Geography: UTM coordinates

Tutoring math, number-oriented topics naturally arise. The tutor gives some simple points about the UTM coordinate system.

UTM stands for Universal Transverse Mercator: it produces a grid on Earth from which locations can be referenced.

UTM organizes the Earth, from the International Date Line towards east, into 60 zones, each six degrees wide. The zones are numbered 1 to 60; here, in Campbell River, we’re in zone 10.

From the South Pole to North Pole, there are reference lines lettered C to X that suggest latitude.

The numbers, going east, and the letters, going north, make a grid. Here in Campbell River, we are in square 10U.

The north (or south) coordinate of UTM is absolute, measured from the equator; the east coordinate, however, is measured relative to the zone the location is in.

Coordinates are measured in metres. Possibly confusing, the east reference point of a zone is located 500,000 metres (500km) west of its centre. Since the zones are less than 1000km (1,000,000m) wide, an east coordinate of zero will never happen. If a zone is 400km wide (they get narrower as you go north, since they converge at the equator), the east coordinate of a location within it could be from 300,000 to 700,000.

Since the north (or south) coordinates are absolute, the letter of the UTM grid square is not always used. Campbell River is in square 10U, but its coordinates might be given zone 10, E:337,196 N:5,544,789.

That’s UTM as I understand it.



Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

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