Fall 2011

All-Source Green's Functions for Fast Responses to Water Level Related Marine Hazards

Zhigang Xu

Maurice Lamontagne Institute
Department of Fisheries and Oceans Canada

4:00 p.m., Thursday, September 29, 2011

Abstract: Tsunamis and storm surges are the most devastating marine hazards. They are long waves, moving as fast as a jetliner in deep water. To mode their propagations in real-time means to have a race in time against the fast moving waves. One has to win the race by a large time margin so that coastal communities can have a sufficient time window to respond to the hazards. It is very difficult to win the race in a vast ocean. The tsunami triggering event is unpredictable, which rules out the possibility to have a pre-event modeling. Storm surges permit a pre-event modeling since their forcing is forecastable. However there is a challenge from the other end of the time line: how to feasibly model storm surges for a centurial long term with a time step in seconds? Concerns for coastal vulnerabilities to future climate changes have requested for such long term simulations.

This talk is to present a new approach in dealing with the challenges. The approach is to use the all-source Green.s function (Xu, 2007; Xu, 2011) to pre-calculate the domain and weights of the dependences (the dependence field) of water level variations at a point of interest. The pre-calculated dependence field makes it possible to immediately forecast the tsunami arrivals, in terms of both times and amplitudes, as soon as a tsunami is triggered in its source region. The pre-calculated dependence field also makes the CFL condition no longer the limiting factor, hence to perform a long term simulation becomes feasible. A dependence field itself can also reveals physics of the ocean dynamic system, independent of external forcing.

No seminar this week

Thursday, October 6, 2011

Title: TBA

Speaker: TBA

Institute

4:00 p.m., Thursday, October 13, 2011

Impact of Environmental Preferences on the Distribution of Marine Animals: Initial Experiments With Simple Models

Keith Thompson and Shiliang Shan

Department of Oceanography
Dalhousie University

4:00 p.m., Thursday, October 20, 2011

No seminar this week

Thursday, October 27, 2011

Special Combined Oceanography Department / POMSS Seminar
Please note special time and place!!

Challenges Facing Marine Renewable Energy Development in Scotland

Scottish Development International Representatives

3:00 p.m., Thursday, November 3, 2011
Room 3655, Oceanography Building

Title: TBA

Speaker: TBA

Institute: TBA

4:00 p.m., Thursday, November 10, 2011

Seismic Oceanography

Berta Biescas

Department of Oceanography
Dalhousie University

4:00 p.m., Thursday, November 17, 2011

Seismic oceanography (SO) is a relatively new discipline (2003), which uses seismic reflection data for oceanographic studies. The seismic reflexions generated within the boundaries of water masses with different thermohaline properties allow us to reconstruct images of the finestructure (staircases, lateral intrusions), as well as mesoscale structures (fronts, eddies, currents). The images obtained by SO have resolutions on the order of 10 m vertical and horizontally, which is a strong improvement in the horizontal dimension, comparing with the data obtained with classical oceanographic instrumentation with typical resolutions on the order of 1 km.
I will show a summary of the main thermohaline structures that have been processed in different areas of the world by different SO work-groups as an example of how can we use this tool for ocean observation.
Beside the imaging processing, we are working also in the inversion of seismic data to oceanographic parameters. Inversion methods can convert seismic images to maps of physical properties (T, S, density). I will present the results of the inversion methodologies (stochastic deconvolution, full wave form inversion, very fast simulated annealing) that have been applied until the present time and the future goals.

No seminar this week - Huntsman Award at BIO

Thursday, November 24, 2011

Title: TBA

Speaker: TBA

Institute: TBA

4:00 p.m., Thursday, December 1, 2011

Extreme Surface and Bottom Currents in the Northwest Atlantic

Eric Oliver

Department of Oceanography
Dalhousie University

4:00 p.m., Thursday, December 8, 2011

No seminar this week

Thursday, December 15, 2011

No Seminar This Week

Thursday, December 22, 2011