July 16, 2023

Isortuarsuup Sermia Lake Drainage September 2022

Posted by Mauri Pelto

Isortuarsuup Sermia ice dammed lake drains between 9-9-2022 and 9-19-2022. The lake area on 9-9-2022 is 29 km². False color Sentinel images illustrate.

Isortuarsuup Sermia terminates in Isortuarsuup Tasia on the west margin of the Greenland Ice sheet   at 63.8 N  W. The glacier dams a proglacial lake that when full has had an elevation of 710 m, and has been observed to periodically drain from 1937-2011 (Geological Survey of Denmark and Greenland, Bull. 27, 2012). Here we examine the drainage event between Sept. 9 and Sept 19, 2022 that has resulted in a lower than usual drained lake level.

The history of this lakes filling and drainage has been relatively conistent  period of 8-10 years from 1937-2011 (GEUS, 2012). The typical low lake elevation of ~650 m.  The lake drains along a marginal channel on the north side of the glacier into Isortuarsuup Tasia. The lake is dammed at Point A. The lake level during July 2017 was at 660-670 m, during the fill cycle. By July 2021 the lake was essentially full. The lake had an area of ~29 km² from July 2021 through 9-9-2022. A rapid drainage event occurred by 9-19-2022 stranding many icebergs on the lake bottom, reducing lake area to 10 km². There is no remaining lake along the Isortuarsuup Sermia glaciers northern margin, indicating a lower lake level than typical during drainage, ~630-640 m. There is ice at the front of Isortuarsuup Sermia after this event, likely from small bergs draining down the outlet channel. By 7-8-2023 the lake shows no indication of filling in a Landsat image. Given the lower drainage level of this event, will this lake refill as has been its pattern for the last century? How et al (2021) in an inventory of Greenland Ice Sheet proglacial lakes, noted a 75% increase in lake frequency from 1985 to 2017 along the western margin of the Ice Sheet, with a decline in average lake area. This lake may fit that pattern.

Isortuarsuup Sermia on July 22, 2017 with lake level on the rise at ~680-690 m, false color Sentinel image.


Isortuarsuup Sermia on July 8, 2023 with lake level on the rise at ~640 m, Landsat image.

Figure from GEUS Bulletin 27 (2012) of lake 710 m.