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The formation of two polar lows over the Gulf of Alaska are studied, using observations taken during the OCEAN STORMS field experiment. Synoptic-scale and mesoscale analyses were constructed using NOAA P-3 aircraft flight-level and radar data and dropwindsonde profiles, in addition to conventional data sources. The synoptic-scale analyses show that polar low development occurred in a low-level mesoscale baroclinic zone near the center of a mature, occluded synoptic-scale low pressure system. The disturbances propagated along the zone in the reverse shear sense, i.e., in the direction opposite to the thermal wind within the zone. The mesoscale analysis reveals a boundary layer jet of 38 m son the cold side of the baroclinic zone accompanying the leading polar low. Indirect evidence suggests that a Sawyer-Eliassen secondary circulation was present; polar low development occurred in the region of a frontogenetical geostrophic deformation. Convective activity was not prominent during the growth phase of the polar lows, as determined from satellite imagery and radar reflectivity measurements. Extremely high ocean waves (~13 m) occurred in response to intense wind forcing on the mesoscale on a sea state preconditioned by moderate forcing on the synoptic scale. The observed synoptic-scale and mesoscale structures are compared with results from previously studied polar lows. This case appears to represent an example of polar low development due primarily to moist baroclinic processes.
The Institute of Marine Science (IMS) maintains an oceanographic database using the Ingres (tm) relational database management system (RDBMS). It contains physical, chemical, biological and geological data from the Gulf of Alaska, Bering Sea, Chukchi Sea, Beaufort Sea, Prince William Sound, Cook Inlet and other coastal waters. Currently, the database contains data as far back as 1970 and it is about 500 Mbytes in size. Access is restricted to IMS researchers. However most data can be extracted from the database and forward to other researchers on a at-cost basis. Copies of most data were submitted to the National Oceanographic Data Center (NODC). Physical Oceanography % STD - Salinity, Temperature and Depth. 60% of the database. % CM - Current Meters. % TG - Tide Gauges. Biological Oceanography % INFAUNA - Benthic Data from the Bering and Chukchi Seas. % PHYTO - Phytoplankton data from the ISHTAR project. % ZOOP - Zooplankton data from the ISHTAR, APPRISE and other projects. % CHL - Chlorophyll data from the ISHTAR project. % PP - Primary productivity, carbon and nitrogen uptake data from the ISHTAR project. Chemical Oceanography % NUTRIENT - Nutrient chemistry data from the ISHTAR project. % METAL - Heavy metal concentration data. (very small) Geological Oceanography % GRAIN SIZE - Sediment grain size data from the Beaufort and Chukchi seas. Exxon Oil Spill Data -------------------- This database is "litigation sensitive." Access is restricted to researchers working on the Coastal Habitat Injury Assessment (CHIA) project. % INTERTIDAL % Invertebrates % Fishes % Algae % Semicircle Density % Limpet Growth/Survivorship % Mussel Growth/Survivorship % Swath Data % Mussel Histology % Photo Analysis % SUBTIDAL % Shallow Infaunal and Epifaunal Data % Deep Infaunal Data, 40+ Meters The Institute of Marine Science (IMS) is the oldest and the largest unit of the School of Fisheries and Ocean Sciences. It is active in research and graduate training at the masters and doctoral levels, supports coastal facilities at Seward and Kasitsna Bay, and operates the 133-foot research vessel Alpha Helix for the National Science Foundation.
The diets of commercially important Groundfish species in the waters surrounding the Aleutian Islands during the summer of 1991 were studied. Important prey types, predator-prey size relationships, and prey distribution are discussed in detail.
A numerical procedure has been developed to determine the tsunami response of an island system and the surrounding underwater topography. The main algorithm is based on the Eulerian equations of motion and continuity which correspond to the classical, linear, long-wave equation in the absence of friction and rotation. It performs an integration of these equations in terms of an explicit scheme based on centered differences. The computations are carried out on a Cartesian grid network and employ a condition of no normal flow at the island shoreline representation as well as an approximate radiation condition for the scattered portion of the wave field at the outer boundaries. The responses at the island shorelines are determined by introducing a time sequence input with a stipulated spectrum covering the tsunami range (4-90 min). Computations are continued for a duration sufficient to establish a statistical equilibrium within the system. The shoreline time series of water elevations are then Fourier-analyzed to obtain the spectrum for each point. Each spectrum is normalized by the spectrum of a time series taken of the forcing function, propagating on a grid of constant, deep water depth at a central position in the model. The normalized spectra or energy ratios are averaged for each island and for the entire set of shoreline points to produce the responses. The results are presented as graphs of averaged normalized spectra and as contours of (energy ratio)ﾽ on period vs island perimeter plots. An application of the technique is given for the Hawaiian Islands with a northern (Alaskan) wave approach angle. The results indicate energetic response is possible at ten periods from 12.5 to 73.1 min.
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When an American wheat farmer loses his crop to a flood or drought, insurance he purchased from the federal government helps cushion the blow. As Doug Schneider reports in this weekﾒs Arctic Science Journeys Radio, Alaskaﾒs beleaguered salmon fishermen may soon be able to insure their "crop" against disaster as well.
The major components of the marine boundary layer biogeochemical sulfur cycle were measured simultaneously onshore and off the coast of Washington State, U.S.A. during May 1987. Seawater dimethylsulfide (DMS) concentrations on the continental shelf were strongly influenced by coastal upwelling. Concentrations further offshore were typical of summer values (2.2 nmol/L) at this latitude. Although seawater DMS concentrations were high on the biologically productive continental shelf (2-12 nmol/L), this region had no measurable effect on atmospheric DMS concentrations. Atmospheric DMS concentrations (0.1-12 nmol/m), however, were extremely dependent upon wind speed and boundary layer height. Although there appeared to be an appreciable input of non-sea-salt sulfate to the marine boundary layer from the free troposphere, the local flux of DMS from the ocean to the atmosphere was sufficient to balance the remainder of the sulfur budget.
Results from the winter 1995 echo integration-trawl survey of spawning walleye Pollock (Theragra chalcogramma) in the southeastern Aleutian Basin near Bogoslof Island are presented. The survey, conducted in two passes between 26 February and 9 March, covered an area between 165°51'W and 170°27'W long., from the Aleutian chain north to between 53° 45' N and 54° 40' N lat. Isolated Pollock aggregations were encountered off the edge of the shelf north of Akutan Island and over deep water northeast of Bogoslof Island. Extremely dense Pollock aggregations were observed along the north side of Umnak Island from 168° W to 169° 30' W long. Pollock vertical distribution ranged from 250 m to 750 m below the surface; their average depth was higher in the water column during pass 2 than during pass 1. Sex composition in hauls ranged from 8% to 94% female, averaging around 60% female. Evidence of vertical stratification by sex showed males inhabiting lower depth layers than females. Little evidence of a "non-spawner" component of the Pollock biomass (as had been observed in 1993 and 1994) was observed, and most female Pollock were in a pre-spawning reproductive state. The spawning biomass estimate, 1.10 million metric tons (I), was more than twice the March 1994 estimate of 0.49 million t. This large increase in the Bogoslof spawning population can be partially explained by strong recruitment of Pollock from the 1989 year class. However, population and biomass increases also occurred across most of the age groups. Potential reasons for the population increase are discussed.
500 - hPa field and H500 geopotential anomalies structural peculiarities are analyzed in January 1950 - 1998 over the northwestern part of the Pacific (NWP). 500-hPa fields of 1950s, 1960s, 1970s, 1980s and 1990s are determined. The main differences of 500-hPa filed are in the position of Okhotsk low (area of low barometric pressure) and ridge of the Pacific high (area of high barometric pressure) these years.
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