Previous Seminars

Theory and applications of the Ensemble Transform Kalman Filter (ETKF) for adaptive sampling

Speaker: 
Prof. Sharan Majumdar
Affiliation: 
University of Miami
Seminar Date: 
6. May 2011 - 10:00 - 11:00

Over the past decade, the Ensemble Transform Kalman Filter (ETKF) has
been developed and used to provide guidance for targeted observations
in European, North American and Asian field campaigns (mostly under
WMO/THORPEX). The primary goal has been to identify 'sensitive' areas
in which the assimilation of extra mobile observations would be
expected to optimally improve short-range (1-3 day) forecasts of
high-impact weather events. The theoretical aspects of the ETKF, and
in particular the concept of quantitatively predicting 'signal

On the calculation of an attenuation rate for waves travelling through the ice-covered regions of the ocean

Speaker: 
Luke Bennetts
Affiliation: 
University of Otago, NZ
Seminar Date: 
15. April 2011 - 12:30 - 13:00

The waves-in ice modelling component of project WIFAR provides a prediction of the rate of exponential attenuation of ocean waves through regions of the ice-covered ocean.

This attenuation rate is dependent on the prevailing wave and ice conditions.

The model that will be described in this talk considers attenuation produced by three features in the ice-cover, namely floes, cracks and pressure ridges. A parametrisation of viscous damping is also incorporated.

Relationship between the Atlantic Water transformation rate and decadal variability in the Nordic Seas – northern North Atlantic system

Speaker: 
Alexander Korablev
Affiliation: 
NERSC
Seminar Date: 
31. March 2011 - 12:15 - 13:00

The time series of the thermohaline parameters in the northern North Atlantic and Nordic Seas are revised for 1900-2010 using an updated oceanographic dataset. Analysis, focused on Atlantic sector, reveals that the variability is shaped by anomalies propagation with different magnitude, duration and spatial pattern. Over the longer term, the periods with quasi-stable hydrographic regimes were detected. The periods are triggered by sea-ice and freshwater anomalies of Arctic origin, which are likely modulated by the Beaufort Gyre dynamics.

Observation and modelling of marine ecosystems and element cycles at NERSC

Speaker: 
Various
Seminar Date: 
17. March 2011 - 13:00 - 14:00

We will present ongoing and planned activity from various projects with strong components of observation of ocean color, ecosystem dynamics and element cycling, with an aim to identify important processes that can be better understood by a joint approach.

Anton Korosov: Estimation of primary production and CaCO3 concentration by remote sensing

Self-organization of the Ekman boundary layer turbulence forced by the horizontal component of the Coriolis force

Speaker: 
Igor Ezau
Seminar Date: 
10. March 2011 - 12:15 - 13:00

The Coriolis force is recognized as the major control factor in the shear-driven non-stratified turbulent boundary layer since the work of F. Nansen and V. Ekman in 1898. However, in geophysics (meteorology and oceanography), the central attention is paid to the vertical component of the force whereas the horizontal component is generally omitted. Contrary, in turbo-machinery, effects of the latter on certain types of the flow have been rigorously studied.

Distribution of the Northern Water Mass Formation completing the Atlantic Meridional Overturning Circulation

Speaker: 
Helene R. Langehaug
Seminar Date: 
24. February 2011 - 12:15 - 12:45

The warm and saline water masses carried by the North Atlantic Current, forming the upper limb of the Atlantic Meridional Overturning Circulation, undergoes substantial transformation due to air-sea exchanges on their way northward. These water masses feed the regions of deep water formation in the western subpolar North Atlantic and the Nordic Seas. The water mass transformation in the subpolar region has been localized and quantified in a pre-industrial multi-century (600 years) simulation with the Bergen Climate Model (BCM2).

Warm Currents and Cold War. From the history of the study of ocean currents in Bergen

Speaker: 
Gunnar Ellingsen
Affiliation: 
Institutt for arkeologi, historie, kultur- og religionsvitenskap, UiB
Seminar Date: 
17. February 2011 - 12:30 - 13:30

Between 1960 and 1966, the prototype of the current meter later to be known as the Aanderaa current meter was developed here in Bergen during the so-called Buoy Project. The initiative and funding came from NATO, and the ideas behind the project came from oceanographers in a community that met in the NATO Subcommittee for Oceanographic Research. A key member of this community was professor Håkon Mosby at the Geophysical institute.

Meteorological Temperature Profiler MPT5 in Bergen

Speaker: 
Evgeny Miller
Seminar Date: 
10. February 2011 - 12:15 - 13:00

Nansen Centre has bought a new measurement device Meteorological Temperature Profiler MPT5. Its aim is to collect information about the vertical structure of the boundary layer and temperature inversions. This device is now set up and working at GFI. Evgeny Miller - one of its developers - will give a lecture about the device, algorithms and places where other such devices have been installed.

Utilization of the ETKF : an optimal control law for the adaptive optics of the E-ELT ?

Speaker: 
Morgan Gray
Affiliation: 
OAMP, France
Seminar Date: 
3. February 2011 - 12:15 - 13:00

Adaptive Optics (AO) systems require the implementation of techniques intended for real time identification of atmospheric turbulence. Nowadays there are several approaches. One of them is using the Kalman Filter and presents numerous advantages at the level of optimal control. However it will be impossible to install this process within the frame of an AO system for any ELT class telescope (about 42m for the diameter) because of the quantitative leap in the number of parameters (high dimensional system) and consequently the quantitative leap in the cost in real time processes.

Culture of calculations versus culture of simulations. What is wrong with Earth's System Modelling?

Speaker: 
Igor Esau
Seminar Date: 
27. January 2011 - 12:15 - 13:00

Although the models of the Earth's Climate System and a laboratory thermodynamical system could be mathematically similar, their philosophical load could not be more different. Probably unexpectedly, the philosophy of the model has large effect on the interpretation of the model results and not least on the direction of the model development. This seminar will contrast two research cultures.