IEDA: Marine Geoscience Data System IEDA

Local XY Grid System Description

Local XY is a gridding system used by the National Deep Submergence Facility ( operated by the Woods Hole Oceanographic Institution.  It is used during all Alvin, Jason2/Medea, and ABE/Sentry dive operations.

Local XY is a grid system (in meters) that is referenced to a local Latitude/Longitude origin.  The conversion between Latitude/Longitude and Local XY use a simple flat-earth projection with East=X and North=Y.  It is used for relatively small areas (a few kilometers) where the distortion introduced by the projection is minimal. [A conversion utility can be found at:].

Note that conversions cannot be made directly from Local XY to UTM because of the rotation of the UTM grid relative to North and East. Instead, Local XY values must first be converted to Latitude/Longitude
and can then be converted to UTM.