Multiwavelength Scanning Radiometer for Airborne Measurements of Scattered Radiation within Clouds

Abstract

A multi-wavelength scanning radiometer has been developed for measuring the angular distribution of scattered radiation deep within a cloud layer. The purpose of the instrument is to provide measurements from which the single scattering albedo of clouds can be derived as a function of wavelength. The radiometer has a 1° field of view and scans in the vertical plane from 5° before zenith to 5° past nadir (190° aperture). The thirteen channels of the cloud absorption radiometer are located between 0.5 and 2.3 ?n and were selected to avoid the molecular absorption bands in the near-infrared. The first seven channels of the radiometer are simultaneously and continuously sampled, while the eighth registered channel is selected from among the six channels on a filter wheel. This paper describes the optical, mechanical and electrical design of the instrument and presents some early results obtained from measurements taken aboard the University of Washington's B-23 aircraft to illustrate the performance of the instrument.