First successful test mission on board of research aircraft HALO

A first test mission with the Jena Instrument for Greenhouse Gases (JIG) on board of the German High Altitude and LOng Range (HALO) research aircraft was completed successfully in May 2015.

The mission was conducted to test an active remote sensing system measuring column abundances of carbon dioxide (CO₂) and methane (CH₄), developed by the LIDAR group at the DLR Institute of Atmospheric Physics. This system is a so-called airborne simulator for the upcoming MERLIN (Methane Remote Sensing LIDAR Mission) satellite. MERLIN is a German-French climate mission, scheduled currently for launch in 2019.

The airborne LIDAR system uses pulsed laser light, and detects the backscatter from the surface or from clouds as a function of time, providing path length information as well as absorption along the path. The goal of the mission was to evaluate the CO₂/CH₄ LIDAR with the in-situ observations made by JIG, which was originally designed for operation on board of a fleet of passenger aircraft within the ESFRI project 'In-service Aircraft for a Global Observing System' (IAGOS).

The Jena Instrument for Greenhouse Gases, developed as IAGOS P2d for greenhouse gas measurement on board passenger aircraft, was deployed on board HALO during April-May 2015.

JIG uses Cavity Ring-Down Spectroscopy (CRDS) to measure the greenhouse gases carbon dioxide and methane as well as carbon monoxide (CO) and water vapor (H₂O). Measurements are referenced to the World Meteorological Organization (WMO) calibration scales by means of in-flight calibration using compressed gas cylinders.

Carbon dioxide, methane and carbon monoxide mole fractions recorded during a descend over Parma in the Po valley in northern Italy.

After a first test flight ensuring no interference of the measurement systems with the aircraft operation, the mission targeted areas with different surface characteristics to assess the impact on the LIDAR signal. Furthermore, different methane source areas such as the Po valley with intensive agriculture and livestock, and the Silesian coalmines in Poland, were overflown by HALO in order to evaluate the potential of the scientific payload for source detection and quantification. Both instruments performed well throughout the five flights, with a total flight time of about 20 hours. First preliminary data by JIG have been processed; LIDAR data processing is ongoing at the moment.

Future missions planned for 2017 will use a payload augmented by passive remote sensing instruments and by flask a sampling system to allow for analysis of air samples for their isotopic composition, which further helps identifying specific processes contributing to GHG emissions.