1Meteorology Department, University of Reading, Reading, Berkshire, UK
2Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
3Institut de Recherche en Astrophysique et Planétologie, 9 Ave. du Colonel Roche, BP 44 346, 31028 Toulouse Cedex 4, France
Received: 07 Jun 2013 – Revised: 20 Oct 2013 – Accepted: 23 Oct 2013 – Published: 18 Nov 2013
Abstract. We present a new reconstruction of the interplanetary magnetic field (IMF, B) for 1846–2012 with a full analysis of errors, based on the homogeneously constructed IDV(1d) composite of geomagnetic activity presented in Part 1 (Lockwood et al., 2013a). Analysis of the dependence of the commonly used geomagnetic indices on solar wind parameters is presented which helps explain why annual means of interdiurnal range data, such as the new composite, depend only on the IMF with only a very weak influence of the solar wind flow speed. The best results are obtained using a polynomial (rather than a linear) fit of the form B = χ · (IDV(1d) − β)α with best-fit coefficients χ = 3.469, β = 1.393 nT, and α = 0.420. The results are contrasted with the reconstruction of the IMF since 1835 by Svalgaard and Cliver (2010).
Lockwood, M., Barnard, L., Nevanlinna, H., Owens, M. J., Harrison, R. G., Rouillard, A. P., and Davis, C. J.: Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 2: A new reconstruction of the interplanetary magnetic field, Ann. Geophys., 31, 1979-1992, doi:10.5194/angeo-31-1979-2013, 2013.