Articles | Volume 30, issue 10
https://doi.org/10.5194/hess-30-3019-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/hess-30-3019-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
20 May 2026
Research article |
| 20 May 2026
| 20 May 2026
Uncovering the melt: Unmanned Aircraft System (UAS) and in-situ sensor synergies reveal dissolved organic carbon (DOC) pathways in a northern peatland
Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
Pertti Ala-Aho
Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
Bjørn Kløve
Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
Hannu Marttila
Water, Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
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EGUsphere, https://doi.org/10.5194/egusphere-2026-5602, https://doi.org/10.5194/egusphere-2026-5602, 2026
This preprint is open for discussion and under review for Hydrology and Earth System Sciences (HESS).
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This paper utilized field-scale measurements of greenhouse gases and nutrients in drainage water. Nitrogen losses through the drainage were highly seasonal, are affected by the drainage management and the peat depth within the field. Increased greenhouse gas concentrations were observed with increased concentration in drainage water was observed only during the grassland renewal. The results show that management actions can have meaningful impact to mitigate impacts of managed peatlands.
Karoliina Särkelä, Timo Vesala, Torben R. Christensen, Juval Cohen, Angelika Kübert, Xuefei Li, Hannu Marttila, Jouni Pulliainen, Eeva-Stiina Tuittila, and Efrén López-Blanco
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Using a 17-year record of year-round peatland carbon exchange, we found that over half of the carbon sequestrated during summer was released during winter. In one year, CO₂ emissions during snow melt and soil thaw in spring were large enough to shift the peatland from a net carbon sink to a source. These findings demonstrate that winter and early-spring processes have a strong impact over the annual carbon balance of northern peatlands.
Hannah Bailey, Jason E. Box, Ben G. Kopec, Valtteri Hyöky, Hannu Marttila, Jeffrey M. Welker, Jack Kohler, Dmitry V. Divine, and Alun Hubbard
The Cryosphere, 20, 4421–4436, https://doi.org/10.5194/tc-20-4421-2026, https://doi.org/10.5194/tc-20-4421-2026, 2026
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Atmospheric rivers (ARs) are narrow corridors of intense heat and moisture that can deliver extreme weather to the Arctic. We investigate a record March 2022 event in Svalbard using measurements of air and precipitation to track its origin and evolution. While the AR brought unusual winter rain and snow melt, it also delivered substantial snowfall that partially offset glacier mass loss. These findings show that the impacts of ARs on Arctic glaciers are more complex than typically reported.
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Snow can lose water directly to the air, but this process also changes the natural chemical fingerprints stored in snow. We used controlled wind-tunnel experiments with different snow types and airflow conditions to test why these changes vary. We found that wind controls how much snow is lost, but snow structure controls how strongly its fingerprints change. This means climate, water, and ice-record studies may misread snow signals if they ignore snow structure.
Jiahui Qiu, Kari Luojus, Harri Kaartinen, Yubao Qiu, Jari Silander, Epari Ritesh Patro, Björn Klöve, and Ali Torabi Haghighi
Earth Syst. Sci. Data, 18, 2703–2722, https://doi.org/10.5194/essd-18-2703-2026, https://doi.org/10.5194/essd-18-2703-2026, 2026
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Earth Syst. Sci. Data, 17, 6129–6147, https://doi.org/10.5194/essd-17-6129-2025, https://doi.org/10.5194/essd-17-6129-2025, 2025
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This study describes a unique large-scale isotope dataset to study water dynamics in European forests. Researchers collected data from 40 beech and spruce forest sites in spring and summer 2023, using a standardized method to ensure consistency. The results show that water sources for trees change between seasons and vary by tree species. This large dataset offers valuable information for understanding plant water use, improving ecohydrological models, and mapping water cycles across Europe.
Eeva Järvi-Laturi, Teemu Tahvanainen, Eero Koskinen, Efrén López-Blanco, Juho Lämsä, Hannu Marttila, Mikhail Mastepanov, Riku Paavola, Maria Väisänen, and Torben R. Christensen
Biogeosciences, 22, 6343–6367, https://doi.org/10.5194/bg-22-6343-2025, https://doi.org/10.5194/bg-22-6343-2025, 2025
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Our research investigates how plant community composition influences methane emissions in a northern boreal rich fen. We measured methane fluxes year-round using manual chambers across 36 plots. Our findings suggest that sedges, particularly Carex rostrata, significantly impact the fluxes throughout the year. This study enhances our understanding of vegetation-driven methane emissions, providing valuable insights for predicting future changes in peatland methane emissions.
Maiju Ylönen, Hannu Marttila, Joschka Geissler, Anton Kuzmin, Pasi Korpelainen, Timo Kumpula, and Pertti Ala-Aho
The Cryosphere, 19, 4585–4610, https://doi.org/10.5194/tc-19-4585-2025, https://doi.org/10.5194/tc-19-4585-2025, 2025
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We collected snow depth maps four times during the winter from two different sites and used them as input for a model to predict daily snow depth and snow water equivalent (SWE). Our results show similar snow depth patterns at different sites, with snow depths being the highest in forests and forest gaps and the lowest in open areas. The results can extend operational snow course measurements and their temporal and spatial coverage, helping hydrological forecasting and water resource management.
Shaakir Shabir Dar, Eric Klein, Pertti Ala-aho, Hannu Marttila, Sonja Wahl, and Jeffrey Welker
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Using laser based instruments, we observed snow turning directly to vapor inside the pack and at its surface. In cold, calm weather vapor moves slowly upward; on warmer, windy days air pushes vapor deeper into the snow. These dynamics control snow loss and must be included in hydrological and climate models.
Teemu Juselius-Rajamäki, Sanna Piilo, Susanna Salminen-Paatero, Emilia Tuomaala, Tarmo Virtanen, Atte Korhola, Anna Autio, Hannu Marttila, Pertti Ala-Aho, Annalea Lohila, and Minna Väliranta
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Umer Saleem, Ali Torabi Haghighi, Björn Klöve, and Mourad Oussalah
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This preprint is open for discussion and under review for The Cryosphere (TC).
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Getnet Demil, Ali Torabi Haghighi, Björn Klöve, and Mourad Oussalah
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This preprint is open for discussion and under review for The Cryosphere (TC).
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This review explores using advanced image-based methods to estimate snow parameters for water resource management. Deep learning and satellite imagery improve accuracy in predicting snowmelt and depth. Challenges like data availability persist; addressing them requires novel deep learning architectures and better data synchronization. Integration of image-based approaches can revolutionize snow hydrology modeling and environmental management.
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The transport of dissolved organic carbon (DOC) from land into streams is changing due to climate change. We used a multi-year dataset of DOC and predictors of DOC in a subarctic stream to find out how transport of DOC varied between seasons and between years. We found that the way DOC is transported varied strongly seasonally, but year-to-year differences were less apparent. We conclude that the mechanisms of transport show a higher degree of interannual consistency than previously thought.
Jari-Pekka Nousu, Matthieu Lafaysse, Giulia Mazzotti, Pertti Ala-aho, Hannu Marttila, Bertrand Cluzet, Mika Aurela, Annalea Lohila, Pasi Kolari, Aaron Boone, Mathieu Fructus, and Samuli Launiainen
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The snowpack has a major impact on the land surface energy budget. Accurate simulation of the snowpack energy budget is difficult, and studies that evaluate models against energy budget observations are rare. We compared predictions from well-known models with observations of energy budgets, snow depths and soil temperatures in Finland. Our study identified contrasting strengths and limitations for the models. These results can be used for choosing the right models depending on the use cases.
Anssi Rauhala, Leo-Juhani Meriö, Anton Kuzmin, Pasi Korpelainen, Pertti Ala-aho, Timo Kumpula, Bjørn Kløve, and Hannu Marttila
The Cryosphere, 17, 4343–4362, https://doi.org/10.5194/tc-17-4343-2023, https://doi.org/10.5194/tc-17-4343-2023, 2023
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Snow conditions in the Northern Hemisphere are rapidly changing, and information on snow depth is important for decision-making. We present snow depth measurements using different drones throughout the winter at a subarctic site. Generally, all drones produced good estimates of snow depth in open areas. However, differences were observed in the accuracies produced by the different drones, and a reduction in accuracy was observed when moving from an open mire area to forest-covered areas.
Leo-Juhani Meriö, Anssi Rauhala, Pertti Ala-aho, Anton Kuzmin, Pasi Korpelainen, Timo Kumpula, Bjørn Kløve, and Hannu Marttila
The Cryosphere, 17, 4363–4380, https://doi.org/10.5194/tc-17-4363-2023, https://doi.org/10.5194/tc-17-4363-2023, 2023
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Information on seasonal snow cover is essential in understanding snow processes and operational forecasting. We study the spatiotemporal variability in snow depth and snow processes in a subarctic, boreal landscape using drones. We identified multiple theoretically known snow processes and interactions between snow and vegetation. The results highlight the applicability of the drones to be used for a detailed study of snow depth in multiple land cover types and snow–vegetation interactions.
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Short summary
We studied how the melting of snow affects the release of dissolved organic carbon (DOC) in a northern peatland. Using detailed aerial surveys of snow cover, landscape moisture, and continuous water quality measurements revealed that DOC is released as snow cover melts, especially in wetter areas. Our results show how the snowmelt patterns control DOC transport, highlighting the sensitivity of northern peatland ecosystems to climate-driven changes in snow cover.
We studied how the melting of snow affects the release of dissolved organic carbon (DOC) in a...
