NEW
JERSEY

NWS e

WEATHER =
STATION.

FIGURE.1. Location of the study area and points at which water temperature and
wind velocity data were collected.

-6-


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FIGURE 5. Infrared imagery from the NOAA 6 satellite for 15 duly 1981.
Arrow shows location of Atlantic City, New Jersey.

10


“cold waters" being brought in by southerly winds, and describes the
effects of the cooler water on the behavior of several species of
gamefish.

An unusual opportunity to gather evidence of wind-driven coastal
upwelling exists in the area of Atlantic City, New Jersey, as the
consequence of the availability of accurate wind data taken at the
weather station (a first-order station of the National Weather Service
at the Aviation Facilities Experimental Center) and water temperature
data logged four times a day at the tide gauge station on the Steel
Pier. Although the weather station is about 16 km inland from the pier,
wind data collected there and reduced to daily averages realistically
portray general wind field conditions alony the coast and in the
vicinity of the pier.

The trend of the local coastline is about WSW to ENE in the
vicinity of the pier (Fig. 1), which means that a wind from about 250°
would have the maximum upwelling effect, and one from 70° would produce
the maximum convergence and "downwelling". During the summer months,
the monthly mean resultant wind directions (based on 1941-70 data)
observed at the weather station are: June - 140°, July - 260°,

August - 200°, and September - 27U°. (U.S. Department of Commerce 1975).

The wind data used in this study were daily mean vector resultant

velocities taken from Local Climatological Data summaries for the

Atlantic City weather station published monthly by the National Climatic

Data Center, (1) Upwelling wind components are computed from these data

Q) National Climatic Data Center, National Environmental Satellite, Data,
and Information Service, NOAA, Asheville, North Carolina 28801.

2


ABSTRACT

Analysis of nearshore ocean temperature data collected in the
floatwell of a tide gauge on Steel Pier and wind data collected at the
Atlantic City, New Jersey, weather station during summer months of 1981
shows a strong correlation between major cooling or warming events in

the water and the strength of upwelling or downwelling wind components

one day earlieree?

Preceding Page Blank iii

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EVIDENCE OF NEARSHURE’ SUMMER UPWELLING
OFF ATLANTIC CITY, NEW JERSEY

Merton C. Ingham and James Eberwine

One of the tenets of classical theory of coastal upwelling dynamics
(Defant 1961, p. 652) holds that the most effective wind direction for
transporting surface waters offshore, thereby bringing cooler water up
into the surface layer, is one which is parallel to the coastline (with
the land on the left. in the northern hemisphere). Assuming that this is
applicable to the waters over the continental shelf in the Middle
Atlantic Bight, upwelling should occur along the Virginia - New Jersey
coastline during the summer months when winds from the southwestern
quadrant are common (Williams and Godshall 1977; Lettau et al. 1976).

Hicks and Miller (1980) reported indications of summer upwelling in
response to southerly winds, bringing cold bottom water into the surf
zone near Monterey Beach, New Jersey (about 80 km northeast of Atlantic
City, New Jersey). They found upwelling in July 1976 to be vigorous
enough, following two days of strong southerly winds, to bring waters of
the “cold cell" into the surf zone, causing.a drop of 9.3°C (from 18.3°
to 9.0°C) in surf temperature. Their analysis of 1973 and 1974 data
also showed large decreases of surf temperature during July, August, and
September, each preceded one or two days earlier by strony winds from
the south and southwest.

Recreational surf fishermen alony the New Jersey shore. also have
frequently observed the upwelling effects of strony south winds, but
haven't used the term "upwelling" or the concept in describing their

experiences. Wilson (1983), for example, speaks of “cold currents" and


*” PB85150290
man |
ENT OF cg
o i “6,
‘ SE : NOAA Technical Memorandum NMFS-F/NEC- 31

Evidence of Nearshore Summer Upwelling

Off Atlantic City, New Jersey

U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service
Northeast Fisheries Center
Woods Hole, Massachusetts

November 1984

REPRODUCED BY

NATIONAL TECHNICAL
INFORMATION SERVICE

US. DEPARTMENT OF COMMERCE
SPRINGFIELD, VA. 22161


Best-fit linear equations for the three months of high-pass data

are: June, Y = 4.18 - 0.89 X; July, Y = 2.27 - 1.16 X; and August, Y
2.51 - U.91 X, where Y = the one-day change in water temperature (°F)
and X = upwelling wind component (mi/hr). These equations have quite
similar slopes but different intercepts (Fig. 3), which suggests that
changes in upwelling/downwelling wind strength produce comparable
changes in water temperature in each of the three months, but that the
wind strength required for a given change is greater in June than in
July and August, probably because of smaller differences between the
temperature of upwelled bottom water and surface water in June.

In an attempt to document and verify the upwelling events, a search
of a file of infrared imagery from the GOES satellite for summer 1981
was conducted. It revealed that there was clear sky in the Atlantic
City area both before and after just one of the upwelling events, the
one which began about 13 July. Imagery from the Advanced Very High
Resolution Radiometer on the NOAA 6 satellite revealed a narrow band of
cooler water in the Atlantic City area on the 15th that wasn't present
on the 11th (Figs. 4 and 5).

The results of this study of wind and water temperature data from
just one summer suggest that wind-driven upwelling does occur along the
central New Jersey coast. More sophisticated analyses of summertime
conditions in other years should be conducted before more extensive
quantification or modeling is undertaken, however. Specifically, it
would be important to test the assumption that 250° winds are the most
effective for upwelling and to determine more accurately the lag time

between wind conditions and water temperature changes.


by multiplying them by the cosine of the anyle between the published
daily resultant and the 250°-70° line and assigning the appropriate
sign, positive for upwelling or negative for downwelling.

The seawater temperature data were obtained from manuscript records
of 6-hourly observations recorded at the Atlantic City weather station
by telephone link with a thermistor installed in the floatwell of the
National Ocean Service tide station on Steel Pier. The average depth of
the thermistor beneath the surface is 2.4 m, ranging from about 3.2 m at
high tide to 1.9 m at low tide. The 6-hourly data were converted to
daily averages, and daily changes in water temperature were calculated
by subtracting each day's average from the next day's.

Visual comparison of time-series plots of daily water temperature
and wind component data for summer 1981 (Fig. 2) was inconclusive,
though there seemed to be some correspondence between major wind events
and rapid changes in temperature. Linear regression analysis of daily
water temperature changes and the upwelling wind component the day
before yielded correlation coefficients which were too low to imply a
functional relationship. It appeared that random small-amplitude noise
in the water temperature data might be responsible for the poor
correlation. Accordingly, we re-ran the linear regression analysis
using just those water temperature chanyes which were at least one
standard deviation above or below monthly means (high-pass filter). The
results of this analysis were far more conclusive (Fig. 3), yielding
correlation coefficients (R) of -0.777, -0.855, and -0.752 for June,
July, and August, respectively. The coefficients are negative because
upwelling wind components (+) produce decreases in water temperature and

downwelling components (-) produce increases in water temperature.






DAILY AVERAGE WATER TEMPERATURE (°F)

70 4 aay —

WIND COMPONENT (mi/hr)
+ UPWELLING

- DOWN
| JUN JUL

198]

AUG | ~~ SEP

FIGURE 2. Trends in daily average water temperature (°F) measured at the Steel
Pier and upwelling/downwelling wind component (mi/hr) from wind velocity measurements
made at the Atlantic City weather station in 1981.-


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Reproduced from

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FIGURE 4. Infrared imagery from the NOAA 6 satellite for 11 July 1981.
Arrow shows location of Atlantic City, New Jersey.

9


NOAA Technical Memorandum NMFS-F/NEC- 31

This TM series is used for documentation and timely communication of
preliminary results. interim reports, or special purpose information, and
has not received complete formal review, editorial control, or detailed
editing.

Evidence of Nearshore Summer Upwelling
Off Atlantic City, New Jersey

Merton C. Ingham! and James Eberwine?

‘Atlantic Environmental Group, National Marine Fisheries Service, Narragansett, R! 02882
2National Weather Service Office, Atlantic City, NJ 08405

U.S. DEPARTMENT OF COMMERCE

Malcolm Baldridge, Secretary

National Oceanic and Atmospheric Administration
John V. Byrne, Administrator

National Marine Fisheries Service
William G. Gordon, Assistant Administrator for Fisheries

Northeast Fisheries Center
Woods Hole, Massachusetts

November 1984




REFERENCES

Defant, A. 1961. Physical oceanography. Vol. |.

MacMillan Co., New York. 729 pp.

Hicks, D.C., and J.R. Miller. 1980. Meteorological
forcing and bottom water movement off the northern New

Jersey coast. Estuarine Coastal Mar. Sci. 11: 563-571.

Lettau, B., W.A. Brower, Jr., and R.G. Quayle. 1976.
Marine climatology. MESA N. Y. Bight Atlas Monogr. 7.

New York Sea Grant Institute, Albany, N.Y. 239 pp.

U.S. Department of Commerce. 1975. Local climatological
data -- annual summaries for 1974.- Part 11. NEB-WYO.

National Climatological Data Center, Asheville, N. C.

Williams, R.G., and F.A. Godshall. 1977. Summarization and
interpretation of historical physical oceanographic and meteorological
information for the Mid-Atlantic region. Report prepared for the Bureau
of Land Management by the National Oceanic and Atmospheric

Administration. NTIS # PB-277-104. 295 pp.

Wilson, Russ. 1983. 111 wind blows no good. The Fisherman -- The

New Jersey, Delaware Bay Edition, 25 August: 20-21.


A WATER TEMPERATURE (°F)

| @=: JUN = JUN
“8 m= JUL Ne
{  &= AUG “\ AUG

104 198] me

oto
6 4 -2 0 2 4 6 8 W 2 14

COAST - PARALLEL WIND COMPONENT (mi/hr}

FIGURE 3. Best-fit linear regressions of water temperature change (°F) and
upwelling (+)/downwelling (-) wind components: (mi/hr) for high-pass filtered
data (4 water temperatures greater than 1 standard deviation from monthly mean).