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www.biogeosciences-discuss.net/6/4201/2009/
doi:10.5194/bgd-6-4201-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Using satellite-derived backscattering coefficients in addition to chlorophyll data to constrain a simple marine biogeochemical model
The School of GeoSciences, University of Edinburgh, UK
Abstract. Biogeochemical models of the ocean carbon cycle are frequently validated by, or tuned to, satellite chlorophyll data. However, ocean carbon cycle models are required to accurately model the movement of carbon, not chlorophyll and due to the high variability of the carbon to chlorophyll ratio in phytoplankton, chlorophyll is not a robust proxy for carbon. Using inherent optical property (IOP) inversion algorithms it is now possible to also derive the amount of light backscattered by the upper ocean (bb) which is related to the amount of particulate organic carbon (POC) present. Using empirical relationships between POC and bb, a 1-d biogeochemical model is used to simulate bb at 490 nm thus allowing the model to be compared with either remotely-sensed chlorophyll or bb data. Here I test the hypothesis that using bb in conjunction with chlorophyll data can help to constrain more model parameters than using chlorophyll alone. This is done by tuning the parameters of the biogeochemical model with a genetic algorithm, so that the model is fitted to either chlorophyll or to both chlorophyll and bb data at three sites in the Atlantic with very different characteristics. There are several IOP algorithms available for estimating bb. Four of these are investigated and three of them used for model tuning. The effect of the different bb datasets on the behaviour of the tuned model is examined to ascertain whether the uncertainty in bb is significant. The results show that the addition of bb data can have a large effect on the modelled detritus and that differences in the IOP algorithms are not particularly significant.
Discussion Paper (PDF, 1639 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (BG)
Citation: Kettle, H.: Using satellite-derived backscattering coefficients in addition to chlorophyll data to constrain a simple marine biogeochemical model, Biogeosciences Discuss., 6, 4201-4231, doi:10.5194/bgd-6-4201-2009, 2009. Bibtex EndNote Reference Manager XML
