The AMAXDOAS instrument and its application for SCIAMACHY validation

We present a novel spectroscopic instrument operated on aircrafts which will yield profile information for several atmospheric trace gases. The AMAX-DOAS (Airborne Multi-AXis Differential Optical Absorption Spectroscopy) instrument consists of two spectrometers (covering the UV and visible spectral range), each connected to 10 telescopes. Five of which are pointed upwards (i.e. into the stratosphere, when the aircraft operates at its normal cruising altitude at about tropopause level) under different angles while the other 5 telescopes are pointed downwards to the troposphere. Thus, it is possible to separate the tropospheric and stratospheric trace gas columns for a significant number of the observed species (e.g. O3, NO2, OClO, BrO, H2O, SO2, and HCHO). For some of the atmospheric trace gases (most probably for O3 and NO2) it will even be possible to resolve the atmospheric profiles at moderate vertical resolution. The selection of trace gases and the separation of the troposphere and stratosphere makes this instrument ideally suited for the validation of SCIAMACHY on ENVISAT. Together with Lidarand Microwave instruments the AMAXDOAS instruments aboard the DLR Falcon will be used during two major campaigns ranging from the Seychelles to Greenland in 2002 for SCIAMACHY validation. The first test flight of the system was performed in May 2001 and another one is scheduled for December 2001.