The Murchison Widefield Array is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations but is initially focused on three key science projects: detection and characterization of three-dimensional brightness temperature fluctuations in the 21 cm line of neutral hydrogen during the epoch of reionization (EoR) at redshifts from six to ten; solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources; and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broadband active dipoles, arranged into 512 ldquotilesrdquo comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5 km in diameter, with a small number of outliers extending to 3 km. All tile-tile baselines are correlated in custom field-programmable gate array based hardware, yielding a Nyquist-sampled instantaneous monochromaticuvcoverage and unprecedented point spread function quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment, allowing full exploitation of the instrumental capabilities.

A new expression for the mean value of ocean surface sunglint, modeled as a binary-valued random process, is calculated. Multiple sunglint realizations are generated by applying the specular condition for particular viewing geometries to ocean surface elevations with Gaussian roughness spectra. The sunglint mean value is used to determine the relationship between the second-order statistics of the surface slope and sunglint random processes, and this relationship is successfully inverted to retrieve the slope autocorrelation and power spectrum from the simulated sunglint data. The inversion model is then applied to an image recorded coincident with the NASA AIRSAR PACRIM2 field campaign, to retrieve the 1-D elevation power spectrum.

Many multitemporal change detection studies require calibrated sequences of satellite imagery to monitor changes in the Earth surface free of the affects of atmospheric and other influences. Two image calibration procedures were assessed for their ability to estimate the atmospheric contribution to the satellite signal from the calibration results. A sequence of TM and ETM+ imagery over Hay (93/84) was used in the analysis because of the availability of the necessary in situ data. The assessment focussed on the comparison of modeled (from in situ data) and estimated (from the calibration results) values of digital counts associated with a zero surface reflectance. Generally, best agreement with modeled values was observed for band 1-3. Bands 4-7 typically displayed poorer agreement with modeled values due mainly to the increased scatter about the regression lines.