Abstract
Abstract. We present an extension to the carbon-centric Grid Enabled Integrated Earth system model (cGEnIE) that explicitly accounts for the growth and interaction of an arbitrary number of plankton species. The new package (ECOGEM) replaces the implicit, flux-based parameterisation of the plankton community currently employed, with explicitly resolved plankton populations and ecological dynamics. In ECOGEM, any number of plankton species, with ecophysiological traits (e.g. growth and grazing rates) assigned according to organism size and functional group (e.g. phytoplankton and zooplankton) can be incorporated at runtime. We illustrate the capability of the marine ecology enabled Earth system model (EcoGEnIE) by comparing results from one configuration of ECOGEM (with eight generic phytoplankton and zooplankton size classes) to climatological and seasonal observations. We find that the new ecological components of the model show reasonable agreement with both global-scale climatological and local-scale seasonal data. We also compare EcoGEnIE results to the existing biogeochemical incarnation of cGEnIE. We find that the resulting global-scale distributions of phosphate, iron, dissolved inorganic carbon, alkalinity, and oxygen are similar for both iterations of the model. A slight deterioration in some fields in EcoGEnIE (relative to the data) is observed, although we make no attempt to re-tune the overall marine cycling of carbon and nutrients here. The increased capabilities of EcoGEnIE in this regard will enable future exploration of the ecological community on much longer timescales than have previously been examined in global ocean ecosystem models and particularly for past climates and global biogeochemical cycles.
Highlights
The marine ecosystem is an integral component of the Earth system and its dynamics
We start by describing the global distributions of key biogeochemical tracers that are common to both centric Grid Enabled Integrated Earth system model (cGEnIE) and EcoGEnIE
Surface phosphate concentrations are broadly similar between the two versions of the model, except that EcoGEnIE provides slightly lower estimates in the Southern Ocean and equatorial upwellings
Summary
The marine ecosystem is an integral component of the Earth system and its dynamics. Photosynthetic plankton support almost all life in the ocean, including the fish stocks that provide essential nutrition to more than half the human population (Hollowed et al, 2013). The marine biota determine an important downward flux of carbon, known as the “biological pump”. This flux arises as biomass generated by photosynthesis in the well-lit ocean surface sinks into the dark ocean interior, where it is remineralised (e.g. Hülse et al, 2017). Modulated by the activity and composition of marine ecosystems, the biological pump increases the partial pressure of CO2 at depth and decreases it in the ocean surface and atmosphere, and plays a key role in the regulation of Earth’s climate. The existence of the biological carbon pump has been estimated to be responsible for an approximately 200 ppm decrease in atmospheric carbon concentration at steady state (Parekh et al, 2006), with variations in its magnitude being cited as playing a key role in, for example, the late Quaternary glacial– interglacial climate oscillations (Watson et al, 2000; Hain et al, 2014)
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