Ann. Geophys., 38, 1019–1030, 2020 https://doi.org/10.5194/angeo-38-1019-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Entangled dynamos and Joule heating in the Earth’s ionosphere Stephan C. Buchert Swedish Institute of Space Physics, Uppsala, Sweden Correspondence: Stephan C. Buchert (
[email protected]) Received: 9 May 2019 – Discussion started: 21 May 2019 Revised: 2 June 2020 – Accepted: 5 August 2020 – Published: 24 September 2020 Abstract. The Earth’s neutral atmosphere is the driver of the cently by Yamazaki and Maute(2017). Sq is driven by a well-known solar quiet (Sq) and other magnetic variations neutral dynamo. Vasyliunas¯ (2012) has summarized the fun- observed for more than 100 years. Yet the understanding of damental equations for a neutral dynamo and his critical view how the neutral wind can accomplish a dynamo effect has of the understanding within the community. The conceptual been incomplete. A new viable model is presented where a difficulty of the author’s interpretation of the neutral dynamo dynamo effect is obtained only in the case of winds perpen- can be phrased less mathematically as follows: in the frame dicular to the magnetic field B that do not map along B. of the neutral gas the product j · E∗, j the electric current, Winds where u × B is constant have no effect. We identify and E∗ the electric field is in the steady state zero or pos- Sq as being driven by wind differences at magnetically con- itive, because of the well-known Ohm’s law for the iono- jugate points and not by a neutral wind per se.