A Stratospheric Approach to Diagnose the North American Winter Dipole

• Main Author: Panosyan, Henrik
• Format: Text
• Language: unknown
• Published: Utah State University 2020
• Subjects: polar night
• Online Access: https://dx.doi.org/10.26076/f9dc-41a6; https://digitalcommons.usu.edu/etd/7875

It has been well established in the literature that the stratosphere is dynamically coupled with the troposphere during boreal winter. The North American Winter Dipole is comprised of an upper-tropospheric contrast between a ridge over western North America, and a trough over eastern North America. The variance of this circulation regime has increased in recent years, with its amplified states being associated with extremes ranging from drought and floods, to extreme cold air outbreaks. This study explores the stratospheric link to this extreme weather regime, in the hopes of ultimately improving the predictability of this regime on intraseasonal-to-seasonal timescales. We find evidence for barotropic coupling between the stratospheric and tropospheric circulation in the vicinity of the North American Winter Dipole when the phase of the stratospheric perturbation associated with the Polar Night Jet (or Stratospheric Polar Vortex), constructively interferes with its tropospheric counterpart associated with the North American Winter Dipole, and a lack there-of when the phases destructively interfere.