Explanatory Items > 4

4 Coordinates

The coordinates of plot and subplot centres or reference points are specified in:

Degrees Minutes Seconds (D° M’ S“) with a leading “+” or “-”

GENERAL REMARKS

Datum

All coordinates used in the ICP Forests database are based on the datum WGS84 (World Geodetic System 1984).

Latitude

Examples in the format used by the ICP Forests database:

50 degree, 20 minutes, 27 seconds North BECOMES +502027

9 degree, 5 minutes, 7 seconds North BECOMES +090507

Location and distance:

  • north-south position

  • positive values = Northern Hemisphere (North of the equator)

  • negative values = Southern Hemisphere (South of the equator)

  • 1 degree ~ 111.1 km

  • 1 minute ~ 1.852km

  • 1 second ~ 30.5m

Longitude

Examples in the format used by the ICP Forests database:

2 degree, 37 minutes, 9 seconds West BECOMES -023709

17 degree, 40 minutes, 45 seconds East BECOMES +174045

Location and distance:

  • east-west position

  • positive values = East of the prime meridian in Greenwich

  • negative values = West of the prime meridian in Greenwich

  • 1 degree ~ 111.1 x cos(latitude) km

  • 1 minute ~ (111.1 x cos(latitude)) / 60 km

  • 1 second ~ (111.1 x cos(latitude)) / 3.6 m

Examples from the area of the ICP Forests network:

location Latitude (N) 1 degree 1 minute 1 second
Madrid 40° 85km 1.42km 23.6m
Warsaw 52° 68km 1.14km 18.9m
North Norway 70° 38km 0.63km 10.5m

REPRESENTATIONS

The same geographic coordinates can be represented in different formats:

  • Degree Minutes Seconds (D° M’ S“) - Used in the ICP Forests database

  • Decimal Degrees (D.D°) - Representation as a single number sequence

  • Decimal Minutes (D° M.M’) - Default in many GPS units

CONVERSIONS

Degrees Minutes Seconds (D° M’ S“) TO Decimal Degrees (D.D°)

D.D° = d + (m/60) + (s/3600)

EXAMPLE:

D° M' S" = 30d 14m 4s

D.D° = 30 + (14/60) + (4/3600) = 30.2344444°

Degrees Minutes Seconds (D° M’ S“) TO Decimal Minutes (D° M.M’)

D° M.M’ = d AND m + (s/60)

EXAMPLE:

D° M' S" = 30d 14m 4s

D° M.M' = 30 AND 14 + (4/60) = 30° 14.066666'

Decimal Degrees (D.D°) TO Degrees Minutes Seconds (D° M’ S“)

d = integer(D.D°)

m = integer((D.D° - d) × 60)

s = integer((D.D° - d - m/60) × 3600)

EXAMPLE:

D.D° = 30.2345555

d = integer(30.2345555) = 30°

m = integer((30.2345555 - 30) × 60) = 14'

s = integer((30.2345555 - 30 - 14/60) × 3600) = 4''

ICP Forests format: "+301404"

Note - This conversion inculdes a loss of precision!

Decimal Minutes (D° M.M’) TO Degrees Minutes Seconds (D° M’ S“)

d = D° FROM D° M.M’

m = integer(M.M’)

s = round(M.M’ - integer(M.M’)) x 60

EXAMPLE:

D° M.M' = 30° 14.066666'

d = 30

m = integer(14.066666) = 14

s = round(14.066666 - integer(14.066666)) x 60 = 4

Abbreviations:

d = degrees

m = minutes

s = seconds

D.D° = Decimal Degrees

D° M' S" = Degrees Minutes Seconds

D° M.M' = Decimal Minutes