Previous Seminars

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).

Decadal Changes in Salinity in the Oceanic Subtropical Gyres

Speaker: 
Subrahmanyam (Subra) Bulusu
Affiliation: 
Satellite Oceanography Laboratory,School of the Earth, Ocean and Environment, University of South Carolina
Seminar Date: 
19. April 2017 - 11:00 - 12:00

There is evidence that the global water cycle has been undergoing an intensification over several decades as a response to increasing atmospheric temperatures, particularly in regions with skewed evaporation – precipitation (E-P) patterns such as the oceanic subtropical gyres. Moreover, observational data (rain gauges, etc.) are quite sparse over such areas due to the inaccessibility of open ocean regions. We analyzed spatial and temporal salinity trends in five subtropical gyre regions over the past six decades using Simple Ocean Data Assimilation (SODA) reanalysis.

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.

Dynamically constrained uncertainty for the Kalman filter covariance in the presence of model error

Speaker: 
Colin James Grudzien
Affiliation: 
NERSC
Seminar Date: 
4. April 2017 - 11:15 - 11:45

The forecasting community has long understood the impact of dynamic instability on the uncertainty of predictions in physical systems and this has led to innovative filtering design to take advantage of the knowledge of process models. The advantages of this combined approach to filtering, including both a dynamic and statistical understanding, have included dimensional reductions and robust feature selection in the observational design of filters.

Observability of long term Kuroshio variability through four dimensional ocean data assimilation

Speaker: 
Tsuyoshi Wakamatsu
Affiliation: 
JAMSTEC
Seminar Date: 
9. March 2017 - 14:15 - 15:00

Eddy resolved (1/10 degree), long term (1982-current) ocean reanalysis data, FORA-WNP30, covering the Western North Pacific Ocean (117E-160W, 15N-65N) is newly produced using cycled 4DVar data assimilation system with quasi 10 day assimilation period. The reanalysis project was led by joint research group of Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and Meteorological Research Institute (MRI), Japan.

Dynamical systems and transport processes in the ocean: an application to a marine oil spill.

Speaker: 
Ana Mancho
Affiliation: 
ICMAT, Consejo Superior de Investigaciones Científicas, Mardid, Spain.
Seminar Date: 
7. March 2017 - 11:15 - 12:00

The goal of this presentation is to provide evidence on how tools from
dynamical systems theory may help to understand transport processes in the ocean surface.
The role of these techniques will be illustrated through the description of a recent marine oil-spill,
produced after the sinking of the Oleg Naydenov fishing ship, in Spain, close to the
Canary Islands, in April 2015.

Medium range predictability of summertime sea ice in the East Siberian Sea

Speaker: 
Takuya Nakanowatari
Affiliation: 
NIPR, Japan
Seminar Date: 
6. February 2017 - 13:00 - 13:30

A study of medium range predictability of summertime sea ice in the East Siberian Sea based on TOPAZ4 data assimilation system―Impact of initial conditions and atmospheric prediction skills.

An efficient training scheme that improves the forecast skill of a supermodel.

Speaker: 
Francine Schevenhoven
Affiliation: 
UiB
Seminar Date: 
2. February 2017 - 12:30 - 13:00

Weather and climate models have improved steadily over time as witnessed by objective skill scores, although significant model errors remain. Given these imperfect models, predictions might be improved by combining them dynamically into a so-called ``supermodel''. In this study a new training scheme to construct such a supermodel is explored using a technique called Cross Pollination in Time (CPT). In the CPT approach the models exchange states during the prediction.

Acoustic tomography in the Canary Basin (CAMBIOS 1997-8): Meddies and tides

Speaker: 
Brian Dushaw
Affiliation: 
NERSC
Seminar Date: 
26. January 2017 - 12:30 - 13:15

CAMBIOS was an acoustic tomography experiment deployed by IFREMER in the Canary Basin between Madeira and the Azores in 1997-8. The goal of CAMBIOS was to test whether the acoustical observations could quantify the flux of Mediterranean water into the western Atlantic. Such water often is carried as "Meddies" - self-contained, rotating eddies of 100 km horizontal extent and 500 m vertical extent. Meddies carry warm and salty water from the Mediterranean; they are density compensated, but not sound speed compensated. This talk revisits the CAMBIOS data.

Joint effect of sea level variations and wind waves on coastal flooding risks in the future climate – new insights

Speaker: 
Ulpu Leijala
Affiliation: 
Research Scientist at FMI Marine Research Unit and PhD student at University of Helsinki.
Seminar Date: 
19. January 2017 - 13:15 - 13:45

New methods to estimate the effects of extreme coastal sea level events in a more accurate and location-specific way are vital for secure planning and operation of densely populated coastal areas -areas that are strongly vulnerable to climate change consequences. In Finland, the global mean sea level rise predictions together with the past local short-term sea level variability have formed traditionally the basis of the sea level and flood probability projections for the future.