(4 July 1998 -UTM)
(15 June 2007 -Add UPS)


UTM, Universal Transverse Mercator, is a system of world coordinates like latitude and longitude, from 80 degrees south latitude to 84 degrees north latitude, except the measurements are in meters and UTM lines are orthogonal (always at right-angles to each other).  This projection makes all latitude and longitude lines (except the central meridians) curved.

Unlike the regular Mercator, "Transverse Mercator" is a projection with the cylinders rotated 90 Deg (to east-west) and touch the earth "universally" at 60 "central meridian" longitudes. Coordinates are "UTM northing" and "UTM easting."

UTM Northing is the distance north from the equator in meters and Easting is the distance east from 60 central meridians of 6-degree-wide zones starting at longitude 180 degrees.

UTM Northing is divided into 8-degree-high zones from 80 Deg. south latitude to 84 Deg. north latitude using the letters C thru X with the equator at M/N.  A,B and Y,Z are reserved for the UPS coordinate system at the poles. For a map of UTM zones see (HERE).

All UTM coordinates are POSITIVE by incorporating a system of "false" easting and northing.  Adding an arbitrary 500,000m to the central meridians and subtracting the distance south of the equator from 10,000,000m in the southern hemisphere keeps all readings positive.

The UTM map scale increases to either side of the central meridian, so the scale is reduced to 0.9996.  This way there will be two meridians to either side of the central meridian where the scale will be correct which improves the average map scale accuracy.

The original definition of the meter was 1/10,000,000th the distance from the equator to the north pole (which is no longer exact.)  Due to the oblate shape of the earth, UTM (WGS-84 datum) northing for 45 Deg. N latitude is 4,986,272m instead of 5,000,000m. For UTM (NAD-27 datum) the northing value is 4,986,055m.

This 217m difference is related to the UTM northing errors of approximately 200m experienced by posters here on the NG with some DRG maps.  This is due the program, GPS, or user selecting the wrong datum.


THE UNIVERSAL POLAR STEREOGRAPHIC (UPS) SYSTEM coordinates are based on a family of two Polar Stereographic map projections, one for each pole.  The UPS system is defined above 84 degrees north latitude and south of 80 degrees south latitude.  The origin of the UPS coordinate system are the poles (north or south), where both the X and Y coordinate values are 2,000,000m.

The X-axis lies along the meridians 90°E and 90°W. Moving from the pole (north or south), X-values (Eastings) increase along the 90°E meridian and decrease along the 90°W meridian.
The Y-axis lies along the meridians 0° and 180°. Moving from the north pole, Y-values (Northings) increase along the 180° meridian and decrease along the 0° meridian.

(Now don't confuse the "X" and "Y" Axis' with the Zones!!)
Zone Y is the Western Hemisphere.  Zone Z is the Eastern hemisphere.

With the unit set to a Position Format of UTM UPS,
At the North Pole both Easting and Northing are 2,000,000m

(NOTES: The unit will convert from UTM to UPS automatically when traveling northward.
WAAS should be turned OFF, since there are no SBAS corrections at either pole.)

Examples of What a Garmin GPS will Display (In a walk around the North Pole) in UPS Meters

Waypoint:               (A)            (B)            (C)            (D)
Location:            N88° W089°     N88° W001°     N88° E001°     N88° E089°

GPS Readouts

(X Axis, Easting)     Y 1777952      Y 1996124      Z 2003876      Z 2222048
(Y Axis, Northing)  UTM 1996124    UTM 1777952    UTM 1777952    UTM 1996124

Get these waypoints (HERE)

  Jack Yeazel