Ocean Currents

Ocean tides are fully explained with illustrations and examples. It is updated with recent material. It will be highly useful for graduate and undergraduate students. Particularly the material is prepared for the students appearing examinations. All the necessary corrections are made and the equations are made more visible.

The purpose of this study was to analyze the December 1993 breach at Grays Harbor, WA, and assess the threat to the Federal Navigation Project had the breach not been filled the following fall. The study was conducted by quantifying evolution of breach morphology; numerically simulating the ocean wave and water level conditions producing the current through such a breach, including investigation of wide-area implications for the current in Grays Harbor; and numerical modeling breach evolution. Available data on the breach evolution were analyzed with a Geographic Information System. The width of the breach and erosion of the adjacent shoreline are quantified from aerial photographs. Shoreline position and bottom configurations in the vicinity of the now-closed breach are the basis of numerical modeling of wave- and tide-driven currents. Estimates are made of the wave and current climate at South Beach, Pt. Chehalis, and in Half Moon Bay under the assumption of a breach at the jetty....

The problems that exist in Semarang waters are erosion and deposition. This is related to current flow patterns that are closely related to sediment transport patterns. An alternative solution to this problem is to study the sediment transport patterns suspended by the dynamics of the ocean such as ocean waves and ocean currents. The purpose of this study was to determine the pattern of suspended sediment distribution that occurred in the waters of Semarang. In this study, the ocean current and total suspended sediment data were taken when the sea tides and the sea recedes at a depth of 0.2d, 0.6d, 0.8d. Data processing uses a numerical modeling approach. After processing and analyzing the data, an overview of suspended sediment transport patterns that occur in the Semarang Sea is affected by the dynamics of the sea, especially ocean currents.

How plants arrived to originally sterile oceanic islands has puzzled naturalists for centuries. Dispersal syndromes (i.e., diaspore traits that promote dispersal by long-distance dispersal vectors), are generally considered to play a determinant role in assisting island colonization. However, the association between diaspore traits and the potential vectors by which diaspores are dispersed is not always obvious. Fleshy fruits, in particular, are considered to have evolved to promote the internal dispersal of seeds by frugivores (endozoochory), however some fleshy fruits can also float in saltwater, and thus be potentially transported by oceanic current (thalassochory). We performed saltwater floatation and viability experiments with fruits of the 14 European fleshy-fruited species that naturally colonized the Azores archipelago (North Atlantic Ocean). We show that only Corema album (a berry) and Juniperus oxycedrus (a fleshy cone) floated for as long as 60 days, the estimated minimum time needed to reach the Azores by oceanic currents. Regardless the floatation potential, exposure to saltwater largely reduced the viability of most seeds of the 14 species (46% of viability decline within 15 days and 77% within 60 days of immersion), including those of Corema album (61%) and Juniperus oxycedrus (83%). Floatability and viability trials suggest that while some fleshy-fruited species might have arrived to the Azores by oceanic currents, such would have required extreme meteorological events that could largely reduce the duration of the trip. Thus, the alternative hypothesis that fleshy-fruited species were mostly dependent on animal dispersers (endozoochory) to colonize these remote islands is reinforced.

Multiproxy analyses (including benthic and planktonic foraminifera, δ<sup>18</sup>O and δ<sup>13</sup>C records, grain-size distribution, ice-rafted debris, XRF geochemistry and magnetic susceptibility) were performed on a <sup>14</sup>C-dated marine sediment core from Storfjordrenna, located off of southern Svalbard. The sediments in the core cover the termination of Bølling–Allerød, the Younger Dryas and the Holocene and reflect general changes in the oceanography/climate of the European Arctic after the last glaciation. Grounded ice of the last Svalbard–Barents Sea Ice Sheet retreated from the coring site ca. 13 950 cal yr BP. During the transition from the subglacial to glaciomarine setting, Arctic Waters dominated the hydrography in Storfjordrenna. However, the waters were not uniformly cold and experienced several warmer spells. A progressive warming and marked change in the nature of the hydrology occurred during the early Holocene. R...

The East Australian Current (EAC) is the western boundary current of the south Pacific gyre transporting warm tropical waters to higher southern latitudes. Recent modelling shows that the partial separation of the EAC (~32°S) and the coupled formation of the Tasman Front (~34°S) are caused by a steep gradient in the zonally integrated wind stress curl. Analysis of oxygen isotope ratios (δ18O) in the planktonic foraminifer, Globigerinoides ruber, from sediment cores from the Coral Sea and Tasman Sea indicates that the EAC separation shifted northward to between 23 and 26°S during the last glacial. We suggest these results indicate a significant change in the Pacific wind stress curl during the glacial. Given recent evidence for El Niño-like conditions in the Pacific during the last glacial, with a reduction in the east-west sea surface temperature (SST) gradient, we suggest that weaker trade winds combined with more northerly, stronger westerlies were associated with a change to the wind stress curl, which repositioned the EAC separation and Tasman Front. In contrast, by ~11 ka BP, the EAC separation was forced south of 26°S. This southward shift was synchronous with a rapid warming of tropical SSTs, and the onset of a La Niña-like SST configuration across the tropical Pacific. It appears that the south Pacific trade winds strengthened accordingly, causing the EAC to readjust its flow. This readjustment of the EAC marks the onset of modern surface-ocean circulation in the southwest Pacific, but the present EAC transport was only achieved in the late Holocene, after 5 ka BP.