The author has identified the following significant events. The Earth Resources Technology Satellite made a transit over New York Bight on 16 August, 1972. Imagery from this transit shows several oceanographic features that demonstrate the usefulness of remote sensing for large area, synoptic observation of changes in water quality in the coastal zone. Both the extent and turbulent character of the Hudson River plume are discernible in the image. Residue from a dump of waste acid is visible over a five mile area in the apex of the Bight. Little dispersion of this residue has occurred which suggests that this feature will be a persistent signature in images from future satellite transits

Charnell, R. L.

Maul, G. A.

English

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7	 10
OCEANOGRAPHIC OBSERVATION OF NEW YORK BIGHT FROM ERTS-1
N72-33314
(E72- 10156 )
OFFtOMOERT5I1 O
B S E RV ATIO N
 
et
NEW YORK BIGHT
al (National oceanic and Atmo sphe ric
 
OSCL	 [)nclasAdministration)
 
	
Oct 1972 11 ;^	
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Page 2
Robert L. Charnell
Abstract - The Earth Resources Technology Satellite (ERTS-1) 9 made
a transit over New York Bight on 16 August, 1972. Imagery from this
transit shows several oceanographic features that demonstrate the
usefulness of remote sensing for larger area, synoptic observation of
changes in water quality in the coastal zone. Both the extent and
turbulent chara^'.!r of the Hudson river plume are disco no a in the
Image. Residue from a dump of waste acid is visible over a five mile
area in the apex of the Bight. Little dispersion of this residue has
occur*d whibh suggests that this feature will be a persie^tar^t signature
In images from future satellite transits.
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Page 3
Robert L Charnell
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•
On 16 August 1972, the multispectral scanner (MSS) aboard the
first Earth Resources Technology 5,xtellite (ERTS) obtained a set of
Images of the Now York Bight which contain information of oceano-
graphic significance. The images demonstrate the effectiveness of
satellite use in observing surface features that indicate changes of
water quality. The impact of this technique on coastal zone oceano-
Graphic analysis will be widespread.
The 1ASS aboard ERTS has four channels with band pass filters
covering the visible and near infrared bands. Channel 4 covers the
0.6-0.6
	
(green-yellow) band; channel 5 covers the 0.6-0.7vu *%(orange-
red) band; channel 6 covers the 0.7-0.8/Ai% (red) band, and channel 7
covers the 0.8- 1,1,Am (infrared) band. To determine which bands contain
the most information relating to ocean phenomena requires an under-
standing of the manner in which the solar energy is reflected across
the spectrum.
Specular reflectance of solar energy from the sea surface, as
measured by a spacecraft, is a function of atmospheric state, water
depth, water mass characteristics, *#!a bottom characteristics, and of
sea =tat*. To ensure that information about the ocean was being
observed, a calculation was performed to determine the percent of
energy which penetrated the sea surface, was reflected from a per
fact reflector, and was subsequently seen at the surface. These
calculations were made by solving the intensity equation:
Ja
4
•	 Page 4
Robert !. Charnoll
Where I is the intensity observed at a depth L through a band pass
filter qa , which is normalized over the region of wavelength 1 for
the appropriate ERTS channel; I o
., 
is intensity at the sea surface and
a(.X is the spectral attentuation coefficient [1].
The calculations chow that percentage of energy from'a perfect
reflector at a depth of one meter is 86% for the 0.5-0.4.M m bandq 55%
for the 0.6-0.7m band, 11% for the 0.7-0.8rtwi band and 0.2% for the
0.8-1,1 "A band. These results suggest that an oceanographic feature
will not be seen in the 0.8-1.1/ 1% band (reflected infrared). Hence
comparison of suspected water features observed in the visible bands
with those in.the infrared band insures that features suchl as clouds
I
are not mistaken for oceanographic data. Features discussed here have
had such a comparison made.
These calculations also provide a first estimate of the depth of
a feature. For example, a perfect target at five meters will reflect
E
50% in the green-yellow band, 7% in the orange-red band and essentially
none in the red or near infrared bands. I
MSS imagery in the accompanying figure shows an area in the New
'fork Bight approximately 100 miles by 100 miles. The upper left body
of water is Raritan Bay; the land mass at the top is a portion of
Long Island. New Jersey is on the left and the image extends along the
coast to just beyond Barnegat Inlet. The picture is the bulk processed
Imagery of the MSS 5 channel (0-6-0-7/4m ) just as it is received from
the NASA data processing facility. Imagery was obtained at 1507 GMT
when the sun's elevation was 539
 and the azimuth was 1300 . For this
transit, the MSS 5 channel was the most sensitive to oceanic features:
Page S	 j
Robes 'L. Charnell
MSS 4 is obscured by haze induced by atmospheric scatter, and the other
channels show much less detail in sea surface features, as the calcu-
lations would suggest.
The large white features present in the right half of the image are
clouds. They are present in all bands. Shadows cast on the sea surface
by the clouds are the dark areas adjacent to them on the northwest.
The haze over New York City comes from metropolitan-produced smoke
and haze.
The most prevalent oceanic feature in the New York Bight frame
Is the existence of visibly turbid surface water, near the coast. The
light colored water extends a few miles offshore and is produced by the
action of waves and tides at the ocean boundary in maintaining sus-
pended sediment. Further from shore, settling and mixing with shelf
water decrease the turbidity. Evaluation of the extent of this water
adjacent to the southern coast of Long Island is hindered by the exis-
	 N"
tence of high clouds. The general turbid nature of the nearshore water
precludes detection of the sea bottom with MSS. Lateral extent of
coastal turbid water increases in the area of high water velocities
such as would be encountered in Barnegat inlet (lower left hand portion
of the image), where a tidal plume is clearly visible.
A plume of light colored water extends from the mouth of the Now
York Harbor complex south along the New Jersey coast. The plume which
Is approximately IS miles long and 7 miles wide represents the core of
lower salinity water from the Hudson River. Characteristically this time
of year the Hudson River plume is relatively small due to reduced fresh
•
i^I
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Fobert L. Charnell
water outflow and is oushed onto the New Jersey coast by the predomi-
nant winds. surface winds for the proceeding day were less than
10 knots generally from ti., * east.
Clearly, the plume is not homogenous. Patchiness is. Indicative
of the turbulent mixing process by which the plume water is absorbed in-
to the ambient Bight water. The relatively sharp eastern boundary of
the plume indicates dispersion processes are not isotropic.
Fortuitously, surface salinity data were collected in the general
area of the plume [2]. A transect about 10 August and another on 22
August were made perpendicular to Sandy Hook. Although the data &re
too few to define the shape and size of the plu- ►e they indicate that
the low salinity Hudson plume was in this general area depicted in the
MSS 5 image and that the plume was about 2% lower in salinity than the
ambient Bight water.
There is an unusual and interesting feature in the apex of the
Bight about 20 miles southeast of the Harbor entrance that apparently
Is a manifestion of man's activity in the area. The feature consists
of a fairly sharp wavy line and a more diffuse circular patch north
of the line. These features are located in the general area for waste
disposal [3 }
The two major dump sites are for sewer sludge and for waste acid 14 1.
Between 5 and 6 bargeloads of sewer sludge per day are disposed of at a
point about 5 miles southeast of Ambrose light station. An average of
about 2 bargeloads of waste acid are taken each day to a site some 10
miles to the southeast of Ambrose light station. Disposal of acid is
I
Janarnell
7
Robert
made while the vessel is underway; half the load is dumped over
approximately 5 miles in transit to the turning point, the remainder on
the way back. Surface color of waste acid is yellow-green, optimally
detected in the !ASS 4 band; due to atmospheric dispersion, MSS 5 has
•	 •4
processed by NASA) affords higher contrasts in surface features. The
acid is slow to mix with the sea water because the waste is of near
equal density and hence maintains sharp boundaries for substantial
periods of time.
The distinct wavy line is the result of waste acid disposal. The
horthwest-southwest dimension of the feature is approximately five
miles. The less distinct portion of the line may be residue from an
earlier dump. A minor discrepancy occurs in that the turning point in
the picture is approximately S miles nearer the harbor than the
authorized dump site. 	 •
Normally, dumping occurs on a semidaily basis. Thus the relic dump
must be at least 12 hours old and dispersion was very slow. The fact
that the recent dump may have drifted some five miles implies that it
was made several hours before the satellite transit. Even though wind
mixing was low for this day, the implication of the dump durability is
that dumping of this magnitude generally will produce a persistant
surface feature.
The diffuse circular patch to the north of the waste acid dump is
close to the sewer sludge dump site. Surface manifestation of a sewer
sludge dump is much less noticeable than waste acid; only a grey-brown
slick will remain. Initial low intensity of the target makes the
Page 8
Robert L. Charnell
character of the surfacc patch less discernible.
This single image, taken in an area of complex oceanography and high
population density, demonstrates the utility of satellities such as ERTS,
equipped for surveying water quality changesg such as location of river
i
discharge plumes and the effectiveness of waste dumping procedures.
It seems likely that satellites with sensors optimized to view the
ocean in visible and infrared wavelengths, supplying synoptic wide-ore&
,
data# will make management of the coastal zone on a broad scale much
more realistic.
A
s
1
Robert L. Charnell
George A. Maul
NOAA-Physical Oceanography Laboratory
Miami, Florida 33149
•
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Robert L. Charnell
E
REFERENCE a NOTES
(1] The attentuation coefficient for pure water was used in this
calculation. This provides a conservative estimate since oC
for even the cleanest sea water is much larger.
121• Salinity data were kindly supplied brf the Ecosystems Investigations,
Middle Atlantic Coastal Fisheries Centez, Sandy Hook Laboratory.
j .^]. "Effects of Waste Disposal in the New York Bight." Prepared by
National Marine Fisheries Service, Middle Atlantic Coastal
Fisheries Centero Sandy Hook Laboratory, Highlands, New Jersey$
Final Repott, February, 1972,
141 We acknowledge the description of waste dumping procedures
provided by John B. Pearce of the National Marine Fisheries
Laboratories # Sandy Hook, New Jersey.
J-U This research was in part supported by the National Aeronautics
and Space Administration ' s Earth Resources Program. The imagry
was supplied by the NASA Data Processing Facility at Goddard
Space Flight Center for ERTS proposal C315.
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Oceanographic observation of New York Bight from ERTS-1

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