Sea Levels around the Caribbean

1
Sea Levels around the Caribbean
The University of the West Indies

• Keith M Miller
• Lecturer in Geodesy and Hydrography
• Head of Department of Surveying and Land
  Information

2
Climate and Sea Level

• The significance of sea level change
• Recent Sea level change in the Caribbean
• Results of data analysis
• Sea Level Monitoring under MACC
• Strategic plan for measurement
• Accompanying CORS network
• Sustainability through use by surveyors

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Sea level change is due to

• Global warming
• Deglaciation, with water moving towards the
  equator
• Thermal expansion of the ocean
• Movement of magma within the Earths core
• Movement of Earths crust
• Tectonic activity
• Localised deformation
• Anthropogenic
• Mineral extraction

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Methods of Measurement

• Absolute change in distance to sea surface from
  the centre of mass of the Earth.
• Relative Change in height of mean sea level
  with respect to a land mass.

Results presented here are all relative, using
data acquired at sea level gauges from ports and
harbours through the Caribbean.
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Trinidad and sea level change
Implications on people, industry, nature
resources
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People and Communications
2.0m above MSL (1938) rising at 1.6mm/yrTidal
range 1.6m floods start in 700 yrs
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Wildlife and Agriculture
Swamp lt 0.5m above high water, may
survive?Agriculture salt water intrusion in
400 years
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Industry
2.9m above MSL (1938) rising at 3.0mm/yrTidal
range 1.8m floods start in 600 years
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Natural resource issues
Archipelagic baseline definitiondepends on small
land masses for fishing and offshore mineral
rights.
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Relative change in mean sea level at ports in
Central America
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Land Masses Tectonic Processes
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Land Masses Tectonic Processes
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Immediate requirements

• Further monitoring through permanent installation
  of scientific equipment to measure
• Sea level
• Meteorology
• Position
• and to undertake repeat leveling
• Assessment of impact on threatened areas

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Sea Level and Meteorology

• Under MACC
• Bahamas, Antigua, Barbados, Belize, Guyana,
  Jamaica x 2
• Possible other MACC sites
• St. Vincent, Dominica, St. Kitts, Grenada
• Local (state) funding
• Trinidad and Tobago (6 stations)

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Caribbean GPS CORS sites
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International Positioning
IERS Primary points define ITRFUsed in land
survey applications
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Point Coordinates

• Antenna Reference Point(ARP) ST. CROIX VLBA CORS
  ARP PID
  AF9484
• ITRF00 POSITION (EPOCH 1997.0)
  
• Published by the IERS in Mar. 2001.
  
• X 2607771.190 m latitude 17 45
  24.82985 N
• Y -5488076.850 m longitude 064 35
  03.55425 W
• Z 1932767.710 m ellipsoid height
  -31.854 m
• ITRF00 VELOCITY
  
• Published by the IERS in Mar. 2001.
  
• VX 0.0085 m/yr northward 0.0124
  m/yr
• VY 0.0073 m/yr eastward 0.0108
  m/yr
• VZ 0.0121 m/yr upward 0.0009
  m/yr
• L1 Phase Center of the current GPS antenna ST.
  CROIX VLBA CORS L1 PC C The Dorne Margolin T,
  chokerings (TurboRogue) antenna
  (Antenna Code AOAD/M_T) was installed on
  10/13/95.
• The L2 phase center is 0.018 m above the L1
  phase center.

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Regional GPS Networks

• IERS define ITRF
• IGS Tracking network
• NGS Tracking network
• Other networks exist

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Static GPS surveys - baselines

• Baselines from international control processed to
  determine vectors in 3 dimensions

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Static GPS surveys - adjustment

• Network adjusted to compute local CORS
  coordinates and accuracy achieved

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Local short baseline solutions

• Coordinating a point at UWI

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Geodetic Network solution

• 13 receivers
• 2 fixed
• 4 days of obs.
• 4 hr. sessions
• 15 sec. epoch
• 231 baselines, many repeated

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Data Delivery
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Web Access to data
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Use of Belize site locally

• Control point coordination by static positioning
  with dual frequency receiver
• Sub-cm accuracy depends on observation period
• Use data from sites in Nicaragua, Honduras,
  Guatemala for better integrity
• Single frequency gives 10cm accuracy (horizontal)
  up to 10km.

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Belize GPS CORS

• Provided under the MACC programme for the
  specific purpose of deformation monitoring
• Freely available to support control survey work
• To ensure sustainability please use it
• For support contact
• kmiller_at_eng.uwi.tt