Bimodal distribution of the solar wind at 1 AU

Space Weather Research Group, Departamento de Física y Matemáticas, Universidad de Alcalá, A-2, km 33,600, Alcalá de Henares, Spain
e-mail: carlos.larrodera@edu.uah.es, consuelo.cid@uah.es

Received: 13 December 2019
Accepted: 29 January 2020

Abstract

Aims. Here we aim to separate the two main contributions of slow and fast solar wind that appear at 1 AU.

Methods. The bi-Gaussian function is proposed as the probability distribution function of the two main components of the solar wind. The positions of the peaks of every simple Gaussian curve are associated with the typical values of every contribution to solar wind. We used the entire data set from the Advanced Composition Explorer (ACE) mission in an analysis of the data set as a whole and as yearly series. Solar cycle dependence is considered to provide more accurate results for the typical values of the different parameters.

Results. The distribution of the solar wind at 1 AU is clearly bimodal, not only for velocity, but also for proton density, temperature and magnetic field. New typical values for the main parameters of the slow and fast components of the solar wind at 1 AU are proposed.