Warm Water Intrusion Research Articles

A note on the thermal structure of the eastern Bering Sea

A detailed thermal structure in the eastern Bering Sea is described, based on data obtained by the training ship Oshoro Maru during the summers of 1964, 1965, and 1966. The description is based on the movement of extremely cold water over the continental shelf in the eastern Bering Sea and on the intrusions of warm water mainly across the Amukta and Amchitka passes. Some of the tendency of decrease and increase of temperature is also presented in a vertical section. The typical feature of vertical temperature distribution is mostly represented by five stratified thermal layers.

Oceanic variability in the western sector of Algoa Bay, South Africa

The city of Port Elizabeth lies in the western sector of Algoa Bay, and a number of projects have investigated the oceanic temperature, salinity and current structures in the vicinity. This paper analyses past results, and then incorporates measurements of salinity, sea temperatures and currents from projects over the years 1989 to 1998 in order to gain a better understanding of the oceanic variability in this region. Because of the limited inflow of freshwater from rivers, salinity variations from oceanic values were minimal, and it is surmised that the effects of freshwater influxes during floods are likely to be short-lived. The seasonal variation in temperature structures shows that intense thermoclines are established in summer in the deeper sections of the bay, with more isothermal conditions in winter. Marked variability occurred over spatial scales of kilometres, and over time scales of days. Average current speeds close to the coast were generally low, increasing farther offshore, though there was substantial variability. Moreover, in the lee of the harbour and close to the coast spatial scales were also small, and spectral analyses show that tidal and inertial currents were important at times. Driving forces were investigated, and it was found that wind is important in upwelling processes and in bringing colder water onshore from deeper regions of Algoa Bay and around Cape Recife. On the other hand, coastal-trapped waves do not appear to play a significant role. Sporadic intrusions of both warm and colder water were recorded at sites near the harbour, and are attributed to inputs of warm surface water from the Agulhas Current and the above-mentioned colder up-welled water. Such intrusions are probably important in flushing out accumulations of pollutants discharged to sea from Port Elizabeth. Dominant south-westward flow farther offshore at 40m depth also indicates that the Agulhas Current could be important in entraining water from the central areas of Algoa Bay.

Sediment ponding in the deep-sea : Hersey J. B., 1965. Bull. geol. Soc., Am., 76 (11): 1251–1260

We measured the vertical profiles of currents at the eastern mouth of the Suruga Bay using a moored acoustic Doppler current profiler (ADCP). Currents vertical profiles were found to be mostly barotropic in structure when intrusions occurred at the eastern mouth of the bay. Warm-water intrusions at the Suruga Bay and sea level elevations at the bay and at islands on the Izu Ridge located off the bay have the same period of 26 days. The temporal variation in the sea levels occurs in response to Kuroshio frontal waves, and the two phases are consistent. The sea level rise propagates from Hachijo Island to the Suruga Bay via Miyake Island and Kozu Island, i.e., from off the Suruga Bay to in or near the bay. The perturbation of the sea level along the Izu Ridge occurs as waves with a period of 26 days, a wavelength of 500 km, and a phase speed of 23 cm/sec. The propagated waves and those of the Kuroshio frontal waves have the same features. This means that the periodic inflows at the eastern mouth of the Suruga Bay are caused by the passage of Kuroshio frontal waves off the bay.

Coiling Direction Ratios of Foraminifera Globigerina pachyderma (Ehrenberg) in Northeastern Pacific Surface Sediments: ABSTRACT

Coiling direction ratios of Globigerina pachyderma (Ehrenberg) plotted for sediment surface samples from the northeastern Pacific north of 40°N. did not show the consistent relationship which would recommend them as reliable guides for deep-sea core analysis in this region. A generally increasing tendency for sinistral coiling toward the north was noted, from 13 per cent left reported by Parker (1962) from a nearshore sample (40°N.) to a consistent 95-100 per cent left in the northern Gulf of Alaska. Great irregularity in coiling ratios in seaward (east-west) traverses may be related to a nearshore area of warm-water intrusion (Fleming, 1958) affecting the type of plankton supplied to the substrate. Variations from 20-96 per cent left coiling were observed in th se traverses. Dextral coiling percentage usually was higher in samples containing many species and few individuals. The recency of the surface sample also affected the coiling ratios. The problem of distinguishing small Globoquadrina dutertrei (d'Orbigny)--predominantly right coiling--from Globigerina pachyderma (coiling in question) may qualify coiling ratios reported by various authors. Plankton tow samples off Oregon, Washington, and the Aleutian Islands had smaller percentages of G. pachyderma and higher dextral ratios than samples from the underlying sediment surface. End_of_Article - Last_Page 1760------------

Sagitta lyra, a biological indicator species in the subarctic waters of the eastern Pacific Ocean

In the Gulf of Alaska the chaetognath, Sagitta lyra, was most frequently found in areas where the temperature at 150 m exceeded 6 °C and the salinity exceeded 33‰. Water of this character was mainly associated with a northward intrusion of warm water past the Canadian coast. Comparison of surface gillnet catches of salmon with occurrence of S. lyra showed that when S. lyra was present in the zooplankton, the salmon catch was small and when it was absent the catches of salmon could be quite large. This change in catch was even observed (on two occasions) on successive days at a station where the physical properties of the water did not change detectably.

Physical Oceanography of the Strait of Georgia, British Columbia

A descriptive and quantitative analysis of the physical oceanography of the Strait of Georgia has been made.The area has been characterized by extreme seasonal and regional variability of the surface waters. Deep water undergoes only small change. Runoff, principally from the Fraser River, is the major cause of salinity variation. Surface warming by insolation is reflected in high summer surface water temperatures in the Central and Northern Strait.Analysis of the Strait of Georgia has been based on a hypothetical model of a deep, rectangular basin connected to the sea by mixing baffles and a long channel. Fresh water inflow is concentrated near the southern end of the basin. The Strait of Georgia–Juan de Fuca Strait system has basically three water masses: (1) the brackish surface water from runoff in the Strait of Georgia; (2) the deep water of oceanic origin in Juan de Fuca Strait; and (3) a mixture of (1) and (2) which forms at the sills. This mixture contributes to the deep water in the Strait of Georgia and to the upper seaward-flowing layer in Juan de Fuca Strait. Bottom water is formed in late autumn when dense sea water from Juan de Fuca Strait intrudes into the mixing area of the southern sills. An Intermediate Water is formed during some cold winters in the Northern Strait. A slow intrusion of warm Intermediate Water occurs from the southern sills in late summer.A general counter-clockwise circulation exists in the Strait of Georgia. Tides, runoff, and winds are the principal generating forces. Topography, Coriolis force, and centrifugal force are the main directive factors. Circulation has been studied from drift bottle experiments, mass distribution, and isentropic analysis.Some of the effects of winds in mean sea level changes and surface currents have been evaluated. Wind effects are most pronounced in influencing the circulation of the upper brackish layer.Waters are most stable in the Central and Northern Strait. Intensive tidal mixing renders the waters of the Southern Strait nearly homogeneous, particularly in winter. The largest amount of mixing energy comes from the tide, but winds contribute substantially to mixing in the surface water. The potential energy change from a stratified to a mixed column of water in the Southern Strait has been computed. Keulegan's criterion of mixing is applied to the system at the Fraser River estuary.A technique for determining the fresh water budget in the Strait of Georgia has been developed. This has been evaluated on the basis of the 1950 meteorological, hydrological, and oceanographic data. At a particular time there is a volume of fresh water in the Strait of Georgia equivalent to 1⅓ years of Fraser River discharge based on an average salinity of 33.8‰ in the inflowing oceanic water. Little effect in the overall fresh water content of the system is caused by sudden increases or decreases in the runoff.The heat budget based on five stations where the necessary meteorological and oceanographic data were available has been evaluated for 1950. Considerable variation in evaporation is largely dependent on the variation in surface water temperature. Peak evaporation occurs in the Southern Strait in late autumn with negative (condensation) values in late summer. Maximum evaporation occurs in mid-summer in the Central and Northern Strait. On a yearly basis, there is a loss of heat from the system through the transport seaward of surface water.Some concepts of inshore oceanography are given with general guiding principles for the planning and conduct of surveys.