Research Highlights
Research Highlights
A selection of highlights culled from publications by HAO staff.
Magnetic structure of the solar chromosphere-corona transition regions
The bulk of the emission from the plasma called "transition region" plasma originates from structures energetically connected both to the chromosphere and corona. This result resolves decades of debate and opens the door to measuring magnetic energy and its evolution in the corona using transition region emission lines.
On single-point inversions of magnetic dipole lines in the corona
Prompted by a recent paper by Dima and Schad, we re-consider the problem of inferring magnetic properties of the corona using polarimetric observations of magnetic dipole (M1) lines.
Deciphering Deep-Origin of Active Regions From Analysis Of Magnetograms
Dikpati, et. al., derive magnetic toroids from surface magnetograms by employing a novel optimization method based on Trust Region Reflective algorithm.
Design of a Highly Efficient Polychromatic Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer
In 2014 HAO built a polarimetric modulator for the CRISP instrument on the Swedish 1-m Solar Telescope in La Palma, using the principles of polychromatic modulation previously developed by HAO scientists. This paper discusses the processes by which the modulator was designed, built, and tested. The modulator was installed and had been in use since 2015. It is working at close to optimal efficiency and has produced considerable scientific output.
Data-Driven Ensemble Modeling of Equatorial Ionospheric Electrodynamics
A Case Study During a Minor Storm Period Under Solar Minimum Conditions: The dayside equatorial ionospheric electrodynamics exhibits strong variability driven simultaneously by highly changeable external forcings that originate from the Sun, magnetosphere, and lower atmosphere.
Modeling Diurnal Variation Magnetic Fields for Mantle Induction Studies
Accurate models of the spatial structure of ionospheric magnetic fields in the daily variation (DV) band (periods of approximately a few hours to a day) would enable use of magneto-variational methods for three-dimensional imaging of upper mantle and transition zone electrical conductivity. Constraints on conductivity at these depths, below what is typically possible with magnetotellurics, would in turn provide valuable constraints on mantle hydration and Earth’s deep water cycle.
Migrating Semidiurnal Tide during the September Equinox Transition in the Northern Hemisphere
Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (SD-WACCMX) simulations are used to investigate the solar migrating semidiurnal tide (SW2) around September equinox at middle to high latitudes in the Northern Hemisphere.
Planetary-scale Wave Impacts on the Venusian Upper Mesosphere and Lower Thermosphere
Venus’ atmosphere has a cloud layer (~40 km - ~70 km) that encompasses the whole planet that separates the lower atmosphere and upper atmosphere. Images of the clouds show planetary-scale wave patterns that exist from the equator to mid-latitudes and are thought to be a combination of Kelvin and Rossby waves.
Effective vertical diffusion by atmospheric gravity waves
Han-Li Liu has observed that atmospheric gravity waves may transport heat and chemical species in the vertical direction.