The start of frozen dates over northern permafrost regions with the changing climate
Li, Jialing (Nanjing University. International Institute for Earth System Sciences)
Wu, Chaoyang (Chinese Academy of Sciences. Institute of Geographic Sciences and Natural Resources Research)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Ran, Youhua (Chinese Academy of Sciences. Northwest Institute of Eco-Environment and Resources)
Zhang, Yongguang (Nanjing University. International Institute for Earth System Science)

Date:	2023
Abstract:	The soil freeze-thaw cycle in the permafrost regions has a significant impact on regional surface energy and water balance. Although increasing efforts have been made to understand the responses of spring thawing to climate change, the mechanisms controlling the global interannual variability of the start date of permafrost frozen (SOF) remain unclear. Using long-term SOF from the combinations of multiple satellite microwave sensors between 1979 and 2020, and analytical techniques, including partial correlation, ridge regression, path analysis, and machine learning, we explored the responses of SOF to multiple climate change factors, including warming (surface and air temperature), start date of permafrost thawing (SOT), soil properties (soil temperature and volume of water), and the snow depth water equivalent (SDWE). Overall, climate warming exhibited the maximum control on SOF, but SOT in spring was also an important driver of SOF variability; among the 65. 9% significant SOT and SOF correlations, 79. 3% were positive, indicating an overall earlier thawing would contribute to an earlier frozen in winter. The machine learning analysis also suggested that apart from warming, SOT ranked as the second most important determinant of SOF. Therefore, we identified the mechanism responsible for the SOT-SOF relationship using the SEM analysis, which revealed that soil temperature change exhibited the maximum effect on this relationship, irrespective of the permafrost type. Finally, we analyzed the temporal changes in these responses using the moving window approach and found increased effect of soil warming on SOF. In conclusion, these results provide important insights into understanding and predicting SOF variations with future climate change.
Grants:	European Commission 610028 Agencia Estatal de Investigación PID2019−110521GB-I00
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Climate warming ; Permafrost ; Start of frozen ; Start of thawing
Published in:	Global change biology, Vol. 29, issue 16 (Aug. 2023) , p. 4556-4568, ISSN 1365-2486

DOI: 10.1111/gcb.16752

Available from: 2024-08-30 Postprint

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