Dataset Information

Forecasting extreme stratospheric polar vortex events.

ABSTRACT: Extreme polar vortex events known as sudden stratospheric warmings can influence surface winter weather conditions, but their timing is difficult to predict. Here, we examine factors that influence their occurrence, with a focus on their timing and vertical extent. We consider the roles of the troposphere and equatorial stratosphere separately, using a split vortex event in January 2009 as the primary case study. This event cannot be reproduced by constraining wind and temperatures in the troposphere alone, even when the equatorial lower stratosphere is in the correct phase of the quasi biennial oscillation. When the flow in the equatorial upper stratosphere is also constrained, the timing and spatial evolution of the vortex event is captured remarkably well. This highlights an influence from this region previously unrecognised by the seasonal forecast community. We suggest that better representation of the flow in this region is likely to improve predictability of extreme polar vortex events and hence their associated impacts at the surface.

SUBMITTER: Gray LJ

PROVIDER: S-EPMC7492229 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Forecasting extreme stratospheric polar vortex events.

Gray L J LJ Brown M J MJ Knight J J Andrews M M Lu H H O'Reilly C C Anstey J J

Nature communications 20200915 1

Extreme polar vortex events known as sudden stratospheric warmings can influence surface winter weather conditions, but their timing is difficult to predict. Here, we examine factors that influence their occurrence, with a focus on their timing and vertical extent. We consider the roles of the troposphere and equatorial stratosphere separately, using a split vortex event in January 2009 as the primary case study. This event cannot be reproduced by constraining wind and temperatures in the tropos ...[more]

PMID: 32934223

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Project description:Invasive species must often survive combinations of environmental conditions that differ considerably from their native range; however, for a given species it is unclear whether improved tolerance is the result of phenotypic plasticity or genetic adaptation (or both). Agrilus planipennis (Coleoptera: Buprestidae; the emerald ash borer) is an invasive pest of Fraxinus trees in North America and Europe. Previous studies in SW Ontario, Canada, showed that A. planipennis is freeze avoidant, preventing internal ice formation by accumulating Molar concentrations of glycerol in its hemolymph and depressing its supercooling point (SCP, the temperature at which it freezes). The cold tolerance of these SW Ontario animals was used to predict potential distribution, revealing that some Canadian cities should be too cold to allow populations to persist. However, a small population of A. planipennis has persisted in Winnipeg, Manitoba, Canada, through several severe 'polar vortex' events. In 2018/19, we collected A. planipennis larvae and prepupae from Winnipeg, MB and Southern Ontario, and found that individuals from Winnipeg were extremely cold tolerant - with SCPs as low as -52°C in prepupae (compared to -32°C in SW Ontario), and observed survival of unfrozen individuals exposed to -50°C for one hour. This cold tolerance was accompanied by higher hemolymph osmolality and glycerol concentration than in the SW Ontario individuals. To distinguish between phenotypic plasticity and local adaptation, in 2020/21 we overwintered Winnipeg-sourced individuals either outdoors in SW Ontario or in a simulated Winnipeg winter. Simulated Winnipeg winter individuals had cold tolerance similar to those overwintered in Winnipeg, while SW Ontario overwintered individuals had cold tolerance similar to those collected previously in the region. The simulated winter individuals had higher hemolymph glycerol concentrations than SW Ontario overwintered animals, at least in part due to greater dehydration. Thus, A. planipennis are cold-tolerant enough to survive some of the harshest winters where their host trees can grow, and most likely attain this cold tolerance via phenotypic plasticity. These findings raise the importance of delineating sensitivity of conclusions to unexpected phenotypic plasticity when predicting potential distributions of new invasives or responses to climate change.

Dataset Information

Forecasting extreme stratospheric polar vortex events.

Publications

Forecasting extreme stratospheric polar vortex events.

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