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

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.

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.

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.

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.”

Removal of Spectro-Polarimetric Fringes by 2D PCA

Graph depicting the transformation of the PCA basis through a series of carefully chosen rotations
Monday, February 25, 2019

We investigate the application of 2-dimensional Principal Component Analysis (2D PCA) to the problem of removal of polarization fringes from spectro-polarimetric data sets.

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

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.

High cadence visible and infrared spectra of the Sun during eclipse

Graph of raw counts are plotted against wavelength in air for spectral lines
Friday, February 1, 2019

We study visible and infrared spectra, from 310 nm to 5 microns, obtained during the 21st August 2017 eclipse. The instruments were situated at Camp Wyoba (altitude 2402 m) on Casper Mountain, WY.

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.