The investigation of the high-latitude aurora by means of the V.H.F. auroral radar SABRE, (Swedish And British auroral Radar Experiment), developed by the Leicester University Ionospheric Physics group, is described. The first two chapters review previous studies of the atmosphere by radar techniques and includes a description of the SABRE radar. The basic radar equation and velocity relationships are derived and the various loss factors examined. From analysis of the echo signal data for the diffuse aurora, and examination of signal data from a radio star, the SABRE radar parameters are established. An investigation is then undertaken of the variation of the electrojet parameters, (derived from application of the radar equation to the SABRE data), with height, electric field strength and geomagnetic conditions. Evidence is found of backscattering from irregularities generated by both two-stream and gradient drift processes. An examination is also made of the echo signals detected at relatively short ranges, of below 370 km, and several causal mechanisms are investigated including scattering processes in the neutral atmosphere. It is evident that aircraft are predominantly the cause of these short-range echoes. This investigation also reveals a number of software and hardware faults in the initial radar configuration. This Thesis is concluded with suggestions for future development of the radar system, which include the implementation of a height-finding facility and improved spectral resolution.

Remote sensing is becoming an increasingly important tool for ocean wave measurement, and over the past decade much progress has been made in the development of the wave measuring capabilities of HF (High Frequency) radar. This system is able to make detailed and near continuous observations of the sea surface over a wide area. However, because the mathematics of the data extraction process is rather difficult, the statistical properties of the observed data have to date been poorly understood. In this study, the approximate sampling distributions of a variety of measurements from HF radar (including significant waveheight, mean wave period, wind direction, and various spectral parameters) are derived in terms of quantities that are either known or estimable. The resulting confidence intervals are, in the case of significant waveheight and mean wave period, of comparable width to those obtained from the corresponding NURWEC2 (Netherlands UK Radar Wave buoy Experimental Comparison) wave buoy measurements, and in the case of spectral power, they are narrower. Furthermore, methods are derived by which such radar measurements may be compared with their corresponding wave buoy measurements in a statistically valid manner, and their relative biases estimated. These methods are then applied to data taken during the NURWEC2 field trial, which suggest that the radars and the wave buoy show good correspondence for measurements of significant waveheight and of spectral power (over 85 - 125mHz - the frequencies with most wave power, and hence those of most importance). There is also a fair correspondence for mean period measurements in the range 6.8 - 11.0secs. Spectral mean direction shows good correspondence over 85 - 155mHz over the somewhat limited directional range (i. e. as observed during the NURWEC2 storm) of the data.

SAR Wave INteraction for Natural Targets Over Land (SWINTOL) is a project funded by the European Space Agency. The study’s goal is to better understand the interaction of high frequency radar (> X-band) with vegetation and soils, in order to drive the development of a high-frequency electromagnetic model to simulate SAR imagery at high resolution (< 1 m). Existing models work well at C and X band frequencies, but do not work properly at higher frequencies. Cranfield University’s role in this project was to provide the field data necessary for model validation and development. Radar imagery was taken of a barley crop over an entire growing season. The portable outdoor GB-SAR system used the tomographic profiling (TP) technique to capture polarimetric imagery of the crop. TP is a scheme that provides detailed maps of the vertical backscatter pattern through a crop canopy, along a narrow transect directly beneath the radar platform. Fully-polarimetric imagery was obtained across overlapping 6.5 GHz bandwidths over the X- and Ku-band frequency range 8-20 GHz. This gave the opportunity to see the detailed scattering behaviour within the crop at the plant component level, from emergence of the crop through to harvesting. In combination with the imagery, full bio-geophysical characterisation of the crop and soil was made on each measurement date. Surface roughness characterisation of the soil was captured using a 3D optical stereoscopic system. This work details the measurements made, and provides a comparative assessment of the results in terms of understanding the backscatter in relation to biophysical and radar parameters.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / A scatterometer is a radar system designed to make precise measurements of the magnitude of the radar echo scattered from surface. If the measurement is made over the ocean's surface, the surface wind speed and direction can be inferred. In order to better understand the relationship between the radar return and the ocean winds we have developed a unique ultra-wide band research scatterometer known as Yscat. The Yscat radar system is computer controlled, with a separate computer collecting environmental data. During a typical deployment, such as a recently completed 7 month deployment on Lake Ontario, the radar system is required to operate unmanned for weeks at a time, collecting data at a rate of up to 2 GB per week. Controlling such a complex system, and handling such large amounts of data presents a challenging remote operation problem. We used a novel combination of personal computers, telephone controlled switches, modems, and off the shelf software packages to enable us to perform daily monitoring, trouble shooting, and data transfer via a simple telephone connection. Data was stored on 4 mm DAT tapes for weekly pickup by a technician. This paper describes the Yscat system and our approach to control, monitoring, and data storage. While our approach is relatively "low tech", it has been very cost effective. This type of approach may be of interest to other designers of unique instrumentation at remote sites.

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