Signal Processing Enhancements to Improve Instantaneous Accuracy of a Scanning Bolometer: Application to MERBE

Abstract

Cloud radiative forcing climate signals cannot be detected and proved sufficiently by the existing space-based Earth Radiation Budget (ERB) measurements due to the insufficient instrument calibration accuracy, relative to the sizes of mere decadal-scale trends. This paper, therefore, introduces a new project called the Moon and ERB Experiment (MERBE). Its methodology is for all earth observations using broadband thermal detectors, such as bolometers, to adhere toward more traceable calibration standards based on scans of our moon. This traceability limits instrument-dependent biases and spurious drifts for the past decades of existing earth data measurements as well as future measurements. The goal of the MERBE project is to substantially increase existing satellite climate data accuracy; therefore, a reexamination of all aspects of space-based ERB device calibration was also warranted. This paper concentrates on the improvement of ERB data quality from the level of detector voltages and onward. A component model of bolometer thermal and electronic time response and offset effects is used to design an improved inversion filter, which deconvolves path direction dependence of a scanning thermal detector. For every ERB instrument on the TRMM, Terra, Aqua, and SNPP satellites, instantaneous error reductions are achieved in all recovered MERBE radiance measurements. This also will allow for more accurate results from ERB device lunar scans based on improved telescope field-of-view mapping, as presented in other MERBE work.