A field study on ice melting and breakup in a boreal lake, Pääjärvi, in Finland
<p>Lake ice melting and breakup form a fast, nonlinear process with important mechanical, chemical, and biological consequences. The process is difficult to study in the field due to safety issues, and therefore only little is known about its details. In the present work, the field data were c...
| Published in: | The Cryosphere |
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| Main Authors: | , , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-05-01
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| Online Access: | https://tc.copernicus.org/articles/17/2045/2023/tc-17-2045-2023.pdf |
| Summary: | <p>Lake ice melting and breakup form a fast, nonlinear process with
important mechanical, chemical, and biological consequences. The process is
difficult to study in the field due to safety issues, and therefore only
little is known about its details. In the present work, the field data were
collected on foot, by hydrocopter, and by boat for a full time series of the
evolution of ice thickness, structure, and geochemistry through the melting
period. The observations were made in lake Pääjärvi in 2018
(pilot study) and 2022. In 2022, the maximum thickness of ice was 55 cm with
60 % snow ice, and in 40 d the ice melted by 33 cm from the surface
and 22 cm from the bottom while the porosity increased from less than 5 %
to 40 %–50 % at breakup. In 2018, the snow-ice layer was thin, and bottom
and internal melting dominated the ice decay. The mean melting rates were
1.31 cm d<span class="inline-formula"><sup>−1</sup></span> in 2022 and 1.55 cm d<span class="inline-formula"><sup>−1</sup></span> in 2018. In 2022 the
electrical conductivity (EC) of ice was 11.4 <span class="inline-formula">±</span> 5.79 <span class="inline-formula">µ</span>S cm<span class="inline-formula"><sup>−1</sup></span>, which is
1 order of magnitude lower than in the lake water, and ice pH was 6.44 <span class="inline-formula">±</span> 0.28, which is lower by 0.4 than in water. The pH and EC of ice and water
decreased during the ice decay except for slight increases in ice due to
flushing by lake water. Chlorophyll <span class="inline-formula"><i>a</i></span> was less than 0.5 <span class="inline-formula">µ</span>g L<span class="inline-formula"><sup>−1</sup></span> in
porous ice, approximately one-third of that in the lake water. The results
are important for understanding the process of ice decay with consequences
for lake ecology, further development of numerical lake ice models, and
modeling the safety of ice cover and ice loads.</p> |
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| ISSN: | 1994-0416 1994-0424 |