Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: Geophysical Research Letters
Arctic ponds play a key role in permafrost thaw and greenhouse gas emissions; however, their physical mixing processes remain poorly characterized. Most conceptual models assume that vertical, one-dimensional mixing—driven by surface cooling due to which water becomes denser, and sinks vertically, mixing the water mass from the top down—is the primary mechanism for deep water renewal.
Henderson and MacIntyre [2025] challenges that model by showing that two-dimensional thermal overturning circulation dominates in a shallow permafrost pond. Specifically, nighttime surface cooling in shallow areas generates cold, dense water that flows downslope along the pond bed, displacing and renewing deeper waters. Using high-resolution velocity, temperature, and other related measurements, the authors demonstrate that these gravity currents ventilate the bottom despite persistent stable stratification during nighttime. These findings reveal that lateral thermal flows can drive vertical exchange in small water bodies. The results have important implications for biogeochemical modeling and upscaling greenhouse gas fluxes across Arctic landscapes.
Citation: Henderson, S. M., & MacIntyre, S. (2025). Thermal overturning circulation in an Arctic pond. Geophysical Research Letters, 52, e2024GL114541. https://doi.org/10.1029/2024GL114541
—Valeriy Ivanov, Editor, Geophysical Research Letters
Text © 2025. The authors. CC BY-NC-ND 3.0
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