Returns atmospheric correction value [ppm]. Multiply by 10e-6 before applying the correction value to a slope distance [m]. If no relative humidity is passed, the default 60 % of the instrument is used instead.
The slope distance displayed is correct if the scale correction in ppm, mm/km, which has been entered corresponds to the atmospheric conditions prevailing at the time of the measurement.
The atmospheric correction includes:
For highest precision distance measurements, the atmospheric correction should be determined with an accuracy of 1 ppm. The following parameters must be redetermined:
The air humidity influences the distance measurement if the climate is extremely hot and damp. For high precision measurements, the relative humidity must be measured and entered along with the air pressure and the temperature.
If the basic value of 60 % relative humidity as used by the EDM is retained, the maximum possible error in the calculated atmospheric correction is 2 ppm, 2 mm/km.
The formula for visible red laser is taken from the Leica TM30/TS30 User Manual, p. 76.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| real(kind=r8), | intent(in) | :: | temperature |
Air temperature [°C]. |
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| real(kind=r8), | intent(in) | :: | pressure |
Air pressure [mbar, hPa]. |
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| real(kind=r8), | intent(in), | optional | :: | humidity |
Relative humidity from 0.0 to 1.0. |