User guide

Units (gmeterpy.units)

The unit aware calculations is one of the main goals of the gMeterPy. We are using astropy.units sub-package for this. To use units you need to import gmeterpy.units module:

>>> import gmeterpy.units as u

And now you can work with gravity acceleration SI units:

>>> gravity = 9.8 * u.m / u.s**2
>>> gravity
<Quantity 9.8 m / s2>

and convert them to more convinient CGS units:

>>> gravity.to(u.Gal)
<Quantity 980. Gal>

and even use prefixes (u – micro):

>>> gravity.to(u.uGal)
<Quantity 9.8e+08 uGal>

In addition to Astropy built-in units we introduce Eotvos unit for the gravity gradient:

>>> gradient = 0.3086 * u.mGal / u.m
>>> gradient.to(u.E)
<Quantity 3086. E>

Constants (gmeterpy.constants)

The gMeterPy uses astropy.constants sub-package for handling constants. We expand it for some frequently used constants in gravimetry.

Constant

Description

omega

Mean angular rotation rate of the Earth

atm_sens

Default gravity/pressure sensitivity (0.3 uGal / mbar)

International Standard Atmosphere

The Standard Atmosphere (ISO 2533:1975) is used to calculate the normal pressure in the atmospheric pressure correction.

Constant

Description

p0

Standard atmospheric pressure at sea level

L

Temperature lapse rate

Tn

Standard thermodynamic air temperature at sea level

gn

Standard acceleration of free-fall

M

Air molar mass at sea level

R

Universal gas constant