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Gravity, Geoids, and Other Vertical Datums in the Puerto Rico/Virgin Islands Region

Explore geodetic ellipsoidal & orthometric heights, geoid models, gravity anomalies, MSL, and local datums in the region. Get insights on geoid modeling, bias correction, and the need for additional gravity data.

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Gravity, Geoids, and Other Vertical Datums in the Puerto Rico/Virgin Islands Region

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  1. Gravity, Geoids, and Other Vertical Datums in the Puerto Rico/Virgin Islands Region Dr. Daniel R. Roman and Dr. Yan Ming Wang

  2. Geodetic Ellipsoidal Height and/or Datum (h) Geodetic or Orthometric Height and/or Datum (H) Geoid Height (N) h = H + N The geoid and gravity anomalies are related mathematically: Oceanographic Global Mean Sea Level (MSL) Local MSL (LMSL) or Local Mean Tide Mean Dynamic Topography (MDT) MSL + MDT = LMSL MSL => Geodetic Datum LMSL => Local Vertical Datum Significant Concepts & Terms

  3. “P” 0 Deflection of Vertical h = H + N Δg = gP - γQ Normal to geoid Normal to ellipsoid “P” H h Geopotential Surface “Ellipsoid” “Q” N Geopotential Surface “Geoid” Geopotential Surface Earth’s Surface OCEAN

  4. ellipsoid unexpected area of storm surge predicted storm surge reach tide station/datum point actual storm surge reach LMSL local geodetic datum MDT N MSL bias geoid MSL + MDT = LMSL

  5. From the National Geospatial-Intelligence Agency Website at: http://cddis.gsfc.nasa.gov/926/egm96/egm96.html

  6. Statistical Comparison Between Available Geoid Height Models and 13-Point GPS on BM Profile Along NW Puerto Rico Shoreline

  7. Available Elevation Data Sets SRTM 30 mSRTM 90 mNED 1 arcsecond

  8. Conclusions • Tidal and Geodetic datums are related • Additional gravity data are required • Geoid modeling is best constrained with additional oceanic gravity observations • Some limited terrestrial observations will help fill in gapped regions but also help to eliminate any datum problems

  9. Outlook • Improved terrain models already exist to help model the shortest wavelengths • Simultaneous lidar observations would help to model the local sea surface and any implied datum shifts • Impending satellite gravity missions aid in resolving global mean sea level • A future gravimetric geoid can be generated that will cover CONUS & PR/VI

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