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Online Barometer Comparison Self Check Service for Vessels

Port Meteorological Officer (PMO) under the Voluntary Observing Ship (VOS) scheme is a representative of the National Meteorological and Hydrological Services (NMHS) to liaise with shipping community and take care of a fleet of voluntary observing ships.  One of the important duties is to calibrate barometers onboard during regular VOS visits.  Accurate atmospheric pressure readings are crucial for mariners to appreciate the general weather conditions at high seas.  As ship visits have been suspended since the outbreak of the COVID-19 pandemic, on-site calibration of ship barometers by PMO becomes impracticable.  In this regard, the provision of barometer calibration service is currently performed remotely by inviting shipmasters to send a completed "Barometer Comparison Check Service Request Form" with pressure and temperature readings together with ship parameters to the PMO by email when the ship is berthing at Hong Kong.  The PMO will then compute a set of correction indexes and send back to the shipmasters for barometer calibration by themselves.

To further enhance this service, a new e-form for Barometer Comparison Self-check Service has been developed for vessels (Figure 1) to facilitate acquiring the correction indexes by the ship crew to calibrate the barometer onboard the ships when berthing at Hong Kong port.  The ship crews simply input to the e-form the outboard air pressure and air temperature readings as well as information on the height of the barometer onboard the ship.  The correction indexes and total correction (Figure 2) will then be computed automatically for them to adjust the ship barometers and remove the instrumental bias in order to obtain the mean sea level pressure data.  The ship crew now can obtain the calibration results at any time without awaiting for the reply by PMO.  This new service further streamlines the whole process and enhances the efficiency.

Figure 1. Barometer Comparison Self-check Service for vessel webpage. 

Figure 2. Calibration results from the barometer comparison self-check service.

The Barometer Comparison Self-check Service can be accessed via the following links: (English) (Chinese) 

Details of the procedure can be found in the user guide on the e-form.

Chow Chi Kin and Dickson Lau