Design and field-of-view calibration of 114-660-GHz optics of the Earth Observing System Microwave Limb Sounder

This paper describes the optics design and field-of-view (FOV) calibration for five radiometers covering 114-660 GHz which share a common antenna in the Microwave Limb Sounder instrument on the National Aeronautics and Space Administration's Aura satellite. Details of near-field pattern measurements are presented. Estimated systematic scaling uncertainties (3 sigma) on calibrated limb emissions, due to FOV calibration uncertainties, are below 0.4%. 3 sigma uncertainties in beamwidth and relative pointing of radiometer boresights are 0.006 degrees and 0.003 degrees, respectively. The uncertainty in modeled instrument response, due to the scan dependence of FOV patterns, is less than 0.24 K equivalent blackbody temperature. Refinements to the calibration using in-flight data are presented.