What vertical datum and what horizontal datum and adjustment does the Mn/DOT CORS Network use?
Strictly speaking, the MnDOT CORS network is not constrained to a vertical datum. It only facilitates the accurate determination of ellipsoid heights. To produce an orthometric height, an appropriate Geoid separation must be calculated by software within the roving GPS receiver and subsequently applied to the ellipsoid height. This separation can be determined either by performing a calibration to local control, or by using a standard Geoid model (see Question 10 for calibration recommendations). For the NAD83(1996) adjustment, the recommended model is Geoid03. For NAD83(NSRS2007), Geoid09 should be used. Current evidence suggests that the combination of NAD83(NSRS2007) and Geoid09 will provide better agreement with NAVD88 elevations than NAD83(1996) and Geoid03. The horizontal datum is NAD83(CORS1996) or NAD83(NSRS 2007). See this NGS Page for more information. The datum and GPS correction message type used in your application will be determined by the mount point you choose.
