| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
|
| Initial Amendment Date: | July 20, 2021 |
| Latest Amendment Date: | July 20, 2021 |
| Award Number: | 2048926 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Kelly Brunt
kbrunt@nsf.gov (703)292-0000 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | August 15, 2021 |
| End Date: | July 31, 2024 (Estimated) |
| Total Intended Award Amount: | $69,498.00 |
| Total Awarded Amount to Date: | $69,498.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1 NASSAU HALL PRINCETON NJ US 08544-2001 (609)258-3090 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
NJ US 08544-2020 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | ANT Glaciology |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The integrated heat content of the global ocean is a fundamental climate variable for understanding Earth?s energy balance. Accurate estimates of past changes in the global energy budget are essential for understanding the inherent sensitivities of the Earth system. This project will address the accuracy of these estimates by carrying out computer simulations of dissolved gases in the ocean. By analyzing the outcomes of these simulations, the team aims to refine ice-core-based reconstructions of ocean heat content that rely on measurements of gases (Xenon, Krypton, and Nitrogen) in ancient air bubbles preserved in ice cores.
The project aims to produce the first estimates and uncertainty ranges of saturation anomalies of Xenon, Krypton, and Nitrogen in the glacial ocean during the Last Glacial Maximum. Recent analytical advances have permitted measurement of ratios of Xenon to Nitrogen and Krypton to Nitrogen in ice cores at sufficient precision to resolve whole-atmosphere changes in these ratios that reflect warming and cooling of the global ocean at the 0.1ºC level. However, to quantitatively constrain past ocean heat content using inert gas measurements requires assumptions about long-term changes in the global ocean saturation state of these gases, which remains an entirely open problem. Consequently, the team will use the Transport Matrix Method for biogeochemical tracer simulations. They will build on a suite of previously conducted simulations of oxygen and carbon dioxide in the glacial ocean with the University of Victoria Earth System Climate Model to quantitatively constrain the glacial-interglacial change in inert gas saturation state and understand its physical drivers. In addition, the team will add independent experiments using a second model (the MIT global circulation model) and carry out several future warming experiments to consider how ongoing changes in the Earth system may affect physical air-sea gas transfer. Finally, the team will reevaluate existing ice-core inert gas records to produce best estimates of changes in ocean heat content during the Last Glacial Maximum and periods of abrupt warming throughout the last deglaciation.
This is a project that is jointly funded by the National Science Foundation?s Directorate of Geosciences (NSF/GEO) (U.S. participants) and the Natural Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work.
The NSF award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2)
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The temperature-dependent solubility of inert gases in seawater permits the reconstruction of mean ocean temperature from measurements of ratios of krypton, xenon, and nitrogen in ice cores. One complication of this approach is the extent to which these gases do not fully equilibrate due to various physical processes (e.g. bubble injection by breaking waves, rapid cooling, and exchange under sea ice). To address this problem, we implemented noble gas tracers in transport-matrix method (TMM) model simulations to estimate the physical disequilibrium of inert gases in the global ocean during past climate intervals. We carried out sensitivity testing to understand how much inert gas disequilibria could have changed in past oceans. Based on the results, we re-estimated the mean ocean temperature anomaly during the Last Glacial Maximum and re-evaluated its uncertainty, accounting for the uncertainties associated with changes in disequilibrium during this interval. Our findings suggest that changes in noble gas saturation contribute the largest uncertainty to mean ocean temperature estimates during the Last Glacial Maximum (over analytical uncertainties and corrections for air inclusion processes in glacial ice). Further, our sensitivity testing suggests that the largest contributor to uncertainty in past noble gas disequilibrium is related to the uncertainties in changes in the global wind field. Future improvement in our understanding of high latitude wind responses to different climate boundary conditions will help to reduce uncertainties in past mean ocean temperature reconstruction.
Last Modified: 01/16/2025
Modified by: John A Higgins
Please report errors in award information by writing to: awardsearch@nsf.gov.
