A comparison of the variability of biological nutrients against depth and potential density

[摘要] The main biogeochemical nutrient distributions, along with ambient ocean temperature and the light field,control ocean biological productivity.Observations of nutrients are much sparser than physical observations of temperature andsalinity, yet it is critical to validate biogeochemical models against these sparse observations if we are to successfully modelbiological variability and trends. Here we use data from the Bermuda Atlantic Time-series Study and the World Ocean Database 2005 to demonstrate quantitatively that over the entire globe asignificant fraction of the temporal variability of phosphate, silicate and nitrate within the oceans is correlated with water density.The temporal variability of these nutrients as a function of depth is almost always greater than as a function of potential density, with he largest reductions in variability found within the main pycnocline.The greater nutrient variability as a function of depth occurs when dynamical processes vertically displacenutrient and density fields together on shorter timescales than biological adjustments. These results show that dynamical processes can have asignificant impact on the instantaneous nutrient distributions. These processes must therefore be consideredwhen modeling biogeochemical systems, when comparing such models with observations, or when assimilating data into such models.

[学科分类] 地球化学与岩石