Coronal mass ejections and solar wind mass fluxes over the heliosphere during solar cycles 23 and 24 (1996-2014)
Résumé
Coronal mass ejections (CMEs) play a major role in the heliosphere and their contribution to the solar wind mass flux, already considered in the Skylab and Solwind eras with conflicting results, is re-examined in the light of 19 years (1996-2014) of SOHO observations with the Large Angle and Spectroscopic Coronagraph “LASCO-C2” for the CMEs and extended for the first time to all latitudes thanks to the whole-heliosphere data from the Solar Wind ANisotropies “SWAN” instrument supplemented by in-situ data aggregated in the OMNI database. First, several mass estimates reported in the ARTEMIS catalog of LASCO CMEs are compared with determinations based on the combined observations with the twin STEREO/SECCHI coronagraphs in order to ascertain their validity. A simple geometric model of the CMEs is introduced to generate Carrington maps of their mass flux and then to produce annualized synoptic maps. The Lyman-α SWAN data are inverted to similarly produce synoptic maps to be compared with those of the CME flux. The ratio of the annualized CME to solar wind mass flux is found to closely track the solar cycle over the heliosphere. In the near-ecliptic region and at latitudes up to ∼ 55o, this ratio was negligibly small during the solar minima of cycles 22/23 and 23/24 and rose to 6% and 5% respectively at the maximum of solar cycles 23 and 24. These maximum ratios increased at higher latitudes but this result is likely biased by the inherent limitation of determining the true latitude of CMEs.
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