Nitric Oxide Retrieval with SCIAMACHY
Bender, Stefan¹; Sinnhuber, Miriam¹; Langowski, Martin²; Burrows, John²; Funke, Bernd³; López-Puertas, Manuel^3
1KIT, Karlsruhe, GERMANY; ²IUP, Uni Bremen, GERMANY; ³IAA, CSIC, Granada, SPAIN

From 07/2008 until 04/2012, SCIAMACHY performed observations in the mesosphere and lower thermosphere (50--150 km) regularly twice per month; this new limb mesosphere-thermosphere (MLT) state was coordinated with the MIPAS upper atmosphere (UA) mode once every 30 days. We use the UV spectra measured by SCIAMACHY in the range 230--300 nm to retrieve the NO number densities from emissions in the gamma bands in the atmospheric region of interest. We extend the retrieval method to use the SCIAMACHY nominal mode (0 km--93 km) limb scans, giving daily NO density data for the altitude region from 60 km to 95 km.

In the winter 2008/2009, in particular in late January 2009, a sudden stratospheric warming (SSW) occurred with the consequence that in the following weeks, nitric oxide descended from the lower thermosphere around 100 km down to the stratosphere. This event was observed by a number of instruments, such as MIPAS, ACE-FTS, and OSIRIS and SMR on ODIN.

We present the results from our SCIAMACHY MLT and nominal mode retrieval for this time. Our results show the development of the NO density distribution with a good vertical resolution in the altitude range from 70 km to 90 km when using the nominal mode limb scans and with a vertical resolution of about 5--8 km in the altitude range from 70 km to 140 km when using the MLT limb scans. Having daily data gives us the possibility to look at other winters with and without exceptional warming events and to compare and to validate our and other measurements and models. With the SCIAMACHY observations, it is possible to distinguish for the first time between local production of NO in the upper mesosphere due to relativistic electrons from the radiation belts, and transport of auroral NO from the lower thermosphere.