Preprints
https://doi.org/10.5194/egusphere-2023-1762
https://doi.org/10.5194/egusphere-2023-1762
02 Aug 2023
 | 02 Aug 2023

Lake Ice Break-Up in Greenland: Timing and Spatio-Temporal Variability

Christoph Posch, Jakob Abermann, and Tiago Manuel Ferreira da Silva

Abstract. Synthetic aperture radar (SAR) data from the Sentinel-1 (S1) mission with its high temporal and spatial resolution allows for an automated detection of lake ice break-up timings from surface backscatter differences across South (S), Southwest (SW) and Northwest (NW) Greenland (< 71° N latitude) during the period 2017 to 2021. Median break-up dates of the 563 studied lakes range between 8 June and 10 July, being earliest in 2019 and latest in 2018. There is a strong correlation between break-up date and elevation, while no relationship with latitude and lake area could be observed. Lake-specific median break-up timings for 2017–2021 increase (i.e., are later) by 3 days per 100 m elevation gain. When assuming an earlier break- up timing of 8 days which corresponds to the observed median variability of ± 8 days, the introduced excess energy due to a changing surface albedo from ice to water translates to melting 0.5 m thick ice at the melting point or heating up a water depth down to 35 m by 1 K across the entire surface area of each respective lake. Upscaling the results to 100486 lakes across the regions S, SW and NW which correspond to 64.5 % of all lakes or 62.1 % of the overall lake area in Greenland yields an estimate of 1.8 * 106 TJ additional energy input. This translates to melting 5.8 Gt ice at the melting point or warming 432.3 Gt water by 1 K.

Christoph Posch, Jakob Abermann, and Tiago Manuel Ferreira da Silva

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1762', Anonymous Referee #1, 02 Sep 2023
    • AC1: 'Reply on RC1', Christoph Posch, 31 Oct 2023
  • RC2: 'Comment on egusphere-2023-1762', Anonymous Referee #2, 25 Sep 2023
    • AC2: 'Reply on RC2', Christoph Posch, 31 Oct 2023
Christoph Posch, Jakob Abermann, and Tiago Manuel Ferreira da Silva
Christoph Posch, Jakob Abermann, and Tiago Manuel Ferreira da Silva

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Short summary
Radar beams from satellites exhibit different reflection behaviors between water and ice. Utilizing this conditions and the comprehensive coverage and high temporal resolution of the Sentinel-1 radar satellite mission, the timing when ice cover of lakes in Greenland disappear can be automatically detected. We found that per 100 m elevation gain, lake ice breaks up 3 days later because of lower air temperatures with increasing elevation, while latitude has no influence on their break-up timing.