Simulations of ocean physical and biogeochemical fields under different biological functioning in CSIRO Mk3L 1.2 v1.0

Full description

The data included in this repository includes both the physical and biogeochemical fields that were generated by 36 simulations over 10,000 years with an Ocean General Circulation Model (GCM): CSIRO Mk3L v1.2. The 36 simulations represent a factorial experimental set-up, where 6 different parameterisations of ocean biology were broadcast across six different physical states.

The aim of these experiments was to test if new insights into how the cycling of organic matter in the ocean functions can offer some benefit to climate models. But to be sure that a particular process is important to global ocean biogeochemistry (i.e carbon storage), we needed to make these tests across a range of different circulations and physical states.

All physical states were of Pre-Industrial (PI; 1850 CE) climate. They were generated by forcing the Ocean GCM with the boundary conditions produced by piControl runs of CSIRO Mk3L v1.2, GFDL-ESM2G, IPSL-CM5A-MR, HadGEM2-CC, MPI-ESM-MR and MRI-CGCM3. These boundary conditions were sea surface temperature, salinity and the meridional and zonal components of surface wind stresses, and the final 10 years of these runs were averaged and regridded onto the CSIRO Mk3L v1.2 grid space. Therefore, six unique physical ocean states were generated.

Six unique biological states were also generated by implementing different biological parameterisations within the biogeochemical model code. These included variable nutrient dependence for phytoplankton growth (Smith et al., 2009), variable remineralisation profiles with depth that were dependent on temperature (Marsay et al., 2015) or community composition (Weber et al., 2016), and a variable stoichiometry of organic matter based on nutrient concentrations (Galbratih and Martiny, 2015). These four different and already published parameterisations were implemented into the biogeochemical code individually, and once in combination (excluding the temperature-dependent remineralisation), to create five new biogeochemical models. Hence, six unique biological states were created, including the basic, unaltered biogeochemical model.

Climatologies of sea surface temperature, sea surface salinity, and x and y vectors of sea surface wind stresses were produced by both the PI and LGM coupled experiments and were used to force the ocean general circulation model. Additional climatologies of sea ice fractional cover, sea surface wind speeds, net incident short-wave radiation, and the aeolian deposition of iron and reactive nitrogen were important for forcing the biogeochemical model. These climatologies are made available here.

Also available are the three-dimensional global annual averages of oceanic properties for all 36 simulations at their steady-state solutions. These include temperature, salinity, oxygen, apparent oxygen utilisation, dissolved inorganic carbon, alkalinity, phosphate, nitrate and iron concentrations.

A full description of the CSIRO Mk3L v1.2 can be found in both:

Phipps, S. J., Rotstayn, L. D., Gordon, H. B., Roberts, J. L., Hirst, A. C., and Budd, W. F. The CSIRO Mk3L climate system model version 1.0 - Part 1: Description and evaluation, Geosci. Model Dev., 4, 483-509, doi:10.5194/gmd-4-483-2011, 2011.

Phipps, S. J., Rotstayn, L. D., Gordon, H. B., Roberts, J. L., Hirst, A. C., and Budd, W. F. The CSIRO Mk3L climate system model version 1.0 - Part 2: Response to external forcings, Geosci. Model Dev., 5, 649-682, doi:10.5194/gmd-5-649-2012, 2012.

Descriptions of the biogeochemical ocean model that was used can be found in the appendices of:

Matear, R. J. and Lenton, A. Quantifying the impact of ocean acidification on our future climate, Biogeosciences, 11, 3965-3983, doi:10.5194/bg-11-3965-2014, 2014

Buchanan, P. J., Matear, R. J., Chase, Z., Phipps, S. J., and Bindoff, N. J. (2017) The importance of biological heterogeneity for simulating and stabilising ocean biogeochemistry. Global Biogeochemical Cycles.