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

The enduring mystery of the solar corona

Magnetic field lines
Thursday, September 16, 2021

The author reviews why, after almost 8 decades, we still have a coronal heating problem.

Magnetofrictional Modeling of an Erupting Pseudostreamer

3D magnetic eld evolution of an erupting pseudostreamer
Friday, August 13, 2021

In this study, we present a magnetic conguration of an erupting pseudostreamer observed on April 19, 2015 on the Southwest limb embedding a prominence cavity. The eruption resulted in a relatively wide CME with a round front and prominence core intersected by a sharp plume.

Migrating Semidiurnal Tide during the September Equinox Transition in the Northern Hemisphere

migrating semidiurnal tide amplitude in zonal wind
Friday, August 13, 2021

Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (SD-WACCMX) simulations are used to investigate the solar migrating semidiurnal tide (SW2) around September equinox at middle to high latitudes in the Northern Hemisphere.

The Impact of Solar Activity on Forecasting the Upper Atmosphere via Assimilation of Electron Density Data

Geographic latitude and altitude distribution
Friday, August 13, 2021

This study presents a comprehensive comparison of the impact of solar activity on forecasting the upper atmosphere through assimilation of radio occultation (RO)-derived electron density (Ne) into a physics-based model (TIE-GCM) using an ensemble Kalman filter.

Characteristics of small-scale gravity waves in the Arctic winter mesosphere

Histogram of small-scale GWs’ parameters observed by All-sky OH airglow imager at Resolute Bay Observatory
Tuesday, July 13, 2021

Observational datasets in the polar middle atmosphere are extremely valuable for understanding the polar dynamics and coupling between lower and middle atmosphere.

COSMIC Observation of Stratospheric Gravity Wave and Ionospheric Scintillation Correlation

High S4 occurrence (> 0.2) longitudinal and annual variations from 2010 to 2013
Tuesday, July 13, 2021

A correlation study is performed to investigate possible connections between the stratospheric gravity waves and the ionospheric plasma bubble induced GPS signal scintillations.

NO transport via Lagrangian Coherent Structures into the top of the polar vortex

Daily average WACCMX+DART NO profiles
Tuesday, July 13, 2021

The energetic particle precipitation (EPP) indirect effect (IE) refers to the downward transport of reactive odd nitrogen (NOx=NO+NO2) produced by EPP (EPP-NOx) from the polar winter mesosphere and lower thermosphere to the stratosphere where it can destroy ozone.

Post-midnight O+ Depletions Observed by ICON: Data/Model Comparison

Data/Model Comparison
Wednesday, June 30, 2021

The NASA Ionosphere Connection explorer was launched in October 2019 with the goal of understanding the transition from Earth's atmosphere to space by measuring key quantities at low latitudes.

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 occupies part of the NOAA Mauna Loa research site located on the flank of Mauna Loa at an elevation of 3440 meters on the island of Hawaii.

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.