NSF Org:	OCE Division Of Ocean Sciences
Recipient:	UNIVERSITY OF CALIFORNIA SAN DIEGO
Initial Amendment Date:	August 30, 2018
Latest Amendment Date:	January 10, 2022
Award Number:	1829817
Award Instrument:	Standard Grant
Program Manager:	Kandace Binkley kbinkley@nsf.gov  (703)292-7577 OCE  Division Of Ocean Sciences GEO  Directorate for Geosciences
Start Date:	September 1, 2018
End Date:	December 31, 2022 (Estimated)
Total Intended Award Amount:	$890,188.00
Total Awarded Amount to Date:	$965,755.00
Funds Obligated to Date:	FY 2018 = $890,188.00 FY 2022 = $75,567.00
History of Investigator:	Uwe Send (Principal Investigator) usend@ucsd.edu Todd Martz (Co-Principal Investigator)
Recipient Sponsored Research Office:	University of California-San Diego Scripps Inst of Oceanography 8622 DISCOVERY WAY # 116 LA JOLLA CA  US  92093-1500 (858)534-1293
Sponsor Congressional District:	50
Primary Place of Performance:	UCSD-Scripps Institution of Oceanography 9500 Gilman Drive, MC 0230 La Jolla CA  US  92093-0230
Primary Place of Performance Congressional District:	50
Unique Entity Identifier (UEI):	QJ8HMDK7MRM3
Parent UEI:	QJ8HMDK7MRM3
NSF Program(s):	OCEAN TECH & INTERDISC COORDIN
Primary Program Source:	01002223DB NSF RESEARCH & RELATED ACTIVIT 01001819DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	097Z
Program Element Code(s):	168000
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

The net annual flux of CO2 into the ocean helps mitigate climate change, and the transfer of oxygen and organic carbon into the deep sea fuels its vast ecosystem. Linked to that, and equally important, is the net community production (NCP) since it represents the source input at the bottom of the ecosystem food chain, governs the vertical carbon export into the deep ocean, and also has a large controlling influence on the air-sea fluxes of CO2 and O2. The transfers of carbon and oxygen in the water column, their exchange with the atmosphere, and NCP are controlled by both physical and biological processes which vary greatly on seasonal and shorter time-scales, and also interannually. Rates and controlling processes at high latitudes have special significance but are poorly studied and understood, in part due to logistical and technological difficulties. In order to constrain or even fully determine the air-sea fluxes and NCP with in-situ measurements, usually assumptions need to be made since autonomous sensors currently cannot observe the full suite of quantities required for closing the relevant budgets. However, recent and ongoing developments now offer a mix of sensors, partially in prototype form, which could be deployed on the moored profiling system "Seacycler" and which could allow simultaneous determination of net community production (NCP), of the air-sea flux of CO2, and the construction of budgets in important regions of the global ocean.

This research will acquire and fabricate an innovative suite of commercially available and prototype sensors and equipment, in order to integrate and exercise them on SeaCycler in a hierarchy of tests. The goal is to collect sufficient data with these sensors on SeaCycler to demonstrate a) their reliability, b) the functioning in profiling mode on SeaCycler, c) their accuracy, d) the ability to determine total dissolved inorganic carbon (DIC) and calcification (removing the normally made assumptions about Redfield ratios), e) the utility of turbulence profiles in distinguishing mixing vs mixed layers (important for budgets and the role of blooms), f) the robustness of SeaCycler itself. These efforts will lay the foundation for year-long open-ocean deployments of SeaCycler with a suite of accurate and tested sensors to determine the magnitude and variability of the air-sea flux of CO2 and O2 in high-latitude regions such as the Labrador Sea and of the storage/export of DIC and O2 in newly formed water masses. The new capabilities would allow calculation of the magnitude of NCP entirely using biogeochemical budgets, and to capture the physical/chemical controls of its sub-seasonal to inter-annual variability. It is expected that the effects of calcification on carbon budgets and air-sea fluxes can be quantifiable, by observing both CO2/pH and DIC/AT changes with high temporal resolution. The work will bring to bear several technologies developed under NSF OTIC grants, and leverage NSF OOI technology. The new technology will allow experiments to develop algorithms to reduce uncertainty in float and satellite observations. The observations enabled would also be crucial for testing numerical models which simulate biogeochemical processes, air-sea fluxes, and NCP.

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.

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 net annual flux of CO2 into the ocean helps mitigate climate change, and the transfer of oxygen and organic carbon into the deep sea fuels its vast ecosystem. Linked to that, and equally important, is the net community production (NCP) since it represents the source input at the bottom of the ecosystem food chain, governs the vertical carbon export into the deep ocean, and also has a large controlling influence on the air-sea fluxes of CO2 and O2.

The Labrador Sea is one of the most important regions of the ocean where these processes take place, but they are difficult to observe completely and year-round. The moored winched profiler ?SeaCycler? had been specifically developed to enable such observations, partly with NSF support, and resulting from a long Canada-US-Europe collaboration. The current project has vastly enhanced the capabilities of SeaCycler for making complete autonomous observations of the carbon system, of plankton growth, and of turbulent mixing layer development. Additional sensors were integrated, such as a deep Durafet system for pH measurements and an alkalinity sensor, complementing the already integrated CO2 sensors. A turbulence sensor was also added, as well as an autonomous phytoplankton water sampler. Completely new controller hardware boards and firmware were developed and successfully implemented, to allow operation of the more powerful sensor suite.

In addition, an enhanced platform configuration was developed and successfully demonstrated. This consists of a second co-located (subsurface) mooring which carries a substantial ?carbon package? with CO2, pH, and alkalinity sensors, plus a plankton water sampler, all deployed close to the surface. This subsurface mooring communicates acoustically with the SeaCycler mooring. With that a communication path from shore is provided, through the SeaCycler floats, to the carbon package, allowing remote triggering of water samples. The acoustic communication between the moorings and commanding of water samples was demonstrated during the test deployments.

A hierarchy of demonstration deployments were carried out, both in Halifax Basin and the open ocean. The last open-ocean deployment is still in the water. We have no communication with the SeaCycler mooring, but we know both moorings are in place and communicating acoustically. We will learn more after recovery.

Last Modified: 07/11/2023
Modified by: Uwe Send

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