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Ian ChurchOcean Mapping Group
University of New Brunswick
US Hydro 2007The Sixth International Discussion Group Meeting on
Uncertainty Management in Hydrography
Saint JohnSaint John
DigbyDigby
St. AndrewsSt. Andrews
Grand MananGrand Manan
EastportEastport
2
Dee
r Is
land
Cam
pobe
llo
Isla
nd
The Wolves
St. Andrews
Eastport
3
2.8 m
2.3 m
Pass
amaq
uod
dy Bay
MacesBay
M2 Amplitude and Phase
WebTide Scotian Shelf Model
1 Minute Phase Contours
8 Minute Phase Lag Through Letite Passage8 Minute Phase Lag Through Letite Passage
0 km 10 km 20 km
White – 0.2m range contours.Black 1 minute phase ranges.
4
Operations 2007Grand Manan
M2 Amplitude and Phase
WebTide – Scotian Shelf
ModelContours:1 Minute Phase0.2 m Amplitude
Tides:• Observed Tides• Predicted Tides• Hydrodynamic Model
Sounding Datums:• MSL / Geoid• Local Chart Datum
Discrete Steps? Linear Transition? Polynomial Interpolation?
• Co-Tidal Interpolations• Scaled Multiple of the
Local Harmonic Constituents
5
We wish to establish a vertical datum which represents an offset from mean-sea-level, below which “the tide rarely falls”.
Tides in the Bay of Fundywrt Saint John
Options:• Use Predicted Tides • Interpolate Between Stations
Outer Wood Island-15 minutes
-9.5ft
North Head-5 minutes
-5.5ft
Dipper Harbour-2 minutes
-2.6ft
St. Andrews+8 minutes
-2.5ft
St. Stephen+8 minutes
-1.0ft
Partridge Is.-13 minutes
-0.3ft
Welshpool+1 minutes
-4.2ft
Back Bay-7 minutes
-3.8ft
St. Martins+6 minutes
+6.3ft
Cape Enrage+5 minutes
+13.2ft
Hopewell Cape+8 minutes
+18.5ft
Moncton+45 minutes
+26.2ft
Advocate Harbour+5 minutes
+10.3ft
Saint JohnPrimary Port
0 minutesMean Tide – 25.3ft (7.7m)Large Tide – 29.6ft (9.0m)
Margaretsville-18 minutes
+7.6ft
Digby-16 minutes
+1.0ft
Brier Island-44 minutes
-8.3ft
Source:Canadian Tide and Current TablesAtlantic Coast and Bay of Fundy
EastPort MEUSA
Primary Port
6
A Digital Replica of the Water Within a Region
Created using a Coastline and Seafloor Bathymetry
Driven Using Topex-Poseidon Tidal Observation Data and Tide Gauge Data
7
Scotian Shelf ModelScotian Shelf Model
Bay of FundyBay of Fundy
Nova Scotia
Maine
A TIN of the Scotian Shelf, Georges Bank and the Bay of Fundy DUPONT, F.; C.G. HANNAH, D.A. GREENBERG, J.Y. CHERNIAWSKY and
C.E. NAIMIE. 2002. Modelling system for tides for the North–west Atlantic coastal ocean. Can. Tech. Rep. Hydrogr. Ocean Sci. 221:vii+72pp.
Provides a Tidal Prediction for any point within the TIN
Predicted Amplitude and Phase
Tidal Currents Accuracy
• 0.15 metres Amplitude
• 5 deg Phase
8
Dupont, F., C. G. Hannah, D. Greenberg. Modelling the sea level in the upper Bay of Fundy. Atmosphere-Ocean 43(1) 2005, 33-47.
9 Meteorological Effects – Pressure, Wind/Wave Build up, etc.
Non-Tidal Residuals
DigbyDigby
Saint JohnSaint John
EastportEastport
CutlerCutler
Brier IslandBrier Island
NorthHeadNorthHead
YarmouthYarmouth
Cutler Naval Base - MaineCutler Naval Base - Maine
Digby – Nova ScotiaDigby – Nova Scotia
Eastport - MaineEastport - Maine
Brier Island – Nova ScotiaBrier Island – Nova Scotia
0km 25km 50km 100km
10
All Tide Stations within the Area Display Very Similar Non-Tidal Residuals
Non-Tidal Residuals from a Single Station can be Examined
Sounding Datum that Varies Constantly and Smoothly throughout the Entire Model Domain
Based off the Tidal Prediction at Each Node within the TIN
Develop Sounding Datum Based on Hydrodynamic Model
11
Bay of FundyBay of Fundy
Nova Scotia
Maine
Relate ISLW to Existing Chart Datum
Determine Multiplier at Local Tide Stations
Datum = Multiplier * ISLW
Indian Spring Low Water• Suggested by Sir
George Darwin for Indian Waters
• ISLW = MSL – (M2+S2+K1+O1)
12
S2M2
K1O1
ISLW Datum
Saint Andrews
M2 2.722
S2 0.406
K1 0.158
O1 0.114
Sum 3.400
Zo 3.871
Multiplier 1.14Great Britain Hydrographic Office (1969). “Tides and Tidal Streams.” Chapter Two in Admiralty Manual of Hydrographic Surveying, Vol. 2, Somerset, England, 118pp.
Datum = F*S where,
• If (S < 2 m) F = 0.85 • If (S > 5 m) F= 1.0 • Else F is linearly
interpolated between the above values.
13
S2M2K1
O1 N2
Hannah, DFO• S =
M2+N2+S2+K1+O1
Datum
14
RMS = 0.22 m RMS = 0.30 m
38 CHS Tide Stations
Tidal Power Stations Perform Repeat Surveys
Prior to Installation to Observe Existing Sediment Transport
15http://www.rgu.ac.uk/research/innovation/page.cfm?pge=7560
Deer Island
Campobello
Island
Eastport
Passamaquoddy Bay
Provides a Smooth Sounding Datum Throughout the Model
Uniform Transitions Between Datasets
Datum Based on Varying Predicted Tides Throughout the Region
Resolve Tides from Hydrodynamic Model + Non Tidal Residuals
Sounding Datum based on Hydrodynamic Model
Resolve Tides from Hydrodynamic Model + Non Tidal Residuals
Sounding Datum based on Hydrodynamic Model
16
Ian Church
18
Day 1 = BlackDay 2 = Red
Hydrodynamic
ModelTide
Black’s Harbour
Tide
Wilsons Beach Tide
St. Andrew’s Tide
Eastport Tide
Fairhaven Tide
Separation 30cm 80cm 90cm 2cm 35cm 40cm
Multibeam Sonar Swath