Sep 14, 2019

Exceptionally High 2018 Equilibrium Line Altitude on Taku Glacier, Alaska

by
Pelto, Mauri
,
Remote Sensing
  • States that the Juneau Icefield Research Program (JIRP) has been examining the glaciers of the Juneau Icefield since 1946
  • States that the height of the transient snowline (TSL) at the end of the summer represents the annual equilibrium line altitude (ELA) for the glacier, where ablation equals accumulation
  • States that Taku Glacier's ELA has been observed annually from 1946 to 2018
  • Satellite imagery shows that since 1998 multiple annual observations of the TSL in satellite imagery identify both the migration rate of the TSL and ELA
  • Finds that the mean ELA has risen 85 ± 10 m from the 1946–1985 period to the 1986–2018 period
  • In 2018 the TSL was observed at: 900 m on 5 July; 975 m on 21 July; 1075 m on 30 July; 1400 m on 16 September; and 1425 m on 1 October
  • States that this is the first time since 1946 that the TSL has reached or exceeded 1250 m on Taku Glacie
  • States that the 500 m TSL rise from 5 July to 30 July, 8.0. md−1, is the fastest rate of rise observed
  • Combines this with the observed balance gradient in this region, which yields an ablation rate of 40–43 mmd−1, and finds nearly double the average ablation rate
  • Concludes that the result of the record ELA and rapid ablation is the largest negative annual balance of Taku Glacier since records began in 1946