Glacier Ice Surface Properties in South‐West Greenland Ice Sheet: First Estimates From PRISMA Imaging Spectroscopy Data. Issue 3 (24th February 2022)

• Record Type: Journal Article
• Authors: Bohn, Niklas; Di Mauro, Biagio; Colombo, Roberto; Thompson, David R.; Susiluoto, Jouni; Carmon, Nimrod; Turmon, Michael J.; Guanter, Luis
• Is Part Of: Journal of geophysical research. Volume 127:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-24
• Subjects: imaging spectroscopy -- Greenland Ice Sheet -- snow and ice surface properties -- mapping glacier algae -- optimal estimation -- PRISMA; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1029/2021JG006718
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Snow and ice melt processes on the Greenland Ice Sheet are a key in Earth's energy balance and 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. 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. 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 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, frequently repeated observations of changing snow and ice conditions. For example, the impurity index calculated from multiband Sentinel‐3 Ocean and Land Colour Instrument measurements is dependent on dust particles, but we show that algae concentration alone can be predicted from this data with less than 20% uncertainty. Our study evidences that present and upcoming orbital imaging spectroscopy missions such as PRISMA, Environmental Mapping and Analysis Program, Copernicus Hyperspectral Imaging Mission, and the Surface Biology and Geology designated observable, can significantly support research of melting ice sheets. Plain Language Summary: The Greenland Ice Sheet plays a key role in climate change since increased melting over the past decades significantly contributes to global sea level rise and the associated socioeconomic consequences. Melting dynamics are controlled by the amount of solar radiation absorbed by the surface. This amount increases when ice gets darker, which is mainly caused by small particles such as algae and dust accumulating on the surface and reducing its brightness. Therefore, the detection of these particles is essential for predicting melt processes on the Greenland Ice Sheet. A new generation of Earth observation satellites provides the technical prerequisites to achieve this objective. In this study, we present first results from the recently started PRISMA satellite mission using a data set recorded over the Greenland Ice Sheet in late August 2020. We apply a new method to estimate the size of ice crystals, liquid water content, and algae concentration on the surface demonstrating the potential of the new missions to detect and quantify snow and ice properties with a high accuracy. Finally, we evidence that a combination of novel future satellite observations and existing data records from other instruments can decisively support research of melting ice sheets. Key Points: It is the first time that PRISMA imaging spectroscopy data are used for studying the cryosphere on the Greenland Ice Sheet We present an algorithm to detect and quantify patterns of light‐absorbing particles accumulated on the ice surface in the so‐called dark zone Global VSWIR imaging spectrometers open new possibilities of producing multi‐year time series of snow and ice properties mapping