Preprints
https://doi.org/10.5194/egusphere-2023-2722
https://doi.org/10.5194/egusphere-2023-2722
04 Dec 2023
 | 04 Dec 2023

50 years of firn evolution on Grigoriev Ice Cap, Tien Shan, Kyrgyzstan

Horst Machguth, Anja Eichler, Margit Schwikowski, Sabina Brütsch, Enrico Mattea, Sanislav Kutuzov, Martin Heule, Rykul Usubaliev, Sultan Belekov, Vladimir N. Mikhalenko, Martin Hoelzle, and Marlene Kronenberg

Abstract. Grigoriev Ice Cap, located in the Tien Shan mountains of Kyrgyzstan, has a rich history of firn and ice core drilling starting as early as 1962. Until now, the time series ended with a core drilled in 2007. Here we extend the exceptional record and describe an 18 m firn core, drilled in February 2018 on the summit of Grigoriev Ice Cap, at 4600 m a.s.l. The core has been analyzed for firn stratigraphy, major ions, black carbon, water stable isotope ratios and total β-activity. We find that the core covers 46±3 years and overlaps by two to three decades with legacy cores. A good agreement is found in major ion concentrations for the overlapping period. Concentration in ions, susceptible to being washed out, is reduced since the early 2000s. This indicates the onset of meltwater runoff. Apart from runoff evidence, however, the firn appears remarkably unchanged. We find little change in net accumulation since the 1980s. Firn temperatures fluctuate, with 2018 temperatures being the highest on record 1.6 °C at 17 m depth). However, temperatures in 2023 are again similar to the early 2000s at 2.5 °C. We hypothesize (i) that firn temperatures are stabilized by the removal of latent heat through lateral meltwater runoff, and (ii) that mass loss by runoff is compensated by an increase in snowfall. While data from a nearby weather station support the latter hypothesis, thorough testing of both hypotheses will require surface mass balance and firn modelling.

Horst Machguth, Anja Eichler, Margit Schwikowski, Sabina Brütsch, Enrico Mattea, Sanislav Kutuzov, Martin Heule, Rykul Usubaliev, Sultan Belekov, Vladimir N. Mikhalenko, Martin Hoelzle, and Marlene Kronenberg

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Horst Machguth, Anja Eichler, Margit Schwikowski, Sabina Brütsch, Enrico Mattea, Sanislav Kutuzov, Martin Heule, Rykul Usubaliev, Sultan Belekov, Vladimir N. Mikhalenko, Martin Hoelzle, and Marlene Kronenberg
Horst Machguth, Anja Eichler, Margit Schwikowski, Sabina Brütsch, Enrico Mattea, Sanislav Kutuzov, Martin Heule, Rykul Usubaliev, Sultan Belekov, Vladimir N. Mikhalenko, Martin Hoelzle, and Marlene Kronenberg

Viewed

Total article views: 314 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
209 89 16 314 11 12
  • HTML: 209
  • PDF: 89
  • XML: 16
  • Total: 314
  • BibTeX: 11
  • EndNote: 12
Views and downloads (calculated since 04 Dec 2023)
Cumulative views and downloads (calculated since 04 Dec 2023)

Viewed (geographical distribution)

Total article views: 298 (including HTML, PDF, and XML) Thereof 298 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 25 Feb 2024
Download
Short summary
In 2018 we drilled an 18 m ice core on the summit of Grigoriev Ice Cap, located in the Tien Shan mountains of Kyrgyzstan. The core analysis reveals strong melting since the early 2000s. Regardless of this, we find that structure and temperature of the ice have changed little since the 1980s. The cause of this apparent stability is (i) an increase in snowfall and (ii) that meltwater nowadays leaves the glacier and thereby removes substantial amounts of so-called latent heat.