Simulation of the extreme waves generated by typhoon Bolaven (1215) in the East China Sea and Yellow Sea

Record-breaking high waves occurred during the passage of the typhoon Bolaven (1215) (TYB) in the East China Sea (ECS) and Yellow Sea (YS) although its intensity did not reach the level of a super typhoon. Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys. In order to understand how such high waves with long duration occurred, analyses have been made through measurement and numerical simulations. TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements. And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model. Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area. Thus the accuracy of simulations is considerably enhanced, and the computed results are also in better agreement with measured data than before. It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track. As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days, the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.     

Correlation between Rimjingang belt and Dabie-Sulu orogenic belt

The Dabic-Sulu orogenic belt in central-eastern China is considered as a high-pressure and ultrahighpressure metamorphic belt that demensions are comparatively large,and formed as a result of the colli...     

Spatial distribution and comparative evaluation of phosphorus release rate in benthic sediments of an estuary dam

A series of experiments and simulations were performed to ascertain the rate at which phosphorus is released using a water quality model in Saemangeum Lake, an artificially constructed lake located in an estuary. The general inflow of seawater once a day contributed to the formation of a halocline in the lake water, which caused variation in the vertical concentration of dissolved oxygen. The halocline was mainly observed in the deep downstream regions of Saemangeum Lake that are close to the op...     

Spatial and temporal characteristics of nutrient and phytoplankton dynamics in the York River Estuary, Virginia: Analyses of long-term data

Ten years (1985–1994) of data were analyzed to investigate general patterns of phytoplankton and nutrient dynamics, and to identify major factors controlling those dynamics in the York River Estuary, Virginia. Algal blooms were observed during winter-spring followed by smaller summer blooms. Peak phytoplankton biomass during the winter-spring blooms occurred in the mid reach of the mesohaline zone whereas peak phytoplankton biomass during the summer bloom occurred in the tidal fresh-mesohaline transition zone. River discharge appears to be the major factor controlling the location and timing of the winter-spring blooms and the relative degree of potential N and P limitation. Phytoplankton biomass in tidal fresh water regions was limited by high flushing rates. Water residence time was less than cell doubling time during high flow seasons. Positive correlations between PAR at 1 m depth and chlorophylla suggested light limitation of phytoplankton in the tidal fresh-mesohaline transition zone. Relationships of salinity difference between surface and bottom water with chlorophylla distribution suggested the importance of tidal mixing for phytoplankton dynamics in the mesohaline zone. Accumulation of phytoplankton biomass in the mesohaline zone was generally controlled by N with the nutrient supply provided by benthic or bottom water remineralization.     

Phytoplankton Size and Taxonomic Composition in a Temperate Estuary Influenced by Monsoon

Temporal and spatial variations in phytoplankton in Asan Bay, a temperate estuary under the influence of monsoon, were investigated over an annual cycle (2004). Phytoplankton blooms started in February (>20 μg chl l⁻¹) and continued until April (>13 μg chl l⁻¹) during the dry season, especially in upstream regions. The percentage contribution of large phytoplankton (micro-sized) was high (78–95%) during the blooms, and diatoms such as Skeletonema costatum and Thalassiosira spp. were dominant. The precipitation and freshwater discharge from embankments peaked and supplied nutrients into the bay during the monsoon event, especially in July. Species that favor freshwater, such as Oscillatoria spp. (cyanobacteria), dominated during the monsoon period. The phytoplankton biomass was minimal in this season despite nutrient concentrations that were relatively sufficient (enriched), and this pattern differed from that in tropical estuaries affected by monsoon and in temperate estuaries where phytoplankton respond to nutrient inputs during wet seasons. The flushing time estimated from the salinity was shorter than the doubling time in Asan Bay, which suggests that exports of phytoplankton maximized by high discharge directly from embankments differentiate this bay from other estuaries in temperate and tropical regions. This implies that the change in physical properties, especially in the freshwater discharge rates, has mainly been a regulator of phytoplankton dynamics since the construction of embankments in Asan Bay.     

THE EFFECT OF SEEING ON SOLAR MAGNETIC FLUX MEASUREMENTS

We investigate the influence of seeing upon measurement of magnetic flux of photospheric fields. For this purpose we quantify seeing variation in one day's observation at Big Bear Solar Observatory in terms of the Fried function, a Modulation Transfer Function for the atmospheric seeing. The temporal variation of seeing quality is compared with that of magnetic flux measured in a quiet region with size 5 \times 4 near the solar disk center. A good correlation is found between the seeing change and apparent evolution of magnetic flux values, implying, as a possibility, that magnetic flux measurement might have been modulated by seeing. Based on a simple model of ensembles of Gaussian magnetic elements we argue that even the net flux as well as the total flux can change due to seeing variation if the magnetograph has a finite detection threshold and if the intrinsic fluxes in one and the other polarities are unbalanced.