Units of Gravity and Geopotential
Gravity is commonly measured in units of m·s−2, (metres per second squared). This also can be expressed (multiplying by the gravitational constant G in order to change units) as newtons per kilogram of attracted mass.
Potential is expressed as gravity times distance, m2·s−2. Travelling one metre in the direction of a gravity vector of strength 1 m·s−2 will increase your potential by 1 m2·s−2. Again employing G as a multipier, the units can be changed to joules per kilogram of attracted mass.
A more convenient unit is the GPU, or geopotential unit: it equals 10 m2·s−2. This means that travelling one metre in the vertical direction, i.e., the direction of the 9.8 m·s−2 ambient gravity, will approximately change your potential by 1 GPU. Which again means that the difference in geopotential, in GPU, of a point with that of sea level can be used as a rough measure of height "above sea level" in metres.
Read more about this topic: Physical Geodesy
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