Gill GMX100 User Manual page 134

Gill Instruments Ltd
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Pressure at Se a Level
PASL
Outputs Barometric Pressure at Sea Level if HASL figure set (see page 63).
Where: P = adjusted pressure
Pb = pressure (pascals) - as measured by the pressure sensor
Tb = temperature (K)
Lb = standard temperature lapse rate (K/m) in ISA. For the Troposphere this is assumed to be -
0.0065 Kelvin/metre.
h = height (meters) = sensor's height above (or below) sea level, i.e. 'Height Above Sea Level' plus
'Height Above Station'
R = universal gas constant for air: 8.31432 N•m /(mol•K)
g0 = gravitational acceleration (9.80665 m/s2)
M = molar mass of Earth's air (0.0289644 kg/mol)
Result e.g. 1015.7 (hectopascals default).
PSTN - Pressure at Station
Outputs Barometric Pressure at Station (which can be positioned anywhere) if HASTN figure set (see below
and page 63).
Pressure at station shall be computed as:
Where: P = adjusted pressure
Pb = pressure (pascals) - as measured by the pressure sensor
Tb = temperature (K)
Lb = standard temperature lapse rate (K/m) in ISA. For the Troposphere this is assumed to be -
0.0065 Kelvin/metre.
h = height (meters) = 'Height Above Station', i.e. the difference between the sensor height above
(or below) local ground level.
R = universal gas constant for air: 8.31432 N•m /(mol•K)
g0 = gravitational acceleration (9.80665 m/s2)
M = molar mass of Earth's air (0.0289644 kg/mol)
Result e.g. 1001.2 (hectopascals default).
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Issue 3
May 2018