Previous Seminars

Presentation on The Framework for Aquatic Biogeochemical Models (FABM): a Fortran 2003 programming framework for biogeochemical models of marine and freshwater systems.

Speaker: 
Karsten Bolding
Affiliation: 
Bolding & Bruggeman ApS
Seminar Date: 
23. August 2017 - 13:00 - 13:30

Efficient coupling of ocean models (physics) and bio-geochemistry has traditionally been a resource demanding endeavor. Typically the ocean model exists and the bio-geochemistry must be implemented as an add-on without a clear defined application programming interface (API). The result being that each implementation of a new bio-geochemical model in a given physical model lead to ad-hoc solutions only working for the specific models in question.

Geometric tools for the analysis of the stability of traveling waves

Speaker: 
Armand Vic
Affiliation: 
École Normale Supérieure (ENS) of Rennes, France
Seminar Date: 
17. August 2017 - 12:30 - 13:00

Travelling waves appear naturally in many various domains in physics such as fluid mechanics,
electromagnetic theory, etc. Intuitively, a travelling wave is a recognizable shape (of energy for
instance) which is transferred from one part of the medium to another part with a constant
speed of propagation. A broad question tackled in
geophysics is whether small errors in initial conditions can bring huge errors when

Investigation of the impact of correlated observation errors on data assimilation

Speaker: 
Rémy Dubois
Affiliation: 
Ecole des Mines ParisTech
Seminar Date: 
15. August 2017 - 12:30 - 13:10

Data assimilation (DA) are still facing various challenges and one of these challenges is the lack of knowledge on the observation error covariance matrix. Focusing on the observation error correlation, this seminar will begin by presenting Python3's DAPPER environment, followed by the presentation of various DA experiments performed with the EnKF in the Lorenz95 model (e.g. inflation of diagonal R matrices and thinning correlated structures) and the LETKF on the Quasi-Geostrophic model (innovative way to track the observations).

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.

Presentation of IT-group

Speaker: 
Lars-Gunnar Persson (IT Group)
Seminar Date: 
13. June 2017 - 11:15 - 11:45

Information about our IT services and tasks challenges in IT security.

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

Improving the sea ice thickness of TOPAZ by the merged weekly product from Cryosat2 and SMOS

Speaker: 
Jiping Xie from Ocean Modeling
Seminar Date: 
30. May 2017 - 11:15 - 11:45

A merged measurements of Sea Ice Thickness (SIT) from CryoSat2 and SMOS has been distributed in recent years. This product is weekly during the cold season and available since October 2010. As a potential operational SIT observation in Arctic, the quantitative evaluation of its impact on the performance of TOPAZ, which represents the Arctic component of the Copernicus Marine Environment Monitoring Service (CMEMS), is an essential issue due to the well-known SIT errors in most marine forecast systems.

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.

Data assimilation of sea ice concentration: a twin experiment within the Norwegian Climate Prediction Model

Speaker: 
Madlen Kimmritz from Climate Dynamics and Prediction
Seminar Date: 
16. May 2017 - 11:15 - 11:45

A method capable of constraining the sea ice of a coupled climate system in a dynamically consistent manner would be of crucial societal importance.
It would allow for more accurate and reliable reconstruction of the climate that would improve the understanding of the sensitivity of our climate to anthropogenic forcing and enhance the skill of climate prediction on seasonal-to-decadal time scale.

Urban heat island effect in the Arctic

Speaker: 
Victoria Miles from Climate Processes
Seminar Date: 
2. May 2017 - 11:15 - 11:45

Urbanization in the Arctic and sub-Arctic is an increasingly important anthropogenic influence on climate, and has significantly affected terrestrial ecosystems. One of the most evident effects associated with urbanization is the urban heat island (UHI), when urban and suburban areas are warmer then rural areas. The effect is more pronounced in the high latitudes.