Point response function of the Clouds and Earth Radiant Energy System scanning radiometer

G Louis Smith,Kory J Priestley,Susan Thomas,Janet L Daniels

doi:10.1117/1.jrs.8.084991

Abstract

An overview of work related to the point response function (PRF) of the Clouds and Earth Radiant Energy System (CERES) scanning radiometer is presented. The aspects of the CERES design that affect the PRF are described, and then the design of the PRF is explained. The PRF was designed by shaping the field of view so as to minimize the blur plus alias errors of the radiance field reconstructed from the CERES measurements. The design is conducted in the Fourier domain. The PRF can then be computed by transforming the resulting transfer function to the physical domain. Alternatively, the PRF can be computed in the physical plane. The PRF of each model of the CERES instrument has been tested in the Radiation Calibration Facility by use of a PRF source and compared well with prediction. CERES instruments are aboard the Terra, Aqua, and Suomi-NPP spacecraft. In orbit, lunar observations are used to validate the PRF. These results showed nominal performance except for the longwave window channel of flight model 2, for which a region of anomalously high sensitivity was found.

Highlights

The Clouds And Earth Radiant Energy System (CERES) project has two major objectives: to measure radiances so that the radiation fluxes at the top of the atmosphere (TOA) can be retrieved and to compute the radiation fluxes at the surface of the Earth and through the atmosphere.[1]
The CERES instrument is a scanning radiometer, which scans from one limb of the Earth to the other
The shape of the CERES field of view (FOV) was designed following the method of Huck et al.[8,9,10] for the FOV of the Earth radiation budget scanning radiometer

Summary

Introduction

The Clouds And Earth Radiant Energy System (CERES) project has two major objectives: to measure radiances so that the radiation fluxes at the top of the atmosphere (TOA) can be retrieved and to compute the radiation fluxes at the surface of the Earth and through the atmosphere.[1] The CERES instrument is a scanning radiometer, which scans from one limb of the Earth to the other. The effect of radiation from a given point at TOA on the measurement of a channel is defined as its point response function (PRF). The PRF determines the fidelity with which the geographic distribution of the radiation field, or image, is determined by the measurements. The objective of the PRF design is to optimize the fidelity of this image with the observed field. The PRF is determined by the construction of the telescope and electronics of the channel

Methods

Results

Conclusion