Study on scattering wave force of horizontal and vertical plate type breakwaters

The interaction between wave and horizontal and vertical plates is investigated by the boundary element method,and the relations of wave exciting force with plate thickness,submergence and length are obtained.It is found that:1) The efficient wave exciting force exists while plate submergence is less than 0.5 m,and the plate is very thin with order O(0.005 m).2) The maximum heave wave exciting force exists,and it is the main factor for surface and submerged horizontal plate while the roll force can be ignored.3) The maximum sway wave exciting force exists,it is the main factor for surface or submerged vertical plate,and the roll force is about 20 times of horizontal plate.     

Linkage between winter air temperature over the subtropical Western Pacific and the ice extent anomaly in the Sea of Okhotsk

This study deals with the correlation between ice extent in the Sea of Okhotsk and the interannual variability of winter (December–February) air temperature over the subtropical Western Pacific from 1979 to 2008. The analysis indicates that the increase in sea ice extent coincides not only with cooling over the Sea of Okhotsk and the adjacent area, but also with significant warming over the subtropical Western Pacific that extends from the surface to the middle troposphere. This meridional dipole pattern of tropospheric temperature anomalies (cooling in the high latitudes and warming in the low latitudes) primarily results from dynamical processes driven by the large-scale atmospheric circulation change. A heat budget diagnosis reveals that when ice extent in the Sea of Okhotsk increases by one standard deviation, the tropospheric air temperature over the subtropical Western Pacific rises by about 0.25°C. It also suggests that the adiabatic heating and stationary eddy heat flux convergence may be the most important factors, which account for 30 and 15% of the warming, respectively. In addition, these two factors also coordinate to result in significant cooling over the Sea of Okhotsk and the adjacent regions.     

Development and application of an operational tide and storm surge prediction model for the seas around Taiwan

Storm surges are abnormal rises in sea level along coastal areas and are mainly formed by strong wind and atmospheric depressions.When storm surges coincide with high tide,coastal flooding can occur.Creating storm surge prediction systems has been an important and operational task worldwide.This study developed a coupled tide and storm surge numerical model of the seas around Taiwan for operational purposes at the Central Weather Bureau.The model was calibrated and verified by using tidal records from seas around Taiwan.Model skill was assessed based on measured records,and the results are presented in details.At 3-minute resolution,tides were generally well predicted,with the root mean-square errors of less than 0.11 m and an overall correlation of more than 0.9.Storms(winds and depressions) were introduced into the model forcing by using the parameter typhoon model.Five typical typhoons that threatened Taiwan were simulated for assessment.The surges were well predicted compared with the records.     

Phytoplankton productivity in the western subarctic gyre of the North Pacific in early summer 2006

We deployed a profiling buoy system incorporating a fast repetition rate fluorometer in the western subarctic Pacific and carried out time-series observations of phytoplankton productivity from 9 June to 15 July 2006. The chlorophyll a (Chl a) biomass integrated over the euphotic layer was as high as 45–50 mg Chl a m⁻² in the middle of June and remained in the 30–40 mg Chl a m⁻² range during the rest of observation period; day-to-day variation in Chl a biomass was relatively small. The daily net primary productivity integrated over the euphotic layer ranged from 144 to 919 mg C m⁻² day⁻¹ and varied greatly, depending more on insolation rather than Chl a biomass. In addition, we found that part of primary production was exported to a 150-m depth within 2 days, indicating that the variations in primary productivity quickly influenced the organic carbon flux from the upper ocean. Our results suggest that the short-term variability in primary productivity is one of the key factors controlling the carbon cycle in the surface ocean in the western subarctic Pacific.     

Runup of the surface waves of various shapes on a sloping beach

In the long-wave approximation, we perform the numerical analysis of the plane problem of runup of waves of various shapes on a sloping beach. We study transformations of the shape of waves flooding the beach and in the course of their subsequent rundown. The dependence of maximum elevations and lowerings of the sea level on the parameters of the waves approaching the beach, the depth of the shelf, and the slope of the bottom are investigated. It is shown that the shape of waves affects the amplitude characteristics of oscillations of the coastline. The heights of the vertical runup of waves incident on a sloping beach can be several times higher than the amplitude of waves entering the shelf zone.     

Secondary production of the eusirid amphipod <Emphasis Type="Italic">Pontogeneia rostrata</Emphasis> Gurjanova, 1938 (Crustacea: Peracarida) on a sandy shore in Korea

The secondary production of the eusirid amphipod Pontogeneia rostrata Gurjanova, 1938, was examined on a sandy shore in Korea. Secondary production was estimated using a size-frequency method. The biomass structure of P. rostrata included one peak in spring, with maximum biomass occurring in April. The annual secondary production of this species was 0.57 g DW m⁻² yr⁻¹ with an annual P/B ratio of 6.97. Secondary production of P. rostrata fell within the range observed for other amphipods on intertidal sandy shores, although the production/biomass (P/B) ratio was higher than those recorded previously from the sampling site and from other tidal and estuary areas, as the number of generations increases the P/B ratio. The results showing high abundance and P/B ratios suggest that P. rostrata plays an important role in the sandy shore ecosystem as a trophic link between primary producers and higher consumers.     

A stratigraphic and tectonofacies framework of the “calcari aLucina” in the Apennine Chain,Italy

The Apennine Chain provides the first example of stratigraphic (time) and synsedimentary tectonic (space) distribution of the calcari aLucina Miocene equivalents of modern cold-vent carbonates. Chemosynthetic faunal assemblages and related carbonate deposits are found at different stratigraphic levels, with peaks during Langhian-Serravallian and late Tortonian-early Messinian times. A general increase in frequency and volume occurs with time. A genetic link between venting and the Messinian Evaporite event is difficult to demonstrate. However,Lucina limestones are limited to preevaporitic times, and their maximum abundance is reached just before the onset of the Messinian Evaporite accumulation.Lucina limestones occur in almost all tectofacies of the orogen, from backland to foreland.     

Heated diver decompression shelter: The “womb concept”

A hybrid thermal protection method using waste heat from a surface-mounted outboard motor is shown to create a warm “micro-climate” environment for divers. The effects of surface heater capacities, water flow rates, shelter volume and shelter insulation on micro-climate temperatures are characterized. During long, cold-water decompression stops this method offers a reliable, low-cost alternative to surface-supplied hot water suits or diver-carried heating systems. An added bonus for divers using closed-circuit breathing apparatus is prolonged durations of their carbon dioxide scrubbers when surrounded by the warm water “micro-climate”. Closed-circuit and open-circuit options of this diver decompression shelter concept are evaluated.     

Side-scan and acoustic subbottom characterization of the sea floor near the Dry Tortugas, Florida

 Between 2 and 6 February, 1995, a 25 km² area at the Dry Tortugas (Florida Keys) was surveyed with a 100 kHz side-scan sonar system and 3.5-kHz subbottom profiler. The side-scan system revealed a pattern of alternating high and low backscatter. The subbottom profiler showed areas with no acoustic penetration between sediment troughs. The combination of both methods allowed delineation of the boundaries in high-backscatter regions, and sediment samples allowed correlations between high backscatter and coarser-grained sediments.