Airborne Research and Innovation

Humidity System

Modified Meteolabor TP3-ST dewpoint and Viasala HMP45C relative humidity sensors form the core of a dedicated humidity sensing system.

The humidity system sensors are enclosed within the main MET system enclosure and aspirated via a small pump and flow controller. The sensors are temperature stabilised to prevent condensation and to reduce the number of variables affecting performance, and are maintained at a slight positive pressure to prevent entrainment of local air.

The principle sensors employed are:

Meteolabor TP3-ST chilled mirror dewpoint hygrometer

Viasala HMP45C relative humidity sensor

Pressure in each sensor housing is measured to allow us to calculate the mixing ratio; Druck RPT410F pressure sensors are used for this.

A Licor 7500 open path gas analyser, and a Picarro G2301m CRDS analyser also provide humidity measurements, but are described separately.