Measurement of mesospheric constituents from SCIAMACHY limb measurements
Miriam Sinnhuber(1), Christian von Savigny(2), Marco Scharringhausen(2), Nadine Wieters(2), Justus Notholt(2) and John Burrows(2)
(1) University of Bremen, Otto-Hahn Allee 1, 28359 Bremen, Germany
(2) University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany
When SCIAMACHY was launched in 2002, its primary focus was measurement of stratospheric and tropospheric trace gases, derived from absorption measurements. After the launch, it became apparent that information about a number of mesospheric parameters can also be derived from SCIAMACHY limb measurements.
A number of emission signals are observed that originate in the mesosphere: The IR emission of OH - chemoluminescence from the H + O3 reaction - as well as an electronic transition of OH in the UV at 308 nm, which is mainly from resonance fluorescence; the NO gamma bands between 220 and 280 nm; emissions from excited states of O2 and O as well as a number of metallic species and their ions, e.g. Mg, Mg+, Na, Na+, Fe, Fe+ and Fe++. From these emission signals, vertical profiles of number densities of the ground state can be derived if the emissivities originate from resonance fluorescence. A retrieval algorithm for this process has been developed, and first results will be shown for mesospheric profiles of NO, Mg and Mg+. As the observed 1Delta and 1Sigma band emissions of O2 originate partly from ozone photolysis, ozone can be derived from these emissions. Additionally, the total air density is derived from Rayleigh single scattering in the UV below 305 nm. Particle number densities and radii of polar mesospheric clouds can be derived if the backscattering signal deviates significantly from the Rayleigh background. Mesospheric temperatures are derived from the vibrational transitions of OH observed in the near-IR; in principle, mesospheric temperatures can also be derived from the gradient of the number density.
We will give an overview over the mesospheric parameters developed and retrieved in Bremen, and show first results of a number of these parameters. Measurements in the mesosphere are generally rare for a number of reasons, and the SCIAMACHY data set should enhance our understanding of this region of the atmosphere significantly; for some species - e.g., Mg / Mg+ - the SCIAMACHY measurements are the first ever measurements on a global scale.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,