Thermal structure and water-ice heat transfer in a shallow ice–covered thermokarst lake in central Qinghai-Tibet Plateau

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http://hdl.handle.net/10138/333987

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Huang , W , Zhang , J , Leppäranta , M , Li , Z , Cheng , B & Lin , Z 2019 , ' Thermal structure and water-ice heat transfer in a shallow ice–covered thermokarst lake in central Qinghai-Tibet Plateau ' , Journal of Hydrology , vol. 578 , 124122 . https://doi.org/10.1016/j.jhydrol.2019.124122

Title: Thermal structure and water-ice heat transfer in a shallow ice–covered thermokarst lake in central Qinghai-Tibet Plateau
Author: Huang, Wenfeng; Zhang, Jinrong; Leppäranta, Matti; Li, Zhijun; Cheng, Bin; Lin, Zhanju
Contributor: University of Helsinki, Institute for Atmospheric and Earth System Research (INAR)
Date: 2019-11
Language: eng
Number of pages: 10
Belongs to series: Journal of Hydrology
ISSN: 0022-1694
URI: http://hdl.handle.net/10138/333987
Abstract: A large number of lakes and ponds are unevenly distributed over the Qinghai-Tibet Plateau (QTP). Little is known about their ice processes and thermal regimes. Seasonal ice mass balance, thermal regime and stratification of under-ice water were investigated in a shallow thermokarst lake in central QTP using in situ observations and global reanalysis data. Congelation ice grew to 60–70 cm depth while continuous surface sublimation caused a total ice loss of over 30 cm. The bulk lake temperature below ice remained above 3.0 °C through the ice freezing period and rose gradually up to 7–9 °C during the melting period. The vertical thermal structure of under-ice water consisted of a stable strongly stratified interfacial layer (IL) and an underlying convective layer reaching the lake bottom. A warm layer existed just beneath the IL since the middle equilibrium period and increased in thickness and temperature. There was seasonal variation of IL depth and temperature gradient in response to the ice thermodynamics and atmospheric conditions. The calculated daily water-ice heat flux (Fw) was of 10 W m–2 magnitude. Seasonal variation of Fw manifested both diffusive and convective heat transport to the ice-water interface. This study suggests that strong penetration of solar radiative flux is the dominant contributor to high Fw, which results in a relatively thin ice compared with other equivalent high-latitude climate.
Subject: 1171 Geosciences
Qinghai-Tibet Plateau
Thermokarst lake
Ice thickness
Temperature
Thermal stratification
Ice-water heat flux
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