Woods Hole Oceanographic Institution

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The Woods Hole Oceanographic Institution is a private, independent, not-for-profit corporation dedicated to research and higher education at the frontiers of ocean science.

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  • Book
    Synoptic studies in fog
    (Massachusetts Institute of Technology, 1930) Willett, Hurd C.
    This study of fog formations at Hadley Airport was carried out during the winter of 1928-29 with the intent of finding out how far a careful scrutiny of local records might assist in explaining and forecasting local fogs. It was meant to be supplementary to a more general discussion of fog and haze formation which had appeared previously in the Monthly Weather Review for November, 1928. This study is based on the general fog classification set forth there.
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    Characteristic weather phenomena of California : a regional analysis based on aeronautical weather observations
    (Massachusetts Institute of Technology, 1931) Byers, Horace R.
    During the fiscal year beginning July 1, 1928, the Daniel Guggenheim Fund for the Promotion of Aeronautics maintained an experimental meteorological service for the benefit of air transportation between San Francisco and Los Angeles. The system was designed as a first approach toward a model weather reporting organization for air traffic. Its main feature was the gathering of simultaneous weather observations from about 35 stations in Southern and Central California covering an area of, roughly, 65,000 square miles. The observation hours were 6.30 a.m., 8 a.m., 9.30 a.m., 11 a.m., 12.30 p.m., and 3.30 p.m., 120th meridian time. The regular Weather Bureau observations furnished additional data for 5 a.m. and 5 p.m. A description of the organization has been published by E. H. Bowie. Since the service was organized strictly for the purpose of informing airplane pilots of weather conditions over their routes and not with a view of furnishing a fertile field for meteorological investigations, certain instrumental readings which are important in meteorological research were not provided. Thus humidity observations are lacking, except as subsequently obtained from the few but more thoroughly equipped stations of the U. S. Weather Bureau, the U. S. Navy and the University of California. A series of airplane ascents made at the Naval Air Station at San Diego provided pressure, temperature and relative humidity observations from the upper atmosphere for part of the period investigated. Three pilot balloon stations were established by the Fund to supplement those of the Government, so that ample free air wind data are available. Non-professional part-time observers were employed at most of the stations. For this reason, inaccuracies are likely to have lessened the value of the reports. These errors occurred chiefly in the determination of cloud forms. When the uncertainties of cloud classification and the diffculties it presents even to the trained meteorologist are fully appreciated, the errors in these observations are not surprising. It is the opinion of the authors that the cloud forms herein recorded are for all practical purposes correct. During the year in which this service was conducted by the Fund, some interesting data were collected to add to the knowledge of meteorological conditions in California. This applies particularly to the movement of fronts and the development, distribution and dissipation of the persistent and frequent fogs in the area. Some of these results will be presented below.
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    Thermodynamics applied to air mass analysis
    (Massachusetts Institute of Technology, 1932) Rossby, Carl-Gustaf
    Since the beginning of 1929 systematic work has been carried out at the Massachusetts Institute of Technology to develop practical methods for the identification and characterization of air masses with the aid of upper air soundings of pressure, temperature and humidity. A brief report on this work was published in October 1930. It was then shown that by plotting against each other two meteorological elements, which under certain well defined conditions are recognized as conservative, namely, specific humidity and potential temperature, curves are obtained which, in winter time, to a high extent remain unchanged and characteristic of the individual air masses. In view of this property the curves were named "invariant curves." Since the invariance is restricted to the winter season, but the curves always may be advantageously used to determine the vertical structure and life history of air masses, they shall, in the following, be referred to as "characteristic curves." The report also stated that by means of characteristic curves a new method had been created of indicating certain differences in stability between the principal American air masses. These differences may be expressed in terms of the variation with elevation of specific entropy, and it was therefore decided to continue the investigation and to include in it a study of the equivalent-potential temperature, which, in an easily comprehensible form, measures the specific entropy of moist air. The excellent results obtained by Robitzsch through the introduction of equivalent-potential temperature into practical meteorological work lent additional support to this decision.
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    Scientific results of the "Nautilus" Expedition, 1931 : under the command of Capt. Sir Hubert Wilkins. Parts I to III
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1933-03) Sverdrup, Harald U. ; Soule, Floyd M.
    In 1930 Sir Hubert Wilkins announced his plan for exploring the Polar Sea by submarine. Thanks to the courtesy of the U. S. Navy Department and the U. S. Shipping Board the submarine 0 12 was placed at his disposal and the constructor of this vessel, Mr. Simon Lake, undertook to rebuild it and make it suitable for travelling underneath the Arctic pack-ice. After rebuilding the submarine was in the spring of 1931 named Nautilus. ... The expedition did not reach its goal and the scientific results are, therefore; small as compared to what had been hoped for. But we have shown that an extensive scientific program can be carried out under the conditions onboard a submarine, and it is hoped that the following papers will add to our knowledge of the region which was visited.
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    American air mass properties
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1933-06) Willett, Hurd C.
    In this paper the term Air Mass is applied to an extensive portion of the earth's atmosphere which approximates horizontal homogeneity. The formation of an air mass in this sense takes place on the earth's surface wherever the atmosphere remains at rest over an extensive area of uniform surface properties for a suffciently long time so that the properties of the atmosphere (vertical distribution of temperature and moisture) reach equilibrium with respect to the surface beneath. Such a region on the earth's surface is referred to as a source region of air masses. As examples of source regions we might cite the uniformly snow and ice covered northern portion of the continent of North America in winter, or the uniformly warm waters of the Gulf of Mexico and Caribbean Sea. Obviously the properties of an air mass in the source region will depend entirely upon the nature of the source region. The concept of the air mass is of importance not only in the source regions. Sooner or later a general movement of the air mass from the source region is certain to occur, as one of the large-scale air currents which we find continually moving across the synoptic charts. Because of the great extent of such currents and the conservatism of the air mass properties, it is usually easy to trace the movement of the air mass from day to day, while at the same time any modification of its properties by its new environment can be carefully noted. Since this modification is not likely to be uniform throughout the entire air mass, it may to a certain degree destroy the horizontal homogeneity of the mass. However, the horizontal differences produced within an air mass in this manner are small and continuous in comparison to the abrupt and discontinuous transition zones, or fronts, which mark the boundaries between air masses. Frontal discontinuities are intensified wherever there is found in the atmosphere convergent movement of air masses of different properties. Since the air masses from particular sources are found to possess at any season certain characteristic properties which undergo rather definite modification depending upon the trajectory of the air mass after leaving its source region, the investigation of the characteristic properties of the principal air mass types can be of great assistance to the synoptic meteorologist and forecaster. We owe this method of attack on the problems of synoptic meteorology to the Norwegian school of meteorologists, notably to T. Bergeron. Investigation of the properties of the principal air masses appearing in western Europe has been made in particular by O. Moese and G. Schinze. The purpose of this paper is to give the results of a similar investigation of the properties of the principal air masses of North America, and to comment on some of the striking differences which appear between conditions here and in Europe.
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    Scientific results of the "Nautilus" expedition, 1931 under the command of Capt. Sir Hubert Wilkins. Parts IV and V
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1933-06) Villinger, B. ; Stetson, Henry C.
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    Studies of the waters on the continental shelf, Cape Cod to Chesapeake Bay. I. The cycle of temperature
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1933-12) Bigelow, Henry Bryant
    When the U. S. Bureau of Fisheries, in cooperation with the Museum of Comparative Zoology, commenced the oceanographic survey of the Gulf of Maine in the summer of 1912 (Bigelow, 1925-1927), it was in the hope that this might later be extended to the coastal waters thence southward; eventually even as far as the Gulf of Mexico. Cruises carried out in connection with investigations of the biology of the mackerel, by the Fisheries' steamer "Albatross II" from 1927 to 1932, supplemented by those of the research ship "Atlantis" of the Woods Hole Oceanographic Institution, have made it possible to extend the detailed examination of the physical oceanography of the continental shelf as far as the offing of Chesapeake Bay, and to the offing of Cape Hatteras for some of the months. The present account of the temperature of the region will, it is hoped, be followed shortly by corresponding accounts of salinity, of circulation and of the dominant planktonic communities.
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    The meteorological airplane ascents of the Massachusetts Institute of Technology. Part I. On the technique of meteorological airplane ascents. Part II. Aircraft instruments in meteorological flying
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1934-08) Lange, K. O. ; Draper, C. S.
    The aerological flights at Boston are part of the general research program of the Meteorological Division of Massachusetts Institute of Technology, which program since 1929 has been directed especially toward the study of American air masses and fronts. Recently, some results of these studies were published by Willett, who based his investigations on a series continuous over three years of mornìng and evening weather maps, analyzed at the Institute, together with upper air soundings from the United States Weather Bureau stations at Dallas, Omaha, Chicago, Groesbeck, Atlanta and from the United States Navy at Seattle, Anacostia, Pensacola and San Diego. These upper air data facilitated the determination of the properties of the air masses and so proved of inestimable value for the study. But the use of the data also showed that improvement both in the number of stations and in the quality of observations was highly desirable. Ascents in the northeastern part of the United States were lacking. Knowledge of the vertical structure of air masses reaching this region, however, is of special interest in forecasting for this densely populated district. For these reasons and since the direct comparison of actual local weather developments with upper air conditions is also con- sidered to be very valuable, the Institute started its own airplane station at Boston. In addition to "regular" ascents at the time of the morning surface observations, special flights were made when particularly interesting weather situations prevailed. On a number of days series of ascents were carried out to obtain cross sections through fronts passing over Boston. Other special flights were made to obtain information on atmospheric turbulence. For this same purpose and also in order to study the diurnal changes of temperature in the lowest 5,000 feet, several series are planned of a number of comparatively low altitude flights at short intervals throughout the day.
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    The distribution of oxygen in the western basin of the North Atlantic
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1934-08) Seiwell, Harry Richard
    The distribution of dissolved oxygen in the sea is controlled by a combination of its physical, chemical and biological characteristics; on the one hand, the chemical and biological activities tend to vary the content of the dissolved gas whereas, on the other, the circulatory agencies tend to redistribute the oxygen and bring about equilibrium. The fact that there is a constant consumption of dissolved oxygen in the depths and that frequent supersaturation with oxygen occurs at or near the surface of the ocean was observed on the "Challenger" expedition (Dittmar, 1884). An explanation of the cause of supersaturation of oxygen, however, was not forthcoming until 1899 when Martin Knudsen suggested that it was caused by photosynthetic activities of vegetable plankton. The original oxygen content of ocean waters has been obtained from a-thin surface layer in contact with the atmosphere and as a product of photosynthetic activity. In modern concepts of oceanography it is a generally accepted fact that the water masses of the depths of the oceans have at some time and place been at the surface where under the influence of climatic conditions they acquired distinct temperature, salinity and oxygen characteristics. The sinking of the surface layers in the so-called regions of convergence and their ultimate distribution by means of quasi-horizontal and convectional currents results in the whole of the ocean basins being filled with water which has acquired its fundamental characteristics while under the influence of atmospheric conditions. From general knowledge of oceanic circulation, based on researches of Nansen (1912), Jacobsen (1929), Wüst (1928), etc., the water of the western basin of the North Atlantic is probably of several origins and consequently of different ages and oxygen contents. Thus, the deepest part of the whole basin, up to depths of 2000-1500 meters appears to contain water which, for the most part, originated at the surface in high North Atlantic latitudes. Lying on top of this deepest water there is, in the northern half of the region, what appears to be a mixture of it and other North Atlantic water, while in the southern half of the region there is at intermediate depths a mass of water which apparently originated at the surface in high latitudes of the South Atlantic.
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    The cycle of phosphorus in the western basin of the North Atlantic
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1935-04) Seiwell, Harry Richard
    The importance of phosphorus for organic production in the sea appears to have been recognized first by Brandt (1899) and the earlier determinations of this element in the coastal seas of northern Europe (Brandt, 1920; Raben, 1920; Mathews, 1917) suggested a correlation between seasonal variation of phosphate and growth of phytoplankton. These earlier determinations were later shown to be too high (Atkins, 1926, a) and did not indicate the complete exhaustion of phosphate from the water, so it was not until several years later that Atkins (1923), employing the rapid and more accurate colorimetric ceruleo-molybdate method of Deniges, illustrated the complete dependence of algal growth on phosphate (in the English Channel) and thus established the foundation for modern studies of marine chemical fertility. The beginning of our knowledge of phosphate content of the open ocean may, as far as is known to me, also be attributed to Atkins (1926, a) and even though these early results were frequently somewhat vitiated by storing of the samples before analyses, they represented the order of magnitude of phosphate concentration in the sea. Within recent years phosphate determination has become a component part of the program of most deep sea investigations and much general information on its distribution and variation in the open ocean has been brought to light.
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    The layer of frictional influence in wind and ocean currents
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1935-04) Rossby, Carl-Gustaf ; Montgomery, Raymond B.
    The purpose of the present paper is to analyze, in a reasonably comprehensive fashion, the principal factors controlling the mean state of turbulence and hence the mean velocity distribution in wind and ocean currents near the surface. The plan of the investigation is theoretical but efforts have been made to check each major step or result through an analysis of available measurements. The comparison of theory and observations is made diffcult by the fact that in most cases measurements have been arranged without the aid of a working hypothesis concerning the dynamics of the effect studied; thus information is often lacking concerning parameters essential to the interpretation of the data.
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    Studies of the waters on the continental shelf, Cape Cod to Chesapeake Bay. II. Salinity
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1935-07) Bigelow, Henry Bryant ; Sears, Mary
    The present paper forms a sequel to the account of the temperature of the same region (Bigelow, 1933)... the continental shelf between the offings of Cape Cod (longitude about 70°) and Chesapeake Bay;-extended southward, for occasional months, to the offing of Cape Hatteras; and with such discussion of conditions along the continental slope as is justified by occasional profiles.
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    Discussion and illustration of problems suggested by the analysis of atmospheric cross-sections
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1935-07) Willett, Hurd C.
    The preparation of atmospheric cross-sections, in which the fields of the various meteorological elements are represented in the vertical plane containing a number of synoptic aerological soundings, has long been a part of the technique applied to the investigation of problems in synoptic meteorology. However, owing to the lack of adequate observational material, the number of such cross-sections prepared in the past has been very small. The method was applied only in a few cases chosen for careful analysis and study. Consequently no uniform technique of analysis of such cross-sections has been developed, nor have the possibilities of this method of synoptic investigation received much attention. In the fall of 1933 the author decided that the possibilities of the cross-section method of synoptic representation warranted the systematic preparation and analysis of a large number of cross-sections. For this purpose a number of periods during which the synoptic maps seemed to indicate interesting atmospheric developments, and for which numerous aerological observations were available, were chosen from the maps of the preceding two or three years for detailed cross-sectional study. In all, ten periods of from two to six days each were chosen, a total of 36 days, entailing the preparation of about 90 cross-sections, and the use of about 400 aerological soundings.
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    On the momentum transfer at the sea surface. I. On the frictional force between air and water and on the occurrence of a laminar boundary layer next to the surface of the sea. II. Measurements of vertical gradient of wind over water. III. Transport of surface water due to the wind system over the North Atlantic
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1936-06) Rossby, Carl-Gustaf ; Montgomery, Raymond B.
    I. It is fairly generally assumed that the horizontal circulation of the ocean "troposphere" is maintained by the large scale permanent wind system of the atmosphere. Accurate knowledge of the tangential force exerted by the wind on the surface of the water should therefore be a prerequisite for every attempt to analyze the movements of the surface water. Very few data are available from which this shearing force may be accurately determined, although several, in principle simple, methods of attack are available. Recently some estimates of the wind force have appeared in studies not primarily concerned with the oceanographic aspects of the problem. In view of the conflicting results obtained and in view of the importance of the problem to physical oceanography it seems desirable to examine the question theoretically and to study critically the empirical determinations just referred to. II. Despite the great importance, in studies of the frictional forces between atmosphere and ocean, of wind gradient measurements next to the ocean surface, to my knowledge the only observations that have been published are those of Wüst and of Shoulejkin. Both of these are so fragmentary that one would find it very difficult to draw general conclusions from them alone. Feeling that further measurements of any sort might prove useful, and lacking time and facilities for a large program, the author felt justified in making the following simple measurements during September 1935, which may be regarded as preliminary. III. The results of Section I above and of our previous paper are here applied to the specific computation of the transport of the drift current system over the North Atlantic. Only the computation is given here, but the authors of this paper expect to discuss in later articles its significance in connection with the surface salinity distribution and with the Equatorial Current.
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    A study of the circulation of the western North Atlantic
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1936-08) Iselin, Columbus O’Donnell
    With the opening of the Woods Hole Oceanographic Institution in July 1931, there was inaugurated a program of investigations in the deep waters of the western North Atlantic for which there had long been a great need. In contrast to most deep-sea investigations, which have had to be planned as single expeditions, the Institution was able to initiate a general program which could be carried out gradually in order to take advantage of knowledge gained during the course of the work. Suffcient funds having been provided for the continuous operation of its research vessel "Atlantis," work could be planned for all seasons of the year. Although these investigations have not been in progress for long and new data are continually being brought in by the "Atlantis," there are several reasons that make it seem desirable at this time to publish a preliminary report based on the completed temperature and salinity observations. In the first place, the problem of oceanic circulation is such that we cannot hope for a satisfactory solution for a long time to come. Moreover, it would be unwise to allow too much data to accumulate, because several years may pass before we can arrive at more important conclusions. Secondly, both the chemical and biological programs undertaken at the same time, require as a background the general scheme of circulation in the western North Atlantic as well as the distribution of temperature and salinity. It is, in fact, the necessity of taking into consideration the movements of the sea water which ties together the whole subject of oceanography. Therefore, it is the duty of those interested in ocean circulation to make available their findings as soon as possible for investigators of other problems in the same area. The "Atlantis" temperature and salinity observations discussed in these pages were planned with two main purposes in view. The first objective was an intensive study of seasonal changes along sections running from the southwestern corner of Nova Scotia to Bermuda and from Bermuda to the mouth of Chesapeake Bay.! This, of course, included an examination of fluctuations in the Gulf Stream, as well as of the variations in the water masses on each side of it. Second, there has been planned and partly carried out, a more general survey of the western North Atlantic, where accurate, deep stations have been sadly lacking.
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    Dynamics of steady ocean currents in the light of experimental fluid mechanics
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1936-08) Rossby, Carl-Gustaf
    The present investigation may be regarded as a part of a systematic effort to introduce into meteorology and physical oceanography methods and results which for a number of years have contributed to the rapid growth and increasing practical significance of experimental fluid mechanics. This science has recognized that the exact character of the forces controlling the motion of a turbulent fluid is not known and that consequently there is very little justification for a purely theoretical attack on problems of a practical character. For this reason fluid mechanics has been forced to develop a research technique all of its own, in which the theory is developed on the basis of experiments and then used to predict the behavior of fluids in cases which are not accessible to experimentation. In oceanography it has long been regarded as an axiom that the movements of the water are controlled by three forces, the horizontal pressure gradient, the deflecting force, and the frictional force resulting from the relative motion of superimposed strata. It is significant that thirty-five years of intensive theoretical work on this basis have failed to produce a theory capable of explaining the major features of the observed oceanic circulation below the pure drift current layer. The present investigation considers a force which has been completely disregarded by theoretical investigators although its existence has been admitted implicitly by practically everyone who has approached physical oceanography from the descriptive side, namely the frictional force resulting from large-scale horizontal mixing. The intro- . duction of this force permits us to see how motion generated in the surface layers may be diffused and finally dissipated without recourse to doubtful frictional forces at the bottom of the ocean.