Publications

Barnie, Talfan; Oppenheimer, Clive (2015). Extracting High Temperature Event radiance from satellite images and correcting for saturation using Independent Component Analysis. REMOTE SENSING OF ENVIRONMENT, 158, 56-68.

Abstract
We present a novel method for extracting the radiance from High Temperature Events (HTEs) recorded by geo-stationary imagers using Independent Component Analysis (ICA). We use ICA to decompose the image cube collected by the instrument into a sum of the outer products of independent, maximally non-Gaussian time series and images of their spatial distribution, and then reassemble the image cube using only sources that appear to be HTEs. Integrating spatially gives the time series of total HTE radiance emission. In this study we test the technique on a number of simulated HTE events, and then apply it to a number of volcanic HTEs observed by the SEVIRI instrument. We find that the technique performs well on small localised eruptions and can be used to correct for saturation. The technique offers the advantage of obviating the need for a priori knowledge of the area being imaged, beyond some basic assumptions about the nature of the processes affecting radiance in the scene, namely that (i) HTE sources are statistically independent from other processes, (ii) the radiance registered at the sensor is a linear mixture of the HTE signal and those from other processes, and (iii) HTE sources can be reliably identified for the reconstruction process. This results in only five free parameters the dimensions of the image cube, an estimate of the data dimensionality and a threshold for distinguishing between HTE and nonHTE sources. While we have focused here on volcanic HTEs, the methodology can, in principle, be extended to studies of other kinds of HTEs such as those associated with biomass burning. (C) 2014 The Authors. Published by Elsevier Inc.

DOI:
10.1016/j.rse.2014.10.023

ISSN:
0034-4257