HIRAD Brightness Temperature Image Geolocation Validation

The Hurricane Imaging Radiometer (HIRAD) is an airborne microwave radiometer developed to provide wide-swath hurricane surface wind speed and rain rate imagery for scientific research. This letter presents a geometric evaluation of the brightness temperature (Tb) images produced by HIRAD for high-contrast land/water targets. Methodologies used to validate geolocation accuracy and spatial resolution are discussed, and results are presented to provide quantitative pixel geolocation accuracy and the effective image spatial resolution of the Tb image.

I. Introduction

The objective of the airborne Hurricane Imaging Radiometer (HIRAD) is to provide 2-D of hurricane surface wind speed and rain rate fields for scientific research. This remote sensor, developed by the NASA Marshall Space Flight Center (MSFC), is a microwave synthetic thinned aperture radiometer, which simultaneously measures the ocean brightness temperature (Tb) at 4 C-band frequencies. From these measurements, it is possible to retrieve hurricane force ocean surface winds in the presence of tropical rains with 2–6 km spatial resolution over a wide swath of typically 60 km (from a 20-km aircraft altitude).