Tracer Versus Observationally-Derived Constraints on Ocean Mixing Parameters in an Adjoint-Based Data Assimilation Framework
"This study investigates the possibility of using an ocean parameter and state estimation framework to improve knowledge of mixing parameters in the global ocean. Multiple sources of information about two ocean mixing parameters, the diapycnal diffusivity and the Redi coefficient, are considered. It is first established that diapycnal diffusivities derived from multiple observational data sets with a strain-based parameterization of finescale hydrographic structure can be used to ameliorate model biases in diapycnal diffusivities from the Estimating the Circulation & Climate of the Ocean (ECCO) framework and the GEOS-5 coupled Earth system model. [...]"
Source: Earth and Space Science Open Archive
Authors: David Trossman et al.
Microbial metabolite fluxes in a model marine anoxic ecosystem
"Permanently anoxic regions in the ocean are widespread and exhibit unique microbial metabolic activity exerting substantial influence on global elemental cycles and climate. Reconstructing microbial metabolic activity rates in these regions has been challenging, due to the technical difficulty of direct rate measurements. In Cariaco Basin, which is the largest permanently anoxic marine basin and an important model system for geobiology, long‐term monitoring has yielded time series for the concentrations of biologically important compounds; however, the underlying metabolite fluxes remain poorly quantified. [...]"
Authors: Stilianos Louca et al.
The Equatorial Undercurrent and the Oxygen Minimum Zone in the Pacific
"Warming‐driven expansion of the oxygen minimum zone (OMZ) in the equatorial Pacific would bring very low oxygen waters closer to the ocean surface, and possibly impact global carbon/nutrient cycles and local ecosystems. Global coarse Earth System Models (ESMs) show, however, disparate trends that poorly constrain these future changes in the upper OMZ. [...]"
Source: Geophysical Research Letters
Authors: Julius J.M. Busecke, Laure Resplandy and John P. Dunne
Assessment of the impact of spatial resolution on ROMS simulated upper-ocean biogeochemistry of the Arabian Sea from an operational perspective
"The resolution of the model emerges to be an important factor in simulating the real oceanic features. In this paper, the performance of two coupled bio-physical models, having spatial resolutions 1/12° (∼9 km) and 1/4° (∼25 km) configured using Regional Ocean Modeling System (ROMS), have been evaluated in simulating upper ocean dynamics of the Arabian Sea. [...]"
Source: Journal of Operational Oceanography
Authors: Kunal Chakraborty et al.
The impact of primary and export production on the formation of the secondary nitrite maximum: A model study
"The so-called secondary nitrite maximum (SNM) is a pronounced subsurface feature in many oxygen deficient zones of the ocean. A nitrite layer of up to several hundred meters thickness indicates high microbial activity and nitrogen loss from the system. To study the effects of primary and export production on the SNM, we have developed a one-dimensional ecosystem model for oxygen deficient zones. Our model couples the marine nitrogen and oxygen cycles with physical water column processes, includes euphotic, aphotic, aerobic and anaerobic processes and thereby dynamically describes source and sink processes for nitrite. [...]"
Source: Ecological Modelling
Authors: Aike Beckmann and Inga Hense
Projected Centennial Oxygen Trends and Their Attribution to Distinct Ocean Climate Forcings
"We explore centennial changes in tropical Pacific oxygen (O2) using numerical models to illustrate the dominant patterns and mechanisms under centennial climate change. Future projections from state‐of‐the‐art Earth System Models exhibit significant model to model differences, but decreased solubility and weakened ventilation together deplete thermocline O2 in middle to high latitudes. In contrast, the tropical thermocline O2undergoes much smaller changes or even a slight increase. [...]"
Source: Global Biogeochemical Cycles
Authors: Yohei Takano, Takamitsu Ito & Curtis Deutsch