Infrared spectroscopy is a powerful diagnostic tool for compositional analysis of geological materials. There is a strong need for ground-truthing studies on Earth if we are to ever truly understand remote sensing data on other planetary bodies. I collect natural samples of volcanic deposits of various textures and compositions (basalt to rhyolite) and textures (lava to ash) and compare their IR spectral signatures at different levels of resolution
- Detailed laboratory spectra taken on individual samples with hyperspectral resolution
- Multispectral data from airborne imagery (e.g. TIMS, MASTER), typically with 4-6 bands and spatial resolution on the order of meters to tens of meters
- Multispectral data from satellite instruments (e.g. ASTER, MSG-SEVRI), typically with 4-6 bands and spatial resolution on the order of hundreds of meters to kilometers
The laboratory spectrometer offers the most ideal conditions, sampling individual and uniform rock surfaces and minimizing the effects of atmospheric CO2 and H2O. But it fails to incorporate the diversity of textures that can be observed in a natural outcrop. Even in a compositionally uniform landscape, each pixel in airborne and satellite imagery likely samples radiated energy from several types of surfaces (solid outcrops, solids, regolith, etc.), possibly with various levels of weathering. My hypothesis is that weathering and the variability of outcrop surfaces within a pixel affect the measured radiation in remote sensing data in similar ways, making it challenging to distinguish bedrock heterogeneity from weathering.
I strive to develop extensive and exhaustive libraries of natural samples to guide the interpretation of orbital data from other planets, where validation is at best a difficult exercise, and in most cases simply not possible.
