Daily-scale planetary wave patterns and the modulation of cold season weather in the northern extratropics

TitleDaily-scale planetary wave patterns and the modulation of cold season weather in the northern extratropics
Publication TypeJournal Article
Year of Publication2017
AuthorsXie, Zuowei, Black Robert X., and Deng Yi
JournalJournal of Geophysical Research: Atmospheres
Volume122
Pages8383 - 8398
Date Published08/2017
Abstract / Summary

Tropospheric planetary waves, often linked to asymmetries in lower boundary forcing, significantly modulate atmospheric blocking and storm track structures that are, in turn, linked to extreme surface weather events. Day-to-day variability in the planetary scale circulation, taken as wave numbers 1 to 5 in the daily 500 hPa geopotential heights, and the associated impact on storm tracks and regional weather are studied for the period 1950–2005. Six boreal cold-season distinct planetary wave patterns are identified via hierarchical cluster analysis. The first, second, and sixth patterns feature a prominent zonal wave number 1 structure, while the fourth and fifth patterns resemble the negative and positive phases of northern annular mode, respectively. The second pattern represents an amplification of the climatological mean wave structure, while the third pattern resembles the zonal wave number 3 pattern. A multitaper spectral analysis of the daily projection indices indicates that the planetary wave patterns are primarily intraseasonal in nature. The first (sixth) pattern combines the positive (negative) phase of the Pacific-North American teleconnection pattern and negative (positive) phase of the North Atlantic Oscillation, inducing poleward (equatorward) shifts in the Pacific storm track and a weakened (strengthened) Atlantic storm track. In contrast, the fourth (fifth) pattern results in a simultaneous equatorward (poleward) displacement of both storm tracks. Extreme cold waves over the continental United States (U.S.) are favored during occurrences of the fourth and sixth patterns. During episodes of the first pattern, increased rainfall prevails over much of the U.S., while precipitation anomalies induced by the other patterns are more regional in nature.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/2017JD026768/abstract
DOI10.1002/2017JD026768
Journal: Journal of Geophysical Research: Atmospheres
Year of Publication: 2017
Volume: 122
Pages: 8383 - 8398
Date Published: 08/2017

Tropospheric planetary waves, often linked to asymmetries in lower boundary forcing, significantly modulate atmospheric blocking and storm track structures that are, in turn, linked to extreme surface weather events. Day-to-day variability in the planetary scale circulation, taken as wave numbers 1 to 5 in the daily 500 hPa geopotential heights, and the associated impact on storm tracks and regional weather are studied for the period 1950–2005. Six boreal cold-season distinct planetary wave patterns are identified via hierarchical cluster analysis. The first, second, and sixth patterns feature a prominent zonal wave number 1 structure, while the fourth and fifth patterns resemble the negative and positive phases of northern annular mode, respectively. The second pattern represents an amplification of the climatological mean wave structure, while the third pattern resembles the zonal wave number 3 pattern. A multitaper spectral analysis of the daily projection indices indicates that the planetary wave patterns are primarily intraseasonal in nature. The first (sixth) pattern combines the positive (negative) phase of the Pacific-North American teleconnection pattern and negative (positive) phase of the North Atlantic Oscillation, inducing poleward (equatorward) shifts in the Pacific storm track and a weakened (strengthened) Atlantic storm track. In contrast, the fourth (fifth) pattern results in a simultaneous equatorward (poleward) displacement of both storm tracks. Extreme cold waves over the continental United States (U.S.) are favored during occurrences of the fourth and sixth patterns. During episodes of the first pattern, increased rainfall prevails over much of the U.S., while precipitation anomalies induced by the other patterns are more regional in nature.

DOI: 10.1002/2017JD026768
Citation:
Xie, Z, RX Black, and Y Deng.  2017.  "Daily-scale planetary wave patterns and the modulation of cold season weather in the northern extratropics."  Journal of Geophysical Research: Atmospheres 122: 8383 - 8398.  https://doi.org/10.1002/2017JD026768.