Novel Tools for Ocean Biogeochemical Models
Ocean general circulation models of the IPCC class have biases even when simulatingpresent-day conditions, which may bring into question their predictions of futureconditions. This dissertation is about tools for, and results from assessing biases in theCommunity Earth System Model (CESM) ocean comp...
Main Author: | |
---|---|
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
eScholarship, University of California
2014
|
Subjects: | |
Online Access: | http://www.escholarship.org/uc/item/4mb8t1kp http://n2t.net/ark:/13030/m5z33d06 |
id |
ftcdlib:qt4mb8t1kp |
---|---|
record_format |
openpolar |
spelling |
ftcdlib:qt4mb8t1kp 2023-05-15T17:36:51+02:00 Novel Tools for Ocean Biogeochemical Models Bardin, Ann Marie 203 2014-01-01 application/pdf http://www.escholarship.org/uc/item/4mb8t1kp http://n2t.net/ark:/13030/m5z33d06 en eng eScholarship, University of California http://www.escholarship.org/uc/item/4mb8t1kp qt4mb8t1kp http://n2t.net/ark:/13030/m5z33d06 public Bardin, Ann Marie. (2014). Novel Tools for Ocean Biogeochemical Models. UC Irvine: Earth System Science. Retrieved from: http://www.escholarship.org/uc/item/4mb8t1kp Biological oceanography Physical oceanography global ocean modeling implicit solver Indian Ocean oxygen minimum zones pre-bomb radiocarbon water mass analysis dissertation 2014 ftcdlib 2016-10-07T22:55:05Z Ocean general circulation models of the IPCC class have biases even when simulatingpresent-day conditions, which may bring into question their predictions of futureconditions. This dissertation is about tools for, and results from assessing biases in theCommunity Earth System Model (CESM) ocean component, by itself and when combinedwith the Biological Ecosystem Cycling (BEC) model. Newly developed tools and theirapplications are listed.1. An offline matrix tracer transport model for the ocean component of CESM.2. A fast Newton-Krylov implicit tracer equilibrium solver for both the annually-averagedand the seasonally-varying circulation.3. An effective preconditioner for the solver simulating radiocarbon. Application results: For a natural radiocarbon simulation, an equilibrium solution was obtained in 23 model-years, a dramatic decrease from the 4000 model-years reported for time-stepping. The modeled circulation in the deep Pacific Ocean produced radiocarbon ages twice those of observations.4. A capability for computing the surface origin of water mass fractions as well as theage of the various water masses. Application results: The North Atlantic was the major supplier of ventilated water to not only the Atlantic, but also the Pacific and Indian Oceans. A lack of formation of bottom water in the Southern Ocean was discovered.5. A capability for restricting the tracer simulation domain to a limited region of theocean while retaining the effectiveness of advection and diffusion fields on theboundary. This reduces computational costs and allows separating local versusremote impacts of tracer sources on the biogeochemical tracer concentrations. Thiscapability has the potential to provide a platform for further biogeochemical studies. Application results: The Indian Ocean region was isolated. Global versus regional circulation effects were determined using radiocarbon. Most of the bias within the region was eliminated by using observational, rather than globally calculated values, on the boundaries. Oxygen production and consumption from a CMIP5 BEC simulation were used to drive a regional oxygen model. Boundary values of oxygen from the CMIP5 BEC simulation were replaced with observations, resulting in less bias within the region. However, significant bias in the location of the Arabian Sea oxygen minimum zone remained. Doctoral or Postdoctoral Thesis North Atlantic Southern Ocean University of California: eScholarship Indian Pacific Southern Ocean |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Biological oceanography Physical oceanography global ocean modeling implicit solver Indian Ocean oxygen minimum zones pre-bomb radiocarbon water mass analysis |
spellingShingle |
Biological oceanography Physical oceanography global ocean modeling implicit solver Indian Ocean oxygen minimum zones pre-bomb radiocarbon water mass analysis Bardin, Ann Marie Novel Tools for Ocean Biogeochemical Models |
topic_facet |
Biological oceanography Physical oceanography global ocean modeling implicit solver Indian Ocean oxygen minimum zones pre-bomb radiocarbon water mass analysis |
description |
Ocean general circulation models of the IPCC class have biases even when simulatingpresent-day conditions, which may bring into question their predictions of futureconditions. This dissertation is about tools for, and results from assessing biases in theCommunity Earth System Model (CESM) ocean component, by itself and when combinedwith the Biological Ecosystem Cycling (BEC) model. Newly developed tools and theirapplications are listed.1. An offline matrix tracer transport model for the ocean component of CESM.2. A fast Newton-Krylov implicit tracer equilibrium solver for both the annually-averagedand the seasonally-varying circulation.3. An effective preconditioner for the solver simulating radiocarbon. Application results: For a natural radiocarbon simulation, an equilibrium solution was obtained in 23 model-years, a dramatic decrease from the 4000 model-years reported for time-stepping. The modeled circulation in the deep Pacific Ocean produced radiocarbon ages twice those of observations.4. A capability for computing the surface origin of water mass fractions as well as theage of the various water masses. Application results: The North Atlantic was the major supplier of ventilated water to not only the Atlantic, but also the Pacific and Indian Oceans. A lack of formation of bottom water in the Southern Ocean was discovered.5. A capability for restricting the tracer simulation domain to a limited region of theocean while retaining the effectiveness of advection and diffusion fields on theboundary. This reduces computational costs and allows separating local versusremote impacts of tracer sources on the biogeochemical tracer concentrations. Thiscapability has the potential to provide a platform for further biogeochemical studies. Application results: The Indian Ocean region was isolated. Global versus regional circulation effects were determined using radiocarbon. Most of the bias within the region was eliminated by using observational, rather than globally calculated values, on the boundaries. Oxygen production and consumption from a CMIP5 BEC simulation were used to drive a regional oxygen model. Boundary values of oxygen from the CMIP5 BEC simulation were replaced with observations, resulting in less bias within the region. However, significant bias in the location of the Arabian Sea oxygen minimum zone remained. |
format |
Doctoral or Postdoctoral Thesis |
author |
Bardin, Ann Marie |
author_facet |
Bardin, Ann Marie |
author_sort |
Bardin, Ann Marie |
title |
Novel Tools for Ocean Biogeochemical Models |
title_short |
Novel Tools for Ocean Biogeochemical Models |
title_full |
Novel Tools for Ocean Biogeochemical Models |
title_fullStr |
Novel Tools for Ocean Biogeochemical Models |
title_full_unstemmed |
Novel Tools for Ocean Biogeochemical Models |
title_sort |
novel tools for ocean biogeochemical models |
publisher |
eScholarship, University of California |
publishDate |
2014 |
url |
http://www.escholarship.org/uc/item/4mb8t1kp http://n2t.net/ark:/13030/m5z33d06 |
op_coverage |
203 |
geographic |
Indian Pacific Southern Ocean |
geographic_facet |
Indian Pacific Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
Bardin, Ann Marie. (2014). Novel Tools for Ocean Biogeochemical Models. UC Irvine: Earth System Science. Retrieved from: http://www.escholarship.org/uc/item/4mb8t1kp |
op_relation |
http://www.escholarship.org/uc/item/4mb8t1kp qt4mb8t1kp http://n2t.net/ark:/13030/m5z33d06 |
op_rights |
public |
_version_ |
1766136469152333824 |