Timing and duration of ephemeral Antarctic water tracks and wetlands using high temporal–resolution satellite imagery, high spatial–resolution satellite imagery, and ground-based sensors in the McMurdo Dry Valleys

ABSTRACT

Antarctic water tracks and ephemeral wetlands are a primary location for biogeochemical soil processes driving cold desert soil formation. Though the spatial extent of water tracks and wetted soils has been mapped in the McMurdo Dry Valleys (MDV) on the basis of mapping darkened pixels in high-resolution commercial satellite imagery, the timescale over which water tracks and wetlands form and the duration of these biogeochemically active environments remain unknown. Here, we determine the start date and end dates and the duration of wetted soils at ten sites located across the MDV using a combination of in situ soil sensors and two complementary remote imaging platforms (Planet and WorldView) to understand the hydroclimatic processes that drive water track and wetland formation. Our remote sensing employs a terrain correction workflow that removes the contribution of differential direct illumination and small-scale shadowing on pixel brightness, reducing false positives (soils identified as wetted when in fact they are shadowed or darkened as a consequence of high phase angle). Our findings extend the water track and wetland hydroperiod by over a month, showing darkening occurring from November to March, suggesting hydrological contributions from ground ice thaw, snowmelt, and salt deliquescence and soil brine growth.

KEYWORDS:

• Antarctica
• water track
• wetland
• hydroperiod
• remote sensing

Acknowledgments

Thanks to the Colgate Martians undergraduate data analysis team, including Kyle Baun, Max Wang, MC Rapoza, Izzy King, and Gary Kuang.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Weather station data used in this study are available for download from the MCM-LTER at mcmlter.org. Active layer temperature and soil moisture data used in this station are archived at the U.S. Antarctic Program Data Center and can be accessed at https://www.usap-dc.org/view/dataset/600139. Planet data were made available to this project under the Planet Federal Contract. WorldView data were provided via the Polar Geospatial Center.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15230430.2022.2123858.

Additional information

Funding

This work was supported by the National Science Foundation under grants OPP-1847067 to JSL and OPP-2046260 to MRS. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. Geospatial support for this work was provided by the Polar Geospatial Center under NSF-OPP awards 1043681 and 1559691. Access to Planet data was provided under the Commercial Smallsat Data Acquisition (CSDA) Program.