Algae Blooms on the Greenland Ice Sheet Detected Through Solar-Induced Fluorescence

Gerlein-Safdi, Cynthia; Köhler, Philipp; Wang, Shujie; Flanner, Mark; Keppel-Aleks, Gretchen; Frankenberg, Christian

doi:10.1109/tgrs.2023.3305194

Published August 14, 2023 | Version Published

Journal Article Open

Algae Blooms on the Greenland Ice Sheet Detected Through Solar-Induced Fluorescence

1. University of California, Berkeley
2. European Organization for the Exploitation of Meteorological Satellites
3. Pennsylvania State University
4. University of Michigan–Ann Arbor
5. California Institute of Technology
6. Jet Propulsion Lab

Glacial algae blooms on the Greenland ice sheet darken the surface albedo, enhancing surface melt. Sentinel-3 data was the first to highlight the extent of these blooms, which are expected to become larger as climate changes. Here, we propose a novel use of solar-induced chlorophyll fluorescence (SIF) data from TROPOspheric monitoring instrument (TROPOMI) to confirm the Sentinel-based maps and extend the data to daily levels to understand year-to-year variations in algae blooms. We combine the SIF data with a random walker algorithm to identify algae-covered areas. The SIF-based maps are found to be highly correlated with the Sentinel-based ones. The extent and the timing of the algae bloom are consistent between 2018 and 2020. This work opens the door to a new, complementary method for the monitoring of algae blooms on ice sheets and improving our understanding of their impact on glacier melt rate.

Copyright and License

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
For more information, see https://creativecommons.org/licenses/by-nc-nd/4.0/.

Funding

The work of Cynthia GerleinSafdi was supported in part by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory through U.S. Department of Energy under Contract DE-AC02-05CH11231 and in part by the Fellowship from the Michigan Society of Fellows. The work of Philipp Köhler and Christian Frankenberg was supported by the Earth Science U.S. Participating Investigator under Grant NNX15AH95G. The work of Shujie Wang was supported by the NASA’s Cryospheric Sciences Program under Grant 80NSSC22K0384.

Data Availability

The TROPOMI SIF and NIR surface reflectance data can be accessed through https://doi.org/10.22002/D1.1347. The Sentinel-3 OLCI level-1B data (https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-3-olci/level-1/fr-or-rr-toa-radiances) are freely available on the Copernicus Open Access Hub (https://scihub.copernicus.eu/), courtesy of the European Space Agency.

Supplemental Material

Supplemental items: This file contains five additional figures in support of the main article (PDF)

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