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 Piscataqua Mouth Estuarine Circulation Study
Experiment Overview
 RV Gulf Surveyor January 2021

John E. Hughes Clarke and Indra Prasetyawan
EM2040 and ADCP ops
 Matt Rowell and Dan Tauriello
RVGS Operations
 Class of ESCI 896.02 (2021)
Applied Physical Oceanography
for Hydrographic Surveyors


Daily RVGS Operations

In January 2021, as part of ESCI896.02 Applied Physical Oceanography for Hydrographic Surveyors, five days were allocated in the J-Term to operating the RV Gulf Surveyor in the outer harbour and inner shelf. The aim was to provide a complementary practical laboratory to allow the students to simultaneously investigate two aspects:

The labs took place on five spaced weekdays from ~ 10 am to 2pm local time. By spacing the outings over the 3 week period of the J-Term (January), the circulation was investigated at multiple phases of the tide and as the tide varied from neaps to springs.

all tides
showing the 5 tide windows utilized in January

Being January, the circulation was expected to reflect the seasonal conditions (low/no river flow, colder are than ocean temperatures).

Each of those ~4 hour tide windows  examined a slightly different phase of the tide:

January 6th
 January 8th January 12th January 14th January 20th
tide
 tide tide tide tide
mid flood
 late ebb and slack
 early to mid ebb
 around HW
 early to mid flood
map
 map map map map
first testing, establishing transects
 focus offshore out to
Isle of Shoals.
 testing 600/700 kHz
out to thing 1/2
 transects
 focus on sandwaves


Comparison with Salme Cook's model:

As part of the Phd thesis of Salme Cook (now as USGS Woods Hole), she developed a 3D baroclinic hydrodynamic model with wetting and drying that described the tidal evolution of flow in the Piscataqua River/ Great Bay Estuary system.

Cook S.E., Lippmann T.C., Irish J.D., 2019, Modeling nonlinear tidal evolution in an energetic estuary,
Ocean Modelling, V. 136, 2019, p. 13-27, ISSN 1463-5003, https://doi.org/10.1016/j.ocemod.2019.02.009

She kindly provide an overview of the depth-averaged results around the mouth of the Piscataqua. these can be directly compared to the ADCP sections acquired as part of this class. Significant stages of the tide are presented below:

model
 model model model
late flood -1hr before HW.
Note the well developed flood stream
 turn of the tide ~1.5 hour after HW.
Note the eddy north of Fort Point
 established ebb ~ 3 hours after HW.
Note ebb stream close to Fort Point
and then around the sand bank
 late ebb ~ 1 hour before LW.
offshore plume just starting to develop
model model model
continuation ebb ~ 1 hour after LW
note clear development of :
  • offshore jet on west side of harbour
  • offshore eddy east of jet
  • eddy around sand wave in lee of Fort Point
 First actual flood stream ~ 3 hrs after LW
mote :
  • still stand where old jet was
  • inflow around Wood and White  islands
  • flow over sand waves.

 Well established flood ~ 2 hours before HW
note:
  • even inflow across mouth
  • even flow across sandwaves
  • eddy upriver of Fort Point


page developed by JEHC Jan 2021