Marque IPSL


SAWfPHY (for Surface Acoustic Wave frost-Point HYgrometer) is an instrument capable of measuring stratospheric water vapor. Figure SAWfPHY : SAWfPHY’s sensing head, cooled by a Peltier TEC element.

It was designed at LMD within the Stratéole-2 project to study troposphere-stratosphere exchanges in the tropics. SAWfPHY made its first stratospheric superpressure balloon flight in Seychelles Islands in 2019.
The instrument is a frost point hygrometer, using surface acoustic waves for condensate detection. The sensitive element of SAWfPHY is developed by FEMTO-ST ( in Besançon, France.


Figure SAWfPHY : SAWfPHY inlet and radiator used during its first long-duration flight in Seychelles in 2019.