Glacier ice surface properties in South-West Greenland Ice Sheet: first
estimates from PRISMA imaging spectroscopy data
Abstract
Snow and ice melt processes on the Greenland Ice Sheet are a key in
Earth’s energy balance and hydrological cycle, and they are acutely
sensitive to climate change. Melting dynamics are directly related to a
decrease in surface albedo, amongst others caused by the accumulation of
light-absorbing particles (LAPs). Featuring unique spectral patterns,
these accumulations can be mapped and quantified by imaging
spectroscopy. In this contribution, we present first results for the
retrieval of glacier ice properties from the spaceborne PRISMA imaging
spectrometer by applying a recently developed simultaneous inversion of
atmospheric and surface state using optimal estimation (OE). The image
analyzed in this study was acquired over the South-West margin of the
Greenland Ice Sheet in late August 2020. The area is characterized by
patterns of both clean and dark ice associated with a high amount of
LAPs deposited on the surface. We present retrieval maps and
uncertainties for grain size, liquid water, and glacier algae
concentration, as well as estimated reflectance spectra for different
surface properties. We then show the feasibility of using imaging
spectroscopy to interpret multiband sensor data to achieve high
accuracy, fast cadence observations of changing snow and ice conditions.
In particular, we show that glacier algae concentration can be predicted
from the Sentinel-3 OLCI impurity index with less than 10 %
uncertainty. Our study evidence that present and upcoming orbital
imaging spectroscopy missions such as PRISMA, EnMAP, CHIME, and the SBG
designated observable, can significantly support research of melting ice
sheets.