Research

HAO Science

...from the Sun's interior to the Earth's atmosphere

The High Altitude Observatory, through its collaboration with scientists and scientific organizations around the world is recognized as one of the premier authorities of Sun and Sun-Earth studies.

Tightly integrated activities between HAO's scientific staff and its Instrumentation Group (engineering team) strengthen its core program, and in turn yield a variety of exciting results in the scientific exploration of the Sun and the influences it exerts on the terrestrial atmosphere and climate.

The scientific program of HAO is solar-terrestrial physics, broadly interpreted. Included is solar physics, physics of the heliosphere, the study of geospace and space weather, and the physics of the Earth's magnetosphere and upper atmosphere.

Research Highlights

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.

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.

Neutral hydrogen, helium and solar and stellar coronae

Graphic image of Line Profiles of He I and He II Resonance Line
Wednesday, June 17, 2020

In the context of the solar atmosphere, we re-examine the role of of neutral and ionized species in dissipating the ordered energy of intermediate-mode MHD waves into heat.

Physics Of MHD Rossby Waves In The Sun

Graphic image of the physics Of MHD Rossby Waves In The Sun
Wednesday, June 10, 2020

Evidence of the existence of hydrodynamic and MHD Rossby waves in the Sun is accumulating rapidly.

Preliminary Evidence of Madden-Julian Oscillation Effects on Ultra-Fast Tropical Waves in the Thermosphere

Graphic image of altitude (50-260 km) versus MJO phase depiction
Wednesday, June 10, 2020

Over the past two decades mounting evidence demonstrated that terrestrial weather significantly influences the dynamics and mean state of the thermosphere.

Some thoughts on emission-line spectroscopy

Graphic image of intensity and polarization data surrounding the current sheet formed on Sept 10 2017
Tuesday, June 2, 2020

Philip Judge states that the interpretation of emission lines formed in large astrophysical plasmas such as the solar atmosphere faces many challenges. Relatively simple line-ratio estimates of physical parameters, while appealing, are heavily laden with assumptions.

Global Modeling of Equatorial Spread F with SAMI3/WACCM-X

Graphic image of the comparison of 135.6 nm emissions
Tuesday, June 2, 2020

We report the first results of a global ionosphere/thermosphere simulation study that self-consistently generates large-scale equatorial spread F (ESF) plasma bubbles in the post-sunset ionosphere.

Simulated trends in ionosphere-thermosphere climate due to predicted main magnetic field changes from 2015 to 2065

Photograph of TEC in 2015
Friday, May 15, 2020

Summary or Abstract: The strength and structure of the Earth's magnetic field is gradually changing. These changes do not only affect the difference between the geographic and magnetic pole, which we have to consider when we hike in higher latitude regions.

Global-scale Measurements of the Limb and Disk (GOLD) Mission Implementation: Instrument Design and Early Flight Performance

Schematic of the sectional view of a GOLD spectroscopic imaging channel
Tuesday, May 12, 2020

The Global-scale Observations of the Limb and Disk (GOLD) is a NASA mission of opportunity designed to study how the Earth’s ionosphere-thermosphere system responds to geomagnetic storms, solar radiation and upward propagating tides on time scales as short as 30 minutes.

Areas of Focus

A Whole Atmosphere Community Climate Model (WACCM)

The Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) is a comprehensive numerical model, spanning the range of altitude from the Earth’s surface to the upper thermosphere.

Assimilative Mapping of Ionospheric Electrodynamics (AMIE)

The AMIE procedure is an optimally constrained, weighted least-squares fit of electric potential distribution to diverse types of atmospheric observations. Knowledge of these distributions is important in many areas of magnetospheric, ionospheric, and thermospheric physics.

Challenges in Observing Short-term Tidal Variability

Modeling the upper levels of the Earth’s atmosphere, is one of the strengths of the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) supported as a community model by scientists at the High Altitude Observatory.

Coupled Magnetosphere Ionosphere Thermosphere Model (CMIT)

The Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model consists of the Lyon-Fedder-Mobarry (LFM) model of the magnetosphere coupled to the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM).

Data-Optimized Coronal Field Model (DOCFM)

DOCFM is an NCAR/CfA collaboration that is funded by AFOSR to model the global coronal magnetic field using magnetometric and other observations, with the goal of improving space weather forecasts of magnetic orientation within c

FORWARD Model

The FORWARD model is a suite of IDL and fortran codes that calculates simulated coronal polarization signals from numerical and analytical models of the corona.

Global Airglow Model

The GLobal airglOW model, also known as GLOW, is a toolkit of subroutines and driver programs for performing calculations of optical emissions in the upper atmosphere, particularly the thermosphere and ionosphere, above about 100 km altitude.

Global Scale Wave Model (GSWM)

The GSWM solves the linearized and extended Navier-Stokes equations for steady-state global temperature and wind perturbations. GSWM may be used to calculate an "unforced" planetary wave response for a specified period and zonal wavenumber, or the thermally-driven response for either a diurnal or semidiurnal atmospheric tide.

LYON-FEDDER-MOBARRY (LFM) GLOBAL MHD CODE

The LFM Code is an integrated simulation model for the global magnetosphere-ionosphere system. The heart of the model is a time-dependent, ideal MHD calculation of the state of the magnetosphere.

Thermosphere Ionosphere Electrodynamic General Circulation Models (TGCMs)

The NCAR TGCM's are three-dimensional, time-dependent models of the EARTH's neutral upper atmosphere.

Fabry Perot Interferometer at Resolute Bay, Canada

Resolute, Canada (75N) is the site chosen for the deployment of the National Science Foundation Advance Modular Incoherent Scatter Radar (AMISR). AMISR is a state of the art phase array radar, which allows fast electronic steering of the radar beam to track fast moving auroral features.

Fabry-Perot Interferometer at Boulder, Colorado

On March 16, 2012, a Fabry-Perot Interferometer (FPI) was installed at the NCAR Marshall field site, just to the south-east of Boulder, to observe thermospheric and mesospheric winds.

Fabry-Perot Interferometer at Palmer, Antarctica

The Palmer station Fabry-Perot interferometer project is funded by the National Science Foundation Office of Polar Programs. The goal is to study the upper atmosphere and ionosphere over the Antarctica Peninsula. Palmer station is an year-around US Antarctica Research station located on the Anvers Island near the Antarctica Peninsula.

HiWind

HiWind was the first balloon borne Fabry-Perot interferometer designed to measure summer time polar cap thermospheric neutral winds. Thermospheric wind measurements are critically needed for space weather research. HiWind was launched June 14, 2011 from Kiruna, Sweden.

Mauna Loa Solar Observatory

The Mauna Loa Solar Observatory (MLSO) has been operating since the mid-1960s, providing a nearly-continuous record of solar data to the community. MLSO data includes white light corona, emission corona, H-alpha (disk and limb), He-I, and photometric.

The Community Spectro-polarimetric Analysis Center (CSAC)

CSAC provides a suite of community resource tools for analysis of the precision polarization data for remote sensing of magnetic fields in the outer solar atmosphere.

Collaborating with Fudan University

HAO Senior Scientist Philip Judge spent three weeks at China's Fudan University in October 2015. As an official Visiting Researcher, Philip worked with his host Roger Hutton, and recent graduate Wenxian Li, on magnetically sensitive emission lines formed in the solar corona.

Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR)

CEDAR is a national and international research program, sponsored by the National Science Foundation, to study the Earth's upper atmosphere. The emphasis is on the energetic and dynamical processes that determine the composition and structure of the atmosphere, and the coupling between different regions.

Preparing for the 2017 total Eclipse

On 21 August 2017 a total solar eclipse will pass across the continental United States, from Oregon on the west coast to South Carolina on the east. The eclipse will be a phenomenal experience for the millions of people who see it, but it also offers a unique opportunity to conduct scientific research of the solar atmosphere.

The Community Spectro-polarimetric Analysis Center (CSAC)

CSAC provides a suite of community resource tools for analysis of the precision polarization data for remote sensing of magnetic fields in the outer solar atmosphere.

A TIEGCM Simulation of the Anomalous Electron Heating Effect on the E-region Ionosphere

In the ionospheric E-region, the electrons are magnetized because their frequency of rotation around the magnetic field is much greater than their frequency of collisions with the neutrals. Thus, the electrons drift mostly perpendicular to the electric fields.

CME Initiation, Evolution, and Interplanetary Consequences

HAO scientists have carried out 3D isothermal MHD simulations of the evolution of the large scale coronal magnetic field as a twisted magnetic flux tube is driven (slowly) through the lower boundary into a pre-existing coronal arcade field.

Coronal and Heliospheric Evolution

The magnetic field in the Sun's atmosphere continuously evolves through processes of emergence, diffusion, and reconnection, resulting in ongoing reorganizations of the global coronal/helio- spheric magnetic morphology, as well as in the slow buildup of magnetic energy in twisted or sheared magnetic fields.

Impact of Energetic Particles on the upper Atmosphere

Energetic particles, namely electrons and protons, released from the magnetosphere cover a wide range of energies from a few electron volts (eV) to hundreds of milli-electron volts (MeV).

Long-Term Solar Variability

HAO scientists pursue an interdisciplinary, system-wide view on the origins and impacts of solar and stellar cycle variation, with a particular focus on magnetic minima as times of low activity and relatively simple heliospheric structure.

Magnetic Flux Emergence

Understanding the process of magnetic flux emergence through the solar convection zone is crucial for understanding the link between the observed magnetic activities at the surface and the dynamo-generated magnetic fields in the interior.

Modeling high-speed flows in the Earth’s Magnetotail

The magnetosphere is created by the interaction between the solar wind and the Earth’s magnetic field. On the dayside of the Earth pressure from the solar wind compresses the Earth’s dipole magnetic field and on the night side this interaction stretches it out forming a region of space commonly referred to as the magnetotail.

Satellite Drag Physical Modeling for Transition to Operations

The ionosphere and upper atmosphere play a major role in space operations, including communications, navigation, and satellite drag. Satellite drag, the drag force exerted by the tenuous upper atmosphere on orbiting bodies, is the leading cause of error in predicting the locations of objects in low-Earth orbit.

Solar Convecton and Mean Flows

Any inquiry into the ultimate origins of solar magnetic activity must soon confront turbulent thermal convection. Convection is a means by which the Sun shines. Energy liberated by nuclear fusion deep in the core of the Sun filters outward by the diffusion of photons.

Studying Atmosphere Coupling Using Mesoscale-resolving WACCM

An important pathway for the terrestrial weather to affect the space weather is through atmosphere waves, such as atmospheric tides, planetary waves and gravity waves. The impacts of the planetary-scale waves have been extensively studied observationally and numerically.

Sunspots and Photospheric Dynamics

Sunspots are the most prominent manifestations of magnetic field in the visible layers of the solar atmosphere. Their origin is a dynamo process operating in the solar convection zone.

The Sun as a Dynamo

The ultimate origins of solar variability lie below the visible surface, where turbulent convection, differential rotation, and meridional flows work together to produce magnetic fields through the operation of a stellar dynamo, giving rise to the 22-year solar magnetic cycle.