The MAX-DOAS is a remote sensing instrument collecting scattered sunlight in the UV and visible wavelength range. Applying the differential optical absorption spectroscopy (DOAS) which is based on Lambert-Beer's law it is possible to quantify the amount of trace gases in the atmosphere.

The Bremen MAX-DOAS instrument consists of a grating spectrometer equipped with a cooled CCD detector and a separate telescope unit connected to the main instrument via a quartz fibre bundle. The spectrometer is temperature stabilized to avoid wavelength drifts. Although the CCD used is a 2-dimensional detector, it is operated in full vertical binning for optimal signal to noise. The quartz fibre bundle efficiently depolarizes the incoming light and also provides flexibility for instrument set-up.

To optimize spectral coverage and resolution, the Bremen MAX-DOAS Instrument are equipped with two spectrometers, one for the UV and one for the visible part of the spectrum. The instruments share the telescope unit through a quartz fibre bundle that splits into two ends on the spectrometer side.

Several in situ instruments are used in the project to measure local volumes of different trace gases such as nitrogen oxides (NO_x), sulfur dioxide (SO₂), carbon dioxide (CO₂), and ozone (O₃).