Explain What You Understand By UTM Coordinates And How They Are Derived

A Universal Transverse Mercator is an accurate projection in narrow zones. A map projection refers to any mathematical transformation of the globe onto some other surface, including many, which cannot be physically realized by any actual optical projection system. One of the widely and familiar used Mercator projection is the cylindrical projection. This projection is used because the world is encircled by an imaginary cylinder touching at the equator with the earth being projected onto the cylinder. This cylindrical projection is different from the cylindrical gnomonic in that the cylindrical projection is not what would result from placing a light at the center of the earth and projecting the surface onto the cylinder unlike the cylindrical gnomonic, which results in very extreme distortions especially in polar regions and therefore; has virtually no practical use. Since the Transverse Mercator is an accurate projection in narrow zones, it has become the common reference for the global coordinate system, which is known as the UTM system (Universal Transverse Mercator System). This system was developed to set the universal world system for mapping.

The world is subdivided into narrow longitude zones, which are projected onto a Transverse Mercator projection. A grid is constructed on the projection, and used to locate points. The upside of the grid system is that, since the grid is rectangular and decimal, it is far easier to use than latitude and longitude. The downside is that, unlike latitude and longitude, there is no way to determine grid locations independently. The Transverse Mercator Projection was used in sixty positions so as to create sixty zones around the world, with each zone six degrees in width. Positions on the earth are measured using Eastings and Northings, and are measured in meters rather than in degrees and minutes, which are the standard units of measurements for Latitudes and Longitudes. Eastings begin at 500,000 on the centre of the earth’s meridian of each zone, while Northings begin at 0 from the equator and increases moving pole wards.

The UTM system divides the earth into 60 zones that are each 60 longitude apart. These zones define the reference points for a UTM grid coordinate within a particular zone. UTM zones extend from latitude 800S to 840N. Within the Polar Regions, the Universal Polar Stereographic grid system becomes used. UTM zones are numbered from 1 to 60 starting at the International Date Line, longitude 1800, and then proceed east. Each zone is then divided into horizontal bands, which are 80latitude. These bands are assigned a letter from south to north beginning with C (omitting I and O in order to avoid confusion with numbers) and later ending with X, which is the latitudinal band and is the only exception that spans 120. When using UTM coordinates, these band letters are included in the description as well as the zone number.

In order to determine one’s location on the globe, one must be in the hemisphere and zone in which they are in. this is because coordinates will be identical from zone to zone without the zone number and zone grid letter. An example of a valid location is 15 S 0342911 E/4302262N, bearing in mind coordinates are given in terms of eastings and northings.

15 represent the UTM zone

S represents the UTM band

0342911E represent Latitude in meters

4302262N represent Longitude in meters

Reference

Garmin Corporation. (2005). Using a Garmin GPS with Paper Maps for Land Navigation. Kansas: Garmin International, Inc