[{"awards": "1842059 Huber, Matthew", "bounds_geometry": ["POLYGON((-180 90,-144 90,-108 90,-72 90,-36 90,0 90,36 90,72 90,108 90,144 90,180 90,180 72,180 54,180 36,180 18,180 0,180 -18,180 -36,180 -54,180 -72,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -72,-180 -54,-180 -36,-180 -18,-180 0,-180 18,-180 36,-180 54,-180 72,-180 90))"], "date_created": "Tue, 13 May 2025 00:00:00 GMT", "description": "Included are 100 years of monthly mean ocean model output from CESM1.2 integrations for the Eocene carried out by Adam Aleksinski and Matthew Huber, with critical assistance from Alexandra Jahn, and with assistance and support from Jiang Zhu (NCAR). These simulations were carried out at NCAR. These simulations incorporate results using the standard Eocene Deepmip 1 boundary conditions (Lunt et al, 2017), including the boundary condition datasets (Herold et al., 2014), and were branched off originally from simulations carried out at NCAR by Jiang Zhu (Zhu et al., 2020). The three simulations included here incorporate neodymium in them for the first time and span a range of CO2 and gateway configurations that make it appropriate for the Middle Eocene to late Eocene. \r\n\u003cbr/\u003e\r\n\u003cbr/\u003eThe continuation (\u201cSF_SU_55Ma_init-hycont\u201d) experiment run continued from the end of Zhu et al. (2020)\u2019s 3x preindustrial pCO2 (854.1 ppm) experiment, which used DeepMIP compliant geography and bathymetry for simulating the early Eocene. This simulation was run for a total of 4,800 years. Two runs each branched from this SF_SU_55Ma_init-hycont after 1,200 years of runtime, and each ran for 3,600 years after that point. In the Open Drake Passage experimental run (SF_SU_55Ma_open-hycont), the atmospheric pCO2 concentration from the continuation simulation was retained, and the bathymetry of the Drake Passage and Tasman Seaway were both lowered to a depth of 1973 mbsl. In the Halved pCO2 experiment SF_SU_55Ma_cool), the Herold et al original bathymetry was retained, but atmospheric pCO2 was reduced by a factor of half, to 427.05 ppm.\r\n\u003cbr/\u003e\r\n\u003cbr/\u003e The model output is global in extent and is netcdf format, which has been tarred and gzipped, and follows standard conventions for ocean GCMs. The data are on an irregular \u0027POP\u0027 grid. All the necessary information to read and process these data are included in the netcdf metadata.", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Cryosphere; Eocene; Neodymium; Ocean Circulation Model; Ocean Model; Oxygen Isotope; Paleobathymetry; Paleoclimate; Paleoecology; Paleogeography; Paleoproxies; Paleotemperature; Sharks", "locations": "Antarctica", "north": 90.0, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Huber, Matthew; Aleksinski, Adam; Jahn, Alexandra", "project_titles": "Collaborative Research: Integrating Eocene Shark Paleoecology and Climate Modeling to reveal Southern Ocean Circulation and Antarctic Glaciation", "projects": [{"proj_uid": "p0010146", "repository": "USAP-DC", "title": "Collaborative Research: Integrating Eocene Shark Paleoecology and Climate Modeling to reveal Southern Ocean Circulation and Antarctic Glaciation"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "CESM1.2 Ocean Model Output for Eocene Including Neodymium and Oxygen Isotopes", "uid": "601931", "west": -180.0}, {"awards": "1341464 Robinson, Rebecca", "bounds_geometry": ["POLYGON((-170.4 -60.8,-170.36 -60.8,-170.32 -60.8,-170.28 -60.8,-170.24 -60.8,-170.2 -60.8,-170.16 -60.8,-170.12 -60.8,-170.08 -60.8,-170.04 -60.8,-170 -60.8,-170 -61.34,-170 -61.88,-170 -62.42,-170 -62.96,-170 -63.5,-170 -64.04,-170 -64.58,-170 -65.12,-170 -65.66,-170 -66.2,-170.04 -66.2,-170.08 -66.2,-170.12 -66.2,-170.16 -66.2,-170.2 -66.2,-170.24 -66.2,-170.28 -66.2,-170.32 -66.2,-170.36 -66.2,-170.4 -66.2,-170.4 -65.66,-170.4 -65.12,-170.4 -64.58,-170.4 -64.04,-170.4 -63.5,-170.4 -62.96,-170.4 -62.42,-170.4 -61.88,-170.4 -61.34,-170.4 -60.8))"], "date_created": "Mon, 14 Feb 2022 00:00:00 GMT", "description": "Tracking variations in the surface ocean supply and demand of nitrate, a key marine nutrient, can help constrain the contribution of biological production in driving past climate shifts. The nitrogen isotopic composition (as \u03b415N) of organic matter in marine sediments is a proxy for surface ocean nitrate supply and demand over time but it may be subject to alteration during sinking and burial. The isotopic composition of nitrogen contained in the shells, or frustules, of diatoms (\u03b415NDB) is protected and is therefore a potentially more robust tracer of nitrate use in the past. Here we show that \u03b415NDB in Southern Ocean community cultures does not depend on species composition. We found the \u03b5DB (= biomass \u03b415N - \u03b415NDB) of the community growouts was -4.8 \u00b1 0.8\u2030, more than 10\u2030 different from previous monospecific growouts, but statistically indistinguishable from previous Southern Ocean and North Pacific surface ocean observations. The two community growouts, seeded with populations from 66\u00b0 and 61\u00b0S, had distinct community compositions but indistinguishable \u03b5DB, suggesting species composition does not primarily set \u03b415NDB values in the Southern Ocean. Our results demonstrate that under nitrate-replete conditions, \u03b415NDB values of frustules sinking from the surface ocean robustly track surface ocean nitrate \u03b415N values and therefore nitrate supply and demand. ", "east": -170.0, "geometry": ["POINT(-170.2 -63.5)"], "keywords": "Antarctica; Nitrogen Isotopes; Oceans; Paleoproxies; Southern Ocean", "locations": "Antarctica; Southern Ocean", "north": -60.8, "nsf_funding_programs": "Antarctic Earth Sciences", "persons": "Jones, Colin; Robinson, Rebecca; Brzezinski, Mark; Riesselman, Christina; Closset, Ivia; Kelly, Roger; Robinson, Rebecca ", "project_titles": "Collaborative Proposal: A Field and Laboratory Examination of the Diatom N and Si Isotope Proxies: Implications for Assessing the Southern Ocean Biological Pump", "projects": [{"proj_uid": "p0010083", "repository": "USAP-DC", "title": "Collaborative Proposal: A Field and Laboratory Examination of the Diatom N and Si Isotope Proxies: Implications for Assessing the Southern Ocean Biological Pump"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -66.2, "title": "Surface Southern Ocean community growouts to evaluate the diatom bound N isotope proxy", "uid": "601522", "west": -170.4}]

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Dataset Title/Abstract/Map	NSF Award(s)	Date Created	PIs / Scientists	Project Links	Abstract	Bounds Geometry	Geometry	Selected	Visible
CESM1.2 Ocean Model Output for Eocene Including Neodymium and Oxygen Isotopes	1842059	2025-05-13	Huber, Matthew; Aleksinski, Adam; Jahn, Alexandra	Collaborative Research: Integrating Eocene Shark Paleoecology and Climate Modeling to reveal Southern Ocean Circulation and Antarctic Glaciation	Included are 100 years of monthly mean ocean model output from CESM1.2 integrations for the Eocene carried out by Adam Aleksinski and Matthew Huber, with critical assistance from Alexandra Jahn, and with assistance and support from Jiang Zhu (NCAR). These simulations were carried out at NCAR. These simulations incorporate results using the standard Eocene Deepmip 1 boundary conditions (Lunt et al, 2017), including the boundary condition datasets (Herold et al., 2014), and were branched off originally from simulations carried out at NCAR by Jiang Zhu (Zhu et al., 2020). The three simulations included here incorporate neodymium in them for the first time and span a range of CO2 and gateway configurations that make it appropriate for the Middle Eocene to late Eocene. <br/> <br/>The continuation (“SF_SU_55Ma_init-hycont”) experiment run continued from the end of Zhu et al. (2020)’s 3x preindustrial pCO2 (854.1 ppm) experiment, which used DeepMIP compliant geography and bathymetry for simulating the early Eocene. This simulation was run for a total of 4,800 years. Two runs each branched from this SF_SU_55Ma_init-hycont after 1,200 years of runtime, and each ran for 3,600 years after that point. In the Open Drake Passage experimental run (SF_SU_55Ma_open-hycont), the atmospheric pCO2 concentration from the continuation simulation was retained, and the bathymetry of the Drake Passage and Tasman Seaway were both lowered to a depth of 1973 mbsl. In the Halved pCO2 experiment SF_SU_55Ma_cool), the Herold et al original bathymetry was retained, but atmospheric pCO2 was reduced by a factor of half, to 427.05 ppm. <br/> <br/> The model output is global in extent and is netcdf format, which has been tarred and gzipped, and follows standard conventions for ocean GCMs. The data are on an irregular 'POP' grid. All the necessary information to read and process these data are included in the netcdf metadata.	["POLYGON((-180 90,-144 90,-108 90,-72 90,-36 90,0 90,36 90,72 90,108 90,144 90,180 90,180 72,180 54,180 36,180 18,180 0,180 -18,180 -36,180 -54,180 -72,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -72,-180 -54,-180 -36,-180 -18,-180 0,-180 18,-180 36,-180 54,-180 72,-180 90))"]	["POINT(0 -89.999)"]	false	false
Surface Southern Ocean community growouts to evaluate the diatom bound N isotope proxy	1341464	2022-02-14	Jones, Colin; Robinson, Rebecca; Brzezinski, Mark; Riesselman, Christina; Closset, Ivia; Kelly, Roger; Robinson, Rebecca	Collaborative Proposal: A Field and Laboratory Examination of the Diatom N and Si Isotope Proxies: Implications for Assessing the Southern Ocean Biological Pump	Tracking variations in the surface ocean supply and demand of nitrate, a key marine nutrient, can help constrain the contribution of biological production in driving past climate shifts. The nitrogen isotopic composition (as δ15N) of organic matter in marine sediments is a proxy for surface ocean nitrate supply and demand over time but it may be subject to alteration during sinking and burial. The isotopic composition of nitrogen contained in the shells, or frustules, of diatoms (δ15NDB) is protected and is therefore a potentially more robust tracer of nitrate use in the past. Here we show that δ15NDB in Southern Ocean community cultures does not depend on species composition. We found the εDB (= biomass δ15N - δ15NDB) of the community growouts was -4.8 ± 0.8‰, more than 10‰ different from previous monospecific growouts, but statistically indistinguishable from previous Southern Ocean and North Pacific surface ocean observations. The two community growouts, seeded with populations from 66° and 61°S, had distinct community compositions but indistinguishable εDB, suggesting species composition does not primarily set δ15NDB values in the Southern Ocean. Our results demonstrate that under nitrate-replete conditions, δ15NDB values of frustules sinking from the surface ocean robustly track surface ocean nitrate δ15N values and therefore nitrate supply and demand.	["POLYGON((-170.4 -60.8,-170.36 -60.8,-170.32 -60.8,-170.28 -60.8,-170.24 -60.8,-170.2 -60.8,-170.16 -60.8,-170.12 -60.8,-170.08 -60.8,-170.04 -60.8,-170 -60.8,-170 -61.34,-170 -61.88,-170 -62.42,-170 -62.96,-170 -63.5,-170 -64.04,-170 -64.58,-170 -65.12,-170 -65.66,-170 -66.2,-170.04 -66.2,-170.08 -66.2,-170.12 -66.2,-170.16 -66.2,-170.2 -66.2,-170.24 -66.2,-170.28 -66.2,-170.32 -66.2,-170.36 -66.2,-170.4 -66.2,-170.4 -65.66,-170.4 -65.12,-170.4 -64.58,-170.4 -64.04,-170.4 -63.5,-170.4 -62.96,-170.4 -62.42,-170.4 -61.88,-170.4 -61.34,-170.4 -60.8))"]	["POINT(-170.2 -63.5)"]	false	false

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