Methodology for calculating volcano vent temperature using optical remote sensing data

Abstract

Conventional methods to estimate volcano vent temperature using ground-based methods are hazardous, and there is need to explore alternate methods like those involving the utilization of remote sensing data. A volcano eruption took place recently in Barren Island of Andaman and Nicobar group of islands. Unusal event of this nature generated a lot of interest. A methodology of temperature estimation of volcano vent using optical remote sensing data of Landsat Thematic Mapper (TM) is presented. The dynamic range of thermal infrared band gets saturated as it has been designed for normal terrestrial temperatures. The sensitivity of various spectral bands is discussed and the utility of near IR band data for the measurement of vent temperature is emphasized. The effect of sub-pixel size vent in the estimation of pixel-integrated temperature is estimated by assigning weighted radiation value to the non-vent component of the pixel using values of surrounding background pixels. It is inferred that if the volcanic vent occupies 21% area of the pixel, the computed pixel-integrated temperature of the vent is within 1% error. Even if the vent occupies 10% of pixel area, the error in volcano vent temperature estimate would be around 3%. This is due to the exponential nature of Plank's black body function.