Solar wind measurements with SOHO - The CELIAS/MTOF proton monitor

• Published in: Journal of Geophysical Research 1998-08, Vol.103 (A8), p.17
• Main Authors: Ipavich, F M, Galvin, A B, Lasley, S E, Paquette, J A, Coplan, M A, Gloeckler, G, Hefti, S, Bochsler, P, Reiche, K-U, Hovestadt, D
• Format: Article
• Language: English
• ISSN: 0148-0227

The proton monitor, a small subsensor in the Charge, Element, and Isotope Analysis System/Mass Time-of-Flight (CELIAS/MTOF) experiment on the SOHO spacecraft, was designed to assist in the interpretation of measurements from the high mass resolution main MTOF sensor. In this paper we demonstrate that the proton monitor data may be used to generate reasonably accurate values of the solar wind proton bulk speed, density, thermal speed, and north /south flow direction. Correlation coefficients based on comparison with the solar wind measurements from the SWE instrument on the Wind spacecraft range from 0.87 to 0.99. On the basis of the initial 12 months of observations, we find that the proton momentum flux is almost invariant with respect to the bulk speed, confirming a previously published result. We present observations of two interplanetary shock events, and of an unusual solar wind density depletion. This large density depletion, and the correspondingly large drop in the solar wind ram pressure, may have been the cause of a nearly simultaneous large increase in the flux of relativistic magnetospheric electrons observed at geosynchronous altitudes by the GOES 9 spacecraft. (Author)