Physical and Biogeochemical Controls on Ocean Acidification in the U.S. Northeast: Insights from a Coupled Physical–Biogeochemical Model
SMAST East 101-103
: 836 S. Rodney French Boulevard, New Bedford MA 02744
Callie Rumbut
c.rumbut@umassd.edu
https://umassd.zoom.us/j/93758230260
Seminar Announcement
Department of Fisheries Oceanography
"Physical and Biogeochemical Controls on Ocean Acidification in the U.S. Northeast: Insights from a Coupled Physical–Biogeochemical Model"
Dr. Lu Wang
Research Assistant Professor, Fisheries Oceanography, UMass Dartmouth
Wednesday, October 14, 2026
3:00 - 4:00 pm
SMAST E 101-103 and via Zoom
Abstract:
The Northeast Biogeochemistry and Ecosystem Model (NeBEM) was developed by coupling the Northeast Coastal Ocean Forecast System (NECOFS) with the European Regional Seas Ecosystem Model (ERSEM) to simulate the coupled physical and biogeochemistry dynamics of the U.S. Northeast continental shelf. Applied to 2017-2018, the model reproduced the seasonal variability of key physical, chemical, biological variables, providing a robust framework for investigating ocean acidification (OA) across environments ranging from estuaries to the continental shelf.
Process-oriented analyses revealed distinct regional drivers of aragonite saturation state (Ωa). Variability in Ωa was primarily influenced by variability dissolved inorganic carbon (DIC) in the Middle Atlantic Bight (MAB), Georges Bank (GB) and Scotian Shelf (SS), whereas both DIC and total alkalinity (TA) contributed substantially in the Gulf of Maine (GOM).
Strong tidal-mixing and river-shelf interaction regions, including the western Scotian Shelf, Bay of Fundy, Nantucket Shoals, Long Island Sound, and estuaries connected to the northern GOM, were identified as particularly vulnerable to OA. From January through April, the inner shelf, particularly near river mouths, experienced low Ωa values (<1.0), with the greatest spatial extent in March. This seasonal minimum was associated with elevated surface DIC levels resulting from atmospheric CO2 uptake and the transport of DIC-rich water through the Northeast Channel. On the outer shelf, slope-water intrusion supplied substantial DIC, while warm-core rings and eddies enhanced the onshore DIC transport.
The simulated normalized TA-DIC (nTA:nDIC) relationship agreed well with observations, supporting the model’s representation of the major biogeochemical processes affecting carbonate chemistry. Regional variations in the nTA:nDIC slope reflected contrasting biogeochemical pathways: nitrification and denitrification were primary contributors to TA and DIC variability in the GOM and MAB, air-sea CO2 exchange dominated in offshore waters, and multiple interacting processes shaped carbonate chemistry in the SS and GB. These findings provide new insights into the regional variability of ocean acidification and its underlying processes across the U.S. Northeast shelf ecosystem.
Join Meeting
https://umassd.zoom.us/j/93758230260
Note: Meeting ID and passcode required, email contact to obtain.
For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu