Fine-scale Measurements of Turbulence in the Lower Troposphere: an Intercomparison between a Kite- and Balloon-borne, and a Helicopter-borne Measurement System

Two state-of-the-art, high-resolution, in situ turbulence measurement systems, which can be deployed at altitudes well above the atmospheric surface layer, are compared: the Tethered Lifting System (TLS) of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, Boulder, Colorado, and the helicopter-borne turbulence measurement system HELIPOD of the Technical University Braunschweig, Germany, and the University of Hanover, Germany. While the CIRES TLS is a fixed-point platform, HELIPOD is a moving platform. On the basis of data taken with the two systems in separate field campaigns, the system capabilities are quantified and discussed. Criteria for instrumental requirements are presented. It is shown that both the CIRES TLS and HELIPOD are well suited for measuring fine-scale turbulence that is characterized by very small temperature structure parameters (10−6 K2 m−2/3 and smaller) and very small energy dissipation rates (10−7 m2 s−3 and smaller). The authors are not aware of any other turbulence measurement systems that have similar capabilities and can be deployed at altitudes of up to several kilometres. The HELIPOD is ideal for high-resolution horizontal measurements while the TLS is ideal for high-resolution vertical measurements using multiple sensors attached to a suspended line.