High resolution airborne multispectral and thermal infrared imagery (1-meter pixel resolution) was acquired over several
hydrothermal areas in Yellowstone National Park both in September of 2011 and in early March, during the winter of
2012, when snow cover was still present in most of the Park. The multi-temporal imagery was used to identify the extent
of the geothermal areas, as snow accumulation is absent in hydrothermal areas. The presence or absence of snow
depends on the heat flow generated at the surface as well as antecedent snow precipitation and temperature conditions.
The paper describes the image processing and analysis methodology and examines temperature thresholds and conditions
that result in the presence or absence of snow cover.
High-resolution multispectral images in the green (0.57 μm), red (0.65 μm), near-infrared (0.80 μm) and
thermal infrared (8-12 μm) bands were acquired using the Utah State University airborne multispectral
system over several active geothermal areas in Yellowstone National Park as part of an ongoing monitoring
program initiated in the Fall of 2005. The imagery was acquired under clear sky conditions at two different
times of the day, early afternoon and midnight, with the objective of studying the geothermal properties of
the different active thermal areas in the park as well as providing calibrated thermal imagery for long-term
monitoring of changes. The paper will describe the image acquisition and processing methodology, as
well as surface emissivity and atmospheric corrections conducted to obtain at-surface temperatures.
Examples of the products obtained over different areas will be shown and discussed.