Sun-Earth connection

The Multiscale Atmosphere-Geospace Environment (MAGE) model

kolinski — Mon, 11 Jul 2022 21:20:33 +0000

The Multiscale Atmosphere-Geospace Environment (MAGE) model kolinski Mon, 07/11/2022 - 15:20

The Molecular Oxygen Density Structure of the Lower Thermosphere as Seen by GOLD and Models

kolinski — Mon, 11 Jul 2022 20:39:20 +0000

The Molecular Oxygen Density Structure of the Lower Thermosphere as Seen by GOLD and Models kolinski Mon, 07/11/2022 - 14:39

Publication: Geophysics Research Letters; Author's: K. R. Greer, F. Laskar, R. Eastes, J. Lumpe, H.-L. Liu, and N. Pedatella

Author:

kolinski

Jul 11, 2022

Comparisons of local time structure of molecular oxygen at 21°N, 170 km altitude. Red dots are for the longitude of 33°E, while blue dots are for the longitude of 128°W. Panel (a) shows molecular oxygen densities as observed by the GOLD instrument for one star, HD74280, between January 2019 and July 2021. Panel (b) are results from the MSISE-00 empirical model sampled for the same locations and conditions as the GOLD observations. Panel (c) is as panel (b) but for the MSIS2.0 empirical model. Panel (d) shows the SD-WACCM-X model sampled for the GOLD observations. The observations show a distinctly diurnal structure in local time, while all the model results indicate a semidiurnal structure.

This paper compares new observations from the Global-scale Observations of Limb and Disk (GOLD) mission of molecular oxygen (O2) in the lower thermosphere (130 - 200 km in altitude) to widely used models in the aeronomy community. The main finding is that the local time structure of the observed molecular oxygen has a minimum at 6 hours local time and a peak near 18 hours local time while the models all show a structure that has peaks at both 6 and 18 hours local time. This significant difference not only influences the total neutral thermospheric density results from the models, but may ultimately impact the calculated ionospheric plasma density and its temporal variability. Understanding ionospheric plasma densities is vital for the proper modeling of the propagation of communications and navigational signals.

3rd Eddy Cross Disciplinary Symposium 2022

kolinski — Fri, 04 Mar 2022 16:23:44 +0000

3rd Eddy Cross Disciplinary Symposium 2022 kolinski Fri, 03/04/2022 - 09:23

Impact of Thermospheric Wind Data Assimilation on Ionospheric Electrodynamics using a Coupled Whole Atmosphere Data Assimilation System

kolinski — Thu, 03 Mar 2022 21:39:21 +0000

Impact of Thermospheric Wind Data Assimilation on Ionospheric Electrodynamics using a Coupled Whole Atmosphere Data Assimilation System kolinski Thu, 03/03/2022 - 14:39

Publication: Journal of Geophysical Research, Space Physics; Authors: Chih-Ting Hsu, Nick Pedatella, Jeff Anderson

Author:

kolinski

Mar 3, 2022

Three Observing System Simulation Experiments (OSSEs) are carried out in this study. Thermospheric wind and temperature states are updated using synthetic data sampled from a Nature Run (NR) in this experiment. The updated thermospheric states will further change the plasma drift and electron density in the ionosphere. This figure shows the longitude-latitude maps of NmF2 from the NR (first column) and the difference of NmF2 between OSSEs and NR (second to fourth columns) at six different times. From top to bottom rows are maps at 1200 UT on 05, 10, 15, 20, 25, and 30 December 2009. From the second to fourth columns are the difference of NmF2 between OSSE-MIGHTI-ELF, OSSE-MIGHTI-GC, and OSSE-GC and NR.

The upward plasma drift and equatorial ionization anomaly (EIA) in the Earth's ionosphere are strongly influenced by the zonal electric field, which is generated by the wind dynamo. Specification and forecasting of thermospheric winds thus plays an important role in ionospheric weather prediction. In this study, we assess the impact of assimilating thermospheric wind observations from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument on NASA's Ionospheric CONnection (ICON) explorer satellite on the ionospheric electrodynamics. Empirical Localization Functions (ELFs) of ICON/MIGHTI zonal and meridional winds are also computed and applied to our data assimilation experiments, enabling improved assimilation of the ICON/MIGHTI wind observations. A set of Observing System Simulation Experiments (OSSEs) are performed using the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX) with data assimilation provided by the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. The results show that assimilating the ICON/MIGHTI wind observations with the ELF improves the zonal and meridional wind root mean square error (RMSE) by 16-18% and 7-10%, respectively. The improved wind specification further improves the low-latitude ExB vertical drift RMSE by about 18%. The response of electron densities is slower, and the overall impact is smaller. The improvement of the ionosphere F-region maximum electron density (NmF2) between -45 to 45 degree is about 8% after 18 days of data assimilation.

The Dimmest State of the Sun

kolinski — Thu, 03 Mar 2022 20:10:48 +0000

The Dimmest State of the Sun kolinski Thu, 03/03/2022 - 13:10

Authors: Kok Leng Yeo, Sami K. Solanki, Matthias Rempel, Anusha Bhasari, Natalie A. Krivova, Alexander I. Shapiro, Rinat V. Tagi

Author:

kolinski

Mar 3, 2022

Measured and modelled total solar irradiance. (A) The model reconstruction of TSI (black) based on 3D MHD simulations and solar imagery from the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory, which operated from 2010, and the measurements from the Total Irradiance Monitor onboard the SOlar Radiation and Climate 5 Experiment (red), which monitored TSI over the same period except between August 2013 and February 2014. (B) A blowup of the boxed period, 1 March 2014 to 28 February 2015, which encompasses the maximum of solar cycle 24, which occurred in April 2014. The root-mean-square difference between the two time series is 0.068 Wm-2 and the Pearson’s correlation coefficient is 0.987, i.e., the model replicates about 97% of the apparent variability in the TIM 10 record.

How the solar electromagnetic energy entering the Earth’s atmosphere varied since pre-industrial times is an important consideration in the climate change debate. Detrimental to this debate, estimates of the rise in total solar irradiance, TSI, between the Maunder minimum, an extended period of weak solar activity preceding the industrial revolution, and the last solar 15 cycle minimum in 2008 differ markedly, ranging from 0.4 to 6 Wm-2. As a consequence, the exact contribution by solar forcing to the rise in global temperatures over the past centuries remains inconclusive. Adopting a novel approach based on state-of-the-art solar imagery and numerical simulations, we establish that TSI could not have risen since the Maunder minimum by more than 2.1±0.7 Wm-2, restricting the role of solar forcing in global warming.

Link to publication: Geophysical Research Letters

The Sun, The Earth, and Near-Earth Space

kolinski — Mon, 22 Nov 2021 17:58:39 +0000

The Sun, The Earth, and Near-Earth Space kolinski Mon, 11/22/2021 - 10:58

Author:

kolinski

Nov 22, 2021

While solar radiation enables and sustains life on Earth, it also produces “space weather” that can profoundly impact different technologies, including telecommunications, satellite navigation, and the electric power grid. Solar flares can produce x-rays resulting in radio blackouts that block high-frequency radio waves. Solar Energetic Particles can penetrate satellite electronics and cause electrical failure. Coronal mass ejections (CMEs) can cause geomagnetic storms that induce ground currents and degrade power grid operations, sometimes catastrophically.

Cover of Jack Eddy's book "The Sun, The Earth, and Near-Earth Space".

"The Sun, The Earth, and Near-Earth Space", written by late astronomer Dr. John A. Eddy, assembles concise explanations and descriptions—easily read and readily understood—of what we now know of the chain of events and processes that connect the Sun to the Earth, with especial emphasis on space weather and Sun-Climate. The COMET Program collaborated with NASA to help supplement the content with varied interactions and media items. The original 301-page text resource is made available courtesy of the National Aeronautics and Space Administration and is not produced, owned or hosted by UCAR/The COMET Program.

Measuring the magnetic origins of solar flares, CMEs and Space Weather

kolinski — Mon, 15 Nov 2021 22:54:57 +0000

Measuring the magnetic origins of solar flares, CMEs and Space Weather kolinski Mon, 11/15/2021 - 15:54

Publication: ApJ; First HAO Author: Philip Judge

Author:

kolinski

Nov 15, 2021

We take a broad look at the problem of identifying the magnetic solar causes of space weather. The challenges are best met through a combination of near UV lines of bright Mg II, and lines of Fe II and Fe I (mostly within the 4s − 4p transition array) which form in the chromosphere up to 20,000 K. Both Hanle and Zeeman effects can in principle be used to derive vector magnetic fields. However, for any given spectral line the τ = 1 surfaces are generally geometrically corrugated owing to fine structure such as fibrils and spicules.

A smoothed UV spectrum of α alpha Cen A, obtained by the Hubble Space Telescope, is displayed as a proxy for the mean solar intensity spectrum. The large number of lines of Fe I and Fe II are indicated and annotated with their mul- tiplet terms. The Mg II spectrum is also annotated including the 3s − 3p h and k lines, and the 3p − 3d lines.

By using multiple spectral lines spanning different optical depths, magnetic fields across nearly-horizontal surfaces can be inferred in regions of low plasma β, from which free energies, magnetic topology and other quantities can be derived.

Geospace response to an extreme solar flare

kolinski — Mon, 15 Nov 2021 21:58:00 +0000

Geospace response to an extreme solar flare kolinski Mon, 11/15/2021 - 14:58

Publication Name: AGU Advances; HAO Author: Jing Liu; Authors names as listed: Jing Liu, Wenbin Wang, Liying Qian, William Lotko, Alan G. Burns, Kevin Pham, Gang Lu, Stanley C. Solomon, et al.

Author:

kolinski

Nov 15, 2021

Solar flares—a sudden eruption of electromagnetic radiation at the Sun—are known to have significant impacts on Earth’s upper atmosphere and ionosphere, but their collective effects on geospace as an integrated system have never been examined. We use a newly developed whole geospace model, combined with key observational data, to study the effects of the 6 September 2017 X9.3 flare on the geospace system.

Solar flare effects on magnetospheric convection and ionospheric potential. Comparison of 50-minute averages (12:02-12:51 UT) from LTR simulations of magnetospheric and ionospheric states on September 6, 2017 with and without solar flare effects. Bottom row: LTR-simulated magnetospheric convection velocity in equatorial plane (ZGSM = 0) with (A) and without (B) solar flare effects and their difference (C). Arrows indicate direction and magnitude (also in color) of the convection velocity projected onto the plane. Top row: High-latitude electric potential, essentially convection streamlines in the ionosphere with (D) and without (E) solar flare effects and their difference (F). The minimum and maximum potentials are labeled below panels (D-F).

The analysis shows that the solar wind-magnetosphere interaction, magnetotail, field-aligned current distribution, auroral precipitation and high-latitude ionospheric convection respond to atmospheric absorption of solar flare radiation. This study, for the first time, demonstrates that a rapid and large increase in the iono-spheric E-region photoionization due to a solar transient event globally modifies the electrodynamic cou-pling of the geospace system.

Sun-Earth connection

The Multiscale Atmosphere-Geospace Environment (MAGE) model

Recent News

The Molecular Oxygen Density Structure of the Lower Thermosphere as Seen by GOLD and Models

Recent News

3rd Eddy Cross Disciplinary Symposium 2022

Recent News

Impact of Thermospheric Wind Data Assimilation on Ionospheric Electrodynamics using a Coupled Whole Atmosphere Data Assimilation System

Recent News

The Dimmest State of the Sun

Recent News

The Sun, The Earth, and Near-Earth Space

Recent News

Measuring the magnetic origins of solar flares, CMEs and Space Weather

Recent News

Geospace response to an extreme solar flare

Recent News