Testing the electrodynamic method to derive height-integrated ionospheric conductances

Weimer, Daniel; Edwards, Thom

doi:https://doi.org/10.5194/angeo-39-31-2021

Articles | Volume 39, issue 1

https://doi.org/10.5194/angeo-39-31-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/angeo-39-31-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 39, issue 1

Regular paper

|

14 Jan 2021

Regular paper |

| 14 Jan 2021

Testing the electrodynamic method to derive height-integrated ionospheric conductances

Daniel Weimer and Thom Edwards

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Final revised paper (published on 14 Jan 2021)
Supplement to the final revised paper
Preprint (discussion started on 19 Aug 2020)
Supplement to the preprint

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review for Weimer and Edwards: "Testing the Electrodynamic Method to Derive Height-Integrated Ionospheric Conductances"', Anonymous Referee #1, 22 Sep 2020
- AC2: 'Response to Referee #1', Daniel Weimer, 20 Oct 2020
RC2: 'Referee report 1', Anonymous Referee #2, 07 Oct 2020
- AC1: 'Response to Referee #2', Daniel Weimer, 20 Oct 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Publish subject to revisions (further review by editor and referees) (21 Oct 2020) by Steve Milan

AR by Daniel Weimer on behalf of the Authors (29 Oct 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (31 Oct 2020) by Steve Milan

RR by Anonymous Referee #2 (17 Nov 2020)

Suggestions for revision or reasons for rejection

Daniel Weimer and Thom Edwards, Testing the Electrodynamic Method to Derive Height-Integrated Ionospheric Conductances, MS No.: angeo-2020-60

The paper applies three, separate empirical models to the formulas proposed by Amm (2001) to calculate the distributions of the ionospheric Pedersen and Hall conductivities for various conditions.

I appreciate the responses from the authors although I am not sure I succeeded in conveying my concerns.

I appreciate the response of the authors to some of my concerns. I was unsuccessful in conveying some of them or the authors chose to disagreed which they, of cause, are in the full rights to do. The assumption that the distributions of the ionospheric electrodynamic parameters are related to the drivers (SW, F10.7, tilt angle and so on) essentially ignore processes in the magnetosphere since these are not parameterizes other than through some probabilistic relationship. This is fine assuming that the goal is to reproduce scale sizes of R1-R2 FAC or the two-cell convection pattern which we, however, have known for decades. The paper should, as I mentioned, provide some information regarding the extent these patterns agree with individual events. The 20-50% is vastly insufficient. The conductances are indeed parameters derived in a first-principle fashion from the basic set of equations shown but since there are many uncertainties in the distributions of the measured parameters the conductances are simply factors that allow a solution. This is what I meant as fudge-factors, not derogatory, but merely pointing out that they are not constrained by any direct measurement. As such they are allowed to have any value and in certain locations these can be argued to be unphysical because of our knowledge of what these parameters represent. Within the polar cap (certainly in the winter) and at sub-auroral latitudes the ground based magnetic field is not associated with overhead ionospheric currents. Further, the reason AMPERE is superior is simple. AMPERE provide quasi instantaneous global solutions and as such does not rely of gathering data from many different events and times in the hope that these measurements are due to the same distribution of the ionospheric electrodynamics. The individual Iridium measurement is indeed inferior to the vastly precise measurements on e.g. SWARM but this is washed out anyway as this paper clearly show. I short, the long list of assumptions on which this approach is based (a list of various delays between assumed drivers and ionospheric electrodynamics; repeatability of ionospheric electrodynamics for these drivers; exclusion of magnetospheric processes; and many more) can be justified by providing polar plots of some measure of the error between solution and actual measurements.

The authors suggest this could be used for space-weather modelling but the solutions merely reproduce the well-known large-scale behavior which have little, if any, societal impact.

In conclusion, I recommend publish as is, although I do believe the impact of the paper is insignificant unless some support of the solutions is provided (an error estimation exceeding the 20-50% quote).

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ED: Publish as is (24 Nov 2020) by Steve Milan

AR by Daniel Weimer on behalf of the Authors (25 Nov 2020) Manuscript

Short summary

The electrical conductivity of the Earth's ionosphere is an important parameter in the study of the polar, auroral currents that produce magnetic disturbances on the ground. Yet the values of the conductances, and how they vary, are not known with great precision. In our study we tested a method for deriving the conductivity values that requires use of three empirical models for the electric fields above the ionosphere and the magnetic field perturbations both on the ground and in space.