Previous Seminars

Arctic Amplification and mid-latitude extreme weather

Speaker: 
Prof. Edward Hanna
Affiliation: 
School of Geography and Lincoln Centre for Water and Planetary Health, College of Science, University of Lincoln, UK
Seminar Date: 
29. August 2018 - 11:15 - 12:00

Recently there has been a significant increase in some types of extreme weather over the UK and other northern mid-latitudes: for example winters 2013/14 & 2015/16 in the UK were exceptionally mild, wet and stormy, while large parts of winters 2009/10 and 2010-11 were unusually cold and had record deep snows. Snowmageddon hit the eastern seaboard of the USA in the last few winters. Meanwhile several recent summers, most notably 2007 and 2012, experienced record UK rainfall and widespread flooding.

Optimization of stochastic parameterizations for model error treatment using nested ensemble Kalman filters

Speaker: 
Guillermo Scheffler
Affiliation: 
University of Buenos Aires, Argentina
Seminar Date: 
16. August 2018 - 12:30 - 13:00

Stochastic parameterizations have been successfully used to represent the uncertainty associated with the parameterization of unresolved scale processes for ensemble forecasting and data assimilation systems. In order to accurately describe the uncertainty associated with numerical predictions, these parameterizations have to be optimized. We will introduce a novel technique based on hierarchical ensemble Kalman filters for the optimization of stochastic parameterizations for data assimilation applications.

Liouville solutions for low complexity systems: characterisation of PDF evolutions

Speaker: 
Alejandro Hermoso
Affiliation: 
University of Balearic Islands.
Seminar Date: 
13. July 2018 - 11:00 - 11:30

The prediction of weather and climate is one of the most challenging problems faced nowadays by the scientific community, not only for its incalculable value for macroevolution planning but also for civil protection and man- agement of a myriad of socioeconomic assets. One of the main causes why numerical weather forecasts made with dynamical models are uncertain is the lack of knowledge about the state of the atmosphere with infinite preci- sion.

Creating a Madden-Julian oscillation (MJO) without convection

Speaker: 
Dr Jun-Ichi Yano
Affiliation: 
Meteo France
Seminar Date: 
12. July 2018 - 12:15 - 13:00

The Madden--Julian oscillation (MJO), a planetary--scale eastward propagating coherent structure with periods of 30--60 days, is a prominent manifestation of intraseasonal variability in the tropical atmosphere.
It is widely presumed that small--scale moist cumulus convection is a critical part of its dynamics.
However, the recent results from high--resolution modeling as well as data analysis suggest that the MJO may be understood by dry dynamics to a leading--order approximation.

Particle trajectory modelling for improved understanding of the South African shelf sea meso- and submesoscale variability and applications in operational oceanography

Speaker: 
Michael G. Hart-Davis
Affiliation: 
Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, South Africa
Seminar Date: 
5. July 2018 - 12:30 - 13:30

This seminar will focus on previous work done in collaboration with the Nansen Environmental and Remote Sensing Center as well as the planned working being done at NERSC and throughout the M.G. Hart-Davis master thesis.

Impact of Winter Storms in a Thinner Arctic Sea-ice Regime

Speaker: 
Polona Itkin
Affiliation: 
Norwegian Polar Institute
Seminar Date: 
5. June 2018 - 10:00 - 11:00

The integrative effects of increased winter storm activity in the Arctic's Atlantic sector were studied using a collection of field observations and analyses. In early 2015, during the six-month N-ICE2015 expedition in the pack ice north of Svalbard, we observed a chain of events in the atmosphere-ice-ocean system that was triggered by several powerful winter storms. Our unique, interdisciplinary observations show that these winter storms entail significant effects that last much longer than the short-lived storm events themselves.

On the ongoing development of a new rheological model for a better representation of the drift and deformation of sea ice

Speaker: 
Véronique Dansereau
Affiliation: 
Centre National de la Recherche Scientifique - Institut des Sciences de la Terre, Grenoble, France, and Nansen Environmental and Remote Sensing Center, Bergen, Norway
Seminar Date: 
4. June 2018 - 11:00 - 11:30

Dansereau, V.*, Weiss, J., Saramito, P., Rampal, P., Bouillon, S., Olason, E.

Introductory Course On Statistical Modeling Of Extreme Values

Speaker: 
Hans Wackernagel
Affiliation: 
Equipe de GEOSTATISTIQUE - MINES ParisTech - PSL
Seminar Date: 
31. May 2018 - 10:15 - 1. June 2018 - 15:00

Extreme value theory is based on different principles than those
of conventional statistics as it is designed to study and model
exceptional events rather than the average characteristics of
natural phenomena.

This two-day introductory course will start by presenting
exploratory tools to analyze the behavior of extreme values in
geophysical data. This will help to motivate the basic principles
of the statistical modeling of extreme values and the
distributions that characterize them. The two common approaches
for assessing the risk of extreme events at a given level, i.e.

Study of the Kuroshio intrusion events by the identified paths into the South China Sea using an improved synthetic method

Speaker: 
Dazhi Xu
Affiliation: 
Visiting Scholar from South China Sea Marine Prediction Center, Guangzhou China
Seminar Date: 
28. May 2018 - 13:00 - 13:45

Originating from the North Equatorial Current (NEC), the Kuroshio is the strongest ocean current in the northwest Pacific, which is characterized by high temperature, high salinity, narrow band, and large flow velocity and its variable rate. When passing by the Luzon Strait (LS), a branch of the Kuroshio flows into the South China Sea (SCS) and affects the circulation and temperature-salinity structure in the SCS.

Ocean Acoustic Tomography in the North Atlantic

Speaker: 
Brian Dushaw
Affiliation: 
Nansen Center, Bergen, Norway
Seminar Date: 
15. May 2018 - 13:00 - 14:00

An objective mapping exercise was used to assess the resolution capabilities of ocean acoustic tomography in combination with Argo floats. Basis functions for a basin-wide area are derived from a covariance computed using an ocean state estimate. As is demonstrated by the formal uncertainty estimates from this computation, Argo and tomography are complementary measurements. In several examples, each separately gives results with comparable uncertainty, while when both are employed, uncertainties are reduced by O(50%).