On the effect of moisture on the detection of tropospheric turbulence from in situ measurements

• Main Authors: R. Wilson, H. Luce, H. Hashiguchi, M. Shiotani, F. Dalaudier
• Format: Article
• Language: English
• Published: Copernicus Publications 2013-03-01
• Series: Atmospheric Measurement Techniques
• Online Access: http://www.atmos-meas-tech.net/6/697/2013/amt-6-697-2013.pdf

The present paper addresses the detection of turbulence based on the Thorpe (1977) method applied to an atmosphere where saturation of water vapor occurs. The detection method proposed by Thorpe relies on the sorting in ascending order of a measured profile of a variable conserved through adiabatic processes, (e.g. potential temperature). For saturated air, the reordering should be applied to a moist-conservative potential temperature, θ_m, which is analogous to potential temperature for a dry (subsaturated) atmosphere. Here, θ_m is estimated from the Brunt–Väisälä frequency derived by Lalas and Einaudi (1974) in a saturated atmosphere. The application to balloon data shows that the effective turbulent fraction of the troposphere can dramatically increase when saturation is taken into account. Preliminary results of comparisons with data simultaneously collected from the VHF Middle and Upper atmosphere radar (MUR, Japan) seem to give credence to the proposed approach.