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- Title
Tree‐Ring Derived Avalanche Frequency and Climate Associations in a High‐Latitude, Maritime Climate.
- Authors
Peitzsch, E. H.; Hood, E.; Harley, J. R.; Stahle, D. K.; Kichas, N. E.; Wolken, G. J.
- Abstract
Snow avalanches are a natural hazard in mountainous areas worldwide with severe impacts that include fatalities, damage to infrastructure, disruption to commerce, and landscape disturbance. Understanding long‐term avalanche frequency patterns, and associated climate and weather influences, improves our understanding of how climate change may affect avalanche activity. We used dendrochronological techniques to evaluate the historical frequency of large magnitude avalanches (LMAs) in the high‐latitude climate of southeast Alaska, United States. We collected 434 cross sections throughout six avalanche paths near Juneau, Alaska. This resulted in 2706 identified avalanche growth disturbances between 1720 and 2018, which allowed us to reconstruct 82 years with LMA activity across three sub‐regions. By combining this tree‐ring‐derived avalanche data set with a suite of climate and atmospheric variables and applying a generalized linear model to fit a binomial regression, we found that February and March precipitation and the Oceanic Niño Index (ONI) were significant predictors of LMA activity in the study area. Specifically, LMA activity occurred during winters with substantial February and March precipitation and neutral or negative (cold) ONI values, while years not characterized by LMAs occur more frequently during warm winters (positive ONI values). Our examination of the climate‐avalanche relationship in southeast Alaska sheds light on important climate variables and physical processes associated with LMA years. These results can be used to inform long‐term infrastructure planning and avalanche mitigation operations in an urban area, such as Juneau, where critical infrastructure is subject to substantial avalanche hazard. Plain Language Summary: Snow avalanches pose a hazard in mountainous regions throughout the world. By calculating how often large destructive avalanches recur in an area and combining these avalanche records with climate data from the same period, we gain a better understanding of how climate influences avalanche activity. To achieve this, we collected samples from trees in avalanche paths and analyzed tree growth rings to determine how often an avalanche occurs in a single avalanche path. We were able to date large avalanches from tree‐ring records because an avalanche can cause mechanical damage to a tree and result in a growth disturbance for that year. We completed this analysis across six avalanche paths in southeast Alaska, United States. We found that large avalanches tended to occur during winters with higher‐than‐normal mid‐winter precipitation and those with a neutral or negative (i.e., cold) Oceanic Niño Index, an index representative of short‐term temperature variability in the study area. Our results suggest that temperature influences the type of precipitation (rain vs. snow) and, when combined with mid‐winter precipitation, influences whether a winter is characterized by large avalanches or not. These results can be used to inform infrastructure planning and avalanche mitigation in and around Juneau, Alaska. Key Points: We collected 434 cross sections throughout six avalanche paths, resulting in 2706 identified growth disturbances due to avalanchesLarge magnitude avalanches (LMAs) in the study area occur every 9 years (median)Mid‐winter precipitation amount and type, as driven by temperature, influence the frequency of LMAs in this high latitude maritime climate
- Subjects
ALASKA; JUNEAU (Alaska); MARINE west coast climate; AVALANCHES; TREE-rings; INFRASTRUCTURE (Economics); TREE growth; CLIMATE change
- Publication
Journal of Geophysical Research. Earth Surface, 2023, Vol 128, Issue 8, p1
- ISSN
2169-9003
- Publication type
Article
- DOI
10.1029/2023JF007154