Improvement of detritus description in the BFM biogeochemical model and exploitation of the improved model, jointly with observations from ARGO floats to characterise the carbon pump in the Mediterranean.
Ocean Sciences, Climate
Research area
The dynamics of the ocean carbon pump are crucial for understanding the marine c
arbon cycle, and yet they remain poorly constrained in marine biogeochemistry mo
dels. These models represent an essential tool to both understand carbon cycle dynamics and to assess how will it change in the future under climate change. At the same time observation infrastructures such as the BGC-Argo fleet are providing unprecedented amounts of observational data on marine biogeochemistry cycles. Yet these data are still not fully exploited in marine biogeochemistry models.
My research project aims at finding novel ways to integrate observational data in marine biogeochemistry modelling frameworks.
Project goals
I am looking at how carbon fixed by primary producers in the upper ocean layers is exported at depth through the production of sinking particulate organic matter (detritus). This is called the gravitational carbon pump and represents a crucial driver of the marine carbon cycle.
Scientific questions I'm addressing include how the gravitational carbon pump scales with productivity and other oceanographic gradients (e.g. mixing), how does this contribute to nutrient cycling, what is the overall magnitude of the carbon exported in different oceanographic regions, and how is all of this expected to be imacted by climate change.
Computational approach
For my research I use 3D coupled physics-biogeochemistry ocean models. These are typically computationally intensive models, requiring HPC infrastructures to run (on several nodes) and large storage space for their outputs (typically 100s of TB). Due to their computationally intensive nature, fine tuning of these models is impractical.
To overcome this I am employing lighter 1D ocean column models, which can be effectively constrained by observations and/or by selected outputs of the 3D model.
These light-weight models allow to test different configuration more efficiently, and can be used to inform the parameterization of the larger 3D model.
Image
Simplified scheme of the state variables (P: phytoplankton, Z: zooplankton, D: detritus, B: bacteria) and fluxes between them that contribute to detritus carbon export (JDsink). The plots on the right represent the shape of the functional responses between model fluxes in input and output of control boxes (dashed rectangles).
Giovanni Galli
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale
After graduating in Environmental Engineering, at the University of Padova, I completed a PhD with OGS and the University of Trieste. My thesis was on modelling Mediterranean Benthic assemblages and their response to climate change. I was for five years employed as research scientist at the Plymouth Marine Laboratory (PML) in the UK, where I worked on coupled physics-biogeochemistry regional ocean models. Recently I re-joined OGS, Where I work on the marine carbon cycle in the Mediterranean.