3D model of the ionosphere F-region developed by NRL scientists

January 17, 2011 By Daniel Parry
Contour plot of the electron density as a function of magnetic local time (MLT) and altitude. A fully 3D spatial model of ESF describing the motion of ions along and transverse to the geomagnetic field in a narrow longitudinal wedge of the post-sunset ionosphere. Credit: U.S. Naval Research Laboratory (2010)

The first global simulation study of equatorial spread F (ESF) bubble evolution using a comprehensive 3D ionosphere model, SAMI3, has been demonstrated. The model self-consistently solves for the neutral wind driven dynamo electric field and the gravity driven electric field associated with plasma bubbles.

Developed by Dr. Joseph Huba and Dr. Glenn Joyce at the NRL Plasma Physics Division, SAMI3 is a fully three-dimensional model of the low- to mid-latitude ionosphere. SAMI3 has been modified recently to use a sun-fixed coordinate system to eliminate rotation of the dawn-dusk line and a high-resolution longitudinal grid to capture the evolution of equatorial plasma bubbles in the pre- to post-sunset sector.

The new modeling capability with SAMI3 has found that ESF can be triggered by pre-sunset ionospheric density perturbations and that an existing ESF plasma bubble can trigger a new bubble.

"Understanding and modeling ESF is important because of its impact on ," said Dr. Joseph Huba, head of the Space Plasma Physics Section of the Beam Physics Branch. "ESF anomalies can cause radio wave scintillation that degrades communication and navigation systems and serves as the primary focus of the Air Force Communications/ Navigation Outage Forecast System.

Post-sunset ionospheric irregularities in the equatorial F-region were first observed in 1938 by researchers, H.G. Booker and H.W. Wells at the Carnegie Institution of Washington. During that time, analysis of the scattering of by the F-region of the ionosphere at an equatorial location (Huancayo, Peru) revealed ESF is fundamentally a nighttime event, with greatest frequency of occurrence in the period from four hours before midnight to four hours after midnight.

"The ionosphere builds up after sunrise and reaches a maximum in mid-afternoon, said Huba. "Subsequently, the ionosphere can be lifted to higher altitudes just after sunset because of the pre-reversal enhancement of the eastward . During this time the ionosphere can become unstable."

The F-region of the ionosphere is home to the F-layer, or Appleton layer, and is the densest part of the ionosphere as it extends from about 200 km to more than 500 km above the surface of Earth. Beyond this layer is the topside ionosphere. Here extreme ultraviolet solar radiation ionizes atomic oxygen. The F-layer consists of one layer at night, but during the day, a deformation often forms creating layers labeled F1 and F2 . The F-region is the region of the that is very important for high-frequency (HF) radio wave propagation facilitating HF radio communications over long distances.

The upgraded version of SAMI3 represents a unique resource to investigate the physics of equatorial spread F, particularly the processes that control the day-to-day variability of ESFs. Future improvements to the current model include: modification to the geomagnetic field to have a tilt allowing the inclusion of longitudinal effects; coupling SAMI3 with a physics-based model of the thermosphere; and replacement of the full donor cell algorithm, currently being used for crossfield transport, with a high-order flux transport algorithm allowing for the capture of complex bubble evolution involving bifurcation.

Explore further: View of the Upper Atmosphere

Related Stories

View of the Upper Atmosphere

December 5, 2005

Scientists from NASA and the National Science Foundation discovered a way to combine ground and space observations to create an unprecedented view of upper atmosphere disturbances during space storms.

NRL sensor to measure natural airglow in the upper atmosphere

November 6, 2006

The second of five Special Sensor Ultraviolet Limb Imager (SSULI) remote sensing instruments, developed by the Naval Research Laboratory, was launched on November 4, 2006 on board the DMSP F-17 satellite. SSULI is the first ...

Longest lightning storm on Saturn breaks Solar System record

September 15, 2009

A powerful lightning storm in Saturn’s atmosphere that began in mid-January 2009 has become the Solar System’s longest continuously observed thunderstorm.  It broke the record duration of 7.5 months set by another thunderstorm ...

NRL sensor provides critical space weather observations

November 3, 2009

Launched from Vandenberg Air Force Base, Calif., aboard an United Launch Alliance Atlas V launch vehicle, Oct. 18, 2009, the Special Sensor Ultraviolet Limb Imager (SSULI) developed by NRL's Space Science Division and Spacecraft ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

Exploring the physics of a chocolate fountain

November 24, 2015

A mathematics student has worked out the secrets of how chocolate behaves in a chocolate fountain, answering the age-old question of why the falling 'curtain' of chocolate surprisingly pulls inwards rather than going straight ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Jan 17, 2011
Really nice article with good data.

Looks like another tech. using electrons in ionisphere for microwave wireless power transmission.

search google with phrase below.

p2pnet news Blog Archive Space-based microwave power

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.