MK 2 precision aneroid barometer (photo by G. Allen, Met Office)
The following text is based on an Aneroid barometer reading, if the reading is taken from
another kind of barometer please use corrections as advised by your PMO, Offshore Adviser
or Meteorological Service.
In general the aneroid barometer should be set to read the pressure at the level of the
instrument. On board ships and at fixed sea stations (rig, platform) however, the instrument
may be set to indicate the pressure at Mean Sea Level, provided the difference between the
station pressure and the Mean Sea Level pressure can be regarded as constant. The reading
should be corrected for instrumental errors. If the pressure reading is not indicating the
pressure at Mean Sea Level this program will correct the (instrument error corrected) reading
to Mean Sea Level. The computed and automatically applied Height correction (sometimes
called altitude correction or reduction constant) depends on the information provided by the
observer.
Fuess aneroid barometer in use by for instance DWD and KNMI (photo KNMI)
Vaisala PTB330 increasingly used on VOS
NOTE (auxiliary ships only)
- Because auxiliary ships
are not equipped with tested instruments permitting the
determination of tenths of hPa of pressure, tenths cannot be inserted.
