SWUSV: a Space Weather Microsatellite Program to Investigate CMEs Precursors and the Influence of Solar UV Variability on Climate
Résumé
The Sun is the primary source of energy responsible for governing both the weather and climate of Earth. Changes in the amount and type of energy Earth receives alter its weather and climate. The variability of the solar flux during the solar cycle occurs mainly in the ultraviolet and especially at wavelengths below 250 nm where it may exceed 3% and even 20 to 40% in the far UV (FUV). This spectrum does not reach the surface: it is completely absorbed by stratospheric ozone and oxygen, playing an important role in the stratosphere where it modifies the fields of temperature, pressure and wind and therefore the conditions of propagation of atmospheric waves that couple the lower and upper layers of the atmosphere. A Space Weather and Ultraviolet Solar Variability microsatellite (SWUSV), is proposed to monitor UV and FUV (Lyman-Alpha 121.6 nm, 200{220 nm Herzberg continuum) in imaging and irradiance (radiometers). This for early precursor Flares and CMEs detection in Lyman-Alpha for Space Weather awareness, and to have information on the physical causes of the changes of irradiance observed, to identify the causes of these changes and measure their parameters according to solar magnetism: what only an imaging instrument of the whole disc, with a fair spatial resolution and a good rate of observation, can do. The nature of the variations of Lyman-Alpha will help to directly interpret the variations of ozone, on short and long terms. An overview and the objectives of the SWUSV program is presented as well as the FUV imaging telescope (an evolution of SODISM/PICARD), and instrumentation for solar spectral irradiance (radiometers' ensemble: evolution of the LYRA/PROBA-2 experiment), thermal plasma measurements and magnetometer (evolution of PROBA-2 instruments), and Earth radiative budget (SERB) to complete stratospheric information. The program is Franco-Egyptian, presently in definition phase, but extension to Belgium, Switzerland and other partners is expected soon.