Characterising Spatial and Temporal Ionospheric Variability with a Network of Oblique Angle-of-arrival and Doppler Ionosondes

Ionospheric variability exists on a broad range of scales, and routinely impacts skywave propagation modes of high frequency radio waves, to the detriment of radar and communication systems. In order to better understand the electron density structures associated with such variability at mid-latitudes, a network of oblique angle-of-arrival (AoA) and Doppler ionosondes were installed in central and northern Australia as part of the ELOISE campaign in 2015. This thesis analyses observations from the ELOISE AoA ionosondes, with a focus on characterising the influence of medium- to large- scale gradients and signatures of travelling ionospheric disturbances (TIDs). Following an overview of the experiment, the design and calibration of the new ionosonde system is described. With multi-channel receivers connected to each element of two twin-arm arrays, a total of eleven AoA paths of between 900 and 2700 km were collected, including nine with interleaved Doppler measurements using a special channel scattering function (CSF) capability. On-board signal processing was developed to perform real-time clear channel evaluation and CSF scheduling, and generate the AoA ionograms and delay-Doppler images with fitted electron density profiles. In further offline analysis, peak detection and mode classification was carried out, to support reflection point mapping and tilt estimation. Significant testing and validation of the new ionosonde before and after the experiment revealed AoA uncertainties on the scale of 0.2–0.5° in bearing and 0.4–0.9° in elevation. Having identified a low-elevation bias, models of tropospheric refraction and antenna mutual coupling effects were considered as possible correction strategies, but ultimately an empirical approach based on aggregated ionospheric returns was implemented. Small-scale (intra-dwell) ionospheric variability also has the potential to compromise results, through unresolved multi-mode mixing, and this has been investigated using a combination of spatial and temporal variability metrics derived from the CSF data. The analysis of large quantities of F2 peak data shows persistent diurnal patterns in the oblique AoA observables that are also well-captured by a conventional data-assimilative ionospheric model, even without the benefit of AoA and Doppler inputs. Furthermore, Doppler measurements are reproduced remarkably well using just the midpoint fitted profiles. A statistical study has quantified the level of consistency between observations and model, to provide greater confidence in the results. Many of the geophysical features can be interpreted as ionospheric gradients, as evident in the tilt estimates, and horizontally moving structures such as TIDs, using a form of Doppler-based drift analysis. While signatures of TIDs vary considerably, two simple wave-like perturbation models have been evaluated to help classify quasi-periodic behaviour in the AoA observations, as well as understand the directional filtering effect imposed by the path geometry. In some cases, a set of TID parameters can be determined by eye, but in others automatic parameter inversion techniques may be more viable. Two such techniques were implemented but results using both real and synthetic data demonstrated some significant limitations. Finally, attempts to relate TID signatures across multiple paths shows promise, but there still appears to be a strong dependence on path geometry that is difficult to eliminate.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Middle Atmosphere Program. Handbook for MAP. Volume 30: International School on Atmospheric Radar

Broad, tutorial coverage is given to the technical and scientific aspects of mesosphere stratosphere troposphere (MST) meteorological radar systems. Control issues, signal processing, atmospheric waves, the historical aspects of radar atmospheric dynamics, incoherent scatter radars, radar echoes, radar targets, and gravity waves are among the topics covered

Middle Atmosphere Program. Handbook for MAP, volume 4

Topics include winter in the Northern Hemisphere, temperature measurement, geopotential heights, wind measurement, atmospheric motions, photochemical reactions, solar spectral irradiance, trace constituents, tides, gravity waves, and turbulence. Highlights from the Map Steering Committee and a Map Open Meeting including organizational structure are also given

IEEE Geoscience and Remote Sensing Letters: Vol. 10, No. 6, November 2013

1. Merchant Vessel Classification Based on Scattering Component Analysis for COSMO-SkyMed SAR Images / Hong Zhang, et al. 2. Multibaseline PolInSAR Using RADARSAT-2 Quad-Pol Data: improvements in interferometric Phase Analysis / Samira Alipour, et al. 3. Semantic Annotation of High-Resolution Remote Sensing Images via Gaussian Process Multi-Instance Multilabel Learning / Keming Chen, et al. 4. An Azimuth-Dependent Phase Gradient Autofocus (APGA) Algorithm for Airborne/ Stationary BiSAR Imagery / Song Zhuo, et al. 5. Unsupervised Detection of Built -Up Areas From Multiple High-Resolution Remote Sensing Images / Chao Tao, et al. 6. Fast Nonlocal Remote Sensing Image Denoising Using Cosine Integral Images / Bindang Xue, et al. 7. Multichannel InSAR DEM Reconstruction Through Improved Closed-Form Robust Chinese Remainder Theorem / Zhihui Yuan, et al. 8. EBG Antenna for GPR Colocated With a Metal Detector for Landmine Detection / Ian T. McMichael, et al. 9. Swarm Optimization of Structuring Elements for VHR Image Classification / Abdelhamid Daamouched, et al. 10. Considerations for Ku-Band Scatterometer Calibration Using the Dry-Snow Zone of the Greenland Ice Sheet / Kevin R. Moon, David G. Long 11. Unsupervised Coastal Line Extraction from SAR Images / Fabio Baselice, Giampaolo Ferraioli 12. Detection of 3-D Individual Trees in Urban Areas by Combining Airborne LiDAR Data and Imagery / Wei Yao, Yuzhang Wei 13. Inversion of Sweep Frequency Backscatter Ionogram from Monostatic HF Sky-Wave Radar / Ning Li, et al. 14. Utilizing Versatile Transmission Waveforms to Mitigate Pulse-Compression Range Sidelobes with the HIWRAP Radar / Matthew L. McLinden, et al. 15. Space-Time Cube Representation of Stream Bank Evolution Mapped by Terrestrial Laser Scanning / M.J. Starek, et al. etc