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UNCLASSIFIED
-LIIJWITY CLASSIFICATION OF THIS PAQEfWian Data Bntertd)
20. (Continued)
proper, with a superimposed slow net flow toward the south.
This net flow can be simulated in the models and tuned with the
prescription of a proper slope to the two open boundaries.
The diffusion computations over a short period of time in
the large grid models do not give fully satisfactory results
with the diffusion model used at present in the HN models,
instead, the transport of the centers of release points have
been computed and presented. Furthermore, the net transport
through various sections in the area has also been computed.
The single-layer model is applicable for the winter season when
the area is fully mixed from surface to the bottom.
In the two-layer HN model, which is applicable for summer
conditions when stratification of the waters occurs, some inputs
such as internal friction, need some additional numerical
experimentation and adjustment and above all proper field
measurements as nearly no data is available for the selection of
a proper internal friction coefficient. Furthermore, internal
waves (internal fluctuations) occur in the interface after
introduction of the wind into the model run. These fluctuations
diminish with time, and subsequently require a longer real-time
computation period and as a consequence, more computer time.
Such fluctuations are known to occur in the sea as recordings
of thermal structure changes with depth and time over the
continental shelf, as well as sea-level recordings near the
coasts have shown.
Of practical importance is the knowledge of differences in
the currents in upper and lower layers and the time and space
variation of these differences. The results of the model show
that in many areas a different net flow occurs in the lower
layer than in the surface layer. This is partly demonstrated
in the report with some of the output from special selected
points and agrees with the results from sea-bed drifter
experiments.
There is a coastward movement of the deeper layers off
Long Island Sound, making this area less desirable for sludge
disposal. The Hudson Submarine Canyon divides the hydrographic
regime in New York Bight. The flow south of the canyon is
stronger and toward the south. A potential use of this type
of study is in the selection of general areas where sludge
dumping may be less troublesome than in others.
UNCLASSIFIED
SECURITY CLASSIFICATION OF THIS PAGEftWian Data Enl*r»d)
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FOREWORD
This report describes the results of the application of
Hydrodynamical-Numerical (HN) models to New York Bight. The
results of computer runs with a large, two-open boundary,
single-layer model, as well as with a two-layer model for the
same area, are presented. Many of the problems in the applica-
tion of these models are connected with the treatment of the
open boundaries. The Environmental Prediction Research Facility
(EPRF) has found a few satisfactory methods for the treatment
of these boundaries, some of which are briefly mentioned in
this report. The method is further described in Part 2 of the
report series where the two-layer model is documented (see
references).
Verification of the New York Bight models is very brief,
due to scarcity of proper observations. However, the models
have been verified in other applications, to the extent that
they are considered to be ready for operational and real-time
use. It could be mentioned that a 3-layer version of the models
have now been applied at EPRF to larger open ocean areas with
considerable success. The experiences from these applications
have been indirectly used in this work and are available to EPA.
j
in
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CONTENTS
FOREWORD i i 1
LIST OF FIGURES vi
1. INTRODUCTION 1
2. SINGLE LAYER LARGE GRID SIZE MODEL FOR NEW YORK
BIGHT AND LONG ISLAND SOUND 3
2.1 The Inputs into the model 3
2.2 The Tides 3
2.3 The Currents 4
2.4 The Transport of Water Through Various
Sections 6
2.5 Dispersion and Diffusion of Pollutants 7
3. TWO-LAYER LARGE GRID SIZE MODEL FOR THE NEW YORK
BIGHT 8
3.1 Sea Level and Mixed Layer Depth 8
3.2 Currents in Two Layers 9
3.3 Transport and Dispersion of Pollutants 10
4. RECOMMENDATIONS FOR APPLICATIONS OF THE MODEL
RESULTS AND FOR FURTHER DEVELOPMENT 15
REFERENCES 17
v
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LIST OF FIGURES
Figure Page
1 Computational grid and locations of special
output points and sections in the single-
layer model 18
2 Tides at Sandy Hook, computed with harmonic
method and with HN model 19
3 Sea-level change and currents at Point 5 ... 20
4 Sea-level change and currents at Point 10 . . . 21
5 Computed currents at Point 4 ........ . 22
6 Computed currents at Point 5 ......... 22
7 Computed currents at Point 6 22
8 Computed currents at Point 10 ... . 23
9 Computed currents at Point 13 23
10 Computed currents at Point 18 ........ . 23
11 Computed currents at Point 19 24
12 Computed currents at Point 20 ... 24
13 Computed currents at Point 21 ........ . 24
14 Computed currents at Point 22 . . 25
15 Computed currents at Point 24 ... . 25
16 A Mean tidal currents at Scotland Lightship
(40°26.61N; 73°55.2'W) (from Haight, 1942 )
B Tidal currents (spring tides)- at Point 22 , 37 . 26
17 Currents during low water at Sandy Hook .... 27
18 Currents during 2 hours after low water at
Sandy Hook 28
19 Currents during 2 hours before high water at
Sandy Hook 29
vi
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LIST OF FIGURES (cont. )
Fi gure Page
20 Currents during high water at Sandy Hook ... 30
21 Currents during 2 hours after high water at
Sandy Hook 31
22 Currents during 2 hours before low water at
Sandy Hook 32
23 Rest currents after a full tidal cycle and
with SW wind, 9 m sec-1 33
24 Nontidal currents at Lightship stations,
Montauk Point to Barnegat Bay (Haight, 1942) . 34
25 Transport through section CC6 35
26 Transport through section BB6 36
27 Transport through section CC7 37
28 Transport through section BB7 38
29 Net transport through section CC6 39
30 Net transport through section BB6 40
31 Net transport through section CC7 41
32 Net transport through section BB7 42
33 Concentration of "pollutants" after a full
tidal cycle (initial release 10000 units
each point) 43
34 Movement of a water particle during one
tidal cycle at Point 13 (wind- 9 m sec"'
from SW) 44
35 Movement of a water particle during one
tidal cycle at Point 14 (wind 9 m sec-1
from SW) 45
36 Movement of a water particle during one
tidal cycle at Point 15 (wind 9 m sec-l
from SW) 46
v i i
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LIST OF FIGURES (cont.)
Figure Page
37 Movement of a water particle during one
tidal cycle at Point 16 (wind 9 m sec-1
from SW) 47
38 Movement of a water particle during one
tidal cycle at Point 17 (wind 9 m sec-l
from SW) 48
39 Movement of a water particle during one
tidal cycle at Point 18 (wind 9 m sec*'
from SW) 49
40 Movement of a water particle during one
tidal cycle at Point 19 (wind 9 m sec"'
from SW) 50
41 Movement of a water particle during one
tidal cycle at Point 20 (wind 9 m sec-1
from SW) 51
42 Movement of a water particle during one
tidal cycle at Point 21 (wind 9 m sec"'
from SW) 52
43 Comparison of sea-level changes at Sandy
Hook; A. Computed with two-layer HN model;
B. Harmonic tidal predictions 53
44 A. Sea-level changes and currents in upper
layer at Point 5 as computed with 2-layer HN
model (wind 9 m sec-1 from SW);
B. Change of mixed layer depth from mean
and currents in lower layer at Point 5 .... 54
45 A. Sea-level changes and currents in upper
layer at Point 7 as computed with 2-layer
HN model (wind 9 m sec"' from SW);
B. Change of mixed layer depth from mean
and currents in lower layer at Point 7 ... . 55
46 A. Sea-level changes and currents in upper
layer at Point 10 as computed with 2-layer
HN model (wind 9 m sec"' from SW);
B. Change of mixed layer depth from mean
and currents in lower layer at Point 10 . . . 56
viii
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47
48
49
50
51
52
53
54
55
56
57
58
59
60
LIST OF FIGURES (cont.)
Page
Change of sea level and mixed layer depth
change at Point 20 (location see Figure 1) . . 57
Mean tidal currents at Ambrose Channel
Lightship (40°28.0'N, 73°50.0'W) (from Haight,
1942); and currents in upper layer computed
with HN model at grid 23,37; wind 9 m sec"'
from SW 58
59
Currents at Point 5: A. Upper layer;
B. Lower layer (wind 9 m sec"' from SW). . .
Currents at Point 7: A. Upper layer;
B. Lower Layer (wind 9 m sec"' from SW). ... 60
Currents at Point 10: A. Upper layer;
B. Lower Layer (wind 9 m sec"l from SW). ... 61
62
Currents at Point 12: A. Upper layer;
B. Lower layer (wind 9 m sec"' from SW). . .
Currents at Point 13: A. Upper layer;
B. Lower layer (wind 9 m sec"' from SW). ... 63
Currents at Point 14: A. Upper layer;
B. Lower layer (wind 9 m sec"' from SW). ... 64
Currents at Point 15: A. Upper layer;
B. Lower layer (wind 9 m sec"' from SW). ... 65
Currents at Point 20: A. Upper layer;
B. Lower layer (wind 9 m sec-1 from SW). ... 66
Currents at Point 24: A. Upper layer;
B. Lower layer (wind 9 m sec-1 from SW). ... 67
Currents in surface layer at low water at
Sandy Hook (wind 9 m sec"' from SW) 68
Currents in bottom layer at low water at
Sandy Hook (wind 9 m sec-l from SW) 69
Currents in surface layer at 2 hours after
low water at Sandy Hook (wind 9 m sec"'
from SW) 70
IX
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LIST OF FIGURES (cont. )
Figure Page
61 Currents in bottom layer at 2 hours after
low water at Sandy Hook (wind 9 m sec"'
from SW) 71
62 Currents in surface layer 2 hours before
high water at Sandy Hook (wind 9 m sec"'
from SW) 72
63 Currents in bottom layer at 2 hours before
high water at Sandy Hook (wind 9 m sec"'
from SW) 73
64 Currents in surface layer at high water at
Sandy Hook (wind 9 m sec"' from SW) 74
65 Currents in bottom layer at high water at
Sandy Hook (wind 9 m sec"' from SW) 75
66 Transport rate through section BB6 in
surface layer in calm and with SW winds
gm/sec 76
67 Net transport through section BB6 in
surface layer in calm and with SW winds
gm/sec 77
68 Computed concentrations of "pollutants"
24 hours after release 78
69 Bathymetric chart of New York Bight 79
x
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I. INTRODUCTION
One of the limiting problems in the past, in the applica-
tion of HN models off the open coasts has been the difficulty
of treating several open boundaries. Considerable efforts
has been made at EPRF for over two years to devise methods to
solve this problem. Two methods have been found to be rela-
tively satisfactory for this purpose (see part 2 in this report
series). These methods have been applied and tested further
in the application of HN models to the New York Bight, which
are described in this report.
This report describes the application and the results of
a single-layer and a two-layer HN model with several open
boundaries. Many applied problems in estuaries and off coasts
in stratified conditions require the use of at least a two-
layer HN model, as different movements and transports occur
in different layers with the presence of sharp thermoc.line
and/or pycnocline. This condition in turn has profound
influence on the transport of polluted waters, in the design
of waste water outlets, and in the selection of waste disposal
areas.
Only essential results of the numerical computations are
described and summarized in this report. A voluminous amount
of numerical data created by these models will be available at
the EPA laboratory in Corvallis. Furthermore, these models,
especially the two-layer models, have a great number of various
application possibilities all of which could not be foreseen,
demonstrated, or explored within this project.
Finally, it should be mentioned that one of the limiting
factors in the application of the two-layer model (as, indeed,
in all numerical experimentation) is the computer cost. This
model requires a large computer with a relatively large core
and long computation times due to the short time steps dictated
by numerical stability. Various investigations are in progress
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to find ways to decrease the time step by applying, e.g., both
an explicit and an implicit method simultaneously for solution
of the equations. Further reports will be forthcoming in this
subject as well as on the comparison of various methods on
computational application of hydrodynamical methods.
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2. SINGLE-LAYER. LARGE GRID SIZE MODEL FOR
NEW YORK BIGHT AND LONG ISLAND SOUND
2.1 INPUTS INTO THE MODEL
The grid net for the large scale New York Bight model
and the locations of special output points and sections are
shown in Figure 1. This model was run with two open bound-
aries. The area was predetermined and the grid net selected
so that the model could be run on CDC 7600 computer without
large core memory. The grid size thus became 6.556 km and the
corresponding time step dictated by stability criterium was
30 sec.
Each input of tide was made with four tidal constituents.
The tidal amplitudes and phases were interpolated along the
imput boundaries from the harmonic constants of Atlantic City
and those of Montauk Point. The time difference between these
two stations was ascertained, and the difference was extra-
polated over the input boundary to derive a realistic time
difference at the seaward corner of the grid. Some additional
adjustment was made at the southernmost end of the input
boundary off Atlantic City. This was necessary to effect the
net flow along the continental shelf in this area. The winds
used were the same typical summer and winter winds as used in
smaller scale models (see part 3 of this report series).
2.2 TIDES
A comparison of the tides computed with HN models and the
harmonic tides at Sandy Hook are given in Figure 2. Sandy Hook
is located a considerable distance from the boundaries. As is
apparent from this figure, it will take the model about 12 hours
to reach the proper equilibrium with the tides at this location.
After equilibrium is reached, the HN computed and harmonic tides
are in good agreement.
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Callaway (unpubl.) has made measurements with deep sea
tide gauges at 39°37.51N; .73°42.01W (off Barnegat Inlet) and
at 40°27.8'N and 71 028.41W (South.of Montauk Point). Some of
his data on amplitudes of tidal constituents are given in
Table 1 together with available data from International
Hydrographic Bureau's (IHB) tidal constituent sheets.
Table 1. Amplitudes of tides (cm) from IHB tidal constituent
list and as measured with deep sea tide gauge by Callaway
(unpublished) .
Constituent
m2
S 2
n2
K1
°1
39°37.51N , 73°42 .0 ' W
(Cal 1 away)
54.8
10.8
12.4
10.3
7.2
39021'N, 74°26'W
(IHB, No. 507)
58.3
11 .9
13.7
10.3
7.7
40°27.81N , 71 028. 4 1 W
(Cal 1 away
43.0
8.6
8.4
6.6
3.7
41°03'N , 71 0 58 ' W
(IHB, No. 2213)
28.3
6.9
7.7
6.6
5.0
Taking into consideration the distances between the
locations, there is a good agreement between Callaway's and
IHB data, with exception of amplitude off Montauk Point.
Considering other tidal data from New York Bight area, the re
is reason to believe that IHB amplitude for tide at Montauk
Point is in error. The IHB data were used in the model run,
as Callaway data became available later.
The sea level and currents at Points 5 and 10 (for loca-
tion see Figure 1) are shown in Figures 3 and 4. A comparison
of these figures shows that the tidal amplitudes decrease
somewhat from the coast to offshore (as is known from empirical
observations). The rate of decrease is variable and depends
on several factors, including the change of depth and slope
of the bottom.
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2.3 CURRENTS
Figures 5 to 15 show the current ellipses at various
output points (for locations, see Figure 1). These figures
serve to illustrate the nature of tidal currents and their
variations. When accurate data are required, e.g., the
relation between the direction of the current to the tidal
amplitude stage, they can be extracted from printouts. Nearly
every point has certain local peculiarities. Figure 5 shows
the reversing (back-and-forth) tide at the mouth of the Ambrose
Channel. A comparison of the current speeds with those at
Point 5 (Figure 6) reveals the pronounced effect of the channel
on the currents. Figure 7 shows the currents somewhat closer
to the coast and in shallower water than those shown in
Figure 6, and indicates the slightly stronger currents in this
location (as expected from empirical knowledge). Comparisons
of Figure 9 (Point 13) with Figures 10 (Point 18) and 11
(Point 19) demonstrates the widening of the tidal ellipses to
nearly circular tides at Point 20 (Figure 12) further offshore.
Figure 14 shows a comparison of mean tidal currents at
Scotland Lightship (Haight, 1942) and the currents computed at
the nearest grid point (22,37 in Figure 1).
As can be recognized from this figure, the current
directions and speed of computed currents are in reasonable
agreement with the measured currents at the Lightship. The
special output Point 4 in Ambrose Channel (see Figure 4 for
location), from which the currents are presented on Figure 5, is
about 9.3 km from Point 22,37 (grid coordinates) from which
the currents are presented on Figure 16B. Comparison of the
two figures (15 and 16B) indicates again, relatively great
changes of currents over a relatively short distance.
Another comparison of measured and computed currents can
be made at Fire Island Lightship (40 ° 2 5' N; 73C11'W; Point IV
on Figure 1) with currents extracted from a nearby grid point
(Point 10 in Figure 1, for which currents are given in Figure 8).
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According to Haight (1942) the mean flood at Fire Island
Lightship is 0.23 kt to 96°. Converting the mean speeds given
by Haight (1942) to the strength of currents, results 18 cm
sec"1. Figure 8 gives approximately the same directions,
(85°) but the strength of the computed current is about 25 cm
sec-1. However, the currents presented in Figure 8 are tidal
currents during spring tides, thus should be somewhat stronger
than the strength of the current at mean tides.
Snapshot pictures of the distribution of current direc-
tions and speeds during different stages of the tides are shown
in Figures 17 to 22. Figure 17 shows the currents during low
water at Sandy Hook, and Figure 18 shows the currents two hours
later at the start of flooding current. Figure 19 shows the
currents two hours before high water at Sandy Hook. The
essential feature of this figure is the strong inflow into the
New York Bight in the region of the Hudson Submarine Canyon
(bathymetry, see Figure 69) and the turning of this coastward
flow south toward Atlantic City. Figure 20 shows the currents
during near-slack water at Sandy Hook, which is the high water
time at this location. The effect of Hudson Submarine Canyon
is also clearly depicted on this figure. This figure depicts
best the bifurcation of the currents near the head of Hudson
Canyon, mentioned in a NOAA (1972) report. Figure 21 shows
the beginning of the ebbing current, and an additional shapshot
picture of the ebbing current 2 hours later is given in Figure
22. These two last figures show a slight intrusion of water
in the deeper part of Hudson Submarine Canyon and the nearly
continuous southward flow off Atlantic City.
The net currents after a full tidal cycle with southwest
winds of 9 m sec"1 are shown in Figure 23. The stronger
currents around the Hudson Submarine Canyon and off Atlantic
City are essential features of this figure.
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The recent measurements of McClennen (1973) of tidal
currents 1.5 to 2.0 m above the bottom off the New Jersey
coast show that the mean speeds are on the order of 15 cm sec~\
with a maximum speed 40 cm sec"^ and that there is a net trans-
port to the SW at the continental slope. The results of these
measurements are in good general agreement with the computed
currents in the SW corner of the computational grid.
Figure 23 also shows the net circulation in the New York
Bight in good agreement with the results of drift bottle studies
of Powers (1951). The essential features of this net circula-
tion are: (a) a weak westerly flow in the central part of the
Bight turning towards stronger southerly flow off the New Jersey
coast; (b) main inflow along the Hudson Submarine Canyon (and
south of it) and. a weaker inflow from the east; (c) a weak
towards-the-coast flow off the eastern part of Long Island,
and (d) a net flow from Long Island Sound through the East
River and Lower Bight.
Nontidal (net) currents at various lightship stations
are shown in Figure 24 according to Haight (1942). These
relatively incomplete data indicate the same circulation
pattern as described above.
2.4 THE TRANSPORT OF WATER THROUGH VARIOUS SECTIONS
3 1
The transport rate of water (msec ) through a few
sections are presented in Figures 25 to 28 as examples. The
transport has been computed at each time step, using current
components perpendicular to the section at each grid point
and averaged hourly. Of greater interest are Figures 29 to
32 showing the net transport (accumulative net transport)
through the given sections. A tendency of the change of net
transport with time is apparent on these figures, which is due
to several factors, such as the change of tides from spring
towards neap tides and wind. Such a transport change has been
empirically observed and is physically explainable, but has
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not been underlined in past literature. The transport computa-
tions through predetermined sections within a tidal cycle can
be used for computation of half-life of the water in various
sub-areas (i.e., the flushing times) using the total volume of
the water inside the areas bounded by sections. The flushing
times vary considerably from one area to another as well as
with the stage of tides and especially with the winds. A
separate study and report is planned in this subject in the
continuation of this project. Only a preliminary estimate was
made with the transport computations at hand, which indicated
that the Bight is flushed by net circulation in about each
two weeks. This estimate is in general agreement with estimates
by Ketchum, ejt al_ (1951) and Home (1971).
2.5 DISPERSION AND DIFFUSION OF POLLUTANTS
Attempts were made to compute the dispersion and diffusion
of "pollutants" in this model with the same formulation as in
the small grid model and the concentrations through a full
tidal cycle after release are shown in Figure 33. However,
certain limitations of this approach in large-grid size models
are apparent, especially with respect to the movement of the
central values of the "blobs". The main limitation of diffusion
and dispersion computations with the Lagrangian method is that
the grid size should be smaller than half of the distance of
tidal excursion. The excursion of the centers of the "original
releases" (blobs) at various points were computed and the
results are given in Figures 34 to 42. The release was affected
at the grid point shown with the crossed 1ines on the figures.
The numbers on these grid lines indicate the tenths of grid
size. The central position of the blob is given for each 2
hours. Furthermore, the net transport (the difference between
the original position and the position after a full tidal
cycle) is shown with a thick dashed line on these figures.
Detailed evaluation of the water (and pollution) movement, and
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comparison of the movement, in various parts of the Bight can
be obtained by comparing these figures. It should be noted
that, besides the variation of the magnitude of "tidal excur-
sion", the selected release points fall into two categories:
(a) those with little or no net transport showing the movement
of a particle in a tidal ellipse (e.g., Figures 34 and 39) and
(b) those with considerable net transport after a full tidal
cycle, (e.g., Figures 38 and 42).
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3. TWO-LAYER. LARGE GRID SIZE MODEL FOR THE NEW YORK BIGHT
3.1 SEA LEVEL AND MIXED LAYER DEPTH
The computational grid for the two-layer model and the
special output points are the same as for the single-layer
large scale model (Figure 1).
A comparison of the tides computed with the harmonic
method and those computed with the two-layer HN model at Sandy
Hook is given in Figure 43. First, it will be noticed that
it will take more than 12 hours to achieve computational
equilibrium, as was the case with the single-1ayer, large-grid
size model. Furthermore, after about 22 hours, the tides
computed with two-layer HN model do not follow well the harmonic
tidal curve, but show various oscillations. After several
numerical experiments with and without the wind input, it was
found that the oscillations of the sea level and the oscilla-
tions of the depth of the thermocline are caused mainly.by
the wind, especially when the thermocline depth was not in
equilibrium with the prescribed wind system. The sea-level
oscillations caused by wind have been observed at tide gauge
stations and demonstrated in several works by Professor Hansen
in the application of the single-layer model' for computations
of storm surges in the North Sea. Consequently, in order to
obtain a steady state picture of the sea level and currents
with a given steady wind, computations should be done over
several tidal cycles. This was not possible within this
project due to limitations of funds and .time.
The wind effects vary considerably from one place to
another over the whole Bight. These changes can be followed
in Figures 44 to 46. Starting with Point 5, (Figure 44) and
following farther offshore (i.e., Figure 45, Point 7, and
Figure 46, Point 10) it can be observed that the fluctuations
of the mixed layer depth increase with increasing depth and
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increasing distance from the coast, whereas the sea-level
change (amplitude of the tides) decreases as already observed
with a single-layer model. These figures also show currents in
both layers at two-hourly intervals, showing that the currents
in the second layer turn more to the opposite direction of
surface currents with increasing distance from the coast, thus
compensating the transport in the surface layer.
At Point 20 (Figure 47), the crest of the mixed layer
depth occurs approximately midway between high and low water at
the surface (i.e., about 4 to 5 hours before the change at the
surface). This is a theoretically correct case for progressive
waves. Considerable variation occurred from this case, however,
as Figures 45 and 46 indicate.
3.2 CURRENTS IN TWO LAYERS
Comparisons of the speed and direction of mean tidal
currents at Ambrose Channel Lightship with the tidal currents
in the surface layer as computed with the two-layer HN model
using a wind of 9 m sec"^ from the SW are shown in Figure 48.
The computed currents show somewhat stronger outflow from the
Lower Bay, which might be partly due to the fact that the East
River was programmed wider in this model than in the nature,
thus allowing greater flow from Long Island Sound.
The effects of SW winds on the surface layer currents
are apparent in Figures 49 and 50 where the current data
extracted from various output points are presented as examples.
An inter-comparison of currents in Figures 51 to 57 and the
locations of corresponding points (Figure 1) shows the various
effects of distance from the coast and water depth on the
currents in both layers. Especially noticeable and of practical'
importance is the shoreward movement of currents in the lower
layer off Long Island (Figures 53 to 55).
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The shoreward movement of bottom drifters has been
observed in this area as well as in Hudson Submarine Canyon
by Home (1971), NOAA ( 1 972 ) and Callaway (MS) which verifies
the correctness of the two-layer HN model in reproducing the
currents and suggests that the area off Long Island is unsuit-
able for the disposal of large amounts of sludge.
A comparison of the strength of the currents in upper and
lower layers presented in Figures 49 to 57 reveals that the
currents are of about the same strength at both depths. This
condition was found by Haight (1942) from direct current
measurements. Only in Hudson Submarine Canyon (and possibly
in the Ambrose Channel) does the current in the lower layer
have a higher velocity during flood than in the surface layer.
It should be emphasized, however, that the directions of net
flow in the surface and lower layers can be considerably different,
and that these differences vary with locations and winds.
Figures 58 to 65 give snapshot pictures of the horizontal
currents in the upper and lower layers during various stages
of the tide with reference to the Sandy Hook tides. Of con-
siderable interest in these figures are two conditions: First,
the effect of the Hudson Submarine Canyon can be traced clearly
in every figure (see bathymetry of the Bight, in Figure 69).
There is a greater in- and outflow along the axis of the canyon
and sometimes a gyral is located at its mouth on the continental
slope. Secondly, most of the water flowing into the New York
Bight along the canyon is flowing to the south off Atlantic
City. The effects of wind are also clearly recognizable on
these figures, especially in areas where they are not masked
by other strong currents (i.e.,. off Long Island). A comparison
of upper and lower level currents at the same output time
indicates considerable differences of net current direction and
some differences in speed in both layers.
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3.3 TRANSPORT AND DISPERSION OF POLLUTANTS
The transport of water arid net circulation in a relatively
shallow bight (e.g., the New York Bight) is determined greatly
by winds as well as tides. Thus for a complete investigation
of transport and flushing, computations must be made with
various prevailing winds. The computed data on transport
through various sections are available in computer printouts
and only a few examples are presented below.
The transport rates through section BB6 (location, see
Figure 1) in the upper layer in calm conditions and with
9 m sec"^ winds from SW are shown in Figure 66. Although the
transport varies in both cases in tidal rythm, the eastward
component prevails with the SW winds. The net transport
through the same section is given in Figure 67. In calm
conditions a slight westward transport occurs through section
BB6 which is in agreement with the general circulation pattern
in the New York Bight. With SW winds the net transport through
this section is toward the east.
Figure 68 shows the computed concentration of "pollutants"
in the upper layer 24 hours after instantaneous release. The
same limitations of diffusion computations apply to the
relatively coarse two-layer model as to the-si ngl e-1 ayer, large1
grid size model. The results shown in this figure are also
similar to the corresponding results from the single-layer
model. Thus in order to compute dispersion and diffusion with
a Lagrangian method in a grid which is larger than half of the
distance of tidal excursion, either of the following methods
should be used:
a. the excursion of the water particle (e.g., at the
center of the release point) can be computed with
the HN model as described in Chapter 2.5. The eddy
diffusion of the blob can be computed with any
Eulerian type of method of which there are several
avai Table;
- 13 -
-------
the diffusion and dispersion can also be computed
with a Lagrangian method in a smaller subgrid, for
which the currents are extracted and interpolated
in each time step from the large-scale grid output.
This method requires an additional computer run.
if the diffusing blob is large and initially covers
many grid points, dispersion and diffusion computations
can be made in a large grid with Lagrangian approach
(e.g., distribution of river outflow).
- 14 -
-------
4. RECOMMENDATIONS FOR APPLICATIONS OF THE
MODEL RESULTS AND FOR FURTHER DEVELOPMENT
1. As a considerable amount of numerical output (results)
is produced by an HN model, it is impossible to describe and
reproduce all the possible results in reports. The latter
serve mainly to present examples and the model capabilities
as well as verifications. In any specific application, and
in search for an answer to a specific question, the numerical
data in the printouts from the model run should be consulted
and/or used.
2. The HN models have proven to be of great use for
obtaining data on currents at various levels and with various
winds for the computation of diffusion, dispersion and flushing,
for selection of proper waste disposal areas, and for a variety
of other purposes.
3. Although general verifications of the HN models have
been made in various areas, there is a continued need for
further specific verification, especially of the multi-layer
models. This verification should be done with specific short-
term recordings (few days) of (a) sea level at specific points
with portable tide gauges, (b) current recordings, and (C)
thermal structure variation recordings. (The latter is espe-
cially required to improve the boundary input into the multi-
1ayer models.)
4. Additional research is required on the treatment of
multiple open boundaries and especially on the methods of input
of tides in deeper layers at the open boundaries.
5. The diffusion and dispersion computations require
further verification for which results from better large-scale
dye experiments can be used (e.g., the multi-national experi-
ments carried out by the International Council for the
Exploration of the Sea). Further numerical experimentation is
required on the computation of dispersion and diffusion in
large grid size models.
- 15 -
-------
6. The single layer HN model has become a proven tool
for investigation and reproduction of dynamic processes in
shallow coastal waters and estuaries. It would be desirable
to use this model for the computation of a number of "type
conditions," such as (a) the effects of offshore bars on
exchange of coastal waters with offshore waters, (b) the
effects of bathyme trie slopes and irregularities on currents
and mixing, and (c) other conditions pertinent to waste disposal
in coastal waters.
- 16 -
-------
REFERENCES
Baumgartner, D.J., 1972: A brief outline of a study of sewage
sludge dumping in the New York Bight. Mimegr. Rpt. EPA,
Pac. NW Env. Res. Lab. :
Callaway, R., MS: Bottom drifter study in New York Bight.
Haight, F.J., 1942: Coastal currents along the Atlantic Coast
of the United States. U.S. Dept. of Commerce, Coast and
Geodetic Survey, Spec. Publ. 230: 73 pp.
Home, R.A., A.J. Mahler and R.C. Rossello, 1971: The marine
disposal of sewage sludge and dredge spoil in the waters
of the New York Bight. Woods Hole Oe. Inst., MS rpt to
coastal Eng. Res. Center, Corps of Engineers.
Ketchum, B.H., A.C. Redfield and J.C. Ayers, 1951: The
oceanography of the New York Bight. Papers in Phys.
Oceanogr. and Met. Cambridge and Woods Hole, 12(1): 1 -46.
McClennen, C.E., 1973: New Jersey continental shelf near
bottom current meter records and recent sediment activity.
J. Sedimentary Petrology, 43(2):371 -380.
NOAA, 1972: The effects of waste disposal in the New York
Bight. Sect. 6. Surface and bottom water movement.
Rpt. for Coastal Eng. Res. Center., Corps of Engineers.
Pearce, J.B., 1970: The effects of waste disposal in the
New York Bight - Interim Rpt. for Jan 1970. MS Rpt for
Corps of Engineers.
Powers, C.F. and J.C. Ayers, 1951: Drift bottle studies in
the Newport Bight and New York Bight areas. MS rpt to
ONR (N6 onr 264, task 15).
Reports in this series:
Part 1: A vertically integrated hydrodynamical-numerical
model (W. Hansen type): Model description and operating/
running instructions.
Part 2: A multi-layer hydrodynamical-numerical model (W.
Hansen type): Model description and operating/running
i nstructi ons.
Part 3: Computation of tides, currents and dispersal of pollu-
tants in Lower Bay and Approaches to New York with fine
and medium grid size hydrodynamical-numerical models.
Part 4: Computation of tides, currents, and dispersal of
pollutants in the New York Bight from Block Island to
Atlantic City with large grid size, single and two-layer
hydrodynamical-numerical models. (This report.)
- 17 -
-------
74
73
72
40
3 S
30
15
10
20
AC
3S
41
<41
30
30
25
75
20
20
CC 5
C C
,17
40
40
C C7
C 8
40
30
35
20
25
10
74
73
72
Figure 1
Computational grid and locations of special output
points and sections in the single layer model
-------
2007
Coapated (RH)
Figure 2
Tides at Sandy Hook, computed with har-
monic method and with HN model
-------
150
100
-50
-100
-150
-200
Figure 3
Sea level change and currents at Point
5 (location see Figure 1)
-------
Figure 4 Sea level change and currents at Point
10 (location see Figure 1)
-------
Figure 5
Figure 6
Figure 7
Computed currents at Point 4 (locations
see Figure 1)
Computed currents
see Figure 1)
at Point 5 (location
Computed currents at Point 6 (location
see Figure 1)
0 20 40 60
* * *
cm /sec
- 22 -
-------
Figure 8
Figure 9
Figure 10
Computed currents at Point 10 (location
see Figure 1)
Computed currents at Point 13 (location
see Figure 1)
Computed currents at Point 18 (location
see Figure 1)
0 20 40 60
*
cm /tec
- 23 -
-------
Figure 11
Computed currents at Point 19 (location
see Figure 1)
Figure 12
Computed currents at Point 2 0 (location
see Figure 1)
Figure 13
Computed currents at Point 21 (location
see Figure 1)
20 40 60
i i i
cm/sec
- 24 -
-------
Figure 14
Computed currents at Point 22 (location
see Figure 1)
Figure 15 Computed currents at Point 24 (locatior
see Figure 1)
0 20 40 60
¦
cm/kec
- 25
-------
20
40
60
i
cm/sec
Figure 16 A
B
Mean tidal currents at Scotland Lightship
(40°26.61N; 73°55.2'W) (from Haight, 1942)
Tidal currents (spring tides) at grid point
22,37 (see Figure 1).
- 26 -
-------
74°
73°
72°
0 ?5 50
cm/tit
t , ,
t V V
t V f
* *
V
~ ~
~ /
/ ~
/ /
/ /
/ /
« v v
\ \
V^-
* y / * ' *
V I / I 1 » f » *
V
V V V
? f V V
r* i * /
f V (
1 * I ~
* «
* * *r *r
r * * *r jr
* » >
\ * *
\ * -
t *
* * * *
* ' / /
*¦»***
s
/
/
» t 4
-L t L.
y
*
s
/
/
/
/
/
/
/
/
~
s s
/ /
/ /
/ ~
/ /
/ /
/ / / /
I
«
» V
: //
/
/ *. * * *¦
///-'*'
/ / ^ ^ "
/ / ' ' *
» * t
» t «
* » <
- * M.
^ X
# /
* #
V *
\ *
4 t
/
/
»
*
«
/
/
»
i
/ /
' *
» f
i
» >
\
73'
72°
Figure 17
Currents during low water at Sandy Hook
-------
Figure 18
Currents during 2 hours after low water
at Sandy Hook
-------
74° 73° 72°
0 2
«¦/
s?
"«« ...
v v «
V V V V V V
^ .
v « v
« « mm
r i A * *
«
f X t r
. . . j
V
f
v V
« « i
V
\
V
V
V
V
V
V
V
f
V
t / 4 * »
V 1 V « vvv
/.
* . *
t « « « v | » »
* » f t
t » « 4 4
t «
v f 4 « « % V 1
^ !
^ V V \ \ *
< -k v V \ N \ *
V V V \ >
- 4 * * /
4 * t f
1 * t t
4 ~ » f
1**1
* \ \ ^
\ \ * *
\ \ \ \
\ \ \ *
\ \ t " »
d
V .
I
/
/
/ ^
/ ^ -
^ ^ V \ N V V y
s. vN \ \ N \ ^
\ \ v v ^
N >
\ \ 1 ~
\ » i *
\ % ft 4
m. % % t
~ * % ^
- - f
74° 73° 72°
Figure 19
Currents during 2 hours before high water
at Sandy Hook
-------
74°
73°
72°
25
cm/sec
/. ::
- » t
-y?»r~
\ \
' / ,
9 S y T V
f V V
/ ' '
« f f f
^ /
I / '
< \ *
I t
~ f
-
-
-
>»
A
J>
*
/
/
/
/
/
/
f
/
/
t
f
f
f
f
t
t
t
t
t
t
t
f
f
~
V
1
«
^ ^
/
\* s
/
/
/
/
V ^
/ /
/ /
/ /
/ /
/ /
/ /
/ /
/
/
/
/
~
: /
/
/
/
/
(
/
/
/
/
/
/ / ^
/ / '
/ s y
/ x- /
V
4
\
\
t
f
/
/
/
\ \
74°
Figure 20
73c
72°
Currents during high water at Sandy Hook
-------
74c
73°
72'
0 26 50
1 cm/set '
^ » * r
v » * « » » »
» / *
r - - /-
r ' *
- * « / ' *
#
J U II U D
* * V
' 4
v V %
/ « .
/ /
/
\
t
/
/
/
/
I
«
#
/
~
* *
~
t
»
* 4
< » ¦«
I » <¦
# / -
, x \ \ V
f I
* r * r
74e
73°
72c
Figure 21
Currents during 2 hours after high water
at Sandy Hook
-------
74° 73° 72°
0 2
cm
5 50
)sec « « *
» v *
?»*»»»
- - ^
/» * *
* , » > - * *
- » J> » ,
*
* \ % *
* ₯ »
' ' '
V
»
V
..' I
- N
*
« « v «
V
*
V
V
V
T
V
«
« \ r * f *
r f * » » » » *
4 *
f «
» »
» » «
i < > - X * |
» »
* V w * « ^ ^ ^
s \ \
-X -v \ \
» /- / /
» * f t
\ r ~ i
* » » t
X k k I
¦ V \ ^ \
* \ V V \
* \ \ V \
V \ \ V V
\ \ V \ \
V
* k
*
V
V
*
»
»
/ /
\ r , \ * *> »
/~//'" *
^ ^ N. \ \
^ -» ^ N.
- - - ^ ^
* - ' " ^ N> N>
* ^ * * * > .
\ \ \ I >
^ \ \ ' '
N. >*. V 1 ~
. *. * * x
- * ' \
74° 73°
Figure 22
Currents during 2 hours before low water
at Sandy Hook
-------
Co
co
? ffS *
mmm
ft m *
3.
mmm mmh
km
HM
3? 3S
x- ::;:!
^ &
Figure 23
Rest currents after a full tidal cycle
and with SW wind, 9m sec"^
-------
Atlantic Coast
Montauk Point to Barnegat Bay
-3d)
I
|
O U.S.S. Cardinal
OCT
VJG
'JUL DtC
Ram lil$nd Reel
OCT
U.S.S. Finch
Barnegat
Explanation
The location ol each lightship station is shown by a circle
accompanied by the name of the station.
The dneci.ons and velocities of the average nontidal cur-
rents lor different months ol the year are shown by arrows
for a number of stations. The length o< the arrow repre-
sents the average velocity on the scale shown below. The
month is indicated *t the arrow head.
Each arrow represents a resultant velocity and direction
derived from a large number of observations taken during
the month indicated. Under each diagram is the name of
the lightship station to which it applies.
Bertlelt Reel
Cornfield Po
NOV
i
Scale of velocities
1 I I
Ambrose Channel (1917.22)
0 0 0.1 0.2 0.3 0.4 0.5 0-6 07 0 8 Knot
MAR
U S.S falcon
o
U.S.S. Falcon
JAN
Ambrose Channel (iQJt '8)
MAY .
I \
*AR \
JAN NOV
Berne gat
U.Z.S. Finch
JUNE*
APR
U S c. Ca,d;«-
A
SEP
" \
MAR v .
Ular.d
T?"
TT"
Figure 24
Nontidal currents at Lightship stations,
Montauk Point to Barnegat Bay (Haight, 1942)
- 34 -
-------
500
u
o>
«/>
250
u
ui
l- o
c/>
-250
500
8
Figure 25
CC6
12 16 20 ' 24
TIME (hrs.)
Transport through section CC6
-------
500
-500
0
Figure 26
BB6
lii ii i
4 8 12 16 20 24
TIME (hrs.j
Transport through section BB6
-------
1500
-1500
0
Figure
CC7
I i i i »
12 16 20 24
TIME (hrs.j
Transport through section CC7
-------
1500
u
a>
ts>
Ul
CO
CO
750
750
-1500
0
Figure
BB7
¦
12 16 20 24
TIME (hrs.)
Transport through section BB7
-------
CC6
Q 4 1 tt 16 20 24
TIME |hrs.|
Figure 29 Net transport through section CC6
-------
5.0
o
I/)
2.5
0
2.5
5.0
CO
03
n
Figure 30
BB6
8 12 16
TIME (hrs.)
20
24
Net transport through section BB6
-------
10
Figure
CC7
8 12 16 20 2i
TIME (hrs.)
Net transport through section CC7
-------
10
Figure 32
BB7
8 12 16 20 24
TIME jhrs.)
Net transport through section BB7
-------
ii
Figure 33
Concentration of "pollutants" after a
full tidal cycle (initial release 10000
units each point)
-------
*
km
Movement of a water particle during one
tidal cycle at Point 13 (location see Figure
1) (Wind 9m/sec, from SW)
-------
¦ft
U)
Figure 35
a*.9-
17.9
27.1
0
t-
0.5
*
1.0
km
Movement of a water particle during one
tidal cycle at Point 14 (location see
Figure 1) (Wind 9m/cec, from SW)
-------
I
o»
i
Figure 36
21.?-
Movement of a water particle during one
tidal cycle at Point 15 (location see
Figure 1) (Wind 9m/sec, from SW)
-------
1?9
Figure 37
22 .H
0.5
1.0
km
Movement of a water particle during one
tidal cycle at Point 16 (location see
Figure 1) (Wind 9m/sec, from SW)
-------
Figure 38
16.9-
0.5 1.0
km
Movement of a water particle during one
tidal cycle at Point 17 (location see
Figure 1)(Wind 9m/sec, from SW)
-------
17.1
17.1-
i
lt.l
0
0.5
i
1.0
Figure 39 Movement of a water particle during one
tidal cycle at Point 18 (location see
Figure 1) (Wind 9m/sec, from SW)
-------
0.5
km
Figure 40
Movement of a water particle during one
tidal cycle at Point 19 (location see
Figure 1)(Wind 9m/sec, from SW)
-------
U1
S.9
Figure 41
ii.»-
T~
9.1
13.1-
0
4.
0.5
1.0
km
Movement of a water particle during one
tidal cycle at Point 20 (location see
Figure 1) (Wind 9m/sec,from SW)
-------
U1
N>
Figure 42
11.9-
Movement of a water particle during one
tidal cycle at Point 21 (location see
Figure 1) (Win
-------
U!
VjJ
200
_ 100
UJ 0
-100
Computed (HN)
Harmonic
-200
i I ¦
* * ' ' T | ^ *
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
TIME |hrs.)
Figure 43
Comparison of sea level changes at Sandy
Hook; A-computed with twr- layer HN model;
B-harmonic tidal predictions
-------
20
TIME, hours
>f X >v ± 4 \ * !f i ^
- 0
to
SCALE
c«/itr
J70 j
I
110
Figure 44 A
B
10
20
TIME (hrs.
30
40
Sea level changes and currents in upper
layer at Point 5 (location see Figure 1)
as computed with 2-layer HN model; wind
9m/sec~l from SW.
Change of mixed layer depth from mean and
currents in lower layer at Point 5 (loca-
tion and wind the same as for upper layer)
- 54 -
-------
»CA 1 I
i>li»
J ? 0 ^ - « '
10
20
TIME ihrs.)
30
40
Figure 45 A Sea level changes and currents in upper
layer at Point 7 (location see Figure 1)
as computed with 2-layer HN model; wind
9m/secfrom SW
B Change of mixed layer depth from mean and
currents in lower layer at Point 7 (loca-
tion and wind the same as for uooer laver)
- 55 -
-------
100
50
U
-50
«/»
100
L
100
10
20
TIME, hours
30
40
E
o
50
5 -50
-100
10
scui
C HI )S V C
20
TIME, hours
30
2 7 C -* -A vfl
I
no-
40
Figure 46 A
B
Sea level changes and currents in upper
layer at Point 10 (location see Figure 1)
as computed with 2-layer HN model; wind
9m/sec~l from SW
Change of mixed layer depth from mean and
currents in lower layer at Point 10 (loca-
tion and wind the same as for upper layer)
- 56 -
-------
U1
75
0
-75
-150
level (Zj)
150
75
0
ISJ
Mixed layer depth deviation
from the mean |Z2)
-75
-150
0 4 8 12 16 20 24 28 32 36 40
TIME (hrs.)
Figure 4 7
Change of sea level and mixed layer depth
change at Point 20 (location see Figure 1)
-------
AMBROSE CHANNEL LIGHTSHIP
(40028- 01N - 73°50.0W)
CURRENT COMPUTED AT GRID
23,37
Figure 48
Mean tidal currents at Ambrose Channel
Lightship (40°28.0,N, 73°50.0'W) (from
Haight, 1942) and currents in upper layer
computed with HN model at grid 23,37;
wind 9m sec~l from SW
- 58 -
-------
32,34 1
22,16 a
B
270-
90
iao
20
40 AO
SCALE
Figure 49
Currents at Point 5 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec" from SW
- 59 -
-------
J70*
*0
110
0 30 40 «0
ICAIE
Figure 50 Currents at Point 7 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec"! from sw
- 60 -
-------
*9.36 I
B
33.26 X
170"
vo
iao
>o
40
«
SCALE «a/M«
Figure 51
Currents at Point 10 (location see Figure 1)
A; upper layer; B: lower layer, Wind 9m
sec~l from SW
- 61 -
-------
1,0 40 *0
I I I
SCALE c a/scc
Figure 52 Currents at Point 12 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec~l from SW
- 62 -
-------
Figure 53
J?
4.0
Jf
SCALE cm/ft
Currents at Point 13 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec~l from SW
- 63 -
-------
Figure 54
20 40 40
1 I I
SCALE ca/ttc
Currents at Point 14 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec~l from SW
- 64 -
-------
Figure 55
4.0
_J£ 2
SCALE iyki(
Currents at Point 15 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec"! from SW
65 -
-------
SCALE ca/%«c
Figure 56 Currents at Point 20 (location see Figure 1)
A: upper layer; B: lower layer. Wind 9m
sec--!- from SW
- 66 -
-------
10 40 40
-J J J
SCALE cm/U*
Figure 57 Currents at Point 24 (location see Figure 1)
A: upper layerj B: lower layer. Wind 9m
sec"1 from SW
- 67 -
-------
74° 73° 72°
74° 73° 72°
Figure 58 Currents in surface layer at low water at
Sandy Hook (wind 9m sec~l from SW)
-------
74e
73'
41°
-o
40c
* *
0 50 100
¦-*
cm/sec
» »
»
% 9 9 t « 9 » i
a i %
V
*
m 9 9 9 >
», » t j* J*
u.
* ' ' -
i ~ ~ -
/ ^ -
- / ^ -
/ -
/
« .v
» ¦ %
^ X
m.- V
* ' >
- ' -
t t » » »
* « *
I « »
« » » »
» »
» » ~'
* f * /
* V
%' . *. > *
I > / / > /
> ^ / / / /
-> > > >; ^ ' 0
j* j» > * #
4 #
4 /
S \ ~ ' # *
V \ \ t , .
\ \ N v .
L v \ \ x ^
¦ 2<>
<: »:
AV
40c
74°
Figure 59
73:
72°
Currents in bottom layer at low Water at
Sandy Hook (wind 9m sec~l from SW)
-------
74° 73° 72°
50
100
cm/sec
74° 73° 72°
Figure 60 Currents in surface layer at 2 hours after
low water in Sandy Hook (wind 9m sec-1 from
SW)
-------
50 100
cm/sec
I -
t
» *
% < t I
* «
s \ V «
I I »
« *
»
» I .
I 4
* ~ *1
1 » »
*
» «
I »
« V V
I »
*
I
» »
I t
* »
*
I I I 4 «
tilt*
« f 4 #
t ( t I t
»
*
~
I
»
I
4
I
~
»
~
%
I
I
#
»
*
t
I
*
»
#
~
~
»
\
\
*
%
«
t
»
%
* i
» i
» t
» v
74°
Figure
73c
72<
61
Currents in bottom layer at 2 hours after
low water at Sandy Hook (wind 9m §ec~l
from SW)
-------
74c
73c
72'
50
100
cm/sec
41°
40°
Figure 62 Currents in surface layer 2 hours before
high water at Sandy Hook (wind 9m sec~l
from SW)
-------
74°
73°
72°
50 100
cm/sec
41'
» t » » . *
« * I** « * *
* * «
UJ
i
N V \
40°
« » »
*
*
~
« *
%
*
-
V
t
\
V
*
S
V
\
\
\
\
\
v.
V
\
\
\
\
\
\
\
\
\
\
\
\
X
V
\
\
\
\
\
X
\
\
\
\
\ \
V
X
\
\
\
\
\ \
«
V «
. r
/
/
/
f
t
»
r
t
f
f
Figure 63
Currents in bottom layer 2 hours before
high water at Sandy Hook (wind 9m sec~l
from SW) .
-------
72°.
100
50
cm/sec
Figure 64
Currents in surface layer at high water at
Sandy Hook (wind 9m sec-^- from SW)
-------
73! !L
0 50 100
1
cm/sec * *
* * *
« t
» »
* lit
/
1 » » » » ~ 1
» » »
^ V « * » » 1
X *
1 1 *
% * ~
f
~
*
~ 1
1
%
«
%
*
»
~
9
* 9 «* V *
v « t % %
* * *
% V
% *
t * 1 » t \ 1
t * t 1 \ \ \
« \ \ \ \ \ \
t V X \ \ \ \
1 %. V V \ \
» » » »
, . , / f
« %
* » » » / ^ ^
» # / / y >
* / t t f t *
# # t f f * *
» # t t f / *
) I t t t / s
\ \ t t f / s
\ \ t t / / s
/ / t
' / / /
p J" * *
' y ^
' ^ ^ >
^ ^ ^
* jr *
^ jr
*
V
*
«
' V
1
1
*
. ~ - ^ x \
» 1 ^ \ \
--s\
/
1
\ 1 I !// S
\ \ t ! / s s
\ \ \ t t / s
\\\ \ t / *
x\\ \ \ N
k \ \ \ \ v . .
»
- » -
' » » »
740 73° 72°
Figure 65 Currents in bottom layer at high water at
Sandy Hook (wind 9m sec-1 from SW)
-------
WINDS, 9a/sec fran SW
p»
o
r»
E
20
«x
ae
~
30
40
12
20
24
0
8
16
4
WINDS, CALM
8
c
0 uj
4
2
0
8
0
24
4
12
16
20
TIME (hours ) TIME (hours)
Figure 66 Transport rate through section BB6 in surface layer in calm
and with SW wind 9m/sec.
-------
100
WIND. CALM
50
50
B 6
100
I 12
TIME (hoars)
16
24
100
WIND, 9a/iet frta SV
SO
50
IB 6
100
20
24
I 12
TIME (boors)
Figure 67 Net Transport through section
9m/sec.
BB6 in calm and with SW winds
-------
74° 73' 77°
Figure 6 8 Computed concentrations 24 hours after
release.
-------
74
73
72°
o
i
!*I
wmm
c
74° 73° 72°
Figure 69 Bathymetric charts of New York Bight (isobaths in fathoms)
-------