HAO

NCAR High Altitude Observatory

Planetary wave (PW) generation in the thermosphere driven by the PW-modulated tidal spectrum

Graphic image of Q6DW zonal wind amplitudes
Thursday, July 16, 2020

The National Center for Atmospheric Research thermosphere-ionosphere-electrodynamics general circulation model (TIE-GCM) is used to conduct numerical experiments that isolate and elucidate a substantial modication of the quasi-6-day wave (Q6DW) above 110 km due to presence of the planetary wave (

Assimilation of Ionosphere Observations in the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX)

Graphic image of WACCMX+DART experiments
Thursday, July 16, 2020

The Earth’s upper atmosphere impacts a wide range of technologies, including satellite communication and navigation signals. Specification and forecasting of the upper atmosphere are critical for mitigating these effects.

Statistical Dependence of EMIC Wave Scattering on Wave and Plasma Parameters

Graphic image of Electromagnetic Ion Cyclotron (EMIC) waves
Thursday, July 16, 2020

A recent statistical study (Qin et al., 2018) has suggested that not all electromagnetic ion cyclotron (EMIC) waves can scatter relativistic electrons. However, knowledge of the factors that influence the EMIC wave scattering efficiency is still limited in observations.

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.

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.

Explicit Form of the Radiative and Collisional Branching Ratios in Polarized Radiation Transport with Coherent Scattering

Schematic diagram showing the polarized radiation transfer in a Lambda-type atomic transition
Tuesday, October 17, 2017

We consider the vector emissivity of the polarized radiation transfer in a Lambda-type atomic transition, which we recently proposed in order to account for both CRD and PRD contributions to the scattered radiation.

Convolutional Neural Networks for Predicting the strength of the Near-Earth Magnetic Field Caused by Interplanetary Coronal Mass Ejections

Image depicting examples of various initial GLOW configurations
Thursday, July 9, 2020

In this paper, regression-based deep convolutional neural networks (CNN), with 12 layers, are developed for predicting the maximal amplitude of the southward component of the near-Earth magnetic field from a passing interplanetary coronal mass ejection (ICME).

A Rare Transit of Venus

Graphic image of individual frames from the movie showing Venus' transit

A coronagraph instrument at the Mauna Loa Solar Observatory on Hawai’i is used by a team of two scientists to record the rare transit of Venus across the Sun's corona.

Responses of the Thermosphere and Ionosphere System to Concurrent Solar Flares and Geomagnetic Storms

Graphic depicting simulated vertical E x B drift velocity
Wednesday, July 1, 2020

We conducted numerical simulations to examine dayside thermosphere and ionosphere responses to concurrent solar flares and a geomagnetic storm during September 6th – September 11th, 2017, as well as the interplay of flare and storm effects.

On the Cores of Resonance Lines Formed in the Sun's Chromosphere

Graphic image depicting a comparison of 1D and 3D calculations
Wednesday, July 1, 2020

We re-examine a 50+ year-old problem of deep central reversals predicted for strong solar spectral lines, in contrast to the smaller reversals seen in observations.

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