Comparison of Lyman-alpha and LI-COR infrared hygrometers for airborne measurement of turbulent fluctuations of water vapour

Sammanfattning

To investigate if the LI-COR humidity sensor can be used as a replacement of the Lyman-alpha sensor for airborne applications, the measurement data of the Lyman-alpha and several LI-COR sensors are analysed in direct intercomparison flights on different airborne platforms. One vibration isolated closed-path and two non-isolated open-path LI-COR sensors were installed on a Dornier 128 twin engine turbo-prop aircraft. The closed-path sensor provided absolute values and fluctuations of the water vapour mixing ratio in good agreement with the Lyman-alpha. The signals of the two open-path sensors showed considerable high-frequency noise, and the absolute value of the mixing ratio was observed to drift with time in this vibrational environment.On the helicopter-towed sensor system Helipod, with very low vibration levels, the open-path LI-COR sensor agreed very well with the Lyman-alpha sensor over the entire frequency range up to 3 Hz.The results show that the LI-COR sensors are well suited for airborne measurements of humidity fluctuations, provided that a vibrationless environment is given, and this turns out to be more important than close sensor spacing.

Publicerad i

Atmospheric Measurement Techniques
2018, Volym: 11, nummer: 4, sidor: 2523-2536
Utgivare: COPERNICUS GESELLSCHAFT MBH

SLU författare

• Larmanou, Eric

  • Enheten för skoglig fältforskning, Sveriges lantbruksuniversitet
    
  • Deutsches GeoForschungsZentrum GFZ

UKÄ forskningsämne

Meteorologi och atmosfärforskning


Publikationens identifierare

DOI: https://doi.org/10.5194/amt-11-2523-2018

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/95318