Martin | SuiteSparse Matrix Collection

Group Description	Martin/marine1: chemical oceanography; a marine nitrogen cycle inverse model A matrix submitted by Taylor Martin, Stanford, discussed the following paper: Title: Modeling oceanic nitrite concentrations and isotopes using a 3D inverse N cycle model Authors: Taylor S. Martin(1), Francois Primeau(2), and Karen L. Casciotti(1) (1) Stanford University, Department of Earth System Science (2) University of California, Irvine, Department of Earth System Science Received: 05 Sep 2018 Abstract. Nitrite (NO2-) is a key intermediate in the marine nitrogen (N) cycle and a substrate in nitrification, which produces nitrate (NO3-), as well as water column N loss processes, denitrification and anammox. In models of the marine N cycle, NO2- is often not considered as a separate state variable, since NO3- occurs in much higher concentrations in the ocean. In oxygen deficient zones (ODZs), however, NO2- represents a substantial fraction of the bioavailable N, and modeling its production and consumption is important to understanding the N cycle processes occurring there, especially those where bioavailable N is lost from or retained within the water column. Here we present the expansion of a global 3D inverse N cycle model to include NO2- as a reactive intermediate as well as the processes that produce and consume NO2- in marine ODZs. NO2- accumulation in ODZs is accurately represented by the model involving NO3- reduction, NO2- reduction, NO2- oxidation, and anammox. We model both 14N and 15N and use a compilation of oceanographic measurements of NO3- and NO2- concentrations and isotopes to place a better constraint on the N cycle processes occurring. The model is optimized using a range of isotope effects for denitrification and NO2- oxidation, and we find that the larger (more negative) inverse isotope effects for NO2- oxidation along with relatively high rates of NO2- oxidation give a better simulation of NO3- and NO2- concentrations and isotopes in marine ODZs. How to cite: Martin, T. S., Primeau, F., and Casciotti, K. L.: Modeling oceanic nitrite concentrations and isotopes using a 3D inverse N cycle model, Biogeosciences Discuss., https://doi.org/10.5194/bg-2018-397, in review, 2018.

Martin/marine1: chemical oceanography; a marine nitrogen cycle inverse model

A matrix submitted by Taylor Martin, Stanford, discussed the following paper:

Title: Modeling oceanic nitrite concentrations and isotopes using a 3D
inverse N cycle model
Authors: Taylor S. Martin(1), Francois Primeau(2), and Karen L. Casciotti(1)
(1) Stanford University, Department of Earth System Science
(2) University of California, Irvine, Department of Earth System Science
Received: 05 Sep 2018
Abstract. Nitrite (NO2-) is a key intermediate in the marine nitrogen (N) cycle
and a substrate in nitrification, which produces nitrate (NO3-), as well as
water column N loss processes, denitrification and anammox. In models of the
marine N cycle, NO2- is often not considered as a separate state variable,
since NO3- occurs in much higher concentrations in the ocean. In oxygen
deficient zones (ODZs), however, NO2- represents a substantial fraction of the
bioavailable N, and modeling its production and consumption is important to
understanding the N cycle processes occurring there, especially those where
bioavailable N is lost from or retained within the water column. Here we
present the expansion of a global 3D inverse N cycle model to include NO2- as a
reactive intermediate as well as the processes that produce and consume NO2- in
marine ODZs. NO2- accumulation in ODZs is accurately represented by the model
involving NO3- reduction, NO2- reduction, NO2- oxidation, and anammox. We model
both 14N and 15N and use a compilation of oceanographic measurements of NO3-
and NO2- concentrations and isotopes to place a better constraint on the N
cycle processes occurring. The model is optimized using a range of isotope
effects for denitrification and NO2- oxidation, and we find that the larger
(more negative) inverse isotope effects for NO2- oxidation along with
relatively high rates of NO2- oxidation give a better simulation of NO3- and
NO2- concentrations and isotopes in marine ODZs.

How to cite: Martin, T. S., Primeau, F., and Casciotti, K. L.: Modeling
oceanic nitrite concentrations and isotopes using a 3D inverse N cycle model,
Biogeosciences Discuss., https://doi.org/10.5194/bg-2018-397, in review, 2018.

Group Martin