Latitude and Longitude: Latitude refers to the angular distance that a point on the surface of the earth is located north or south from the equator, from 0 degrees at the equator to 90 degrees north and –90 degrees south. Longitude refers to the angular distance of this point east or west from the Prime Meridian, from 0 degrees at the Prime Meridian to 180 degrees east and –180 degrees west. Each degree of latitude covers the same distance on the ground (disregarding variations in the curvature of the surface of the earth), while each degree of longitude varies in distance on the ground depending on how far north or south the equator it lays.
Each degree of latitude and longitude is sub-divided into 60 minutes, and each degree into 60 seconds. Several formats represent these subdivisions - the most common formats that we use are Decimal Degrees and Degrees-Decimal Minutes.
In the Decimal-degrees format, latitude and longitude are single numbers with degrees as the whole number portion and minutes and seconds as the decimal portion of the number. For example, a latitude of 45°34’45” (45 degrees, 34 minutes, and 45 seconds north of the equator) is calculated as 45 + 34 Minutes/60 Minutes per Degree + 45/3600 Seconds per Degree, or 45.579 degrees. The absence of a negative sign indicates that this coordinate is north of the equator.
Degrees- Decimal Minutes representations use whole numbers for the degree portion of the coordinate, and a decimal number for Minutes and Seconds. For example, -122.35456 degrees longitude (west of the Prime Meridian, indicated by the negative sign), the degree number is 122 and 0.35456 * 60 minutes per degree represents the minutes and seconds, giving -122 21.27.
| 45°34'45" | 45.579 | -122.35456 | -122 21.27 |
| Degrees Minutes Seconds | Decimal Degrees | Decimal Degrees | Degrees Decimal Minutes |
UTM: (Universal Transverse Mercator) is a U.S. military-developed system that divides the earth into a series of zones. Locations in each zone are indicated by an easting (distance in meters from the central meridian) and a northing (distance in meters from the equator). Oregon and Washington lie in UTM Zones 10N and 11N.
State Plane Coordinate System: Each state in the United States is divided into state plane zones, and coordinates are usually measured in feet. Oregon and Washington are divided into two zones each – north and south.
If you plan on providing coordinate data for your project, please indicate which coordinate system the data is derived from and what units of measurement the coordinates are in.
