magnetosphere

Magnetosphere-ionosphere coupling via prescribed field-aligned current simulated by the TIEGCM

whawkins — Wed, 12 Oct 2022 19:22:26 +0000

Magnetosphere-ionosphere coupling via prescribed field-aligned current simulated by the TIEGCM whawkins Wed, 10/12/2022 - 13:22

Author:

whawkins

Oct 12, 2022

Hemispherically integrated Joule heating [GW] poleward of 50o magnetic latitude based on simulations with a prescibed empirical electric potential model: Weimer-POT (blue), with prescribed electric potential and auroral particle precipitation based on an assimilative method: AMIE-POT (black), and with prescribed field-aligned current: OIM-FAC (red) cases for the northern hemisphere (top) and southern hemisphere (bottom)

A. Maute, A.D. Richmond, G. Lu, D. Knipp, Y. Shi, B. Anderson assert that the magnetosphere-ionosphere (MI) coupling is crucial in modeling the thermosphere-ionosphere (TI) response to geomagnetic activity. In general circulation models (GCMs) the MI coupling is typically realized by specifying the ion convection and auroral particle precipitation patterns from e.g., empirical or assimilative models. Assimilative models have the advantage that the ion convection and auroral particle precipitation patterns are mutually consistent and based on available observations. However, assimilating a large set of diverse data requires expert knowledge and is time consuming. Empirical models, on the other hand, are convenient to use, but do not capture all the observed spatial and temporal variations. With the availability of AMPERE data, there is an opportunity for employing field-aligned currents (FAC) in numerical models to represent the MI coupling. In this study, we introduce a new method using observed FAC and solve for the interhemispherically asymmetric electric potential distribution. We compared geomagnetic storm simulations using the new approach and two other often-used methods for specifying MI coupling based on empirical and assimilative high latitude electric potentials. The comparison shows general similarities of the thermosphere-ionosphere storm time response and improved temporal variability of the new method compared to using empirical models, but results also illustrate substantial differences due to our uncertain knowledge about the MI coupling process.

2022 Space Weather Summer School

whawkins — Tue, 30 Aug 2022 15:45:48 +0000

2022 Space Weather Summer School whawkins Tue, 08/30/2022 - 09:45

Author:

whawkins

Aug 30, 2022

FYI, we will not be holding a Space Weather Summer School in 2023. We hope to resume in 2024.

HAO held the latest in a series of successful Space Weather Summer Schools in Boulder, Colorado during the last 2 weeks of July. This unique educational workshop brought together 31 students mainly from the United States along with two students from abroad. Lecturers included experts in solar physics, solar wind, magnetsophere, and ionosphere-thermosphere in order to provide the students with a comprehensive background of the complete space weather system. In addition to lectures on the physics of the system, students learned from experts at the Space Weather Prediction Center about the challenges in making accurate space weather forecasts. Specialists provided an understanding of how space weather processes turn into impacts in human systems such as the power grid. Each day of the school included a computer-based laboratory exercise that let the students get hands-on experience with the models used to simulate space weather. HAO was pleased to once again provide students with an informative, comprehensive, and well well-appreciated introduction to space weather.

SWSS 2022 Group Photograph

Impacts of binning methods on high-latitude electrodynamic forcing: static vs boundary oriented binning methods

kolinski — Thu, 18 Nov 2021 18:45:53 +0000

Impacts of binning methods on high-latitude electrodynamic forcing: static vs boundary oriented binning methods kolinski Thu, 11/18/2021 - 11:45

Publication Name: JGR Space Physics; First HAO Author's Name: Art Richmond

Author:

kolinski

Nov 18, 2021

The Earth’s atmosphere is coupled at high latitude to the magnetosphere. This is a crucial region since energy is put into the upper atmosphere of Earth and is redistributed globally. Numerical models such as general circulation models (GCMs) simulate the effects of the high latitude energy input on the thermosphere-ionosphere system.

Distributions of height-integrated Joule heating in the northern hemisphere (geographic coordinates) from two GITM simulations for 2002 September 23 0010 UT: (a) Run 1 with static boundary binning and (b) Run 2 with boundary oriented binning. The hemispherically integrated Joule heating is given at the lower left of each plot. There is an 18% increase in integrated heating when employing the boundary oriented binning method.

However, an outstanding issue in the GCM simulations for Earth’s upper atmosphere is the inaccurate estimation of energy input, especially the Joule heating, which is associated with the inaccuracy of empirical models for high-latitude electrodynamic forcing. Several factors can contribute to the inaccuracy. In this study, we examine the influence of the binning methods used in the development of those empirical models on the Joule heating. Traditionally, data under similar conditions are binned through a static binning approach by using fixed geomagnetic coordinates, in which the dynamic nature of the forcing is not taken into account and therefore the forcing patterns may be significantly smoothed. To avoid the smoothing issue, data can be binned according to some physically important boundaries in the high-latitude forcing, i.e., through a boundary-oriented binning approach. In this study, we have investigated the sensitivity of high-latitude forcing patterns to the binning methods by applying both static and boundary-oriented binning approaches to the electron precipitation and electric potential data from the Defense Meteorological Satellite Program (DMSP) satellites. The forcing patterns obtained from both static and boundary-oriented binning approaches are used to drive Global Ionosphere and Thermosphere Model (GITM) to assess the impacts on Joule heating by using different binning patterns. It is found that the hemispheric-integrated Joule heating in the simulation driven by the boundary oriented binning patterns is 18% higher than that driven by the static binning patterns for southward IMF dominated case.

Simulated trends in ionosphere-thermosphere climate due to predicted main magnetic field changes from 2015 to 2065

kolinski — Wed, 17 Nov 2021 19:59:01 +0000

Simulated trends in ionosphere-thermosphere climate due to predicted main magnetic field changes from 2015 to 2065 kolinski Wed, 11/17/2021 - 12:59

Publication Name: JGR Space Physics; First HAO Author's Name: Astrid Maute

Author:

kolinski

Nov 17, 2021

The strength and structure of the Earth's magnetic field is gradually changing. These changes do not only affect the difference between the geographic and magnetic pole, which we have to consider when we hike in higher latitude regions. The upper atmosphere also reacts to these changes, since the plasma distribution in the upper atmosphere is strongly influenced by Earth's magnetic field, and can feed back to the neutral atmosphere through ion-neutral coupling. With our increasing number of space assets and reliance an them, it is important to understand the space environment changes the Earth's magnetic field will introduce.

TEC [TECU] in 2015 (left) and the difference between 2065 and 2015 (right) at 18 UT averaged over all days of the year. The black triangle marks the location of Jicamarca.

In this study will we use a predictive model of the Earth's magnetic field together with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model to provide some guidance about the expected upper atmosphere changes from 2015 and year 2065. In general, during the next 50 years the dipole moment is predicted to decrease, with the South Atlantic Anomaly expanding, deepening, and continuing to move westward, while the magnetic dip poles move north-westward. The global mean neutral density in the thermosphere is expected to increase slightly, by up to 1% on average, or up to 2% during geomagnetically disturbed conditions (Kp >= 4). These density trends are small compared to other trend drivers. Global mean changes in total electron content (TEC) range from -3% to +4%, depending on season and UT. However, regional changes can be much larger, up to about +/-35% in the region of ~45deg S-45deg N and 110deg W-0 deg W during daytime. Changes in the vertical ExB drift are the most important driver of changes in TEC, although other plasma transport processes also play a role. A reduction in the low-latitude upward ExB drift weakens the equatorial ionization anomaly in the longitude sector of ~105deg W-60deg W, manifesting itself as a local increase in electron density over Jicamarca (12.0deg S, 76.9deg W). The predicted changes in TEC could make a signifcant contribution to observationally detectable trends.

Convolutional Neural Networks for Predicting the strength of the Near-Earth Magnetic Field Caused by Interplanetary Coronal Mass Ejections

kolinski — Wed, 17 Nov 2021 16:26:43 +0000

Convolutional Neural Networks for Predicting the strength of the Near-Earth Magnetic Field Caused by Interplanetary Coronal Mass Ejections kolinski Wed, 11/17/2021 - 09:26

Publication Name: Frontiers in Astronomy; Authors names as they are listed in article: Anna Malanushenko, Natasha Flyer, Sarah Gibson

Author:

kolinski

Nov 17, 2021

In this paper, regression-based deep convolutional neural networks (CNN), with 12 layers, are developed for predicting the maximal amplitude of the southward component of the near-Earth magnetic field from a passing interplanetary coronal mass ejection (ICME). The input to the CNN is the Gibson and Low (GLOW) flux rope model (Gibson and Low, 1998) that describes the coronal properties of a CME, where its morphology and position is controlled by 5 varying parameters, i.e. input sampling occurs over a 5D parameter space. The ultimate goal is to determine the extent to which coronal spectropolarimetric observations at the Sun encode sufficient information to predict southward magnetic field component at the Earth.

Examples of various initial GLOW configurations. Blue and green lines are magnetic field lines sampling the magnetic structure of the GLOW spheromak, shown here with different combinations of parameters for angular size, topology, orientation. Solar surface is shown in thin black lines for reference.

The GLOW model is used as a first simple test of a self-similarly expanding magnetic flux rope which nevertheless allows consideration of the impact of varying CME location, orientation, size, and morphology. The CNN problem is set up in two experiments: 1) given input data near the Sun, three 2D images in the meridional plane of the components of the magnetic field, predict the maximal southward amplitude of the measured magnetic field at the Earth; 2) given line-of-sight integrated images of the Stokes parameters, corresponding to the physical configurations of the over 30K flux ropes from Part 1, predict the maximal southward amplitude of the measured magnetic field at the Earth.

magnetosphere

Magnetosphere-ionosphere coupling via prescribed field-aligned current simulated by the TIEGCM

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2022 Space Weather Summer School

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Impacts of binning methods on high-latitude electrodynamic forcing: static vs boundary oriented binning methods

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Simulated trends in ionosphere-thermosphere climate due to predicted main magnetic field changes from 2015 to 2065

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Convolutional Neural Networks for Predicting the strength of the Near-Earth Magnetic Field Caused by Interplanetary Coronal Mass Ejections

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