DCAR97

DCAR97 is a companion product derived from CARIB97. The geoid is a surface of constant potential which conforms to sea level in an average sense. Deflections of the vertical are the slopes associated with the Earth's equipotential layers. The deflection of the vertical is the departure a plumb bob would take from vertical defined by an ideal ellipsoidal Earth. These quantities are typically a few arc seconds, but can reach an arc minute of departure.

Deflections are used to relate the orientation of a locally-leveled instrument, such as a theodolite, to a spatial reference system. Important uses are corrections to zenith distance (vertical angle) measurements, and the conversion between astronomic and ellipsoidal azimuths (the Laplace correction).

The DCAR97 model is a high resolution deflection of the vertical model covering the region 9-28N, 86-58W. It was computed in a cooperative effort with the National Imagery and Mapping Agency (NIMA). The DCAR97 deflection model has been designed specifically for the Caribbean Sea. Due to data coverage and computational issues, one will find differences between DCAR97 and DEFLEC96 in regions of overlap.

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