气候变化领域集成服务门户(CCPortal): New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: A comparison between permafrost and non-permafrost areas

CCPortal

DOI	10.5194/tc-13-693-2019
	New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: A comparison between permafrost and non-permafrost areas
	Karjalainen O.; Luoto M.; Aalto J.; Hjort J.
发表日期	2019
ISSN	19940416
EISSN	13
起始页码	693
结束页码	707
卷号	13 期号:2
英文摘要	The thermal state of permafrost affects Earth surface systems and human activity in the Arctic and has implications for global climate. Improved understanding of the local-scale variability in the global ground thermal regime is required to account for its sensitivity to changing climatic and geoecological conditions. Here, we statistically related observations of mean annual ground temperature (MAGT) and active-layer thickness (ALT) to high-resolution ( ∼ 1 km 2 ) geospatial data of climatic and local environmental conditions across the Northern Hemisphere. The aim was to characterize the relative importance of key environmental factors and the magnitude and shape of their effects on MAGT and ALT. The multivariate models fitted well to both response variables with average R 2 values being ∼ 0:94 and 0.78. Corresponding predictive performances in terms of root-mean-square error were ∼ 1.31 °C and 87 cm. Freezing (FDD) and thawing (TDD) degree days were key factors for MAGT inside and outside the permafrost domain with average effect sizes of 6.7 and 13.6 °C, respectively. Soil properties had marginal effects on MAGT (effect size = 0.4-0.7 °C). For ALT, rainfall (effect size D 181 cm) and solar radiation (161 cm) were most influential. Analysis of variable importance further underlined the dominance of climate for MAGT and highlighted the role of solar radiation for ALT. Most response shapes for MAGT ≤ 0 °C and ALT were nonlinear and indicated thresholds for covariation. Most importantly, permafrost temperatures had a more complex relationship with air temperatures than non-frozen ground. Moreover, the observed warming effect of rainfall on MAGT≤0 °C reverted after reaching an optimum at ∼ 250 mm, and that of snowfall started to level off at ∼ 300-400 mm. It is suggested that the factors of large global variation (i.e. climate) suppressed the effects of local-scale factors (i.e. soil properties and vegetation) owing to the extensive study area and limited representation of soil organic matter. Our new insights into the factors affecting the ground thermal regime at a 1 km scale should improve future hemispheric-scale studies. © 2019 Author(s).
学科领域	active layer; comparative study; environmental conditions; environmental factor; global climate; human activity; Northern Hemisphere; permafrost; soil property; solar radiation; spatial data; temperature; thermal regime; Arctic
语种	英语
scopus关键词	active layer; comparative study; environmental conditions; environmental factor; global climate; human activity; Northern Hemisphere; permafrost; soil property; solar radiation; spatial data; temperature; thermal regime; Arctic
来源期刊	The Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/118920
作者单位	Geography Research Unit, University of Oulu, Oulu, 90014, Finland; Department of Geosciences and Geography, University of Helsinki, Helsinki, 00014, Finland; Finnish Meteorological Institute, Helsinki, 00101, Finland
推荐引用方式 GB/T 7714	Karjalainen O.,Luoto M.,Aalto J.,et al. New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: A comparison between permafrost and non-permafrost areas[J],2019,13(2).
APA	Karjalainen O.,Luoto M.,Aalto J.,&Hjort J..(2019).New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: A comparison between permafrost and non-permafrost areas.The Cryosphere,13(2).
MLA	Karjalainen O.,et al."New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: A comparison between permafrost and non-permafrost areas".The Cryosphere 13.2(2019).