ACTOS

Airborne Cloud Turbulence Observation System

On behalf of the Institute for Tropspheric Research (IfT) in Leipzig, Germany, enviscope constructed an instrument container which serves as platform for Cloud Turbulence Measurements and which can be carried by a tethered ballon system up to a height of 2000 m above ground.

The instrument platform ACTOS allows the undisturbed measurement of atmospheric turbulence parameters. To ensure proper turbulence measurements, a 150 cm forward looking extension arm made of CRP (Carbon-fibre-Reinforced Plastic) has been fixed to the front of the instrument carrying body of ACTOS. This extension arm carries the major sensors which are:

  • Ultrasonic Anemometer (Gill Research HS)
  • Ultra Fast Thermometer System (UFT)
  • Particulate Volume Monitor (PVM-100)
  • FastFSSP droplet spectrometer
  • on-board video camera
  • two aerosol pre-impactors for droplet and coarse aerosol separation
  • ventilated and radiation protected humidity and temperature measuring duct

The instrument body of ACTOS carries the remainig instrumentation, which mainly consists of

  • Inertial Navigation System (INS) in combination with a TRIMBLE TansVector GPS
  • data acquisition systems
  • two Condensation Particle Counters (CPCs)
  • telemetry systems for data and video signals
  • Li-Ion battery pack

ACTOS has been operated successfully during the Baltex Bridge Campaigns (BBC) in Cabauw (the Netherlands) in the years 2001 and 2003, and the SATURN experiment in Melpitz (near Leipzig, Germany). In spring 2004 the last experiment with MAPS-Y has been carried out within the frame of the European Joint Experiment INSPECTRO II in Osterhofen (Southern Germany).

Since 2005 ACTOS is operated with a Helicopter, type Bell 206 Longranger III of our co-operating partner Rotorflug GmbH in Friedrichsdorf (Germany). For more information on the Helicopter serving as platform for airborne measurements please refer to our page on helicopter measurements. A recent publication on the helicopter-borne measurements with ACTOS can be found here:

Siebert et al. 2006: Probing finescale dynamics and microphysics of clouds with helicopter-borne measurements, Bulletin of the American Meteorological Society, 87, 1727-1738.


For more information on ACTOS please contact Dr. Holger Siebert, who is the responsible scientist for the Air(ship)-borne Cloud Turbulence Observation System at the Institute for Tropospheric Research in Leipzig / Germany.