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⊙, and X-band data from Japan's Akatsuki during June 2016 and October 2022 conjunctions spanning 1.4-10 R⊙. From S-band we obtained wind speeds of 100-150 km s−1 and electron densities of order 1010 m−3. X-band results show speeds ranging from ∼150 km s−1 near the equator to ∼400 km s−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 v and Ne. The formulation enables consistent application across telecommunication bands and complements in-situ probes for coronal plasma studies.
@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