The Solar Wind Proton Monitor on the SoHO Spacecraft

F.M. Ipavich, A.B. Galvin, S.E. Lasley, J.A. Paquette, S. Hefti, K.-U. Reiche, M.A. Coplan, G. Gloeckler, P. Bochsler, D. Hovestadt, H. Grünwaldt, M. Hilchenbach, F. Gliem, W.I. Axford, H. Balsiger, A. Bürgi, J. Geiss, K.C. Hsieh, R. Kallenbach, B. Klecker, M.A. Lee, G.G. Mangadze, E. Marsch, E. Möbius, M. Neugebauer, M. Scholer, M.I. Verigin, B. Wilken, and P. Wurz

Paper submitted to JGR, March 1997.

The Proton Monitor, a small subsensor in the 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. We present Proton Monitor observations of two interplanetary shock events, and of an unusual solar wind density rarefaction. Based on 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. The excellent data coverage from SoHO allows the production of near real time solar wind data that is now accessible on the World Wide Web.

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Last Update: April 4, 1997, Peter Wurz