An FFT-based CLEAN deconvolution method for interferometric microwave radiometers with spatially variable beam pattern

A modification to the extended CLEAN deconvolution method for passive microwave interferometric radiometers is presented which takes into account interferometer beam patterns that vary depending on source position within the interferometer field of view.This method is developed for the newly proposed multi-satellite rotating microwave interferometric radiometer concept for geostationary atmospheric sounding, which is found to have a spatially varying beam pattern.The proposed method is implemented via piece-wise application of Fast Fourier Transform (FFT)-based convolution, where the beam pattern is assumed to remain constant within small segments of a given image.This approach allows the proposed method to exploit the speed advantage of the FFT.Applying this method to the proposed multi-satellite interferometer shows a factor of 2 improvement in the radiometric accuracy of the recovered brightness temperature map, compared to constant beam pattern CLEAN