Abstract
Water temperature serves as a key environmental factor of lakes and the most basic parameter for analyzing the thermal conditions of a water body. Based on the observation and analysis of the water temperature of Qinghuahu Lake in the Heilongjiang Province of China, this paper analyzed the variation trend of the heat flux, effective thermal diffusivity of the icebound water, and revealed the temporal and spatial variation law of the water temperature and the transfer law beneath the ice on a shallow lake in a cold region. The results suggested a noticeable difference existing in the distribution of water temperature beneath the ice during different periods of ice coverage. During the third period, the water temperature vertically comprised three discrete layers, each of which remained unchanged in thickness despite the alternation of day and night. Sediment–water heat flux and water–ice heat flux both remained positive values throughout the freezing duration, averaging about 3.8–4.1 W/m2 and 9.8–10.3 W/m2, respectively. The calculated thermal diffusivity in late winter was larger than molecular, and the time-averaged values increased first and then decreased with water depth, reaching a maximum at a relative depth of 0.5. This research is expected to provide a reference for studies on the water environment of icebound shallow lakes or ponds in cold regions.
Highlights
The temperature remains a principal factor contributing to the formation and growth of ice cover in the water of cold regions
Autumn and winter reveal a gradual decrease in water temperature as the water body constantly transfers heat to the low temperature atmosphere
Tion flux in the prototype observation area, whose latitude is Through a fitting we developed an empirical expression of the solar radiation flux with the ordinal number regression, we developed an empirical expression of the solar radiation flux with the orof dates
Summary
The water temperature in lakes is fundamental to the understanding of their various physical and chemical processes and dynamic phenomena. The formation of ice sheets weakens the energy exchange between air and water and mitigates the disturbances caused by the wind to a lake It reduces the penetration depth of solar radiation passing vertically through a water body and slows the drop in water temperature beneath the ice [8]. Such changes in physical conditions result in differences in thermal conditions and temperature variations between lake water in cold regions and that in temperate and tropical zones [9]. Differences in the distribution and transformation of substances are visible between lakes in cold regions and those in temporal and tropical regions [10]
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