Oceanologia No. 41 (1) / 99
Contents
Papers
Reports
Papers
Algorithms for the exact solution of two matrix equations occurring
in the driven cavity problem
Oceanologia 1999, no 41 (1), pp. 3–23
Maria Ewa Klonowska, Włodzimierz Juliusz
Prosnak
Institute
of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot,
Poland; klonowsk@iopan.gda.pl
Keywords: Navier-Stokes equations, elimination of pressure, driven cavity problem,
improvement of the process of solution
Manuscript received December 10, 1998, in final form January 20, 1999.
Abstract
It is shown that two particular systems of linear equations,
derived in an earlier paper by Prosnak and Kosma (1991), can
be solved in an exact time- and storage-saving manner. First
of all, by the proper elimination of unknowns, each system
can be reduced to a smaller one containing only half of the
unknowns. In the first case, the matrix of coefficients of
the so reduced system turns out to be tridiagonal, its elements
consisting of square submatrices. Moreover, the reduced
system can be split into two independent ones. In the second
case, the matrix of the reduced system can be presented as the
product of two triangular ones, each one being partitioned in
square submatrices. Corresponding algorithms and computer
programs have been developed in order to investigate whether
some economy in storage and computing time is really
attainable. Affirmative conclusions are drawn from the
results of computations. This means that the new method
of solving problems governed by the Navier-Stokes equations,
presented in the cited paper, can be applied in a more
effective manner.
Uncertainty in estimating mean solar radiation fluxes at the Baltic
surface from irregular ship-borne meteorological observations
Oceanologia 1999, no 41 (1), pp. 25–50
Anna Rozwadowska
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland;
ania@iopan.gda.pl
Keywords: solar radiation flux, downward irradiance, estimation errors,
irregular meteorological observations, Baltic Sea
Manuscript received November 12, 1998, in final form January 6, 1999.
Abstract
The influence of the technique of sampling of meteorological conditions and
the number of observations on uncertainties in estimates of the solar radiation
flux in the Baltic region is analysed. A semi-empirical model, applied to regular
meteorological observations from two Baltic island stations, Gotska Sandon and
Arkona, was employed to derive solar radiation fluxes (downward irradiances)
for error analysis. The impact of several factors, i.e. consistent sampling
at one observation time, using both daytime and night-time observations in the
flux calculations, and consistent oversampling during the same part of a month
on systematic uncertainties in the monthly mean flux estimates are discussed.
The random errors resulting from an insufficient number of observations used
in the flux calculations and error reduction with an increasing number of observations
are analysed with respect to batch and random sampling. The statistical correlation
of consecutive meteorological observations (meteorological conditions represented
by the zenithal transmittance of irradiance) was also investigated with respect
to errors in the estimation of the solar radiation flux for the Baltic Sea region.
Early spring microplankton development under fast ice covered fjords of Svalbard, Arctic
Oceanologia 1999, no 41 (1), pp. 51–72
Józef Wiktor
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland;
wiktor@iopan.gda.pl
Keywords: Arctic, phytoplankton, Svalbard
Manuscript received November 16, 1998, in final form December 7, 1998.
Abstract
The chlorophyll a concentration, phytoplankton taxa succession, density,
biomass and sedimentation was studied in three fjords of Svalbard in January,
April and May 1995 and 1996. The fjords were covered with variable fast ice
cover ranging in thickness from 0.4 to 1.5 m. Samples collected from the water
column showed that only 10% of the algae could be classified as ice algae species.
The fjord phytoplankton grew well under very poor light conditions (< 1%
of incident radiation). The phytoplankton biomass ranged from 1.7 gC m-2
in winter to 15 gC m-2 in May. Heterotrophic flagellates made a significant
contribution to the biomass (up to 98%), especially at stations with poor light
conditions (inner fjord basins and thick ice cover).
Temperature and N:P ratio as factors causing blooms of blue-green
algae in the Gulf of Gdańsk
Oceanologia 1999, no 41 (1), pp. 73–80
Marcin Pliński, Tomasz Jóźwiak
Institute of Oceanography, Gdańsk University,
Piłsudskiego 46, 81–378 Gdynia, Poland;
ocemp@univ.gda.pl
Keywords: blue-green algae, blooms, temperature,
Baltic Sea
Manuscript received December 1, 1998, in final form December 14, 1998.
Abstract
The bloom dynamics of two planktonic, nitrogen-fixing species of blue-green
algae Aphanizomenon flos-aquae (L.) Ralfs and Nodularia spumigena
Mertens in the Gulf of Gdańsk were studied. The Gulf of Gdańsk is a shallow
part of the Baltic Sea where the water has a mean salinity of ca 8 PSU.
Increased riverine nutrient input and/or changes in the N:P ratio are indicated
as factors causing blue-green algae blooms. A low N:P ratio appears to trigger
blooms. The mean annual value of N:P in the Gulf of Gdańsk since 1981 is 6.5
with a minimum of ca 3. There could be a link between temperature and
the year-to-year differences in bloom intensities. A huge bloom of toxic N. spumigena
was reported in July 1994 when the water temperature rose to 22oC.
Chlorins in sediments of the Gotland Deep (Baltic Sea)
Oceanologia 1999, no 41 (1), pp. 81–97
Grażyna Kowalewska
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland;
kowalewska@iopan.gda.pl
Boris Winterhalter
Geological Survey of
Finland, Department of Surficial Geology, Betonimiehenkuja 4, FIN–02150
Espoo, Finland
Helen M. Talbot, James R. Maxwell
Organic Geochemistry Unit, School of Chemistry,
University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
Joanna Konat
Institute of
Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712
Sopot, Poland
Keywords: chlorins, pigments, chlorophyll a,
deep sediments, Baltic Sea, Gotland Deep
Manuscript received December 1, 1998, in final form January 5, 1999.
Abstract
The distributions of chlorin components as well as chlorophylls c and β-carotene in postglacial
sediments (down to ca 5 m depth), collected from the Gotland Deep in
July 1997, have been determined. The major pigments were similar to those identified
in recent (0–10 cm) sediment extracts of the Gdańsk Deep. High amounts of well
preserved chlorins, including intact chlorophyll a, provide evidence
for high primary production in the past, anoxic sedimentation and favourable
postdepositional conditions. In addition, the results reveal several extremely
rapid changes in the Baltic environment over the last 8000 years caused by different
physico-chemical conditions and subsequent changes in phytoplankton occurrence,
biomass and algal species.
Derivation of remote sensing reflectance of Baltic waters
from above-surface measurements
Oceanologia 1999, no 41 (1), pp. 99–111
Jerzy Olszewski, Mirosław Darecki
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, 81–712 Sopot, Poland;
olszewsk@iopan.gda.pl
Keywords: Bmarine optics, remote sensing, Baltic Sea
Manuscript received October 20, 1998, in final form January 25, 1999.
Abstract
It has been shown experimentally that the remote
sensing reflectance can be readily calculated
from the total remote sensing reflectance,
provided certain external conditions are fulfilled.
The first condition concerns the solar zenith distance,
which should be limited to the 35–70o
range (suitable to
the Baltic region).
The second condition refers to the sea state,
which should display no foam and no vertically directed solar glitter.
Under such circumstances some simplifying assumptions were possible,
which permitted a proper algorithm, in the form of a linear function,
to be worked out. Coefficients of the function are tabled for 10
discrete wavelengths (widened SeaWiFS standard), and are also given
analytically as linear functions of the wavelength.
Reports
Summary of the Polish National Programme of Marine Research up to 2010
Oceanologia 1999, no 41 (1), pp. 113–126
Czesław Druet
Institute of Oceanology, Polish Academy of Sciences,
Powstańców Warszawy 55, 81–712 Sopot, Poland;
druet@iopan.gda.pl