampled in both space and time. These factors raise questions about the confidence in present sampling strategies and associated machine learning (ML) reconstructions. Previous studies have not yielded a clear understanding of the origin of uncertainties and biases for the reconstructions of the partial pressure of carbon dioxide ( p CO 2 ) at the surface ocean ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>p</mi><msubsup><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn><mi mathvariant="normal">ocean</mi></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="47pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="384f359723e12c1d22fe40db07699d29"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-4171-2022-ie00001.svg" width="47pt" height="15pt" src="bg-19-4171-2022-ie00001.png"/></svg:svg> ). We examine these questions through a series of semi-idealized observing system simulation experiments (OSSEs) using a high-resolution ( ± 10 km) coupled physical and biogeochemical model (NEMO-PISCES, Nucleus for European Modelling of the Ocean, Pelagic Interactions Scheme for Carbon and Ecosystem Studies). Here we choose 1 year of the model sub-domain of 10 ∘ of latitude (40–50 ∘ S) by 20 ∘ of longitude (10 ∘ W–10 ∘ E). This domain is crossed by the sub-Antarctic front and thus includes both the sub-Antarctic zone and the polar frontal zone in the south-east Atlantic Ocean, which are the two most sampled sub-regions of the Southern Ocean. We show that while this sub-domain is small relative to the Southern Ocean scales, it is representative of the scales of variability we aim to examine. The OSSEs simulated the observational scales of <math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" ...