Responsible: Stefan Lossow, Jörg Gumbel, Jacek Stegman, in collaboration with Joachim Urban, Nicolas Lautie, Patrick Eriksson, Donal Murtagh (Chalmers University of Technology)
The submillimeter radiometer (SMR) onboard the Odin satellite measures many minor constistuents globally in the middle atmosphere using the frequency range between 486 and 581 GHz. Among the three water vapour lines measured in this frequency range the line at 556.936 GHz is of major interest for the mesosphere. Using a non-linear scheme based on the optimal estimation method (OEM), abundance informations up to 100 km can be derived with an altitude resolution between 3 and 4 km. Up to now just a small fraction of the measurements have been processed and also the optimisation of the non-linear scheme is further ongoing.
Apart from the global distribution of water vapour the scientific focus is mainly on the polar mesopause region, which exhibits layered phenomena during the summer season, like noctilucent clouds (NLC). In order to clarify the relationship between the water vapour distribution and the existence of ice particles forming the NLC, the Odin-SMR water measurements has to be merged together with measurements of OSIRIS (Optical Spectrograph and Infrared Imaging System) onboard Odin, which provides informations about the scattering of UV and visible light. Every 9th day and, in addition, during two weeks of an annual summer mesosphere mission, Odin is therefore performing only measurements in aeronomy mode scanning up to 110 km, to provide extensive coverage with high temporal resolution.
In January 2005, the Odin water vapour measurements was complemented and validated by rocket and balloon measurements during the MAGIC campaign from Esrange, Sweden.
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Last updated: January 11, 2006
Jörg Gumbel (gumbel@misu.su.se)