The Estuarine Richardson Number and the NeapSpring

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The Estuarine Richardson Number and the
Neap/Spring Transition. Bob Chant Rocky
Geyer IMCS Rutgers University
Collaborators Bob Houghton Jim Lerczak
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Estuarine Conference Schedule

• 2006 PECS (Submit an abstract See David
  Jay)
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS
• John Simpson Retirement Symposium
• PECS

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Estuarine Conference Schedule

• PECS
• John Simpson Retirement Symposium
• 2030 PECS
• 2031 John Simpson Retirement Symposium
• 2032 PECS
• 2033 John Simpson Retirement Symposium
• 2034 PECS
• 2035 John Simpson Retirement Symposium
• 2036 PECS
• 2037 John Simpson Retirement Symposium
• 2038 PECS
• 2039 John Simpson Retirement Symposium
• 2040 PECS
• 2041 John Simpson Retirement Symposium
• 2042 PECS
• 2043 Rocky Geyer Retirement Symposium
• 2044 PECS
• 2045 Rocky Geyer Retirement Symposium
• 2046 PECS

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Channel Cross-section at mooring array
Hudson River
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2
3
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New York
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1
New Jersey
Atlantic Ocean
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GWB
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Thanks to Paul Linden.
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Near Zero River Flow
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Along channel salt sections
Spring
Q800 m3/s
Neap
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Tidal Range(black) and Stratification (Blue)
Lower layer flow
Up River
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Spring neap cycle involves movement primarily
though Estuarine (or Horizontal) Richardson
Number space.
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Along Channel salt/dye sections
May 4th
May 6th
May 7th
Dye Conc 10-11
May 8th
km north of the Battery
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River
Ocean
u1
u2
(Eulerian lower salt Equation rbS)
Neap/Spring transition occurs when V0
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Following Geyer et al. 2000 for u2
u1
RCdU
u2
h1
Neglect time dependent term
h2
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Critical condition occurs (Vs0) when.
From salt equation
u2 from momentum eqn.

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5B
P
a0.5, Rif.15
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Ucrit58 cm/s
A
B
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Conclusions

• Neap-tide increase in stratification is
  characterized by baroclinic
• adjustment and landward advance of isohalines in
  bottom boundary layer.
• 2) Landward advance of isohaline in BBL is
  slowed by vertical mixing
• and reversed approaching spring tides.
• 3) With a salt and momentum equation and a
  turbulence scaling the dynamics
• of the neap/spring can be distilled into the
  horizontal Richardson Number.
• 4) The critical value of Rix 1. For Rix gt 1 the
  estuary is stratified , for
• Rix lt 1 the estuary is mixed.
• 5) S/N transition in Hudson occurs at Ri1.