Redfield Alfred C.

No Thumbnail Available
Last Name
Redfield
First Name
Alfred C.
ORCID

Filters

4 1
5
Reset filters

Settings

Search Results

Now showing 1 - 5 of 5
  • Book
    The tides of the waters of New England and New York
    (Woods Hole Oceanographic Institution, 1980) Redfield, Alfred C.
    From the Preface: This book is written for the many intelligent people who work or play along the coast between Sandy Hook and the Bay of Fundy in the hope that it will give them a better understanding of matters which greatly influence the daily ordering of their activities. It may be of value to the serious student of the tides, at the beginning as an introduction to tidal theory and later as a summary of the tides on this particular coast. The stretch of coast considered and the off-lying ocean contain examples of practically all known tidal phenomena. The book is based for the most part on information given in the tide and current tables published by the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, formerly the Coast and Geodetic Survey. It is not intended to replace these tables if one would know what to expect at any particular place on any particular day. Rather, it attempts to explain why the tide locally is as it is and why it varies from place to place.
  • Book
    The processes determining the concentration of oxygen, phosphate and other organic derivatives within the depths of the Atlantic Ocean
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1942-09) Redfield, Alfred C.
    The great oceans of the world all contain at intermediate depths less oxygen and more nitrate and phosphate than is found at either lesser or greater depths. This is one of the most marked physical features of the sea which must be attributed to the action of biological agencies. Those who have discussed this condition recently are agreed that it originates through the oxidation of organic matter derived primarily from the surface layers of the ocean, where alone the original synthesis of organic matter can occur. The condition obtaining at any depth is considered to depend upon the balance between the rate at which oxygen is removed from the water by respiratory and other metabolic processes and the renewal of oxygen in the layers in question by movements of the water. One group of investigators has emphasized the latter factor as the dominant one in determining the observed distribution of oxygen (Jacobsen, 1916; Dietrich, 1937; Wüst, 1935; Wattenberg, 1929, 1938). Oxygen content is reduced to the greatest extent at those depths in which the water is in minimal motion and hence the renewal of oxygen is least. Seiwell (1937) and Sverdrup (1938) have pointed out that this condition is not a necessity and is indeed in certain situations contrary to the apparent facts. They have shown that the observed distribution of oxygen may be accounted for by assuming various suitable relations between the rates at which oxidation occurs as a function of the depth and the rates of renewal by the circulation of water. These discussions appear to consider the state of the water to depend upon factors operative more or less locally and in situ. Specifically, oxidation is assumed to follow the sinking of organic matter from the surface to the depth in question in the discussions of Wattenberg (1937) and Seiwell (1937). The renewal of oxygen is assumed to depend on the horizontal circulation. Several considerations appear to have been given insuffcient weight in discussions of this subject. It is not at all clear why the depth of the oxygen minimum layer varies so greatly from place to place or what its relation is to the particular nutritive conditions in the sea's surface. Observations made in the relatively shallow water of the Gulf of Maine indicate that organic decomposition and oxidation take place for the most part not far from the sea surface. It seems not unreasonable to assume that the properties of the water which depend upon organic decomposition may have been determined primarily at a time when the water was relatively near the sea surface and that the water has subsequently moved into its observed position. The recent evidence, reviewed by Montgomery (1940), that mixing processes along surfaces of constant potential density may occur with great ease, even in the absence of directional flow, provides a convenient mechanism for establishing a distribution of oxygen and the products of organic activity at great depths which is dependent in large part on processes taking place much nearer the sea surface in remote regions. These considerations have suggested that the wellmarked evidence of decomposition which is observed at great depths in the central Atlantic Ocean may be due to the flow of water along surfaces of equal potential density from regions near the sea surface in high northern and southern latitudes rather than to the decay of organic matter derived directly from the overlying surface waters. This view requires that the characteristics of the water show a marked continuity in their distribution along layers of constant potential density, and that these layers emerge at or near to the sea surface in places suitable to produce the peculiar character of the layers in question. To test this possibility, data secured by the "Meteor," the "Discovery," and the "Atlantis" have been examined. The most illuminating information was secured from two north-south sections which together extend from Greenland to Antarctica. The South Atlantic was traversed by a section, made by the "Discovery" in April-May, 1931, extending along the thirtieth meridian from 57°36'S to 14°27'N ("Discovery" Reports, 1932). This is Section 2 of Clowes (1938). A section of the North Atlantic was constructed from the data secured by the "Atlantis" extending from 1°N to 34°N west of the fortieth meridian in March, 1932 (Stations 1158-1179), and from 39°N to 49°N near the fortieth meridian in September, 1935 (Stations 2485-2491), and by the "Meteor" (Stations 120-125) extending from 50°N to 58°N near the forty-fourth meridian, occupied in March, 1935 (Bull. Hydrographique, 1933, 1936). The data have been converted into suitable common units. Phosphate has been expressed as milligram-a toms phosphorus per cubic meter (γ-atoms P per liter) uncorrected for salt error. The function of the oxygen content which is of importance is the quantity which has disappeared from the water owing to metabolic processes. This has been approximated by assuming the water to have been saturated with air at the time it acquired its temperature and salinity at the sea surface and subtracting the recorded oxygen content from the value calculated on this assumption. The "apparent oxygen utilization" so obtained has been expressed as cubic centimeters per liter. In plotting the data for the sections, a rectangular grid on which latitude is represented horizon tally and sigma-τ is represented vertically has been chosen. Mon tgomery (1938) has shown that surfaces of equal sigma-τ are approximately of constant potential density. Consequently, on such a diagram the path of free movement by lateral mixing or flow is along horizontal lines. Any correlation of the distribution of a component of the sea water with potential density becomes at once apparent, if present. The surface of the sea and surfaces of any particular depth are represented by curved lines on the diagram. A grid of this type has been used by Spilhaus (1941) to distinguish different water types in the complex situation which exists at the margin of the Gulf Stream.
  • Technical Report
    Report to the Towns of Brookhaven and Islip, N.Y. on the hydrography of Great South Bay and Moriches Bay
    (Woods Hole Oceanographic Institution, 1952-04) Woods Hole Oceanographic Institution ; Redfield, Alfred C.
    During the summer of 1950, The Woods Hole Oceanographic Institution conducted a study of the waters of Great South Bay for the Town of Islip, New York, with a view to seeking the cause of the decline of the oyster industry, which has deteriorated steadily during the past twenty years. The report of these studies was submitted in January 1951. The survey revealed two conditions which in combination appeared to be unfavorable to the oyster industry. One unfavorable condition was the local change in circulation occasioned by the opening of Moriches Inlet in 1931, which had increased the salinity of Bellport Bay, creating a condition which might well be detrimental to the production of seed oysters. Aside from this, it was concluded that little change had taken place in the salinity and tidal exchange of the central and western part of the bay during the past twenty years. The second unfavorable condition was the pollution of Great South Bay by wastes from the duck farms located along the Carmans River and the tributaries of Moriches Bay. Chemical studies indicated that the bay water is unusually rich in the products of decomposing organic matter. These materials appeared to arise from the mouth of the Carmans River and the tributaries of Moriches Bay, from which they are carried westward across Great South Bay. They provide nutriment for the growth of an unusually dense population of microscopic plants. Evidence existed that oysters do not feed properly on water containing such large concentrations of plant cells, and available statistics showed a clear correlation over a period of years between the condition of bay oysters and the numbers of plant cells in the water. Finally, the decline in oyster production has been closely paralleled by the growth of the duck industry, which increased fourfold during the period. In the report on the survey of 1950, it was pointed out that a number of questions had been revealed which were not anticipated when the field work was in progress and that these questions merited additional study. One of these related to the behavior of uric acid, the peculiar form in which birds secrete nitrogenous wastes, which promised to provide unambiguous evidence on whether the duck farms are the source of pollution. Another was the more detailed study of the circulation of Moriches Bay and its connection with Great South Bay through Narrow Bay, since this appeared to be the principal avenue of the pollution of Great South Bay. Finally, more detailed information was desired concerning the actual quantities of pollutants arising from the duck farms and of the alterations of its components by biological and other action upon introduction into the bay water. Before these additional studies could be undertaken, the problem acquired a new aspect be cause of the spontaneous closure of Moriches Inlet which occurred on May 15, 1951. While this terminated any possibility of increasing knowledge of the circulation between the bays as it previously existed, it afforded an opportunity to observe the effect of the opening on the condition of the bay waters. This information was of prime importance in view of the proposal to reopen and stabilize Moriches Inlet. Field parties visited the region on three occasions during the sumer. On July 12-14, 1951, a survey was made of the entire system of bays lying between the western extremity of Great South Bay and the Shintecock Canal. Between July 27 and August 5, studies were made of the chemical conditions in Moriches Bay and its approaches, and a detailed examination was carried out on the immediate conditions associated with the duck farms along the Terrell River. On September 24-29, an attempt was made to measure the exchange of water and associated pollutants between Moriches Bay and Great South Bay, and through the Quantuck Canal. On this occasion continuous observations were made at Smith Point and Beach Lane Bridge for a period of fifty hours, including four complete tidal cycles.
  • Book
    The analysis of tidal phenomena in narrow embayments
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1950-07) Redfield, Alfred C.
    The tides of coastal embayments derive their energy from the ocean tides rather than from the direct action of lunar and solar gravitational forces. They are considered to be part of co-oscilating systems in which the period is determined by the tide in the outer sea, while the detailed character of the motion depends on the size and form of the enclosed basin (Defant, 1925; Doodson and Warburg, 1941). In narrow basins of simple form in which the influence of the earth's rotation is small, the motions resemble standing waves. Ideally, such waves are characterized by the simultaneous rise and fall of level on either side of a nodal line at which no change in elevation takes place. The elevation at high water increases with distance from the nodal line and slack water coincides with high and low water. The properties of tides due to standing waves may be deduced by assuming the motion to result from a primary progressive wave moving up the channel which undergoes complete reflection at a barrier. Mathematically, this situation may be treated as the interference of two identical progressive waves moving in opposite directions and so related that both waves are in phase at the barrier. This treatment of standing waves assumes the presence of total reflection, the absence of damping and the absence of effects of the earth's rotation. Since these conditions are not realized in natural tidal basins, the standing wave concept leads to oversimplification. In coastal embayments the most striking departure from the expectations of the standing wave concept is the discrepancy between times of high water and slack water, which may be great near the mouths of the larger bays and sounds. High water does not occur simultaneously within such enclosures but is earlier near the sea. Commonly, the nodal line is represented merely by a region in which the tidal range is small. These are effects which can be explained if damping of the primary and reflected waves by frictional or other effects is taken into account. According to these concepts, the problem of tidal behavior in embayments is to determine numerically the properties of the primary and reflected waves so as to account for the observed relations of amplitude and stream velocity of the actual tide and to correlate these numerical properties with the geographical form of the embayment. In the present paper an attempt is made to treat the tidal behavior in such a way that the observed changes in elevation and motion of the water along the path of the wave may be used to determine the distribution of phase of the primary and reflected waves along the channel and to measure the damping. The relations between the several aspects of a wave as it advances along a channel of uniform depth and width have been developed theoretically so as to show the times of high water and slack water, the range of the tide, and the phase relations of the primary and reflected waves along the channel for any degree of damping. By expressing the relationship of the several aspects of a reflected wave in a form in which the wave period is taken as the unit of time and distance is given in terms of the related phase changes, it is possible to eliminate the purely geographical dimensions and to obtain a wholly general description of the tide which may be used to indicate how any given channel distorts the behavior of the wave as it advances. In the case of irregular channels, in order to justify the application of relations deduced for uniform channels, in which the change in phase of the primary and reflected waves and their damping is proportional to the distance traveled and in which the velocity of the waves is constant, it is necessary to make the following assumptions: 1. That the effect of irregularities in cross section is to alter the velocity of the primary and reflected waves; i.e., to distort the geographical distribution of phase differences. 2.That damping is proportional to the phase change in the waves rather than to the distance traveled. 3. That the damping coeffcient, as defined, is constant along the length of the channel.
  • Book
    The oceanography of the New York Bight
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1951-08) Ketchum, Bostwick H. ; Redfield, Alfred C. ; Ayers, John C.
    The New York Bight consists of the waters lying between Cape May, New Jersey, and Montauk Point, Long Island. A portion of the general southwesterly current known as the Coastal Drift lies in the seaward part of the Bight. Inshore from the Coastal Drift is an area of complex hydrography where the combined outflows of the Hudson River and other rivers enter the sea. In the region where the New Jersey and Long Island coastlines converge, an area 25 nautical miles on each side has been studied at all seasons of the year. This area extends from Sandy Hook southward to a point off Seaside Heights, eastward to 73°15' W longitude, north to the Long Island shore, and westward to Rockaway Inlet. The depth of water in the area averages about 90 feet, except in the innermost part of the Hudson Canyon which runs roughly northwest-southeast across most of the survey area. In the Canyon, depths in excess of 240. feet are found within the limits of the area studied. The hydrographic conditions in the area are in essence similar to those off the mouths of other large rivers. The combined flows of the Hudson and other rivers entering the surveyed area discharge enough fresh water annually to replace about one-half of the total volume of water under the 600 square miles of sea surface extensively surveyed. The salinity within the area is nearly as high as that of adjacent coastal water, however, and the actual quantity of river water within the area at any time rarely exceeds one percent of the total volume of water. Quantitative evaluation of these factors has led to the conclusion that there is an active circulation within the area which rapidly disperses the introduced river effluent. Many surveys of coastal and estuarine waters have been made. Outstanding among these are the survey of the River Tees, (1931, 1935), of the Tamar Estuary, (Hartley and Spooner, 1938; Milne, 1938), and of Alberni Inlet, (Tully, 1949). The general principles of estuarine circulations may be summarized as follows: In order to remove the added river water there must be a non-tidal drift of mixed water in a net seaward direction. When river flow remains constant, a steady state distribution of fresh and salt water throughout the estuary is attained, and at such times the net transport of river water seaward through any complete cross section of the estuary exactly equals the contribution of fresh water from the river during the same interval of time. As the mixture containing the river water moves seaward it gets progressively more saline, as additional sea water is entrained. In order to provide this sea water there must be a counter drift having a net flow in a landward direction. Superimposed on these necessary parts of the circulation are tidal and wind currents. The velocities of the tidal currents are commonly much greater than the velocity of the non-tidal drift, making the latter difficult to measure directly. It can be inferred, however, from the distribution of river water, as derived from the salinity distribution. Using the river water in this way we have evaluated the exchanges of the waters within the New York Bight. Tully (1949) has analyzed the circulation in Alberni Inlet by similar methods. Tidal current measurements made by the Coast and Geodetic Survey at various locations in the northwestern corner of the surveyed area are summarized by Marmer (1935). At Scotland Lightship, which is the location of the stations at the western end of Section A in Figure 1, the total excursion which results from the flood or ebb tidal currents is less than two miles. The currents at Ambrose Lightship, about five miles to the eastward, produce displacements only about half as great. The tidal displacements throughout the rest of the area are presumed to be less than these. The pattern of distribution of properties will be displaced, therefore, a distance less than ±1 mile at various stages of the tide. This distance is small in comparison to the size of the area surveyed, especially when considering the fact that distances between stations ranged from 5 to 8 miles. It was unnecessary, therefore, to attempt to take comparable stations at similar stages of the tide. Other considerations, beside its interesting hydrography, have contributed to the choice of this area for study. Because it is adjacent to centers of dense population and heavy industrial concentration, the New York Bight serves the conflicting purposes of waste disposal and recreation. Sewer effluents and industrial wastes enter the area by way of the rivers. Sewage sludges are barged out and dumped within the region studied. During the period covered by our surveys, The National Lead Company commenced operations to barge and discharge at sea the waste from its titanium plant at Sayreville, New Jersey. Since iron was a major constituent of this waste, analyses for iron in the water were made at each station, and the results have been valuable in checking the rate of the circulation which was computed from the distribution of river effluent. The New York Bight is also used extensively for recreational purposes. Because the area is readily and cheaply accessible by public transportation it must serve the recreational demands of a large part of the population of metropolitan New York. Sport fishing, bathing and boating are the principal recreational activities. Small but valuable commercial fisheries for shellfish and fin-fish also exist. The purpose of this study was to investigate the hydrographic processes in the New York Bight since they have an important bearing on the general problems of coastal oceanography and a knowledge of them should lead to a more successful evaluation and utilization of the area for the diverse purposes it must serve.