Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades

Kulk, G, Platt, T, Dingle, J, Jackson, T, Jonsson, B, Bouman, H, Babin, M, Brewin, RJW, Doblin, M, Estrada, M, Figueiras, F, Furuya, K, González-Benítez, N, Gudfinnsson, H, Gudmundsson, K, Huang, B, Isada, T, Kovač, Ž, Lutz, V, Marañón, E, Raman, M, Richardson, K, Rozema, P, van de Poll, W, Segura, V, Tilstone, GH, Uitz, J, Dongen-Vogels, V, Yoshikawa, T and Sathyendranath, S 2020 Primary Production, an Index of Climate Change in the Ocean: Satellite-Based Estimates over Two Decades. Remote Sensing, 12 (5). 826. https://doi.org/10.3390/rs12050826

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Abstract/Summary

Primary production by marine phytoplankton is one of the largest fluxes of carbon on our planet. In the past few decades, considerable progress has been made in estimating global primary production at high spatial and temporal scales by combining in situ measurements of primary production with remote-sensing observations of phytoplankton biomass. One of the major challengesinthisapproachliesintheassignmentoftheappropriatemodelparametersthatdefinethe photosynthetic response of phytoplankton to the light field. In the present study, a global database of in situ measurements of photosynthesis versus irradiance (P-I) parameters and a 20-year record of climatequalitysatelliteobservationswereusedtoassessglobalprimaryproductionanditsvariability with seasons and locations as well as between years. In addition, the sensitivity of the computed primaryproductiontopotentialchangesinthephotosyntheticresponseofphytoplanktoncellsunder changing environmental conditions was investigated. Global annual primary production varied from 38.8 to 42.1 Gt C yr−1 over the period of 1998–2018. Inter-annual changes in global primary production did not follow a linear trend, and regional differences in the magnitude and direction of change in primary production were observed. Trends in primary production followed directly from changes in chlorophyll-a and were related to changes in the physico-chemical conditions of the water column due to inter-annual and multidecadal climate oscillations. Moreover, the sensitivity analysis in which P-I parameters were adjusted by±1 standard deviation showed the importance of accurately assigning photosynthetic parameters in global and regional calculations of primary production. TheassimilationnumberoftheP-Icurveshowedstrongrelationshipswithenvironmental variables such as temperature and had a practically one-to-one relationship with the magnitude of change in primary production. In the future, such empirical relationships could potentially be used for a more dynamic assignment of photosynthetic rates in the estimation of global primary production. RelationshipsbetweentheinitialslopeoftheP-Icurveandenvironmentalvariableswere more elusive.

Item Type:	Publication - Article
Additional Keywords:	primary production; phytoplankton; photosynthesis; ocean-colour remote-sensing; climate change
Divisions:	Plymouth Marine Laboratory > National Capability categories > Atlantic Meridional Transect Plymouth Marine Laboratory > National Capability categories > National Centre for Earth Observation Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User:	S Hawkins
Date made live:	10 Mar 2020 11:02
Last Modified:	25 Apr 2020 10:02
URI:	https://plymsea.ac.uk/id/eprint/8894

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