Water Vapor Measurement

Water Vapor Measurement (WVM) Development


Benefits of Water Vapor Measurement, chapter 5

History of Water Vapor Measurement

Supplemental Type Certificate (STC) process

Aircraft-based Humidity Measurement flyer


Water vapor plays a key role in the atmosphere and is a critical meteorological variable in most severe weather elements. Accurate and frequent measurements of its intensity and location are essential for weather forecasting and will significantly improve weather services for flight operations. Provision of water vapor makes the AMDAR system commensurate with the radiosonde observing system in terms of the elements measured and the quality of the data obtained. The cheaper operation costs and no waste from consumable products disposed of into the environment are advantages for aircraft-based water vapor measurement compared to radio soundings. 

Three hygrometers suited to airliners have reached the level of operational deployment: the Tropospheric Airborne Meteorological Data Reporting sensor system (TAMDAR, FLYHT Aerospace Solutions Ltd.), the modified capacitive hygrometer developed in the frame of the MOZAIC and IAGOS research programmes, and the Water Vapour Sensing Systems (WVSS-II, FLYHT Aerospace Solutions Ltd.).

The US-AMDAR programme currently has the WVSS-II sensor operationally installed on more than 135 aircraft and the E-ABO programme has installed the equipment on 9 aircraft.

The benefits of water vapor measurement are described in detail in WMO WIGOS Technical Report 2021-1, linked above.