Previous Seminars

Presentation of semester assignment in operational oceanography

Speaker: 
Katriina Juva
Seminar Date: 
16. May 2012 - 14:15 - 14:45

Simulated response in the El Niño-Southern Oscillation to a weakening Atlantic meridional overturning circulation in the Bergen Climate Model

Speaker: 
Lea Svendsen
Affiliation: 
University of Bergen
Seminar Date: 
16. May 2012 - 10:15 - 11:00

Recently, several studies have simulated a reduction in the strength of the Atlantic meridional overturning circulation (AMOC) due to increased freshwater flux to the northern North Atlantic. The present study investigates the climatic response during a weakening AMOC using a freshwater hosing experiment performed with the Bergen Climate Model. The findings are based on monthly means. The main focus is on the large-scale interannual variability of the El Niño-Southern Oscillation (ENSO), and its connection to the Atlantic.

A Remote Sensing Investigation of Folgefonna Glacier: Multi-decadal variations in glacier area, volume and transient snowline

Speaker: 
Ben Robson
Seminar Date: 
10. May 2012 - 12:30 - 13:00

Using an array of sources glacier the evolution of glacier area, volume and the elevation of the transient snowline (TSL) of Folgefonna are analysed. Landsat and ASTER imagery, orthorectified aerial photography and historical cartography are used to quantify changes in glacier area back to 1860, DEMs are generated and compared from multiple sources to analyse changes in glacier elevation and volume back to 1937 while both Landsat TM band 4 and ENVISAT ASAR images are used to map the TSL over the last three decades.

The change of support problem in data assimilation

Speaker: 
Hans Wackernagel
Affiliation: 
Ecole des Mines de Paris. Prof. II at NERSC
Seminar Date: 
4. May 2012 - 14:00 - 14:30

Advance-retreat of outlet glaciers in Sermilik fjord, Southeast Greenland over the past three decades: Changes in seasonality and co-variability

Speaker: 
Victoria Miles
Affiliation: 
Nansen Environmental and Remote Sensing Center
Seminar Date: 
19. April 2012 - 12:30 - 13:00

Greenland’s marine-terminating outlet glaciers have been recently found to vary more rapidly than previously believed, possibly in response to atmospheric and/or oceanic forcing. For most outlet glaciers, the range of variability and degree of co-variability between them is poorly known and there are currently few observations of long-term variability of glacier calving dynamics at high temporal resolution.

The effect of cloud shadows on coherent structures and secondary circulations in the convective boundary layer over homogeneous and heterogeneous terrain

Speaker: 
Sonia Drüke
Affiliation: 
Institut für Meteorologie und Klimatologie Leibniz Universität Hannover
Seminar Date: 
12. April 2012 - 12:30 - 13:15

Coherent flow structures and secondary circulations in the convective boundary layer (CBL) over homogeneously and heterogeneously heated terrain have been studied for many years with large-eddy simulations (LES). However, the effects of boundary-layer cloud shadows on the boundary-layer dynamics have been barely investigated so far. Cloud shadows introduce an additional, dynamically varying surface sensible heat flux heterogeneity, which may affect turbulence and flow structure in the CBL significantly, e.g. by inducing secondary circulations or by modifying existing circulation patterns.

Could we guess the diet of different zooplankton species with data assimilation?

Speaker: 
Ehouarn Simon
Seminar Date: 
29. March 2012 - 12:30 - 13:00

We consider the estimation of the grazing preferences parameters of zooplankton in ocean ecosystem models with ensemble-based Kalman filters. These parameters are introduced to model the relative diet composition of zooplankton that consists of phytoplankton, small size-classes of zooplankton and detritus. They are positive values and their sum is equal to one. However, the sum-to-one constraint cannot be guaranteed by ensemble-based Kalman filters when parameters are bounded. Therefore, a reformulation of the parameterization is proposed.

Surface Current Estimation from Space

Speaker: 
Johnny A. Johannessen
Affiliation: 
NERSC
Seminar Date: 
15. March 2012 - 12:30 - 13:00

Earth observation (EO) from space provides a unique and increasing capability to measure and monitor ocean surface currents at a variety of resolutions and time scales. While some mature techniques are already available to derive ocean surface currents (e.g. altimetry, optical feature tracking), new EO satellites (e.g. GOCE, Cryosat, SMOS) and new techniques are emerging (e.g. SAR range Doppler radial velocities, mean square slope from glitter patterns, improved geoid models) promising additional capabilities to recover ocean surface currents from operating and approved satellite missions.

Atmospheric flow patterns associated with low sea-ice cover in the Barents-Kara Seas

Speaker: 
Svetlana Sorokina
Seminar Date: 
1. March 2012 - 12:30 - 13:00

This study explores links between low sea-ice cover in the Barents-Kara Seas and accompanying atmospheric anomalies by means of re-analysis data and a general circulation model (GCM) control experiment. In both data sets low sea-ice concentrations are associated with enhanced sea-air heat fluxes and a local warm anomalous low pressure in the lower troposphere. In the re-analysis data the local anomaly was deeper and connected with non-local structures reminiscent of a Rossby wave train.

Changes of ice thickness in the Arctic since the Fram expedition

Speaker: 
Vitaly Alexandrov
Seminar Date: 
29. February 2012 - 14:00 - 14:30