NCAR

Congratulations to Gang Lu, elected fellow of the AGU

The High Altitude Observatory is proud to acknowledge Dr. Gang Lu for being among the 2020 class of AGU Fellows, just recently announced. Gang is a Senior Scientist at HAO.

Impact of GOLD Retrieved Thermospheric Temperatures on a Whole Atmosphere Data Assimilation Model

Graphic depicting the whole atmosphere temperature profiles
Tuesday, November 10, 2020

The present investigation evaluates the assimilation of synthetic data which has properties similar to actual Global-scale Observations of the Limb and Disk (GOLD) level-2 (L2) and other conventional lower atmospheric observations.

Simulations of prominence eruption preceded with large amplitude longitudinal oscillations and draining

Graphic depicting prominence-forming twisted coronal flux rope
Friday, November 6, 2020

We present magnetohydrodynamic (MHD) simulations of the evolution from quasi-equilibrium to eruption of a prominence-forming twisted coronal flux rope under a coronal streamer. The prominence condensations form at the dips of the twisted flux rope due to run-away radiative cooling.

Sudden Stratospheric Warmings

Graphic image of ionospheric behavior during the 2009 SSW event
Friday, October 23, 2020

Sudden stratospheric warmings (SSWs) are impressive fluid dynamical events in which large and rapid temperature increases in the winter polar stratosphere (∼10–50km) are associated with a complete reversal of the climatological wintertime westerly winds.

Reconstructing the Coronal Magnetic Field: The Role of Cross-Field Currents in Solution Uniqueness

Graphic image of analytic model magnetic field lines
Friday, October 23, 2020

We present a new 3D magnetohydrostatic (MHS) direct elliptic solver for extrapolating the coronal magnetic field from photospheric boundary conditions in a manner consistent with an assumed plasma distribution.

Holly Gilbert, HAO's new Director

Holly Gilbert. Image: NASA

HAO is proud to announce our new director, Holly Gilbert.

Superstrong photospheric magnetic fields in sunspot penumbrae

Graphic image showing a portion of the inner penumbra in the MURaM sunspot simulation
Friday, October 2, 2020

Recently, there have been some reports of unusually strong photospheric magnetic fields (which can reach values of over 7 kG) inferred from Hinode SOT/SP sunspot observations within penumbral regions.

Formation of Double Tongues of Ionization During the 17 March 2013 Geomagnetic Storm

Graphic image showing polar maps of the simulated electron density
Friday, October 2, 2020

During geomagnetic disturbances, enhanced high‐latitude convection transports ionospheric F2‐region plasma from the dayside midlatitude region into the polar cap, leading to structures such as tongues of ionization (TOIs) and patches.

Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes

Graphic image showing the maps of the E-region horizontal and radial currents
Friday, October 2, 2020

The flow of ionospheric current can be probed by examining magnetic field measurements at the ground and at Low-Earth-Orbit (LEO) altitude.

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

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