CalcDeltaB: An efficient postprocessing tool to calculate ground‐level magnetic perturbations from global magnetosphere simulations

Abstract

Ground magnetic field variations can induce electric currents on long conductor systems such as high‐voltage power transmission systems. The extra electric currents can interfere with normal operation of these conductor systems; and thus, there is a great need for better specification and prediction of the field perturbations. In this publication we present CalcDeltaB, an efficient postprocessing tool to calculate magnetic perturbations ΔB at any position on the ground from snapshots of the current systems that are being produced by first‐principle models of the global magnetosphere‐ionosphere system. This tool was developed during the recent “dB/dt” modeling challenge at the Community Coordinated Modeling Center that compared magnetic perturbations and their derivative with observational results. The calculation tool is separate from each of the magnetosphere models and ensures that the ΔB computation method is uniformly applied, and that validation studies using ΔB compare the performance of the models rather than the combination of each model and a built‐in ΔB computation tool that may exist. Using the tool, magnetic perturbations on the ground are calculated from currents in the magnetosphere, from field‐aligned currents between magnetosphere and ionosphere, and the Hall and Pedersen currents in the ionosphere. The results of the new postprocessing tool are compared with ΔB calculations within the Space Weather Modeling Framework model and are in excellent agreement. We find that a radial resolution of 1/30RE is fine enough to represent the contribution to ΔB from the region of field‐aligned currents.

Regional 3‐D Modeling of Ground Electromagnetic Field Due To Realistic Geomagnetic Disturbances

“… First‐principle modeling of the global magnetosphere‐ionosphere system, namely, 3‐D MHD physics‐based simulations of near‐Earth space, is performed for the event of interest. In our case the modeling is done using the Space Weather Modeling Framework (SWMF, Toth et al, ), which takes as an input the solar wind parameters (density, temperature, velocity, and magnetic field) from a satellite located at L1 Lagrangian point, such as the Advanced Composition Explorer or the Deep Space Climate Observatory. In the next step we use a postprocessing tool CalcDeltaB (Rastätter et al, ) to calculate the external magnetic field perturbations B ext on the ground and on a global scale from the outputs of the SWMF. These outputs are time‐varying 3‐D currents in the magnetosphere, horizontal currents in the ionosphere, and field‐aligned currents flowing between the ionosphere and magnetosphere. Global external magnetic field perturbations B ext are converted into a global current function Ψ .…”

Space Weather Effects Produced by the Ring Current Particles

“…The contributions from the magnetospheric and ionospheric currents were taken into account in the Biot-Savart's integration for the approximation of the Dst-index by the North-South component of the perturbation magnetic field δB Z (in SM coordinates) at the Earth's center location (for details, see . Another challenge was focused on the reproducing the magnetic field variations at the ground-based stations (Pulkkinen et al 2010(Pulkkinen et al , 2011Rastätter et al 2014). As a result of these challenges, the NOAA Space Weather Prediction Center (SWPC) added the SWMF to the operational forecasting tools.…”

Comprehensive Assessment of Models and Events Using Library Tools (CAMEL) Framework: Time Series Comparisons

“…Three global magnetosphere models and two statistical models were run to specify magnetic perturbations on the ground that are caused by changes in the magnetosphere and ionosphere of the Earth (Pulkkinen et al, , ; Rastätter et al, ). Solar wind data for six selected events lasting from 1 to 2 days each were selected and observations at 13 magnetometer stations in “chains” (listed north to south) on the American West Coast (Yellowknife [YKC], Meanook [MEA], Newport [NEW], and Fresno [FRN]), East Coast (Iqaluit [IQA], Poste‐de‐la‐Baleine [PBQ] or Sanikiluaq [SNK; for later events], Ottawa [OTT], and Fredericksburg [FRD]), and Europe (Hornsund [HRN], Abisko [ABK], Wingst [WNG], and Furstenfeldbruck [FUR]) were compared with results obtained from the models.…”

“…When RoR‐NextGen has matured, the CAMEL framework will be able to connect to and search the archive of RoR runs at the CCMC allowing users to find and use all relevant output for their validation efforts. Postprocessing tools: these include existing tools available to a user at CCMC such as the (online) visualization (CCMC‐Vis) that performs extraction of time series data along satellite trajectories or at locations on the ground or in space. CalcDeltaB (Rastätter et al, ) calculates magnetic perturbations at magnetometer stations from electric currents in the magnetosphere and ionosphere (available as a postprocessing run request applied to any magnetosphere model simulation). Other tools at the CCMC include the internally developed and used Flexible Data Ingestion Tool, a generic data parser that reads time series data and stores them in a database table.…”