BIO Coffee Talks: February 2020
Who: Dr. Youyu Lu
Bedford Institute of Oceanography
What: Exploring forcing mechanisms and predictability of ocean variability
Ocean variations respond to external forcing through the modification of ocean dynamics. An essential goal of oceanographic research is to reveal the forcing mechanisms of ocean variations, thus to achieve better understanding of their predictability. The forcing mechanisms and predictability depend on the nature of forcing, the specific aspects of the ocean variations, the time scales and geographic locations. The effective approaches to advance our understanding are applying statistical and dynamic analyses to observational and modelling data for variations of ocean and forcing fields.
Drawing from the research results of the presenter and his collaborators, this presentation provides a review of selected case studies on ocean variations under the influence of atmospheric forcing at time scales from sub-seasonal to inter-annual. Examples are selected from variations of ocean currents, sea levels, temperature and heat content, and sea ice, in regions of basins and shelf seas of the North Atlantic, North Pacific and Arctic, and the equatorial Pacific Oceans. Besides presenting new understanding of forcing mechanisms, remaining challenges for future work will be discussed.
When: Friday, February 28, 2020
Where: 10am, Needler Boardroom, VS-427, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Zhenxia Long
Bedford Institute of Oceanography
What: Climate Change in the Arctic
Under climate change scenarios, the largest lower tropospheric warming is expected to occur in the Arctic. To understand how the Arctic Ocean might respond to the surface warming, we performed simulations from 1970 to 2099 with a downscaling system implemented for the Arctic. This talk will focus on several Arctic climate systems, such as the Beaufort High, sea ice, the freshwater reservoir in the Canada Basin, and the Atlantic Water Layer. In a warmer climate, the Beaufort High tends to be weak due to the increased cyclone activity in the western Arctic. Our simulations also suggest an 11 percent decrease per decade in ice volume, with the Arctic Ocean becoming largely ice free in the summers by about the 2060s. Moreover, due to the increased ice melting and Ekman transport, there is an increasing trend in the freshwater content in the Beaufort Sea. In terms of the Atlantic Water Layer, there is a decreasing trend in its average temperature. In the vertical, the warm Atlantic water core slightly expands before the 2030s, but significantly shrinks after the 2050s, and essentially disappears by 2070-2099 in the southern Beaufort Sea.
When: Friday, February 21, 2020
Where: 10am, Needler Boardroom, VS-427, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Siren Ruehs
Dalhousie University
What: Aspects of the Atlantic Meridional Overturning Circulation studied with high-resolution ocean models
This talk addresses different aspects of the Atlantic Meridional Overturning Circulation (AMOC) that have been studied with high-resolution (eddy-rich) ocean general circulation models. First, the concept and benefits of Lagrangian particle analyses to study the simulated flow field of ocean models in terms of volume transport pathways and along-track water property modifications associated with the AMOC are highlighted. Subsequently, a recent publication is presented, in which Lagrangian particles analyses with high-resolution ocean models have been used to revisit the relative importance of the different sources for the AMOC's upper limb in the South Atlantic, namely, waters entering from the Indian Ocean through the Agulhas Current system versus waters entering from the Pacific through Drake Passage. These analyses reveal a substantially higher volumetric contribution of waters originating at Drake Passage than estimated by previous Lagrangian studies with coarser resolution models. Moreover, the majority of waters with Drake Passage and Agulhas origin experiences substantial water property modifications along their transit through the South Atlantic. The analyses further indicate that the ratio of the two contributions varies with time, in particular, an ongoing increase in Agulhas leakage may evoke an increase in the Agulhas contribution to the upper limb of the AMOC in the tropics, while the Drake Passage contribution decreases. Finally, ongoing research is introduced in which a novel high-resolution ocean-biogeochemistry model is set up to study the physical controls on Northwest Atlantic CO2 uptake. A focus is set on preliminary results regarding the simulated deep convection pattern in the Labrador Sea versus Irminger Sea over the last several decades.
When: Friday, February 14, 2020
Where: 10am, Needler Boardroom, VS-427, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
Who: Don Gordon
Bedford Institute of Oceanography
What: Remembering Hudson 70
A review of the epic voyage of CSS Hudson around the Americas that left BIO in November 1969 and returned October 1970. It will feature onboard images of people, places and equipment from the BIO photo archives that depict the wide variety of programs carried out.
When: Friday, February 7, 2020
Where: 10am, Needler Boardroom, VS-427, Bedford Institute of Oceanography, Dartmouth, Nova Scotia
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