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Wednesday, September 15, 2021
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12:30 PM
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1:30 PM
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Department of Estuarine and Ocean Sciences Seminar Announcement-Dr. Valentina Giunta
- Location: > See description for location
- Contact: > See Description for contact information
- Description: The School for Marine Science and Technology
Department of Estuarine and Ocean Sciences
Seminar Announcement
"Oceanic Mixing and Mixed Layer Depths"
Dr. Valentina Giunta
Department of Estuarine and Ocean Sciences
SMAST at UMass Dartmouth
Wednesday, September 15, 2021
12:30 pm to 1:30 pm
SMAST East Rooms 101/102
And Via Zoom
Abstract
The ocean surface boundary layer (OSBL) is one of the largest global
regulators of climate. There are two definitions associated with its
depth: the mixed layer depth (MLD) and the mixing layer depth (XLD).
The former is estimated using vertical profiles of temperature and
density, and the latter using measurements of the dissipation rate of
turbulent kinetic energy. The relationship between the XLD and MLD has
not been extensively studied in the past, since this requires
specialized instruments which allow simultaneous measurements of ocean
state variables and turbulence across the full depth of the OSBL.
The overarching objective of this presentation is to show the variability of the XLD and MLD under different conditions. To achieve this,
different estimates of the MLD and XLD are applied to vertical
profiles derived from an autonomous vertical profiler (ASIP) deployed
in two different cruises in the North Atlantic. It was found that the
MLD criteria differ between themselves when the stratification is
weaker and the transition between the mixed layer and the pycnocline
is not well defined. On the contrary, the XLD criteria had a better
agreement between themselves, and a new method was proposed to improve
its estimation.
The action of the wind, waves, and buoyancy fluxes impact the
variability of the OSBL. To study the effect of each source of
turbulence in the OSBL, different parameters related to each forcing
were estimated and compared with the MLD and XLD. Given the close link
found between the XLD and each source of turbulence, a scaling for the
XLD was tested by dividing the ocean into different mixing regimes
according to the ratio between the Monin-Obukhov length, the MLD, and
the surface net heat flux. Under periods of convection, the XLD
shows a significant correlation with the MLD.
The results found using ASIP data were extrapolated to build a
climatology of the upper mixing using reanalysis data from ERA5 and
ARGO profiles during a period of 10 years (2009-2018). Significant
differences between the MLD and the XLD climatology were found during
this process.
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Join Zoom Meeting
https://umassd.zoom.us/j/97440069270?pwd=L2Z1bDZESTFCKzJYZWduYVhWenYvZz09
Meeting ID: 974 4006 9270
Passcode: 428029
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Meeting ID: 974 4006 9270
Passcode: 428029
Find your local number: https://umassd.zoom.us/u/adtxYu9NMO
Join by SIP
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Meeting ID: 974 4006 9270
Passcode: 428029
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For additional information, please contact Sue Silva at s1silva@umassd.edu
- Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series
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3:00 PM
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4:00 PM
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Financial Aid Help Labs
- Location: > See description for location
- Contact: > See Description for contact information
- Description: Financial Aid Services wants to remind all students to file their FAFSA! Join the Financial Aid Services Street Team for FA Help Labs on Wednesdays from 3 to 4 p.m. and Fridays from 3 to 4 p.m. in Library 128 for help filing your FAFSA and learning more about financial aid.
Contact Mark Yanni
myanni@umassd.edu
- Topical Areas: Students, Students, Graduate, Students, Law, Students, Undergraduate, Financial Aid
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2:30 PM
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3:30 PM
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Department of Fisheries Oceanography Seminar Announcement-Michael Dadswell
- Location: > See description for location
- Contact: > See Description for contact information
- Description: The School for Marine Science and Technology
Department of Fisheries Oceanography
Seminar Announcement
"The Decline and Impending Collapse of the Atlantic Salmon (Salmo salar) Population in the North Atlantic Ocean: A Review of Possible Causes."
Michael Dadswell
Department of Biology
Acadia University
Wolfville, Nova Scotia, Canada
Wednesday, September 15, 2021
2:30 pm to 3:30 pm
SMAST East, Rooms 101/102
Also Via Zoom
ABSTRACT
Adult returns to many Atlantic salmon wild and hatchery stocks of the North Atlantic have declined or collapsed since 1985. Enhancement, commercial fishery closures, and angling restrictions have failed to halt the decline. Human impacts such as dams, pollution or marine overexploitation were responsible for some stock declines in the past, but adult returns to
river and hatchery stocks with no obvious local impacts have also declined or collapsed since 1985. Multiple studies have postulated that the recent widespread occurrence of low adult returns may be caused by climate change, salmon farming, food availability at sea, or marine predators but these possibilities are unsupported by stocks that persist near historic
levels, loss of stocks remote from farm sites, a diverse marine prey field, and scarcity of large offshore predators. The decline and collapse of stocks has common characteristics: 1) cyclic annual adult returns cease, 2) annual adult returns flatline, 3) adult mean size declines, and 4) stock collapses occurred earliest among watersheds distant from the North Atlantic
Sub-polar Gyre (NASpG). Cyclic annual adult returns were common to all stocks in the past tthat were not impacted by anthropogenic changes to their natal streams. A flatline of adult abundance and reduction in adult mean size are common characteristics of many overexploited fish stocks and suggest illegal, unreported, and unregulated (IUU) fisheries exploitation
at sea. Distance from the NASpG causing higher mortality of migrating post-smolts would increase the potential for collapse of these stocks from IUU exploitation. By-catch of post-smolts and adults in paired-trawl fisheries off Europe and intercept adult fisheries off Greenland, in the Gulf of St. Lawrence, and off Europe have been sources of marine mortality but seem unlikely to be the primary cause of the decline. Distribution in time and space of former, legal high-sea fisheries indicated fishers were well
acquainted with the ocean migratory pattern of salmon and combined with lack of surveillance since 1985 outside Exclusive Economic Zones or in remote northern regions may mean high at-sea mortality occurs because of IUU fisheries. The problem of IUU ocean fisheries is acute, has collapsed numerous stocks of desired species worldwide, and is probably linked to
the decline and impending collapse of the North Atlantic salmon population.
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Zoom Link
https://umassd.zoom.us/j/93758230260?pwd=OHJ5UDloQkZZaCtXcTlBNlR6Qm0rQT09
Meeting ID: 937 5823 0260
Passcode: 426839
One tap mobile
+13017158592,,93758230260#,,,,*426839# US (Washington DC)
+13126266799,,93758230260#,,,,*426839# US (Chicago)
Dial by your location
+1 301 715 8592 US (Washington DC)
+1 312 626 6799 US (Chicago)
+1 646 876 9923 US (New York)
+1 253 215 8782 US (Tacoma)
+1 346 248 7799 US (Houston)
+1 669 900 6833 US (San Jose)
Find your local number: https://umassd.zoom.us/u/acosTPRs4V
****************************************************************************
For additional information, please contact Sue Silva at s1silva@umassd.edu
- Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series
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12:00 PM
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1:30 PM
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Walk-in Study Abroad Advising
- Location: International Programs Office LARTS 016
- Contact: International Programs Office
- Description: Have a quick question for a study abroad advisor? Would you like to start planning your study abroad experience? Drop by the IPO (LARTS 016) Monday through Friday Noon-1:30. Students will be seen on a first-come, first-served basis.
- Topical Areas: Faculty, Staff and Administrators, Students, University Community, Study Abroad
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