English

A generalized method for estimating solar wind speeds and densities using spectral broadening for a Kolmogorov turbulence spectrum

Solar and Stellar Astrophysics 2026-03-26 v1 Space Physics

Abstract

We present a unified method to derive both solar wind velocities and coronal electron densities in the near-Sun corona using Doppler spectral broadening of spacecraft radio signals. The method is generalized to be frequency independent under the assumption that electron density fluctuations follow a Kolmogorov spectrum. We validate the approach using S-band data from India's Mars Orbiter Mission during the October 2021 superior conjunction at 5-8 R_\odot, and X-band data from Japan's Akatsuki during June 2016 and October 2022 conjunctions spanning 1.4-10 R_\odot. From S-band we obtained wind speeds of 100-150 km s1^{-1} and electron densities of order 101010^{10} m3^{-3}. X-band results show speeds ranging from \sim150 km s1^{-1} near the equator to \sim400 km s1^{-1} in coronal-hole regions, with consistent radial trends in density. We provide a compact, frequency-scaled relation that maps Doppler spectral width to both vv and NeN_e. The formulation enables consistent application across telecommunication bands and complements in-situ probes for coronal plasma studies.

Keywords

Cite

@article{arxiv.2603.23929,
  title  = {A generalized method for estimating solar wind speeds and densities using spectral broadening for a Kolmogorov turbulence spectrum},
  author = {Keshav Aggarwal and R. K. Choudhary and Abhirup Datta and Roopa M. V. and Takeshi Imamura and Hiroki Ando},
  journal= {arXiv preprint arXiv:2603.23929},
  year   = {2026}
}

Comments

15 pages, 4 figures, Accepted for publication in Advances in Space Research