The Carbon Strategy Report of the Committee on Earth Observation Satellites (CEOS, 2014) identified a number of pools and fluxes of carbon in the ocean that are amenable to remote sensing. In ESA’s Biological Pump and Carbon Exchange Processes (BICEP) project, we have been investigating satellite methods to map marine primary production, phytoplankton carbon, particulate organic carbon, particulate inorganic matter and dissolved organic carbon. Time series of each of these products at 9 km, monthly resolution is being generated. The main input to the calculations is the ocean-colour fields generated by the Ocean Colour Climate Change Initiative (OC-CCI). These are supplemented by fields of photosynthetically available radiation at the surface of the ocean, sea-surface temperature, and sea-surface salinity (from CCI). For most of the products, the time series extends from 1998 to 2020, unless limited by availability of input data.
The primary production computations (Kulk et al. 2020, 2021) rely on an extensive in situ database of photosynthesis-irradiance parameters. The same parameter set is used, along with a photo-acclimation model, to compute phytoplankton carbon, ensuring that the allocation of resource (light) between production of carbon and chlorophyll is treated in an internally consistent manner. Various algorithms available for calculation of particulate organic carbon have been compared, before selecting one of the better-performing algorithms for generation of the time series. The algorithm for mapping dissolved organic matter is a novel one, that makes use of machine-learning tools.
In situ data bases have been created for validation and comparison of products, and for generation of uncertainty estimates. Algorithms for estimation of biological export production have also been implemented. The next major activity in the project is user consultation, to which end an online workshop on “Ocean Carbon from Space” is being organised on 14-18 February, 2022, with international collaboration and participation.
CEOS (2014) CEOS Strategy for Carbon Observations from Space. The Committee on Earth Observation Satellites (CEOS) Response to the Group on Earth Observations (GEO) Carbon Strategy. Issue date: September 30 2014. Printed in Japan by JAXA and I&A Corporation
Kulk G, Platt T, Dingle J, Jackson T, Jönsson B, Bouman HA, Babin M, Doblin M, Estrada M, Figueiras FG, Furuya K, González N, Gudfinnsson HG, Gudmundsson K, Huang B, Isada T, Kovac Z, Lutz VA, Marañón E, Raman M, Richardson K, Rozema PD, Van de Poll WH, Segura V, Tilstone GH, Uitz J, van Dongen-Vogels V, Yoshikawa T, Sathyendranath S (2020). Primary production, an index of climate change in the ocean: Satellite-based estimates over two decades. Remote Sensing 12:826; doi:10.3390/rs12050826
Kulk G, Platt T, Dingle J, Jackson T, Jönsson B, Bouman HA, Babin M, Doblin M, Estrada M, Figueiras FG, Furuya K, González N, Gudfinnsson HG, Gudmundsson K, Huang B, Isada T, Kovac Z, Lutz VA, Marañón E, Raman M, Richardson K, Rozema PD, Van de Poll WH, Segura V, Tilstone GH, Uitz J, van Dongen-Vogels V, Yoshikawa T, Sathyendranath S (2021). Correction: Kulk et al. Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades. Remote Sensing 13:3462; doi:10.3390/rs13173462