WELMEC standarised gravity formula

ahrs.utils.wgs84.welmec_gravity(lat: float, h: float = 0.0) → float

Reference normal gravity of WELMEC’s gravity zone

Gravity zones are implemented by European States on their territories for weighing instruments that are sensitive to variations of gravity [Sec23].

Manufacturers may adjust their instruments using the reference gravity formula:

\[\mathrm{g} = 9.780318(1 + 0.0053024\sin^2(\phi) - 0.0000058\sin^2(2\phi)) - 0.000003085h\]

where \(\phi\) is the geographical latitude and \(h\) is the height above sea level in meters.

Parameters:

• lat (float) – Geographical Latitude, in decimal degrees.

• h (float, default: 0.0) – Mean sea level height, in meters.

Returns:

g – Normal gravity at given point in space, in m/s^2.

Return type:

float

Examples

>>> ahrs.utils.welmec_gravity(52.3, 80.0)      # latitude = 52.3°, height = 80 m
9.812483709897048