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

Graphic image of scatterplots of hourly mean zonal and meridional wind components
Tuesday, April 6, 2021

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.

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

Graphic image of magnetic perturbation
Thursday, March 25, 2021

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.

Data-Driven Ensemble Modeling of Equatorial Ionospheric Electrodynamics

Graphic depicting root-mean-square difference of the plasma drift
Thursday, February 4, 2021

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.

Migrating Semidiurnal Tide during the September Equinox Transition in the Northern Hemisphere

Graphic depicting migrating semidiurnal tide
Thursday, January 28, 2021

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.

Modeling Diurnal Variation Magnetic Fields for Mantle Induction Studies

Graphic image of the magnetic Bx component
Thursday, January 28, 2021

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.

Day-to-Day Variability of Diurnal Tide in the Mesosphere and Lower Thermosphere Driven From Below

Graphic depicting migrating diurnal tidal amplitudes
Wednesday, December 16, 2020

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.

The 2‐D Evolution of Thermospheric ∑O/N2 Response to Weak Geomagnetic Activity During Solar‐Minimum Observed by GOLD

Graphic image 2D evolution of thermospheric ∑O/N2 response
Wednesday, September 16, 2020

We conduct observational and modeling studies of thermospheric composition responses to weak geomagnetic activity (non-geomagnetic storms). We found that the thermospheric O and N 2 column density ratio (∑O/N 2 ) in part of the Northern Hemisphere measured by

Comparison of GOLD nighttime measurements with total electron content: preliminary results

Graphic image depicting the comparison between the GOLD map and TEC2 map
Friday, August 28, 2020

The National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb and Disk (GOLD) has been imaging the thermosphere and ionosphere since October 2018. It provides continuous measurements over a large area from its geostationary orbit.

Deepak Karan

Deepak Karan is a visiting postdoc at HAO/NCAR. He pursued his Ph.D. work at Physical Research Laboratory, Ahmedabad, India and received a degree in Physics from Indian Institute of Technology Gandhinagar, India.

Medium-scale thermosphere perturbations in the bottomside F region in tropical regions

Graphic image of global distribution of gravity wave activity
Saturday, July 1, 2017

Thermospheric gravity waves in the bottomside F region have been proposed to play a key role in the generation of equatorial plasma bubbles (EPB). However, direct observations of such waves have been lacking.


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