auroral_forecast

Overview

This repository contains estimates for the auroral zones boundaries for the years 2020 and 2070. This repository is a companion to the paper "Climatological Predictions of the Auroral Zone Locations Driven by Low- and High-Energy Space Weather Events" by Maffei et al.

These estimates are based on existing geomagnetic field models and forecasts. In particular the configuration of the geomagnetic field in 2020 is taken from the IGRF13 (Alken et al., 2021), while estimates for the geomagnetic field in 2070 are taken from three different sources:

1. the data assimilation forecast from Sanchez et al., 2020 (MPG forecast). Currently the MPG forecast is only available by the original authors upon reasonable request;
2. a simple linear extrapolation of the IGRF13 model coefficients in time (IGRF13 forecast). Original dataset available at https://www.ncei.noaa.gov/products/international-geomagnetic-reference-field;
3. the single-epoch inversion forecast from Aubert, 2015 (IPGP forecast). Original dataset available at http://www.ipgp.fr/~aubert/tools.html#data.

Content of the repository

Dataset

The folder datasets contains all the raw data necessary to reproduce the study described in Maffei et al.

• datasets/Gorgon: results from the magnetospheric MHD numerical simulations performed in Gorgon with the purpose of locating the poleward edge of auroral zones under different solar wind conditions (see Figure 4 of Maffei et al.);
• datasets/models: Gauss coefficients of the geomagnetic field forecasts used in this study. All datafiles are samples of the original datasets (see above) at 5 years intervals and in a format that is easily accepted by aacgmv2. In all files each row indicates a specific Gauss coefficient's time series. In all models the time index begins in 1590 to be accepted by aacgmv2. All files are generated from the original models via a Python script similar to ````convert_IPGP_to_aacgmv2_magmodel_fmt.py, foun in Python/``` (see later):
  • datasets/models/ipgpMF4aacgmv2_from1590.txt: IPGP forecast (for epochs 2015 onward);
  • datasets/models/magmodel_1590-2020.txt: magmodel file, also provided in the aacgmv2 package and reproduced here for convenience. It is a combination of the gufm1 (Jackson et al., 2000) and IGRF13 models and is valid for epochs 2015 onward. This is not a forecast;
  • datasets/models/magmodel_2020-2140.txt: the IGRF13 forecast (valid from 2020 onward). This is a simple linear extrapolation of the IGRF13 coefficients evolution;
  • datasets/models/mpgMF4aacgmv2_from1590_L13.txt: MPG averaged forecast (valid from 2020 onward);
  • datasets/models/Ensemble: MPG forecast ensemble members.
• datasets/simplemaps_worldcities_basicv1.73: a list of world cities and their coordinates. Taken from https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwji1rqjnqX5AhUaHuwKHT6VCocQFnoECAkQAQ&url=https%3A%2F%2Fgitlab.huma-num.fr%2Fnlambert%2Fresources%2F-%2Ftree%2Fmaster%2Fdatasets%2Fsimplemaps_worldcities_basicv1.73&usg=AOvVaw34lTEr0D5PXeySE2pXxK4s

Python

The folder Python contains the data on the auroral boundary (both for 2020 and 2070) and the Python scripts used to produce figure 6 of Maffei et al.:

• Python/coords2020_bisection and Python/coords2070_bisection contain files in which poleward and equatorward bounds are given as a function of longitude for both the auroral zones and danger zones. Bounds are computed for 2020 from the IGRF13 model and for 2070 from the forecasts mentioned above.
• Python/convert_IPGP_to_aacgmv2_magmodel_fmt.py is a Python scripts used to modify the original IPGP forecast coefficients file (see above) to prepare the file datasets/models/ipgpMF4aacgmv2_from1590.txt. With small modifications, it can be used to convert any geomagnetic field model into a format easily accepted by aacgmv2
• Python/auroral_forecast.py is the script used to reproduce figure 6 of Maffei et al. (also placed in Python/figures). Given that the auroral bounds are already present in the repository (under Python/coords2020_bisection and Python/coords2070_bisection) the script will not recalculate them. If the folders Python/coords2020_bisection and Python/coords2070_bisection are removed, the auroral bounds will be recalculated from the geomagnetic field models and forecast located in datasets/models/.
• Python/aacgm_functions.py a collection of Python functions needed by Python/auroral_forecast.py.

The above Python scripts have been written in Python 3.8 and require the aacgmv2 Python wrapper ( https://github.com/aburrell/aacgmv2 )

References

Aubert, J.: Geomagnetic forecasts driven by thermal wind dynamics in Earth’s core, Geophys. J. Int. 203, 1738-1751, 2015, doi: 10.1093/gji/ggv394

Alken, P., Thébault, E., Beggan, C.D. et al. International Geomagnetic Reference Field: the thirteenth generation. Earth Planets Space 73, 49 (2021). https://doi.org/10.1186/s40623-020-01288-x

Jackson, A., Jonkers, A. R., & Walker, M. R. (2000). Four centuries of geomagnetic secular variation from historical records. Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 358(1768), 957-990.

Maffei et al., Climatological Predictions of the Auroral Zone Locations Driven by Low- and High-Energy Space Weather Events. Submitted to Scientific Reports

Sanchez, S., Wicht, J. & Bärenzung, J. Predictions of the geomagnetic secular variation based on the ensemble sequential assimilation of geomagnetic field models by dynamo simulations. Earth Planets Space 72, 157 (2020). https://doi.org/10.1186/s40623-020-01279-y