Science Seminars

Cloud, Dust and Ozone Retrieval Using SPICAM/UV Nadir

Speaker: Yannick Williame (Belgian Institute for Space Aeronomy)
Date: Thursday, Oct 05, 2017
Time: 4:00 PM
Location: SPSC W120

Seminar Abstract:

We have developed a retrieval method in order to analyse nadir measurements of the SPICAM/UV instrument on board the Mars-Express orbiter. The UV spectrometer has provided measurements during 11 years with a near pole-to-pole orbit that allows to cover latitudes up to 86°. We have used the 220-290 nm range to deduce the quantities of dust, cloud and ozone in the Martian atmosphere and the surface albedo. However, except for ozone which has a specific spectral signature, the three other parameters shows linear spectral effects making difficult to separate their contributions. A cloud detection algorithm was therefore implemented in order to select which 3 independent parameters must be fitted: ozone column and dust opacity are always retrieved, while the third parameter is chosen between the cloud opacity or the surface albedo depending on the cloud presence. More than 4 Martian years of SPICAM data have been analysed using our method and the derived climatologies of dust, cloud and ozone have been used to study their spatial and seasonal distributions.