Research Highlights

The NASA Ionosphere Connection explorer was launched in October 2019 with the goal of understanding the transition from Earth's atmosphere to space by measuring key quantities at low latitudes. On 23 December 2019, the Ion Velocity Meter (IVM) instrument on the ICON satellite measured large depletions in the O+ density and downward drifts in the post-midnight/pre-sunset time sector. Interestingly, the H+ density was not depleted during this time and remained relatively uniform.

We apply the helioseismic methodology of Legendre Function Decomposition to 88 months of Dopp- lergrams obtained by the Helioseismic and Magnetic Imager (HMI) as the basis of inferring the depth variation of the mean meridional flow, as averaged between 20 and 60 degrees latitude and in time, in both the northern and southern hemispheres.

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.

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.

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.

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. 

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.

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.

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.