Get "approximate" lat/long coordinate for UTM grid zone

Question

I have data assigned with a UTM grid zone designators, such as 10S for example. Now I need an approximate latitude/longitude pair, preferably the center point of the given grid zone. Can you give me some advice, on how to map those values?

Answer 1

there are 60 UTM zones starting at -180 of longitude (in other words, one zone is 6 degree wide). Based on this information, you can find the longitude quite easily : (Zone number-1) * 6 - 180 + 3( I've added +3 the center of the zone)

For the latitude, it is less obvious because it is very large. I would take the middle (45 for North and -45 for South). Or you have a letter : in this case, there are 20 latitudinal zones spanning the latitudes 80°S to 84°N and denoted by the letters C to X, ommitting the letter O. You can apply the same type of rule than for the longitude, but be careful for the letter O. The latitude band are of 8 degree, except the X band (12°).

note that you can dowload the grid here

Answer 2

The first digits are the zone number and give you the longitude range. The letter is the latitude band. A good starting point on understanding this is Wikipedia.

Answer 3

Maybe it might be helpful to others; here's what I came up with based on the responses here and some additional research (Java code, validation etc. omitted for brevity):

static final String UTM_BAND_CHARS = "CDEFGHJKLMNPQRSTUVWXX";

public static double[] toLatLng(char band, int zone) {
    int bandIdx = UTM_BAND_CHARS.indexOf(band);
    double lat = bandIdx * 8 - 76;
    double lng = ((zone - 1) * 6) - 177;

    // special case for Norway
    if (band == 'V') {
        if (zone == 31) {
            lng = 1.5;
        } else if (zone == 32) {
            lng = 7.5;
        }
    }
    return new double[] {lat, lng};
}

Answer 4

You can download UTM border shapefiles from the official source http://earth-info.nga.mil/GandG/coordsys/grids/universal_grid_system.html.

Compute the centroid of each zone (an easy task for every GIS software) and save the coordinates of the centroid points for further use.