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Vertical profiles of marine aerosol size distribution and concentration in the marine boundary layer over surf zones depend strongly on wind speed, direction and duration as well as the sea bottom profile. The measurements in the present study were carried out in various seasons of the year with all these factors being taken into consideration. The data with respect to offshore winds were neglected in the calculations, since in such cases the major aerosol contribution was from terrigenous and anthropogenic particles. It was confirmed that in the range of wind speeds from 1 m s−1 to 12 m s−1 there were measurable differences in the concentrations, particularly in the size distribution of marine aerosol particles at two stations differing with respect to their sea bottom profiles.
Since 1992 lidar-based measurements have been carried out under various meteorological conditions and at various times of the year. The aerosol optical properties were determined in the marine boundary layer as a function of altitude using such factors as wind direction, duration and velocity and aerosol size distribution and concentration. It was confirmed that in all cases, the total aerosol concentration, size distribution and aerosol extinction increase with wind speed but decrease with altitude. In the range of wind velocities from 1 to 15 m s−1 the mean aerosol optical thickness of the atmosphere (VIS) obtained from the lidar varied from 0.1 to 0.38 for offshore winds and from 0.01 to about 0.1 for onshore winds, while the ˚Angstr¨om parameter for VIS oscillated around 0.65 for onshore winds and around 1 for offshore winds. Both parameters depended strongly on the history of the air mass above the Baltic Sea. Such aerosol optical thicknesses are in agreement with those obtained by other researchers in the Baltic Sea area.
The paper presents the results of studies of wave transformation on a multi-bar cross-shore profile of the southern Baltic Sea. The field investigations of wave motion were carried out using an offshore wave buoy and string wave gauges at the IBW PAN Coastal Research Station, Lubiatowo (Poland). These experimental results were used to validate statistical relationships between characteristic wave parameters in the coastal region and to assess wave energy dissipation in the surf zone. Asimple model for calculating the residual nearshore wave energy is proposed and tested versus the data collected in situ.
On nine beaches and two transects in the surf zone along the Dutch coast the presence of benthic macrofauna was studied in relation to basic abiotic characteristics. According to Short’s classification system, Dutch beaches are mesotidal and dissipative (Ω = 8.6), and the RTR is low (1.52–1.27), which means that they are not tide-dominated. BSI ranged from 1.4 to 1.1 for the northern and western Dutch coasts respectively and had an overall value of 1.2. The rates of exposure of the beaches varied between 8 and 12, and are therefore regarded as sheltered to moderately exposed. The Dutch beaches display a geographical trend in beach types. Those of the Wadden Sea islands in the northern part of the Netherlands are dissipative, flat, fine-grained, and host high densities of many species of benthic macrofauna. The beaches along the western Dutch coast are less dissipative, steeper, with a higher mean grain size; the species diversity and abundance there are lower. Species diversity and abundance on the beaches increase from the high- to the low-water line. The maximum number of species was found between 0 and –1 m relative to the mean tidal level. The abundance peaks just above the mean tidal level, while the biomass reaches a maximum at the mean tidal level. Species diversity and abundance are low in the surf zone, but increase towards deeper water. Species numbers are high and the abundance is very high in the trough between the two bars. The relation between the diversity and abundance of macrobenthic species on the one hand, and the sediment composition, water column depth, and position between the bars on the other show a clear pattern of zonation for the beach, surf zone and near-shore: (1) a supralittoral zone with insects and air-breathing crustaceans, (2) a midshore zone, with intertidal species, (3) a lower shore zone, whose species extend into the shallow surf zone, and (4) a zone of sublittoral fauna in the trough between the two breaker bars within the surf zone.
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