Improving Field Lava Flow Temperatures with Lab-based Spectral
Emissivities for The 2014--2015 Holuhraun Eruption.
Lava flows are one of the main hazards related to effusive basaltic
volcanism. To minimize their impact during emplacement, we use lava flow
potential distance-to-run predicted by propagation models. These models
are partly based on infrared (IR) measurements of lava radiative heat
fluxes by remote sensing (RS) methods (ground-based or satellite-based
detectors) . These results are however subjected to important
errors related to the poor knowledge of spectral emissivity (ε),
commonly considered constant by these well-established techniques[2,
3]. This oversimplification is an important source of uncertainties in
derived temperatures, which restrain our capacity to accurately model
active lava flows. In this study, we developed new algorithms that take
into account the effect of spectral emissivity for calculating radiative
heat fluxes. We describe the temperature-emissivity relationship with
equations established at two wavelengths of interest for RS (10.9 μm and
1.6 μm) that are retrieved from in situ measurements of spectral
emissivity for basaltic magma from the 2014–2015 Holuhraun eruption.
Spectral emissivity data were systematically acquired over a wide
spectral range (400–8000 cm−1) covering TIR, MIR and SWIR, and up to
1473 K . Our results show that spectral emissivity varies
linearly with temperature in TIR (10.9 μm), and nonlinearly in SWIR (1.6
μm). We confronted our lab-based results to the field IR data retrieved
by  and found that temperature precision increases compared to
data using constant emissivity value. These new insights will ultimately
improve the thermo-rheological models of lava flows  in order to
support hazard assessment in volcanic systems. References: 
Kolzenburg et al. 2017. Bull. Volc. 79:45.  Harris, A. 2013:
Cambridge University press. 728.  Rogic et al. 2019 Remote Sens.,
11, 662  De Sousa Meneses et al. 2015. Infrared Physics &
Technology 69.  Aufaristama et al. 2018, Remote Sens, 10,151.
 Thompson and Ramsey, 2021, Bulletin of Volcanology, 83:41.
Keywords: Spectral emissivity, temperature, IR spectroscopy, remote