Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes

Water Resources Research
By: , and 

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Abstract

Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since many Arctic lakes are shallow and ice grows thick (historically 2-m or greater), seasonal ice commonly freezes to the lake bed (bedfast ice) by winter's end. Bedfast ice fundamentally alters lake energy balance and melt-out processes compared to deeper lakes that exceed the maximum ice thickness (floating ice) and maintain perennial liquid water below floating ice. Our analysis of lakes in northern Alaska indicated that ice-out of bedfast ice lakes occurred on average 17 days earlier (22-June) than ice-out on adjacent floating ice lakes (9-July). Earlier ice-free conditions in bedfast ice lakes caused higher open-water evaporation, 28% on average, relative to floating ice lakes and this divergence increased in lakes closer to the coast and in cooler summers. Water isotopes (18O and 2H) indicated similar differences in evaporation between these lake types. Our analysis suggests that ice regimes created by the combination of lake depth relative to ice thickness and associated ice-out timing currently cause a strong hydrologic divergence among Arctic lakes. Thus understanding the distribution and dynamics of lakes by ice regime is essential for predicting regional hydrology. An observed regime shift in lakes to floating ice conditions due to thinner ice growth may initially offset lake drying because of lower evaporative loss from this lake type. This potential negative feedback caused by winter processes occurs in spite of an overall projected increase in evapotranspiration as the Arctic climate warms.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Depth, ice thickness, and ice-out timing cause divergent hydrologic responses among Arctic lakes
Series title Water Resources Research
DOI 10.1002/2015WR017362
Volume 51
Issue 12
Year Published 2015
Language English
Publisher AGU
Contributing office(s) Alaska Science Center Geography
Description 23 p.
First page 9379
Last page 9401
Country United States
State Alaska
Online Only (Y/N) N
Additional Online Files (Y/N) N