Research Highlights
Research Highlights
A selection of highlights culled from publications by HAO staff.
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.
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.
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.
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.
Gravity-wave-perturbed wind shears derived from SABER temperature observations
Large wind shears around the mesopause region play an important role in atmospheric neutral dynamics and ionospheric electrodynamics. Based on previous observations using sounding rockets, lidars, radars, and model simulations, large shears are mainly attributed to gravity waves (GWs) and modulated by tides (Liu, 2017).
Day-to-Day Variability of Diurnal Tide in the Mesosphere and Lower Thermosphere Driven From Below
The migrating diurnal tide (DW1) is one of the dominant wave motions in the mesosphere and lower thermosphere. It plays a crucial role in neutral atmosphere and ionosphere coupling. The DW1 can vary over a range of time scales from days to years. While the long-term variability of the DW1 is mainly attributed to the source and background atmosphere variability, the driving mechanism of short-term DW1 variability is still openly debated.