OBSERVATION OF STRATOSPHERIC OH AT 2.5 THZ WITH AN AIRBORNE HETERODYNE SYSTEM

First remote measurements of stratospheric OH with an airborne vertica l sounding far-infrared (FIR) heterodyne spectrometer are reported: Th ermal emission from rotational transitions at 2,514 GHz were observed. The measurements were carried out from aboard the DLR jet aircraft FA LCON at about 11 km altitude flying over Germany. Temperature contrast was optimized by observing at elevation angles around 20 degrees. A p revious feasibility study showed that improvements in stability and se nsitivity will allow tile determination of concentration profiles with an altitude resolution of about 10 km over an altitude range from 20 to 50 km.