International scientists from China, the United Kingdom, the United States and Germany (from ZMT/IUP Bremen, IOW Warnemünde and GEOMAR Kiel) went for an one-week intercalibration cruise on the Baltic Sea which started and ended in Warnemünde, Northeast Germany. Marco Drews, PhD student at ZMT, attended the sea cruise to measure the trace gases methane (CH4) and nitrous oxides (N2O) using a Fourier Transformation Infrared spectrometer. Several transects through varying concentrations of CH4 and N2O were investigated to find out, whether measurements of these gases by different working groups and different instruments are comparable under the same conditions. Methane as well as nitrous oxides are major greenhouse gases contributing to global warming. Thus, they are of interest for many working groups worldwide. The results will be communicated as recommendations to the Scientific Committee for Oceanic Research (SCOR). The full press release from our cooperation partner and head of this expedition, the IOW, is available here.