180
4
Discussion
K. Fennel· T. Neumann
A variety of mesoscale patterns in nutrient and plankton distributions are generated by the external forcing, and these correspond qualitatively with the satellite images of chlorophyll distributions (for instance in Siegel et al. 1996). The
course of nutrient and plankton dynamics is well described by the model. Interannual differences are due to the variations in meteorological forcing. Regional
differences are due to bottom bathymetry and background stratification.
The resolution of mesoscale advective processes is important for the chemical-biological dynamics. A change in grid size has a strong influence where spatial scales of advective processes are comparable to grid width. Processes which
are not resolved after increasing the grid size still influence the chemical-biological dynamics. If the grid is fine enough to resolve the advective processes properly, then the differences of both results are negligible. Increasing grid scale filters out parts of the mesoscale variability and may cause significant deviations
of the concentration and distribution of the chemical-biological state variables.
Acknowledgements
The authors thank Prof. Tom Osborn for revising the language. The investigations were partly supported by the project TRUMP of the Bundesministerium
fur Forschung und Technologie (project number: 03F0105B).
Institut fur Ostseeforschung Contribution Number 245.
References
Bodungen vB, Brockel vK, Smetacek V, Zeitzschel B (1981) Growth and sedimentation of the
phytoplankton spring bloom in the Bornholm Sea (Baltic Sea). Kieler Meeresforsch
Sonderh 5:49-60
Fennel W (1995) A model of the yearly cycle of nutrients and plankton in the Baltic Sea.
J Mar Syst 6:313-329
Fennel W, Neumann T (1996) The mesoscale variability of nutrients and plankton as seen
in a coupled model. DHZ 48 Nr.1:49-71
Fennel W, Seifert T (1995) Kelvin wave controlled upwelling in the western Baltic. J Mar Syst
6:289-300
Kaiser W, Schulz S (1978) On the causes for the differences in space and time of the commencement of the phytoplankton bloom in the Baltic. Kieler Meeresforsch Sonderh
4:161-170
Nehring D (1992) Hydrografisch-chemische Langzeitveranderungen und Eutrophierung
der Ostsee. Wasser Boden 44:632-638
Nehring D, Matthaus W (1991) Die hydrografisch-chemischen Bedingungen in der westlichen Ostsee im Jahre 1991. Deutsche Hydrogr Zeitung 44:217-238
Pacanowski RC, Philander SGH (1981) Parametrization of the vertical mixing in numerical
models ofthe trophic ocean. J Phys Oceanogr 11:1443-1451
Schulz S, Kaiser W (1986) Increasing trends in plankton variables in the Baltic Sea - a further sign of eutrophication? OPHELIA Suppl4:249-257
4
Discussion
K. Fennel· T. Neumann
A variety of mesoscale patterns in nutrient and plankton distributions are generated by the external forcing, and these correspond qualitatively with the satellite images of chlorophyll distributions (for instance in Siegel et al. 1996). The
course of nutrient and plankton dynamics is well described by the model. Interannual differences are due to the variations in meteorological forcing. Regional
differences are due to bottom bathymetry and background stratification.
The resolution of mesoscale advective processes is important for the chemical-biological dynamics. A change in grid size has a strong influence where spatial scales of advective processes are comparable to grid width. Processes which
are not resolved after increasing the grid size still influence the chemical-biological dynamics. If the grid is fine enough to resolve the advective processes properly, then the differences of both results are negligible. Increasing grid scale filters out parts of the mesoscale variability and may cause significant deviations
of the concentration and distribution of the chemical-biological state variables.
Acknowledgements
The authors thank Prof. Tom Osborn for revising the language. The investigations were partly supported by the project TRUMP of the Bundesministerium
fur Forschung und Technologie (project number: 03F0105B).
Institut fur Ostseeforschung Contribution Number 245.
References
Bodungen vB, Brockel vK, Smetacek V, Zeitzschel B (1981) Growth and sedimentation of the
phytoplankton spring bloom in the Bornholm Sea (Baltic Sea). Kieler Meeresforsch
Sonderh 5:49-60
Fennel W (1995) A model of the yearly cycle of nutrients and plankton in the Baltic Sea.
J Mar Syst 6:313-329
Fennel W, Neumann T (1996) The mesoscale variability of nutrients and plankton as seen
in a coupled model. DHZ 48 Nr.1:49-71
Fennel W, Seifert T (1995) Kelvin wave controlled upwelling in the western Baltic. J Mar Syst
6:289-300
Kaiser W, Schulz S (1978) On the causes for the differences in space and time of the commencement of the phytoplankton bloom in the Baltic. Kieler Meeresforsch Sonderh
4:161-170
Nehring D (1992) Hydrografisch-chemische Langzeitveranderungen und Eutrophierung
der Ostsee. Wasser Boden 44:632-638
Nehring D, Matthaus W (1991) Die hydrografisch-chemischen Bedingungen in der westlichen Ostsee im Jahre 1991. Deutsche Hydrogr Zeitung 44:217-238
Pacanowski RC, Philander SGH (1981) Parametrization of the vertical mixing in numerical
models ofthe trophic ocean. J Phys Oceanogr 11:1443-1451
Schulz S, Kaiser W (1986) Increasing trends in plankton variables in the Baltic Sea - a further sign of eutrophication? OPHELIA Suppl4:249-257