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

Waldmeier Effect in Stellar Cycles

Graph depicting the second Waldmeier effect-WE2
Tuesday, October 8, 2019

One of the most robust features of the solar magnetic cycle is that the stronger cycles rise faster than the weaker ones. This is popularly known as the Waldmeier Effect, which is known for more than 100 years.

Simulating the solar corona in the forbidden and permitted lines with forward modeling I: Saturated and unsaturated Hanle regimes

Graphic depicting Linear polarization azimuth
Thursday, October 3, 2019

The magnetic field in the corona is important for understanding solar activity. Linear polarization measurements inforbidden lines in the visible/IR provide information about coronal magnetic direction and topology.

Challenges to Understanding the Earth's Ionosphere and Thermosphere

Schematic of plasma and density structures in the IT system
Thursday, October 3, 2019

In this paper we discuss, in a limited way, some of the challenges to advancing our understanding and description of the coupled plasma and neutral gas that make up the ionosphere and thermosphere (I-T).

THE PERSISTENT IONOSPHERIC RESPONSES OVER JAPAN AFTER THE IMPACT OF THE 2011 TOHOKU EARTHQUAKE

Graphic of two-dimensional filtered Global Navigation Satellite System (GNSS) total electron content (TEC) maps
Wednesday, September 11, 2019

Earthquake and tsunami are known to be the source of atmospheric gravity waves that can generate plasma ripples in the space. On March 11, 2011, a magnitude 9.0 earthquake occurred near the east coast of Honshu, Japan, unleashing a savage tsunami to strike offshore of Japan.

Data-optimized coronal field model: 1. Proof of concept

Graphic depicting field-lines from a ground-truth flux-rope magnetic field model
Thursday, August 8, 2019

Deriving the strength and direction of the three-dimensional (3D) magnetic field in the solar atmosphere is fundamental for understanding its dynamics. Volume information on the magnetic field mostly relies on photospheric and/or chromospheric surface vector magnetic fields.

Global-scale Observations of the Equatorial Ionization Anomaly

GOLD image of the daytime airglow and the equatorial ionization anomaly (EIA)
Monday, August 5, 2019

The NASA Global-scale Observations of the Limb and Disk (GOLD) ultraviolet spectrograph began imaging the Equatorial Ionization Anomaly (EIA), regions of the ionosphere with enhanced electron density north and south of the magnetic equator, in October 2018.

Constraining nonlinear dynamo models using quasi-biennial oscillations from sunspot area data

Graphic depicting continuous wavelet spectra of the sunspot area (SSA)
Thursday, July 25, 2019

Solar magnetic activity exhibits variations with periods between 1.5–4 years, the so-called quasi-biennial oscillations (QBOs), in addition to the well-known 11-year Schwabe cycles. The solar dynamo is thought to be the responsible mechanism for the generation of the QBOs.

Predictability of the mesosphere and lower thermosphere based on initialized hindcast experiments

Graph depicting global normalized root mean square error for wavenumbers 0-6
Monday, July 15, 2019

The ability to predict conditions in Earth’s ionosphere and thermosphere is of increasing societal relevance due to the growing dependence on, for example, satellite based communications and navigation (e.g., GPS) systems.

MinXSS CubeSat Mission Overview: Improvements from the Successful MinXSS-1 Mission

Photograph of the MinXSS-2 spacecraft
Monday, July 15, 2019

The second Miniature X-ray Solar Spectrometer (MinXSS-2) CubeSat builds on the success of MinXSS-1. The science instrument is more advanced – now capable of greater dynamic range with higher energy resolution.

What the Sudden Death of Solar Cycles Can Tell us About the Nature of the Solar Interior

140 year record of solar filaments
Monday, July 1, 2019

We observe the abrupt end of solar activity cycles at the Sun’s Equator by combining almost 140 years of observations from ground and space.

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.