Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Climate Changes in the Upper Atmosphere: Contributions by the Changing Greenhouse Gas Concentrations and Earth's Magnetic Field From the 1960s to 2010s

Previous studies have established the importance of the increasing greenhouse gas concentrations in causing trends in the thermosphere and ionosphere (T-I). Recent work indicates that the changing Earth’s magnetic field is also important. We conduct whole atmosphere model simulations to examine T-I trends driven by these two drivers and their relative importance.

SW2 Amplitude In Meridional Wind

Predictability of the Mesosphere and Lower Thermosphere during Major Sudden Stratospheric Warmings

Stratosphere sudden warmings (SSWs) are strong disturbances in the high latitude, wintertime, stratospheric polar vortex. The effects of SSWs are, however, not limited to the stratosphere, and SSWs influence the whole atmosphere, including tropospheric weather, chemistry and dynamics of the middle atmosphere, and the near-Earth space environment.

Geospace response to an extreme solar flare

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.

Variations in thermosphere composition and ionosphere total electron content under ‘geomagnetically quiet’ conditions at solar-minimum

We conducted observational and modeling studies of thermospheric composition and ionospheric total electron content (TEC) variations during two geomagnetically quiet periods (maximum Kp=1.7) at solar minimum. 

Atomic structure calculations of Land ́e g factors of astrophysical interest with direct applications for solar coronal magnetometry

We perform a detailed theoretical study of the atomic structure of ions with ns2npm ground configurations and focus on departures from LS coupling which directly affect the Land ́e g factors of magnetic dipole lines between levels of the ground terms.

Investigation of a neutral ‘tongue’ observed by GOLD during the geomagnetic storm on May 11,2019

The National Aeronautics and Space Administration Global-scale observations of the Limb and Disk (GOLD) mission observed a unique structure of thermospheric column density ratio of O to N2 (∑O/N2) during a geomagnetic storm on day of year (DOY) 130 (May 10) to DOY 132 in 2019. The percentage difference of ∑O/N2 between the storm time (DOY 131) and the quiet time (DOY 128) had a relatively enhanced ∑O/N2 region sandwiched by two depleted regions over North America and the Atlantic Ocean in the Northern Hemisphere.

A smoothed UV spectrum of α alpha Cen A, obtained by the Hubble Space Telescope

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

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.

Scatterplots of hourly mean zonal and meridional wind components at OI layer

A comparison of Fabry-Perot interferometer and meteor radar wind measurements near the polar mesopause region

The neutral winds in the Mesosphere and Lower Thermosphere (MLT) region have been observed at King Sejong Station, Antarctica using a meteor radar and a Fabry-Perot interferometer (FPI) simultaneously. These two independent MLT wind measurements are compared to each other to identify the characteristics of FPI measurement.

Amplitude spectra of ground magnetic northward magnetic perturbation

Ultra-Fast Kelvin Wave (UFKW) Variations in the Surface Magnetic Field

Kelvin waves are large scale wave that is important for Earth’s atmosphere. The Ultra-Fast Kelvin waves (UFKW) are a subset of the Kelvin waves that can propagate to the mesosphere and lower thermosphere (MLT) ~100km and above due to their high zonal phase speeds.