UTM Grid System (Especially for GATE-Geospatial 2022)

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Definition

UTM stands for Universal Transverse Mercator. The UTM geographic coordinate system is a grid-based method of specifying locations on the surface of the earth that is a practical application of a 2-dimensional Cartesian coordinate system.

How Universal Transverse Mercator (UTM) Works

UTM divides the earth from latitude 84 degree north and 80 degree south latitude into 60 vertical zones. There are 60 longitudinal projection zones numbered 1 to 60 starting at , each of these zones is 6 degrees wide. The first zone begins at the International Date Line. The zones are numbered from west to east, so zone 2 begins at and extends to . The last zone begins at and extends to the International Date Line.

There are 20 latitudinal zones spanning the latitudes S to N and denoted by the letters C to X, omitting the letter I and O. note that letter N designates the first latitude band above the equator, so any letter of alphabet after N refer to a band in northern hemisphere and any letter before N refers to a band in southern hemisphere. Each of these is 8 degree south-north, a part from zone x which is 12 degree south-north.

This Figure Shows Universal Transverse Mercator System

Each zone has a central meridian which extends north-south along the middle of the zone, splitting the zone into two equal halves. For example, as shown in the figure, zone 28 is bounded by W meridian to the left and W meridian to the right. The central meridian of the zone lies along W meridian or line of longitude.

Zone divisions with horizontal bands, as above result in each division having dimensions of longitude wide and latitude high. Where dimensions of some zones are adjusted. The northernmost band (X) is latitude high instead of and extends from N to N latitudes. Zone 32V covering west coast of Norway is widened to longitude instead of , resulting in narrowing of zone 31V. Zones 33X and 35X have been widened to to cover Svalbard. Similarly zones 31X and 37X are widened to As a result zones 32X, 34X, and 36X have been omitted.

False Easting and Northing

Using latitude and longitude, each wide UTM zone has a Central Meridian of meters. This central meridian is an arbitrary value convenient for avoiding any negative easting coordinates. All easting values east and west of the central meridian will be positive.

This Figure Shows Central Meridian and Zone Function in UTM …

In the southern hemisphere, the equator starts at meters because all values south of the equator will be positive. This is called a false northing because y-coordinates in the southern geographic region will avoid negative values.

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