Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Fe XIII 1074.68 nm emission over atmospheric absorption (normalized) in the He I Cryo-NIRSP wavelength range with all labeled candidate lines.

A Spectroscopic Survey of Infrared 1–4 μm Spectra in Regions of Prominent Solar Coronal Emission Lines of Fe XIII, Si X, and Si IX

The infrared solar spectrum contains a wealth of physical data about the Sun and is being explored using modern detectors and technology with new ground-based solar telescopes. One such instrument will be the ground-based Cryogenic Near-IR Spectro-Polarimeter of the Daniel K. Inouye Solar Telescope.

CLEDB 2-line magnetic inversion algorithm flowchart. An important aspect is the delivery of multiple possible solutions for each observation at the last step. Note that the x-coordinate of the point in space, as well as nearest electron density, are returned along with B. The figure uses the notation Vobs and Vdb for observed and computed values of the amplitudes of the Stokes parameters corresponding to O3 and S3 (B = 1) in the text.

Efficient and Automated Inversions of Magnetically-Sensitive Forbidden Coronal Lines: CLEDB - The Coronal Line Emission DataBase Magnetic Field Inversion Algorithm

Alin Paraschiv and Philip Judge present CLEDB, a single point inversion algorithm for determining magnetic parameters using spectro-polarimetric measurements of emission lines formed in the solar corona.

The solar spectrum seen at low resolution, below the atmospheric cutoff at 3100 Angstrom

Optimal spectral lines for measuring chromospheric magnetic fields

This paper identifies spectral lines from EUV to infrared wavelengths which are optimally suited to measuring vector magnetic fields as high as possible in the solar atmosphere.

3D view of the simulated corona; bottom panel: magnetogram; back panel: synthetic AIA 211A coronal image; middle vertical plane: volumetric emissivity. Field lines are included for reference.

The Coronal Veil

Coronal loops, seen in solar coronal images, are believed to represent emission from magnetic flux tubes with compact cross sections. We examine the 3D structure of plasma above an active region in a radiative magnetohydrodynamic simulation to locate volume counterparts for coronal loops.

Inversion results for observing geometries away from the disk center

On the (Mis)interpretation of the Scattering Polarization Signatures In the Ca II 8542 A line Through Spectral Line Inversions

Scattering polarization tends to dominate the linear polarization signals of the Ca II 8542 A line in weakly magnetized areas, especially when the observing geometry is close to the limb. In this paper we evaluate the degree of applicability of existing non-LTE spectral line inversion codes at inferring the magnetic field vector and, particularly, its transverse component.

Comparisons of local time structure of molecular oxygen at 21°N, 170 km altitude

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

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 polar view of the percentage difference of simulated ∑O/N2 and GOLD observed ∑O/N2 between DOY 111 and 110 at 15:10 UT in 2019. The perimeter latitude is 30°N

The effects of IMF By on the middle thermosphere during a geomagnetically “quiet” period at solar minimum

Numerical simulations using the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) are performed to elucidate the effects of the interplanetary magnetic field (IMF) on the middle thermosphere composition during a “geomagnetically quiet” period.

Left: Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (SD-WACCMX) Lagrangian coherent structures (LCSs) for a space shuttle launch during (a) spring and (b) summer. Right: Observations of GUVI Lyman-alpha column emission rates in Rayleighs reprinted from Meier et al. (2011) and annotated with the LCS locations.

Lower thermospheric material transport via Lagrangian coherent structures

Lagrangian coherent structures (LCSs), indicating regions of material transport, are derived from models of the lower thermosphere for five space shuttle water vapor plume events. LCSs defined using flow fields from the Specified Dynamics version of the Whole Atmosphere Community Climate Model with thermosphere eXtension (SD-WACCMX) are compared to global ultraviolet imager (GUVI) observations of water vapor documented in the literature.

Interhemispheric differences poleward of 40deg geog. latitude of E-region electron density

Impacts of Different Causes on the Inter–Hemispheric Asymmetry of Ionosphere–Thermosphere System at Mid– and High–Latitudes: GITM Simulations

There are significant differences between the Earth’s two hemispheres such as the Earth's magnetic field and the intensity of solar radiation due to Earth's tilt of the rotation axis with respect to the Sun. Understanding the impact and therefore the importance of these asymmetries on the mid- and high-latitude upper atmosphere is a challenge in the geospace community.