42 research outputs found
Exploring the North Atlantic Ocean on floppy disks
Data from four floppy disks found in the zip fileA selection of hydrographic station data in the Atlantic between 8°S
and 70°N is packed on four 5 1/4" floppy disks. Sample utility programs for
reading and plotting the data are also on the disks. We present this computer
atlas in preliminary form for use by students and professionals, in
the belief that easy access to this valuable historical data will be educational
and stimulating.Funding was provided by the Office of Naval Research
under contract Number N00014-84-C-0134,
and the National Science Foundation
through grant Number OCE86-13810
On the nature of estuarine circulation : part I (chapters 3 and 4)
The reader will quickly see that the subject
matter of Chapter 3 is confined to the hydraulics of sharply
stratified media, whereas real estuaries are always more or
less diffusely stratified. What is more, no discussion is
made of the order of magnitude of the friction terms. In
ordinary single layer flow (such as in rivers) engineers already have crude approximations of the friction terms (Chezy
and Manning formulas), but we do not have even these approximations for two layer flow. For this reason the differential
equations of gradually varied flow of two layers are for the
most part left unintegrated and all that is demonstrated is
the qualitative aspects of the flow.
In the case of entrainment of water from one layer
into another we can only perform integrations of the equations when the amount of entrainment is known, whereas in real estuaries we do not have a priori knowledge of this amount.
The reader will see, therefore, that the subject matter
of Chapter 3 is really very incomplete, leaving undetermined all the constants which depend upon turbulent mixing,
upon the frictional stresses on the bottom, and the
free surface and the walls, and upon the amount of entrainment.
The contents of Chapter 4 are somewhat different.
First of all, they contain summaries of several
of these papers have proceeded on the basis of hypotheses already published papers on the mixing in estuaries. Most
about the nature of the mixing process. The applicability
of these hypotheses appears to be restricted to only certain estuaries, and it must be admitted that more work has
been done that involves guessing what the mixing processes
in an estuary might be, than has been done in trying to
find out what the mixing processes in an estuary actually
are.
As incomplete as the subject matter of Chapter 4
is, it is hoped that it will suggest which of the possible
mixing processes in estuaries may be important in any particular
one which is the subject of study, and that it will
also suggest the type of observations which will be most
desirable in studying a particular estuary. For example:
in an unstratified estuary it seems that a more or less
uniform spacing of stations up and down the estuary is desirable; but in an estuary which appears to be subject to
the constraint of overmixing (Section 4.51) the location of
stations should be largely confined to control sections.Office of Naval Research
under Contract No. N6onr-27701 (NR-083-004)
Origin of the Mediterranean outflow
Toe origin of the Mediterranean outflow is one of oceanography\u27s oldest problems. In this work, the flow of western Mediterranean deep water up and over the sill at Gibraltar is investigated from hydrographic observations and current measurements. The deep water is found to flow westward along the Moroccan continental slope in the western Mediterranean or Alboran Sea and to rise as it approaches the Strait of Gibraltar...
The electrical field induced by ocean currents and waves, with applications to the method of towed electrodes
The purpose of this paper is to discuss the nature
of the electrical field induced in the ocean by
particular types of velocity distribution. It is
believed that these examples will be helpful in the
interpretation of measurements by towed electrodes
in the sea.
The electrical field induced by waves and tidal
streams, originally predicted by Faraday (1832),
was first measured experimentally by Young,
Gerrard and Jevons (1920), who used both
moored and towed electrodes in their observations.
Recently, the technique of towed electrodes has
been developed by von Arx (1950, 1951) and
others into a useful means of detecting water
movements in the deep ocean. While the method
has been increasingly used, the problem of interpreting
the measurements in terms of water movements
has become of great importance. Two of the
present authors have made theoretical studies
(Longuet-Higgins 1949, Stommel 1948) dealing
with certain cases of velocity fields, and Malkus
and Stern (1952) have proved some important
integral theorems. There seems, however, to be a
need for a more extended discussion of the principles
underlying the method, and for the computation
of additional illustrative examples. This is
all the more desirable since some of the theoretical
discussions published previously have been misleading
Barotropic response to cooling
Also published as: Journal of Geophysical Research 85 (1980): 6661-6666Imposed horizontal density differences in a nonrotating fluid generate vertical circulation which has
vanishing vertically integrated transports. When the system is rotating, geostrophic velocities can balance
the density differences and the vertically integrated transports need not vanish locally. In a two-layer
fluid, fin ite amplitude disturbances lead to barotropic flows that have the same direction as the velocity in
the layer that thickens as a result of the disturbance. Specific calculations are carried out for the geostrophic
adjustment model in situations that approximate those in which 18° water is formed south of the
Gulf Stream. The upper layer transport that results from sudden cooling (as simulated by density differences
that are initially unbalanced geostrophically) is in the same direction as the Gulf Stream transport
and comparable to it in magnitude. A lower level transport of the same magnitude flows in the opposite
direction with a maximum value about an internal radius of deformation to the right of that of the upper
layer. The barotropic transport is about 1/ 5 as large and flows downstream in the Gulf Stream and upstream
to the right of the Gulf Stream.Prepared for the Office of Naval Research under Contract
N00014-79-C-0671 and for the National Science Foundation
under Grants OCE 77-19451 and OCE 78-18460
Vertical distribution of temperature and humidity over the Caribbean Sea
The observations presented and discussed in this paper were obtained as part of a
research project conducted under contract NObs-2083 with the Bureau of Ships of
the U. S. Navy by the Woods Hole Oceanographic Institution. The observations
and their original reduction were carried out under the direction of Jeffries Wyman.
The airplane soundings were undertaken by Kenneth McCasland and Alfred Woodcock.
The sea surface temperature was measured on the surface ships by David F. Barnes
and Roger Patterson. The necessary airplane (PBY-SA) and surface boats (PC's) were
made available by the U. S. Navy.
All observations were made during the spring of 1946 at about 19.5°N latitude,
66°W longitude, north of San Juan, Puerto Rico, and at about lO°N latitude, 79.5°W
longitude, north of Coco Solo, Panama. An extensive preliminary report on the results of the expedition with a limited circulation was prepared by Wyman and his collaborators
during the summer of 1946.
The present paper deals with certain phases of the work in a more detailed fashion.
Special attention is given to the temperature and humidity distributions in the vertical
and to their interpretation in the light of meteorological principles. A discussion of
atmospheric turbulence based on airplane measurements has already been published
elsewhere (Langwell, 1948), and an application of the airplane soundings to the theory
of cumulus clouds has been studied by Stommel (1947).
The second and third chapters of this publication deal with the description of observational
techniques used by the expedition, with the methods of reduction and present
the data on which the later discussion is based. It has been thought desirable to publish
these data in extenso because they may be of interest to other meteorologists in view
of the sparsity of upper-air observations in this region. The actual preparation of
Chapters II and III is largely the work of Bunker and Stommel.
In order to show how the observations made off Puerto Rico fit into the general
pattern of climatic and weather conditions in the Caribbean area Chapter iv presents
a survey of the climate of this region and of the weather conditions during the time when
the observations were taken. This Chapter was contributed by Joanne Malkus. It is
pertinent to include in this general introduction the conclusion drawn in Chapter IV
namely that the weather situations encountered represented, in general, a relatively
undisturbed trade-wind regime of early spring.
The homogeneous layer of nearly dry-adiabatic lapse-rate of temperature and almost
constant mixing ratio is one of the most characteristic phenomena in the lowest atmosphere
of this region. It is also of utmost importance for the energy budget of the hydrosphere
and the atmosphere. Therefore, a special discussion of this layer by Bunker is
given in Chapter V.
Because of the nearly dry-adiabatic lapse-rate in the homogeneous layer most of the
heat transfer between water and air in the trade-wind zone must be in the form of latent
heat of vaporization, a conclusion whose thermodynamic implications were discussed
thoroughly by Ficker (1936). For this reason the distribution of water vapor deserves
special attention, and Chapter VI deals with this variable as a problem in turbulent mass
exchange. The analysis presented in this chapter is due to Haurwitz and Stommel
A mathematical framework for critical transitions: normal forms, variance and applications
Critical transitions occur in a wide variety of applications including
mathematical biology, climate change, human physiology and economics. Therefore
it is highly desirable to find early-warning signs. We show that it is possible
to classify critical transitions by using bifurcation theory and normal forms
in the singular limit. Based on this elementary classification, we analyze
stochastic fluctuations and calculate scaling laws of the variance of
stochastic sample paths near critical transitions for fast subsystem
bifurcations up to codimension two. The theory is applied to several models:
the Stommel-Cessi box model for the thermohaline circulation from geoscience,
an epidemic-spreading model on an adaptive network, an activator-inhibitor
switch from systems biology, a predator-prey system from ecology and to the
Euler buckling problem from classical mechanics. For the Stommel-Cessi model we
compare different detrending techniques to calculate early-warning signs. In
the epidemics model we show that link densities could be better variables for
prediction than population densities. The activator-inhibitor switch
demonstrates effects in three time-scale systems and points out that excitable
cells and molecular units have information for subthreshold prediction. In the
predator-prey model explosive population growth near a codimension two
bifurcation is investigated and we show that early-warnings from normal forms
can be misleading in this context. In the biomechanical model we demonstrate
that early-warning signs for buckling depend crucially on the control strategy
near the instability which illustrates the effect of multiplicative noise.Comment: minor corrections to previous versio
The Starbuck essays of Henry Stommel
From the Forward: These essays appeared from time to time over a number of years in The Enterprise, the community newspaper of Falmouth, Massachusetts.
I first encountered "Starbuck" as a youthful editor some forty years ago.
We were early in the cold war. We were in the McCarthy era. Inspired
by McCarthy, persons ambitious for attention were going about the country
discovering Communists. One of these Paul Reveres of the cold war
came to address some gathering on Cape Cod and announced to a startled
audience that there were-he knew for a fact-a thousand or more dedicated
Communists living on Cape Cod.
A thrill of excitement ran through that part of the community that
enjoyed alarms and nourished the idea that there were Russian spies everywhere
in the land. Kicking around the newspaper office was a Rotary Club handbook that
listed the members of the several Rotary clubs on the Cape. I counted the
names. They added up to a couple of hundred. So I ran an editorial saying
that there seemed to be more Communists than Rotarians on Cape Cod. It was the sort of appeal to the ridiculous that delighted Hank
Stommel, and a day or so later he came to me with an appreciative note
that was signed "Starbuck." I regret the note isn't preserved. I remember
that it was amusing and to the point and that I wished that I had written it.
I had met Hank Stommel, but I did not yet know him. That was the
star. Encouraged, I like to think, by my appreciation, the "Starbuck" letters
began to arrive at The Enterprise offce.
These letters, which I correctly called essays, speak wonderfully for
themselves.
Reading the "Starbuck" letters will suggest the pleasure of spending a
sociable evening with Hank Stommel over beer and fresh-shucked oysters.
I can hear his laughter now