What is UTM in geodesy?

• A. A 3D coordinate system with 360 longitudinal zones using the Mercator projection; coordinates are Latitude and Longitude.
• B. A 2D projected coordinate system with 60 longitudinal zones using a transverse Mercator projection; coordinates are Easting and Northing with a zone-based false origin.
• C. A height system based on ellipsoidal elevations and gravity anomalies.
• D. A global geodetic datum without zones.

Answer: (B)

UTM, or Universal Transverse Mercator, is a 2D projected coordinate system designed for mapping small to regional areas in meters. It splits the world into 60 zones, each 6 degrees wide in longitude, and applies the Transverse Mercator projection within each zone to keep distortion minimal along a central meridian. Coordinates are expressed as Easting and Northing in meters, with a zone-specific false origin: a 500,000 meter false easting to ensure positive eastings, and a 10,000,000 meter false northing in the southern hemisphere to keep northings positive. This setup distinguishes UTM from global latitude/longitude systems and from height-based or single-datum systems without zones.