NCAR High Altitude Observatory

Solar eclipse observations from the ground and air from 0.31 to 5.5 microns

Plot showing Spectra of the limb photosphere during the 21st August 2017 eclipse
Friday, March 29, 2019

We present spectra and broad-band polarized light data from a suite of instruments deployed during the 21st August 2017 total solar eclipse. Our goals were to survey solar spectra at thermal infrared wavelengths during eclipse, and to test new technology for measuring polarized coronal light.

Solar Flare and Geomagnetic Storm Effects on the Thermosphere and Ionosphere During 6–11 September 2017

Graphic plots depicting data from Swarm A and Swarm B satellites
Friday, March 29, 2019

The period of September 6 – 11, 2017 was an active period in which multiple solar flares and a major geomagnetic storm occurred. The two largest flares, an X9.3 and an X8.2 flares, were a disk flare and a limb flare, respectively.

Trends and Solar Irradiance Effects in the Mesosphere

Monthly mean global average temperatures graph
Friday, March 29, 2019

We investigate trends and solar irradiance effects in the mesosphere using the Whole Atmosphere Community Climate Model with eXtended thermosphere and ionosphere (WACCM‐X) and radar measurements of winds at Collm (51°N, 13°E), for the period of 1980–2014.

Constraints Imposed by the Square-Root Spin-down Law on Coronal Wind Parameters

Graph depicting Coronal Wind Mass-Loss Rate
Thursday, March 7, 2019

We derive an explicit expression for the coronal wind mass-loss rate. This result is based on a currently used generalized torque formula (per unit rotational velocity) expressed as a product of known monomials, separately for the magnetic field and the mass-loss rate.

Validation of Ionospheric Specifications During Geomagnetic Storms: TEC and foF2 during the 2013 March Storm Event

Multiple scatter plots of Geomagnetic storms
Wednesday, March 6, 2019

To address challenges of assessing capabilities of space weather modeling, the CCMC (Community Coordinated Modeling Center) is leading a newly established “International Forum for Space Weather Modeling Capabilities Assessment.”

Triggering the Birth of New Cycle's Sunspots by Solar Tsunami

Image depicting global tachocline fluid top surface deformations
Monday, February 18, 2019

We demonstrate a novel physical mechanism, namely, that a “solar tsunami” occurring in the Sun’s interior shear-fluid layer can trigger new cycle’s magnetic flux emergence at high latitudes, a few weeks after the cessation of old cycle’s flux emergence near the equator.

Johannes Löhner-Böttcher

Dr. Johannes Löhner-Böttcher is a Postdoctoral Fellow in the High Altitude Observatory (HAO) of NCAR. His scientific research focuses on the systematic physical processes which dominate the lower solar atmosphere.

Space Weather Modeling Capabilities Assessment: Neutral Density and Orbit Determination at LEO

Graph depicting TIE-GCM density ratios computed with 2007 CHAMP data
Monday, February 25, 2019

The specification and prediction of density changes in the thermosphere is a key challenge for space weather observations and modeling, because it is one result of complex interactions between the Sun and the terrestrial atmosphere, and also because it is of operational importance for tracking ob


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