Oceanologia No. 46 (2) / 04




Uncertainty in stratiform cloud optical thickness inferred from pyranometer measurements at the sea surface
Oceanologia 2004, 46(2), 155-174

Anna Rozwadowska
Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: ania@iopan.gda.pl

Keywords: cloud optical thickness, pyranometer, plane-parallel retrieval bias, Monte Carlo, bounded cascade cloud model

Manuscript received 20 January 2004, reviewed 31 March 2004, accepted 20 April 2004.
The relative "plane-parallel" error in a mean cloud optical thickness retrieved from ground-based pyranometer measurements is estimated. The plane-parallel error is defined as the bias introduced by the assumption in the radiative transfer model used in cloud optical thickness retrievals that the atmosphere, including clouds, is horizontally homogeneous on the scale of an individual retrieval. The error is estimated for the optical thickness averaged over the whole domain, which simulates the mean cloud optical thickness obtained from a time series of irradiance measurements. The study is based on 3D Monte Carlo radiative transfer simulations for non-absorbing, all-liquid, layer clouds. Liquid water path distributions in the clouds are simulated by a bounded cascade fractal model. The sensitivity of the error is studied with respect to the following factors: averaging time of irradiance used in an individual retrieval, mean cloud optical thickness, cloud variability, cloud base height and solar zenith angle. In the simulations presented in this paper, the relative bias in the domain averaged cloud optical thickness retrieved from pyranometer measurements varies from +1% for optically thin clouds to nearly -20%. The highest absolute value of the relative bias is expected for thick and variable clouds with high bases (e.g. 1 km) and retrievals based on long-term mean irradiances (averaging time of the order of several tens of minutes or hours). The bias can be diminished by using short-term irradiance averages, e.g. of one minute, and by limiting retrievals to low-level clouds.
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Ammonia and ammonium over the southern Baltic Sea.
Part 1. Preparation of aerosol and air samples for the determination of ammonia by the indophenol method

Oceanologia 2004, 46(2), 175-184

Anita Lewandowska, Lucyna Falkowska
Institute of Oceanography, University of Gdańsk, al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: nadsta@sat.ocean.univ.gda.pl

Keywords: ammonia, ammonium, modification of indophenol method

Manuscript received 20 February 2004, reviewed 15 March 2004, accepted 2 April 2004.
1997 saw the start of a study into the spatial and temporal changes in the chemical composition of the atmosphere over the littoral and offshore waters of the Baltic Sea. Collection of samples and their subsequent chemical analysis was preceded by meticulous laboratory experiments concerning the validation and adaptation of the analytical procedures. The colorimetric indophenol blue technique was used to analyse the aerosol samples for the concentration of ammonium ions and the air samples for their gaseous ammonia. The samples were collected with PTFE-filters and Whatman 41 filters coated with 5% orthophosphoric acid. This acid enhances the aerosol sampling efficacy but reduces the pH of the reaction in which indophenol is formed. The pH of the aerosol samples thus had to be raised, and this in turn required an alteration to the original procedure prior to ammonia determination. It was demonstrated that the addition of 0.1 N KOH to the filters coated with H3PO4 increases the pH of the reaction medium to the required level of pH = 8-11.5 and does not substantially influence the precision of the determination; the error of the modified procedure was of the order of 5.2%.
   Air samples for the determination of gaseous ammonia were collected with annular denuders. Oxalic acid and citric acid are the usual impregnating agents. In the present experiments oxalic acid was used for denuder impregnation; it turned out to be more effective than citric acid under the conditions of the southern Baltic Sea.
   The detection limit of the indophenol blue method in these laboratory experiments was 0.045 mmol dm-3. The respective relative standard deviations (RSD) within the range of higher and lower concentrations were 0.64% and 4.53%.
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Ammonia and ammonium over the southern Baltic Sea. Part 2. The origin of ammonia and ammonium over two coastal stations: Gdynia and Hel
Oceanologia 2004, 46(2), 185-200

Anita Lewandowska, Lucyna Falkowska, Magdalena Bełdowska
Institute of Oceanography, University of Gdańsk, al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: nadsta@sat.ocean.univ.gda.pl

Keywords: aerosol, ammonia and ammonium, aerosol phase state, southern Baltic Sea

Manuscript received 20 February 2004, reviewed 15 March 2004, accepted 2 April 2004.
Ammonia concentrations in aerosols and ammonium concentrations in the air were measured in the coastal zone of the southern Baltic Sea. The main study area was the Hel Peninsula, where measurements were carried out from December 1997 to March 1998. There was a second such area in Gdynia, where the first measurement period extended from May to December 2000, and the second one lasted from February to May 2001. At the same time, chloride, sulphate and sodium concentrations in the aerosols were determined; meteorological parameters were also measured. Aerosol samples were collected with a filter pack, and the gaseous phase species were collected on denuders. At both stations, the ammonium concentration in aerosols was at least one order of magnitude higher than that of the ammonia in the air samples. It was found that the marine boundary layer always contained ammonium chloride and ammonium sulphate. The presence of ammonium nitrate was detected only when winds were slight and was attributed to local anthropogenic sources. The ammonia concentration related to nitrate increased with rising air humidity and a falling temperature. The contribution of marigenic ions in aerosols was noted at onshore wind of speeds >3.5 m s-1. In winter as in summer, conditions occurred facilitating light backscattering by a "wet" aerosol, which contained ammonium nitrate and ammonium sulphate in proportions of 2.5:1 and 1:1.
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Sulphates in particles of different sizes in the marine boundary layer over the southern Baltic Sea
Oceanologia 2004, 46(2), 201-215

Lucyna Falkowska, Anita Lewandowska
Institute of Oceanography, University of Gdańsk, al. Marszałka Piłsudskiego 46, PL-81-378 Gdynia, Poland;
e-mail: lucy@sat.ocean.univ.gda.pl

Keywords: aerosols, nss-sulphate, coastal zone, Baltic Sea

Manuscript received 16 April 2003, reviewed 31 March 2004, accepted 5 April 2004.
Concentrations of sulphate ions and particle size distributions were measured in the marine boundary layer using a ten-cascade Berner impactor at Hel between December 1997 and March 1998, and with a filter pack in Gdynia from February to May 2001. In the marine boundary layer over the Hel Peninsula the presence of natural sea-salt and non-sea-salt sulphate ions (nssSO42-) was confirmed in the aerosols. The nssSO4 were present in all size ranges only in December 1997 and in the first half of January 1998, making up an average of 83.7 ± 2.4% of the total sulphate content. In the other winter months, nssSO42- were recorded only in aerosols of diameters from 0.4 to 1.5 µm, and their average contribution dropped by over 20%. The extended growing season in the Southern Baltic resulted in the formation of fine particles that appeared in the marine boundary layer in early winter. At that time the proportion of nssSO42- in ultra-fine particles ranged from 75.7% to 100%. The concentration of nssSO42-, which varied from 0.8 to 2.3 nmol m-3 in particles < 0.4 µm in size probably constituted the natural background aerosol population in the relatively clean coastal environment of the Southern Baltic Sea. In the coastal urbanised area of Gdynia, the sulphate concentration in aerosols was higher than at Hel (av. 75.3 nmol m-3) but the proportion of nssSO4 was low, of the order of 24%. Sea salt was then the dominant source of sulphate.
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Recent changes in sediment accumulation rates in Adventfjorden, Svalbard
Oceanologia 2004, 46(2), 217-231

Marek Zajączkowski1, Witold Szczuciński2,3, Ryszard Bojanowski1
1Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: trapper@iopan.gda.pl;
2Collegium Polonicum, Kościuszki 1, PL-69-100 Słubice, Poland
3Institute of Geology, A. Mickiewicz University, Maków Polnych 16, PL-61-686 Poznań, Poland

Keywords: 137Cs, 210Pb, sediment accumulation rates, fjord, Svalbard

Manuscript received 19 January 2004, reviewed 15 April 2004, accepted 10 May 2004.

The research was funded by the Polish Ministry of Scientific Research and Information Technology (State Committee for Scientific Research), grant No 6PO405621.
Recent sediment accumulation rates in Adventfjorden (Svalbard), a small subpolar fjord, were determined by 210Pb and 137Cs dating. Modern rates in the central basin decrease downfjord from 1.87 to 0.87 cm y-1 (2.6 to 1.19 g cm-2 y-1). Comparison of the modern values (1986-2001) with older ones (1963-86) reveals a marked increase in sediment accumulation rates in the last ten years. This correlates well with recent climate changes (warming and increase in precipitation). Comparison with particulate matter flux data indicates that a portion of the sediment is passed on to Isfjorden.
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Light minerals of beach sediments from Southern Tamilnadu, south east coast of India
Oceanologia 2004, 46(2), 233-252

Anil Cherian1,*, Nayanarpandian Chandrasekar1, Victor Rajamanickam2,
1Department of Coastal Mining, Centre for Marine Science and Technology, M.S. University, Rajakkamangalam, Nagercoil, 629 502 Tamilnadu, India;
e-mail: anilqq@rediffmail.com;
2Department of Disaster Management, School of Civil Engineering, SASTRA Deemed University, Thanjavur, 613 403 Tamilnadu, India
*present address: National Dewatering and Drainage Services Company, Dubai, United Arab Emirates

Keywords: light minerals, sphericity, quartz, roundness, provenance

Manuscript received 23 February 2004, reviewed 6 May 2004, accepted 17 May 2004.
A brief investigation of light minerals along the beaches between Valinokkam and Tuticorin has been carried out for the first time along the Southern Tamilnadu coast in order to discover the provenance of the sediments. The study spotlights a wide variation in light mineralogy along the three zones of the investigated area (Valinokkam, Vaippar and Tuticorin). A higher percentage of quartz is reported from the Valinokkam (48.34 to 68.63%) and Tuticorin zones (55.66 to 73.05%) than from the Vaippar zone (40.24 to 60.77%). The trend with regard to the maturity index is similar, with appreciably higher values in Valinokkam (1.15 to 1.89) and Tuticorin (1.61 to 1.94) than Vaippar (0.79 to 1.39). Morphological analysis of quartz grains shows a higher order of sphericity and roundness values in Valinokkam and Tuticorin as compared to Vaippar. Moreover, the surface texture of quartz grains observed with the aid of scanning electron microscope (SEM) photographs reveals the presence of different depositional environments and the multiple origin of beach sediments in the study area. From the present study of the light mineralogy of beach sediments, it is inferred that the source of the sediments is a mixed type: igneous and metamorphic crystalline rocks, together with palaeosediments.
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Pelagic coelenterates in the waters of the western part of the Egyptian Mediterranean Coast during summer and winter
Oceanologia 2004, 46(2), 253-268
Howaida Y. Zakaria
National Institute of Oceanography & Fisheries, Kayet Bey, Alexandria, Egypt;
e-mail: howaidazakaria@hotmail.com
Keywords: hydromedusae, siphonophores, Egyptian Coast, Mediterranean Manuscript received 11 November 2003, reviewed 26 April 2004, accepted 5 May 2004.
During August 2000 and February 2001 two cruises were carried out along the Egyptian Mediterranean Coast on the Egyptian r/v "El-Yarmouk". The samples collected were used to study the ecology and distribution of hydromedusae and siphonophores during summer and winter. The density of hydromedusae was high in the inshore waters during summer (av. 71 org × 100 m-3), decreasing to 28 organisms per 100 m3 in the oceanic waters; in winter they were more abundant in the middle and offshore zones. A total of 9 hydromedusae species were recorded during the present study, 8 of them in summer. The most common of these were Aglaura emistoma, Olindias singularis, Liriope tetraphylla and Geryonia proboscidalis. Only 4 species were recorded during winter, including Cunina octonaria, which was not recorded during the summer. The nine species recorded in the present study are circumtropical. The siphonophore density was high in summer. In winter, the average standing crop of siphonophores fell to about 30% of that recorded in summer. 11 siphonophore species were recorded, 10 of them in summer; Cucullus campanula and Eudoxoides spiralis were the most common. Only 6 species were recorded in winter. These 11 species are widely distributed - they have been recorded from the Atlantic, Indian and Pacific Oceans. Strong seasonality is thus a striking feature of Egyptian Mediterranean waters. Temperature is the most variable factor affecting the planktonic community, fluctuating between 26.5 and 27°C in summer and between 16.3 and 17.5°C in winter. The western part of the Egyptian coast, the area under study in this work, is poorly diversified in comparison with the eastern part.
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Effect of iron limitation on cells of the diatom Cyclotella meneghiniana Kützing
Oceanologia 2004, 46(2), 269-287
Jolanta Lewandowska, Alicja Kosakowska
1Institute of Oceanology, Polish Academy of Sciences, Powstańców Warszawy 55, PL-81-712 Sopot, Poland;
e-mail: lewand@iopan.gda.pl;
Keywords: iron, Cyclotella meneghiniana, growth, chlorophyll a, protein, Baltic Sea Manuscript received 9 December 2003, reviewed 16 February 2004, accepted 20 February 2004. The study was carried out as a part of the statutory activities of the Institute of Oceanology PAS (grant No II.3.1) and was supported by the Polish State Committee for Scientific Research (grant No 3 PO4F05923, 2002-2005).
The response of the Baltic diatom Cyclotella meneghiniana to iron deficiency was examined. The following growth parameters were measured: cell number, chlorophyll a and protein content. The results demonstrate the ability of this diatom to grow well with minimal iron availability; however, the rate of growth fell markedly at the lowest iron(III) concentration. The results of spectrophotometric chlorophyll a measurements and protein assays using the Lowry and Bradford methods indicated a significant decrease in their quantities. Iron may therefore be an important regulatory factor controlling the growth of diatom C. meneghiniana in an aquatic ecosystem.
full, complete article (PDF - compatibile with Acrobat 3.0), 189 KB