Seminar

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Weekly Lunch Seminars / Thursday Seminars - an open seminar for all

Climate change in Georgia

Speaker: 
Mariam Elizbarashvili
Affiliation: 
University, Tbilisi, Georgia
Seminar Date: 
9. November 2017 - 14:30 - 15:30

Mariam Elizbarashvili is visitor of Yongqi

Two new PhD students at NERSC presents themselve and their projects.

Speaker: 
Artem Moiseev and Fabio Mangini
Seminar Date: 
12. October 2017 - 12:30 - 13:00

Bergen Teknologioverføring

Speaker: 
Steffen Boga
Affiliation: 
Bergen Teknologioverføring
Seminar Date: 
28. September 2017 - 12:30 - 13:00

As the Technology Transfer Office in Bergen, BTO supports research institutions in the region, from guiding good ideas towards commercialization of research and societal benefits. Innovation is one of the four social responsibilities in the Norwegian Act relating to universities, together with research, education and dissemination. BTO supports researchers developing innovative research ideas.

A fully probabilistic data assimilation approach for range-limited observations

Speaker: 
Abhishek Shah
Seminar Date: 
7. September 2017 - 12:30 - 13:00

Many of the measurements available in the atmospheric or oceanographic systems are only available within a limited interval of actual variation of the quantity due to the limitation of gauge or data retrieval techniques i.e, observations with detection limit. For e.g., SMOS retrieved sea-ice thickness. These observations with detection limits contains hard data (quantitative) and soft data (qualitative). The current work focuses on the development and application of the data assimilation scheme for the observations with detection limit.

A robust solver for viscous plastic sea ice models in a finite element framework

Speaker: 
Carolin Mehlmann
Affiliation: 
"Numerical Mathematics with Applications" group at the Otto-von-Guericke university, Magdeburg, Germany
Seminar Date: 
27. September 2017 - 15:00 - 16:00

Subject of this talk are the mathematical challenges and the numerical treatment of large scale sea ice problems. The model under consideration goes back to Hibler ("A dynamic thermodynamic sea ice model", J. Phys. Oceanogr., Hibler 1979) and is based on a viscous-plastic description of the ice as a two-dimensional thin layer on the ocean surface.

Hydrological modelling & Data Assimilation (at catchment scale)

Speaker: 
Marc Etienne Ridler
Affiliation: 
DHI Group, Copenhagen, Dk
Seminar Date: 
29. June 2017 - 12:30 - 13:00

Hydrological models are used extensively to monitor and manage water resources, and provide flood forecasts. These complex, physically based models are inherently uncertain due to imperfect parameterization, meteorological forcing data, initial conditions, and model discretization. Data assimilation offers a means to incorporate information from measurements to both correct model forecasts and, importantly, provides quantitative uncertainty estimates useful for decision makers.

Estimating model evidence using ensemble-based data assimilation with localization - The model selection problem

Speaker: 
Sammy Metref
Affiliation: 
IFAECI, CNRS-CONICET-UBA, Buenos Aires, Argentina.
Seminar Date: 
31. May 2017 - 11:00 - 11:30

In recent years, there has been a growing interest in applying data
assimilation (DA) methods, originally designed for state estimation, to
the model selection problem. Along this stream of efforts, a contextual
formulation of model evidence (CME) has recently been introduced in
Carrassi et al. (2017) and it has been shown that it can be efficiently
computed using a hierarchy of ensemble-based DA procedures. While the DA
methods analyzed in Carrassi et al. (2017) cover those operationally
used worldwide for atmosphere or ocean prediction, they were not studied

Assimilation of non-conventional observations. Application to the estimating of ocean surface currents.

Speaker: 
Julien Brajard
Affiliation: 
LOCEAN/IPSL, Sorbonne Université, Paris, France
Seminar Date: 
29. May 2017 - 11:00 - 11:30

Data assimilation consists in optimally combining observations of a system with
outputs of a numerical model. In the traditional approaches, observations are
are considered to be eulerian and scalar. Recently, in the field
of earth and ocean observations, there is an increasing number of observations
that are fundamentally non-eulerian and/or non scalars:
Drifters and floats are advected by currents and bring a Lagrangian observation through their successive positions,
satellite data are measuring images that contains structured patterns.

Influence of Madagascar Ridge on ocean mesoscale eddies in a regional ocean model

Speaker: 
Issufo Halo
Affiliation: 
1) Department of Conservation and Marine Sciences, Cape Peninsula University of Technology, Cape Town, South Africa, 8000 2) Nansen-Tutu Centre for Marine Environmental Research, Oceanography Department, University of Cape Town, South Africa, 7700
Seminar Date: 
5. April 2017 - 13:00 - 13:30

The topography of the world's ocean basins are among the least studied oceanographic environments. However, they are fundamental for understanding the oceanic circulation. In this study the role of the Madagascar Ridge on modulating the mesoscale circulation, more specifically the eddy field is being investigated using two climatological solutions derived from a regional ocean model, ROMS. In the first experiment the model runs with an ordinary GEBCO-01 topography, whereas in the second, it runs with a modified topography, where the Madagascar Ridge has been removed.

Wave-ice interactions in the neXtSIM sea-ice model

Speaker: 
Timothy Williams
Affiliation: 
NERSC
Seminar Date: 
27. April 2017 - 12:30 - 13:00

We have added a waves-in-ice model (WIM) into the new sea ice model neXtSIM. The physical effects included so far are the effect of the wave radiation stress (WRS) on the ice drift. Specifically, as waves travel into the ice, they are attenuated and lose momentum. This momentum could go into the ocean or the ice (or the atmosphere), but we transfer it entirely to the ice. The WRS, which is the flux of momentum from the waves to the ice, is relatively high at the ice edge but decays exponentially into the ice (like the wave energy).

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