Department of Fisheries Oceanography PhD Dissertation Defense by Lu Wang
When: Thursday,
April 27, 2023
1:00 PM
-
2:00 PM
Where: > See description for location
Description: The School for Marine Science and Technology
Department of Fisheries Oceanography
PhD Dissertation Defense
"Simulating ocean acidification in the Northeast U.S. region using a fully coupled three-dimensional biogeochemistry and ecosystem model"
By
Lu Wang
Advisor
Prof. Changsheng Chen
Committee Members
Prof. Geoffrey Cowles (UMassD)
Prof. Joseph Salisbury (UNH)
Prof. Kevin D.E Stokesbury (UMassD)
Prof. Rubao Ji (WHOI)
Thursday, April 27, 2023
1:00 pm - 2:00 pm
SMAST East, Room 101
836 S. Rodney French Blvd, New Bedford and via Zoom
Abstract
The Northeast Biogeochemistry and Ecosystem Model (NeBEM) was developed by integrating the Northeast Coastal Ocean Forecast System (NECOFS) with European Regional Seas Ecosystem Model (ERSEM). ERSEM was upgraded to include volume and mass conservation adjustment, total variational diminishing biogeochemical tracer advection scheme, groundwater module, and spatially dependent parameter specifications. NeBEM was first validated through one- and three-dimensional experiments in Massachusetts Bay and then applied to simulate the 2017-2018 physical and biogeochemistry fields in the U.S. region. The model skill assessments demonstrated the NeBEM’s capability of reproducing the seasonal variability of ����3, ����4, ������4, ����, Chl-a, ����, ������, ����, ������2, and ���� in a multi-scale region varying from estuaries to continental shelves. Process-oriented studies suggested that the changes in ���� was predominantly manipulated by ������ variability in the Middle Atlantic Bight (MAB) and Georges Bank (GB), and DIC plus TA in the Gulf of Maine (GOM) and Scotian Shelf (SS). Generally, the tidal-mixed areas, such as the western shelf of Nova Scotia, Fundy Bay, Nantucket Shoals, Long Island Sounds, and estuaries connected to the northern GOM, were most susceptible to the OA. From January to April, the inner shelf, especially near rivers, experienced a period of low ���� (<1.0), with the largest area occurring in March. During this period, the surface ������ was increased by ����2 loading through the air-sea interface via NEC. Over the outer shelf, the total ������ amount was predominantly replenished by the onshore slope-water inflow. The model suggested that warm core rings (WCRs) and eddies (WCEs) played an essential role in enhancing the slope-water transport to the shelf, which accounted for an ~35% increase in the ������ flux.
The observed data generally fell within the range of the simulated n����:n������ slope. The distribution of simulated n����:n������ ratio varied from region to region. The biogeochemical variability of ���� and ������ was primarily controlled by the nitrification/denitrification process in the GOM and MAB, the air-sea ����2 exchange in the open sea (OS), and the multiple biogeochemical processes in SS and GB.
The influence of climate change on OA was assessed using NeBEM by 1) considering observational data-projected increases in ������, atmospheric ����2 loading, and river discharges, and 2) a downscale climate (NCAR-CESEM-BC)-regional (WRF)-NeBEM coupled model. Both approaches consistently show that regional warming will intensify the anticyclonic residual circulation gyre over GB and the cyclonic gyre in Wilkinson Basin but weaken the cyclonic gyre in Jordan Basin. March will still be the highest probability month with the maximum area of a yearly minimum ���� under changing climate. Increased atmospheric ����2 loading against global warming will enlarge yearly minimum ���� area during March by 8% in SS, 3% in the GOM, 18% over GB, and increase the probability of having the minimum ���� to occur earlier. Warming will increase the probability of having the yearly lowest ���� to occur in the bottom layer in the GOM and MAB. Due to the cancellation of global-warming and increased atmospheric ����2 loading effects, the ���� and ������ variability will still be controlled by the nitrification/denitrification process in the GOM and MAB, the air-sea ����2 exchange in OS, and multiple biogeochemical processes in SS and GB.
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Join Zoom Meeting
https://umassd.zoom.us/j/96069484140?pwd=U0xXZjZsbnlCWGpHcEJHdytpb2tndz09
Meeting ID: 960 6948 4140
Passcode: 002494
****************************************************************************
For additional information, please contact Sydney Carreiro at Scarreiro1@umassd.edu
Department of Fisheries Oceanography
PhD Dissertation Defense
"Simulating ocean acidification in the Northeast U.S. region using a fully coupled three-dimensional biogeochemistry and ecosystem model"
By
Lu Wang
Advisor
Prof. Changsheng Chen
Committee Members
Prof. Geoffrey Cowles (UMassD)
Prof. Joseph Salisbury (UNH)
Prof. Kevin D.E Stokesbury (UMassD)
Prof. Rubao Ji (WHOI)
Thursday, April 27, 2023
1:00 pm - 2:00 pm
SMAST East, Room 101
836 S. Rodney French Blvd, New Bedford and via Zoom
Abstract
The Northeast Biogeochemistry and Ecosystem Model (NeBEM) was developed by integrating the Northeast Coastal Ocean Forecast System (NECOFS) with European Regional Seas Ecosystem Model (ERSEM). ERSEM was upgraded to include volume and mass conservation adjustment, total variational diminishing biogeochemical tracer advection scheme, groundwater module, and spatially dependent parameter specifications. NeBEM was first validated through one- and three-dimensional experiments in Massachusetts Bay and then applied to simulate the 2017-2018 physical and biogeochemistry fields in the U.S. region. The model skill assessments demonstrated the NeBEM’s capability of reproducing the seasonal variability of ����3, ����4, ������4, ����, Chl-a, ����, ������, ����, ������2, and ���� in a multi-scale region varying from estuaries to continental shelves. Process-oriented studies suggested that the changes in ���� was predominantly manipulated by ������ variability in the Middle Atlantic Bight (MAB) and Georges Bank (GB), and DIC plus TA in the Gulf of Maine (GOM) and Scotian Shelf (SS). Generally, the tidal-mixed areas, such as the western shelf of Nova Scotia, Fundy Bay, Nantucket Shoals, Long Island Sounds, and estuaries connected to the northern GOM, were most susceptible to the OA. From January to April, the inner shelf, especially near rivers, experienced a period of low ���� (<1.0), with the largest area occurring in March. During this period, the surface ������ was increased by ����2 loading through the air-sea interface via NEC. Over the outer shelf, the total ������ amount was predominantly replenished by the onshore slope-water inflow. The model suggested that warm core rings (WCRs) and eddies (WCEs) played an essential role in enhancing the slope-water transport to the shelf, which accounted for an ~35% increase in the ������ flux.
The observed data generally fell within the range of the simulated n����:n������ slope. The distribution of simulated n����:n������ ratio varied from region to region. The biogeochemical variability of ���� and ������ was primarily controlled by the nitrification/denitrification process in the GOM and MAB, the air-sea ����2 exchange in the open sea (OS), and the multiple biogeochemical processes in SS and GB.
The influence of climate change on OA was assessed using NeBEM by 1) considering observational data-projected increases in ������, atmospheric ����2 loading, and river discharges, and 2) a downscale climate (NCAR-CESEM-BC)-regional (WRF)-NeBEM coupled model. Both approaches consistently show that regional warming will intensify the anticyclonic residual circulation gyre over GB and the cyclonic gyre in Wilkinson Basin but weaken the cyclonic gyre in Jordan Basin. March will still be the highest probability month with the maximum area of a yearly minimum ���� under changing climate. Increased atmospheric ����2 loading against global warming will enlarge yearly minimum ���� area during March by 8% in SS, 3% in the GOM, 18% over GB, and increase the probability of having the minimum ���� to occur earlier. Warming will increase the probability of having the yearly lowest ���� to occur in the bottom layer in the GOM and MAB. Due to the cancellation of global-warming and increased atmospheric ����2 loading effects, the ���� and ������ variability will still be controlled by the nitrification/denitrification process in the GOM and MAB, the air-sea ����2 exchange in OS, and multiple biogeochemical processes in SS and GB.
************************************************************************
Join Zoom Meeting
https://umassd.zoom.us/j/96069484140?pwd=U0xXZjZsbnlCWGpHcEJHdytpb2tndz09
Meeting ID: 960 6948 4140
Passcode: 002494
****************************************************************************
For additional information, please contact Sydney Carreiro at Scarreiro1@umassd.edu
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series