Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Comparison of the whole atmosphere temperature profiles from the true state, lower atmosphere only assimilation (LA), and lower-atmosphere plus GOLD assimilation (LA+GOLD) for 14 UT (left column) and 18 UT (right column) at different locations inside the GOLD field of view (top) and for the zonal mean (bottom)

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

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. The lower atmospheric and GOLD L2 temperature (Tdisk) are assimilated in the Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCMX) using Data Assimilation Research Testbed (DART).

An MHD simulation of the evolution of a prominence-forming twisted coronal flux rope, for which large amplitude longitudinal (LAL) oscillations are excited during the quasi-static rise phase, followed by prominence draining towards the flux rope foot-points and the eventual eruption of the flux rope and the prominence

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

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.

Observations of ionospheric behavior during the 2009 SSW event

Sudden Stratospheric Warmings

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. 

Comparison of analytic model magnetic field lines to results of numerical reconstruction

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

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.

Maps of the E-region horizontal and radial currents for 18 March 2016 at 11:22 UT

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

The flow of ionospheric current can be probed by examining magnetic field measurements at the ground and at Low-Earth-Orbit (LEO) altitude. The interpretation of the magnetic field perturbations with respect of ionospheric current flow is complicated by the fact that the perturbations reflect the integrated effect of current flow close-by and far-away.

Polar maps of the simulated electron density at pressure level 2 (~300 km) in the Northern Hemisphere as a function of geographic latitude and local time on 17 March 2013

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

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. In this study, we investigate the dynamic evolution of TOIs during the 17 March 2013 storm using a high‐resolution coupled thermosphere‐ionosphere‐electrodynamics model and Defense Meteorological Satellite Program (DMSP) satellite observations.

A portion of the inner penumbra in the MURaM sunspot simulation by Rempel (2015) with some filaments hosting a counter-Evershed flow (see also Siu-Tapia et al. 2018)

Superstrong photospheric magnetic fields in sunspot penumbrae

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. These superstrong penumbral fields are even larger than the strongest umbral fields in record and appear associated with supersonic downflows.

(top) The Kp and Dst index of three cases (DOY 145 to 148; DOY 153 to 156; DOY 162 to 165); (middle) latitude-longitude distribution of ∑O/N2 percentage difference between two quiet days in three cases; (bottom) percentage difference of ∑O/N2 between disturbed and quiet days in three cases. Corresponding local time is marked on longitude interval

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

We conduct observational and modeling studies of thermospheric composition responses to weak geomagnetic activity (non-geomagnetic storms).

The comparison between the GOLD map and TEC2 map on DOY 72 in 2019 23:10-23:40 (top) and 23:55-24:25 (bottom)

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

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.