Søk
Viser treff 1-10 av 30
Radio occultation observations of the solar corona over 1.60-1.86R⊙: Faraday rotation and frequency-shift analysis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-02)
The study of coronal energy transport, central to the solar wind acceleration problem, relies upon accurate representation of magnetic fields and plasma electron densities. This information is difficult to obtain in middle‐to‐lower coronal regions that may contain complex magnetic structures. Faraday rotation (FR) solar radio occultation observations, which reveal line‐of‐sight (LOS) integrated ...
Bistatic Observations of the Ocean Surface with HF Radar, Satellite and Airborne Receivers
(Peer reviewed; Book; Bok; Bokkapittel; Chapter, 2017-12-25)
A new concept has been developed which can view vast regions of the Earth's surface. Ground HF transmissions are reflected by the ionosphere to illuminate the ocean over a few thousand kilometers. HF receivers detect the radio waves scattered by the sea and land surface. Using the theory of radio wave scatter from ocean surfaces, the HF data is then processed to yield the directional wave-height ...
Range-Doppler Mapping of Space-Based Targets Using the JRO 50 MHz Radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-12-02)
The Jicamarca Radio Observatory (JRO) two-dimensional square array radar system operating at ~ 6-m wavelength was used to study the Moon and low Earth orbit satellites using the Range-Doppler inverse synthetic aperture radar technique also known as Delay-Doppler imaging. The radar data was collected on Oct 21, 2015. A circularly polarized coded pulse was transmitted from a quarter-array antenna ...
Four dimensional quantification of Kelvin-Helmholtz instabilities in the polar summer mesosphere using volumetric radar imaging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-13)
We present and characterize in time and three spatial dimensions a Kelvin‐Helmholtz Instability (KHI) event from polar mesospheric summer echoes (PMSE) observed with the Middle Atmosphere Alomar Radar System. We use a newly developed radar imaging mode, which observed PMSE intensity and line of sight velocity with high temporal and angular resolution. The identified KHI event occurs in a narrow layer ...
The science case for the EISCAT_3D radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-29)
The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar
facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the
electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere
(the ionosphere). The mainland radars were constructed ...
Investigation of exceptionally radar-dark regions on the lunar nearside
(Conference object; Konferansebidrag, 2019-08)
Remote sensing of planetary surfaces is an effective method for gaining knowledge of the processes that
shape the planetary bodies in our solar system. This is useful for uncovering the environment of the primordial solar system and to study the current state of the upper crusts of the other planets in our neighborhood. A recent 6-meter wavelength polarimetric radar map of the Moon [?] showed ...
Sparse signal recovery in MIMO specular meteor radars with waveform diversity
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-15)
Since the 1950s, specular meteor radars (SMRs) have been used to study the mesosphere and lower thermosphere (MLT) dynamics. Atmospheric parameters derived from SMRs are highly dependent on the number of detected meteors and the accuracy of the meteors' locations. Recently, incoherent and coherent multiple-input-multiple-output (MIMO) radar approaches combined with waveform diversity have been ...
Traveling ionospheric disturbances and ionospheric perturbations associated with solar flares in September 2017
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-10)
Solar flares provide strong impulsive radiation and energy injection to the sunlit upper
atmosphere. The impact on the ionosphere is immense in spatial scale, and therefore, it is not immediately
evident if dramatically elevated neutral heating can lead to excitation of acoustic gravity waves. Using
primary observations from Global Navigation Satellite System differential TEC (total electron ...
Special issue “Recent Advances in MST and EISCAT/Ionospheric Studies – Special Issue of the Joint MST15 and EISCAT18 Meetings, May 2017”
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-18)
The Fifteenth Workshop on Technical and Scientific Aspects of MST Radar (MST15) and the Eighteenth EISCAT Symposium (EISCAT18) were jointly held in Tokyo, Japan, at the National Institute of Polar Research (NIPR) during May 26–31, 2017. The MST workshops have a long history of being the primary international meetings on the applications and development of mesosphere–stratosphere–troposphere (MST) ...
Spacecraft Radio Frequency Fluctuations in the Solar Corona: A MESSENGER–HELIOS Composite Study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-31)
Fluctuations in plasma electron density may play a role in solar coronal energy transport and the dissipation of wave energy. Transcoronal spacecraft radio sounding observations reveal frequency fluctuations (FFs) that encode the electron number density disturbances, allowing an exploration of the coronal compressive wave and advected inhomogeneity models. Primary FF observations from MESSENGER 2009 ...