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Work package 2

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Work package 4

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Water mass formation on shelves

Work package 2

Key personnel and responsibilities:
Peter M. Haugan (Bjerknes):
Principal investigator, coordinating field work 2003.

W. Paul Budgell (IMR): High resolution ice-ocean modelling tools and studies.
Anne Sandvik (Bjerknes): High resolution atmospheric modelling tools and studies.
Alastair Jenkins (Bjerknes): Coupling of atmosphere and ice-ocean models.
Frank Nilsen (UNIS): Contribution to winter field work and under-ice flux studies.
Ragnheid Skogseth(Post Doc UNIS): Field work 2004, modeling the Storfjord polynya.
Lars-Henrik Smedsrud (Bjerknes): Field work 2005-2006, modeling western Barents Sea.


Activities

Ice-ocean modelling: Make the ROMS/TOMS ocean model including a sea ice module available for process studies of water mass formation in polynyas and fronts in the marginal ice zone of the western Barents Sea and Svalbard, improve the sea ice module for high resolution studies, and make the ice-ocean model available for coupling.
Atmospheric modelling: Perform nonhydrostatic 1-2 km resolution atmospheric model studies of Storfjorden and the western Barents Sea, and make the atmospheric model available for coupling to an ice-ocean model.
Coupling of models: Develop a fully coupled fine resolution atmosphere-ice-ocean model based on the components provided, using the coupling software OASIS (Valcke et al. 2000) and experience from development of the global coupled Bergen Climate Model.


Field work 2003: Participation in the Winter Arctic Polynya Study February-April 2003 Polarstern cruise on invitation from Dr. Ursula Schauer, Alfred-Wegener-Institut, Germany. This will include moorings, current profiling and under-ice turbulence measurements in collaboration also with Dr. Miles McPhee.
Field work 2004-2006: Using helicopter access from Longyearbyen, newly formed ice will be sampled, both the solid ice cover and the grease/slush ice layer. Ice types will be determined from thin sections of ice cores. The range in size and suspended volumes of frazil crystals with depth will be measured using a rubber boat. Together with high resolution current and CTD measurements, this will serve as verification for improvements in the modeled ice dynamics.


Discussion, description and motivation:
Simple wind-driven modelling of the Storfjord polynya (Skogseth and Haugan, 2002, Haarpaintner et al 2001) using observation based winds with no spatial structure has successfully reproduced opening and closing as observed from satellite imagery. However, theory and numerical simulations (Sandvik and Furevik, 2001) show that wind conditions are affected by topography over a considerable downstream distance. Ocean modelling with specified surface buoyancy flux (Skogseth, in prep.) provides insight into hydrographic conditions that influence brine properties (Maus, 2002). However, water mass formation in polynyas and fronts in the ice edge region is fundamentally a fully coupled problem. The ROMS model, an updated and rewritten version of the SCRUM model (Song and Haidvogel, 1994), has proved capable of simulating frontal processes in the northern Norwegian Sea (Ådlandsvik et al., 2001) and is presently used at IMR to model the western Barents Sea. Representations of frazil/grease/polynya processes have up to now been very limited in 3D models, and horizontal/vertical models have been based on laboratory experiments (Smedsrud, 2001, Smedsrud, 2002), with one field observation from the Beaufort Sea to serve as verification. The inertial coupling technique formulated by J. A. T. Bye and applied to general circulation models (Bye and Wolff, 2001) will be used in the coupling scheme. Models such as developed by Hans Burchard (Burchard and Bolding, 2001) will be used in a parallel theoretical activity supporting the design of numerical schemes to be implemented with OASIS.

 

References

Burchard, H. and K. Bolding, 2001. Comparative analysis of four second-moment turbulence closure models for the oceanic mixed layer. Journal of Physical Oceanography 31: 1943-1968.

Bye, J. A. T. and J.-O. Wolff, 2001. Momentum transfer at the ocean--atmosphere interface: the wave basis for the inertial coupling approach. Ocean Dynamics 52(2):51--57.

Haarpaintner, J. , J.-C. Gascard and P.M. Haugan 2001. Ice production and brine formation in Storfjorden. J. geoph. res. 106(C7) 14001-14013.

Maus, S. 2002. Interannual variability of dense shelf water salinities in the Barents Sea, submitted to Polar Research.

Sandvik, A.D and B. R. Furevik, 2002: Case study of a Coastal Jet at Spitsbergen - Comparison of SAR and Model Estimated Wind. Mon. Weather. Rev., 130, 104 -1051.

Skogseth, R. and Haugan P. M. Ice freezing in Storfjorden from four winters of satellite and in situ observations. AGU Chapman Conference on High Latitude Ocean Processes, August 2002, Montreal Canada.

Smedsrud, L. H. 2001. Frazil ice entrainment of sediment: large tank laboratory experiments. Journal of Glaciology 158(47), 461-471.

Smedsrud, L. H. 2002. A model for entrainment of sediment into sea ice by aggregation between frazil ice crystals and sediment grains. Journal of Glaciology 160( 48), 51-61.

Song, Y.T. and D.B. Haidvogel DB, 1994. A semi-implicit ocean circulation model using a generalized topography-following coordinate system, J. Comput. Phys., 115, 228-244.

Valcke S., L. Terray, and A. Piacentini 2000. The OASIS Coupler User Guide Version 2.4, Tech. Rep. TR/CMGC/00-10, CERFACS, Toulouse, France.

Ådlandsvik, B., X.B. Shi, L. P. Røed, and W.P. Budgell, 2001, Modelling the Arctic Front in the Nordic Seas, Preliminary Results from an Idealized Test Case, in S.S. Hjøllo (ed) NOClim Technical Report No. 1, p. 49-65.


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