Performance Simulations for a Synthetic Aperture Radiometer Measuring Peak Surface Wind Speed in Hurricanes

The Hurricane Imaging Radiometer, HIRAD, is a microwave remote sensor for improved airborne surveillance of ocean surface winds and rain in hurricanes. HIRAD uses a 1-D synthetic aperture thinned array to image the ocean at four frequencies between 4-7 GHz. This paper presents a brief description of the HIRAD array antenna and an analysis of some of the methods used in computing reconstructed brightness temperature, T_b, images. Various aperture taper functions for shaping the synthesized array patterns are discussed along with their application to several representative T_b profiles from simulations of cross-track scans in Hurricane Frances. Requirements in matrix conditioning to improve the image reconstruction process will also be discussed. Results will demonstrate the importance of these two image reconstruction considerations to the image smoothing and spatial resolution trade-off and to the Gibbs phenomenon ringing artifacts from the Fourier inversion process.