ACRIDICON

In September 2014 the HALO-Mission ACRIDICON (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems) has been started over the Amazon region in Brazil. The aim of the ACRIDICON experiment is to obtain a better understanding of the interaction of aerosols, clouds, and radiation in convective clouds. This airborne mission was accompanied by the ground-based measurement project CHUVA. In addition, the ARM Aerial Facility (AAF) Gulfstream-1 (G-1) has been deployed to obtain measurements of cloud, trace gas, and aerosol properties simultaneously.

enviscope GmbH and Gomolzig Flugzeug- und Maschinenbau (GFM) have been involved in the intense preparation of this challenging mission. The preparation phase included instrument design, manufacturing, documentation, and airworthiness certification for the research aircraft HALO (Gulfstream G550, D-ADLR). Several instruments, which have successfully been operated in the previous mission ML-CIRRUS, had to be re-certified after modifications or checked to certify continued airworthiness. Additionally new in-situ and remote sensing systems were developed and adapted to the HALO aircraft:

• ICU (Inlet Control Unit), developed by enviscope for controlled heating of the intake systems CVI and HASIfor scientific purposes.
• HALO_CCN-Rack, designed/adapted/certified in co-operation with Max-Planck-Institute for Chemistry, Mainz in order to measure aerosol. It encompasses two commercial instruments (SP2 and CCN200 developed by Droplet Measurement Technologies) and an impactor for subsequent particle analysis in the laboratory.
• HALO_C-ToF-AMS, a Time of Flight Aerosol Mass Spectrometer, Max-Planck-Institute for Chemistry, Mainz.
• HALO_AMTEX_TDS, Institute for Atmospheric Physics, DLR Oberpfaffenhofen consisting of modified commercial analyzers (O₃ and CO) and a trace gas sampling system.
• HALO_EAGLE&HAWK, two hyperspectral camera systems (visible and near-infrared) provided by Leipzig Institute for Meteorology and Univerity of München to investigate microphysical properties of clouds. This remote sensing system was adapted into a rack and is looking through two optical windows installed in the side viewport SVP_VIS&NIR.
• HALO_SVP_VIS&NIR, a side viewport designed by enviscope which provides mounting frames for optical windows. These windows can be changed according to scientific purposes.

We are looking forward to the next challenge OMO…., a HALO mission to study oxidation mechanisms.