Dan Roman Research Geodesist
OUTLINE The GEOID team What we produce Next models The future
The Geoid Team Primary Researchers - Daniel Roman, Ph.D.
- Yan Ming Wang, Ph.D.
Support - Gravity database & analysis: Jarir Saleh
- Software & database: William Waickman
What We Produce: Geoid Height Models Q: So what’s a “geoid height” model? A: A model of the separation between a geoid or vertical datum and an ellipsoidal datum. Q: The separation between a what and a what?! A: OK … maybe a brief GEOID 101 tutorial to cover the basics …
Global Relationships Between Geodetic Surfaces/Datums
Local Relationships Between Geodetic Surfaces/Datums
What else is produced? - Derived from geoid height model
- Angle between normals to ellipsoid & geoid
- Useful in navigation functions
Surface Gravity Interpolation
Models Under Development GEOID06: CONUS, PR/VI USGG2006: CONUS - Validation of reference field used (GRACE)
- Already see a half cm improvement nationally when comparing to the GPSBM’s
- Incorporation of coastal aerogravity study
- Comparison at tide gauges and with VDatum
Near Term Research Utility of GPS/INS vs. aerogravity for gravity Assessment of EGM06 and GRACE-based gravity Temporal effects in gravity and geoid Improved theory for determining geoid height models from gravity data Monte Carlo study of current gravimetric geoid height model Error propagation to estimate hybrid geoid errors
Equivalent Pseudo-Geoid Signal for 91s Filter
Long Term Goals Orthometric heights determined from a cm-level accurate gravimetric geoid applied to cm-level accurate GPS-derived ellipsoidal heights An error model of the existing NAVD 88 datum A unifying datum common to all interested countries in the hemisphere (Canada, Mexico, other North & Central American countries, and Caribbean nations). A common basis for an IGLD15 model
QUESTIONS?
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