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R. K. Reed and D. Halpern

Abstract

Data obtained at a time-series station during intense coastal upwelling off Oregon were applied to a model of heat conservation for the upper 8 m, and a thermal eddy diffusivity (horizontal) of 300 M2s−1 was computed. Horizontal advection and horizontal diffusion both appeared to be more important than surface heat exchange in producing changes in heat content. Hourly changes in heat content were quite large, and it appears that advection and diffusion varied appreciably in conjunction with changing tidal currents.

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R. K. Reed and R. E. Brainard

Abstract

In an effort to verify computational methods for ocean heat budgets, observations of insulation under clear skies for 26 days were compared with values computed by a formula previously derived from the Smithsonian Tables. The agreement between the observations and formula was within 2.0% for three groups of data over the Pacific between 10°S and 47°N. Random and systematic errors in the formula appear to be insignificant in these regions, but its validity is uncertain at higher latitudes.

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R. K. Reed and J. D. Schumacher

Abstract

Long-term records from four current meters in the Alaskan Stream off Kodiak Island are presented. The net flows decreases with depth and appeared to be in approximate geostrophic equilibrium. Large fluctuations were not common, and the flow was dominated by low-frequency energy. This behavior, which is also supported by temperature and salinity data, suggests a vertically coherent flow with occasional lateral meanders.

The eddy kinetic-energy levels in this region of the Alaskan Stream were quite low, especially in comparison with those in the Kuroshio and Gulf Stream. The flux of momentum across the inshore edge of the Stream appeared to be onshore and to represent a transfer of energy fron3 the mean flow to smaller scales; an eddy viscosity of not more than 106 cm2 s−1 was indicated. The impact on shelf waters of the small, onshore eddy heat flux is unclear.

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R. K. Reed and W. P. Elliott

Abstract

The problems of using raingages on ships are discussed, and methods of estimating rainfall from weather reports at sea are reviewed, with emphasis on discussion of efforts to verify the assessments derived by Tucker (1961). A raingage was used on cruises of the NOAA ship Oceanographer in the eastern Pacific during 1975 and 1976, and rainfall was estimated from weather reports using Tucker's assessments. In extratropical latitudes (mainly 40–60°N), a catch of 35 cm was obtained; estimates from the weather reports gave a value of 31 cm. Thus Tucker's assessments are essentially in agreement with catches from a small gage in this region. In the tropics, however, the agreement was not good. Almost three times as much rain was caught as was estimated; hence Tucker's coefficients will need to be reevaluated for this area.

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W. P. Elliott and R. K. Reed

Abstract

Climatological estimates of mean annual precipitation over the world ocean are presented and discussed. We obtained a value for mean annual oceanic precipitation (between 65°N and 60°S) of 93 cm, which is smaller than some other estimates. These results are supported by a recent analysis of tropical rainfall based on satellite techniques. Aspects of the need for and utility of climatological information are discussed.

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P. J. Stabeno and R. K. Reed

Abstract

From 1986 through April 1993, 86 satellite-tracked buoys were deployed in the North Pacific and Bering Sea. Most of the buoys were drogued at 40 m. A composite current pattern is derived using these data. The two principal currents (the Alaskan Stream and Kamchatka Current) are clearly evident. Eddy kinetic-mean kinetic energy ratios are low in the stream and along the western Bering Sea basin. An eastward flowing current occurred along the north flank of the Aleutian Islands, this flow was modified by inflow at the passes. Westward flow occurred north of 56°N; its source was the Bering Slope Current. The Kamchatka Current originated near 175°E along the Russian coast. Numerous eddies and meanders were observed in the Kamchatka Current; eddies were also present on the eastern side of the basin.

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R. K. Reed and J. D. Schumacher

Abstract

Data from current moorings at four sites near the shelf break in the Gulf of Alaska are used to present information on the flow, to examine the effects of local winds, and especially to investigate momentum transfer between the offshore and inshore circulation. Net flow at the shelf break in the central and western appears to be similar through the year, but it intensifies appreciably in winter in the northeast Gulf. Only records in the northeast Gulf suggest significant effects on flow by local winds. The eddy fluxes of momentum at the shelf break were extremely small. Although the offshore Alaskan Stream was previously found to transfer momentum toward shore, this flux apparently does not reach the shelf break and influence shelf waters. It appears rather that the gradients of heat and salt observed near the shelf edge result from offshore effects of the coastal flow.

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R. K. Reed, J. D. Schumacher, and J. P. Blaha

Abstract

A current record during February -August 1980 over the continental slope off Kodiak Island provided the first Eulerian measurements in the high-speed region of the Alaskan Stream. The net flow at 980 m during the 6-month period was 6 cm s−1 at 235°, but there were major low-frequency variations in the current. These appeared to result from the occasional advection of meanders past the mooring, however, rather than from features such as planetary waves. The ratio of fluctuating to mean kinetic energy was much lower than reported values in the Kuroshio and Gulf Stream, probably as a result of important kinematic differences in these flows.

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R. K. Reed, J. D. Schumacher, and L. S. Incze

Abstract

Extensive hydrographic surveys were conducted in Shelikof Strait in March and October 1985. The data are used to describe circulation and property distributions and the changes that occurred. The upper layer flows to the southwest throughout the year, but greatest speeds occur in the fall when surface waters are least saline because of a maximum in freshwater discharge. The deep water has its source to the south, and the properties seem to result from vertical mixing of this southern water. Thus Shelikof Strait has an estuarine-like circulation with a northward, deep inflow.

Property distribution showed that isolines were usually deepest on the right side of the channel looking to the southwest; greatest baroclinic speeds were often there also. Differential Ekman pumping may contribute to the development of this structure and its changes. Volume transport estimates varied considerably. In October the southwest flow bifurcated, with part continuing along the Alaska Peninsula and the rest exiting the main channel to the south; in March all upper-layer flow followed the main channel. Shelikof Strait appears to be a system influenced by both density-driven and wind-driven effects.

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Anita Menhofer, Roger K. Smith, Michael J. Reeder, and Douglas R. Christie

Abstract

Results of a field experiment carried out in 1991 to gather upper-air data on the morning-glory environment are presented. The data include daily early morning radiosonde soundings from Burketown in north Queensland, Australia, for a 28-day period during the late dry season, together with pressure, wind, temperature, and humidity data from a number of surface stations in the region. During the experiment, 16 morning glories were recorded. On all but one day, radiosonde soundings were carried out in the pre-morning-glory environment. On 7 days, additional soundings were carried out within an hour or two of the passage of a morning glory.

Soundings made on days on which morning glories were generated over Cape York Peninsula but failed to reach Burketown are compared with those on days when morning glories were recorded at Burketown. The comparison shows that the depth and strength of the surface-based inversion did not differ significantly and that the stratification of the almost neutral layer above the stable layer was similar on days with and without morning glories. An examination of the wind profiles is unrevealing and leads the authors to reject the hypothesis that the trapping of wave energy is the key factor that determines the longevity of the disturbances. That the leakiness of the wave-guide is not the only factor in the ability of disturbances to cover large distances from their place of origin is consistent with a numerical study by Noonan and Smith, which suggests that the morning-glory bore-wave system is formed and maintained by mesoscale circulations associated with the sea breezes over Cape York Peninsula.

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