scholarly journals The Role of Rossby-Wave Propagation in a North American Extreme Cold Event

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Chunhua Shi ◽  
Ting Xu ◽  
Hui Li ◽  
Yannan Gao
Keyword(s):  
Wave Propagation ◽  
North America ◽  
Rossby Wave ◽  
North American ◽  
Early Stage ◽  
Wave Activity ◽  
Cold Wave ◽  
Cold Event ◽  
The Pacific ◽  
Rossby Wave Propagation

The Eliassen–Palm flux and Plumb wave activity flux are calculated using the European Centre for Medium-Range Weather Forecasts interim reanalysis daily dataset to determine the propagation of Rossby waves before a North American cold wave in January 2014. The results show that the upward wave activity fluxes mainly come from planetary waves 1 and 2, which provide a stable circulation background for the influence of the subplanetary-scale waves 3 and 4. The Rossby-wave propagation anomalies between the troposphere and the stratosphere are due to the modulating effects of waves 3 and 4 on waves 1 and 2. During 9–14 January 2014, the modulating effects helped strengthen upward and eastward wave activity fluxes over the Atlantic region and enhance the Pacific high in the stratosphere in its early stage. Later in 19–24 January, the downward wave activity fluxes over the east Pacific due to the modulating effects were beneficial to downward development of the stratospheric high over the Pacific and the formation of a blocking high over the west coast of North America in the troposphere accompanied by a strong adjacent cold low on the east side. These circulations benefit the southward invasion of polar cold air reaching the lower latitudes of east North America, leading to the cold wave outbreak.

scholarly journals Rossby Wave Propagation from the Arctic into the Midlatitudes: Does It Arise from In Situ Latent Heating or a Trans-Arctic Wave Train?

2020 ◽  
Vol 33 (9) ◽  
pp. 3619-3633 ◽  
Author(s):  
Tingting Gong ◽  
Steven B. Feldstein ◽  
Sukyoung Lee
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Wave Train ◽  
The Arctic ◽  
Latent Heating ◽  
Latent Heat Release ◽  
Rossby Wave Propagation ◽  
Rossby Wave Train ◽  
In Situ Generation

AbstractThe relationship between latent heating over the Greenland, Barents, and Kara Seas (GBKS hereafter) and Rossby wave propagation between the Arctic and midlatitudes is investigated using global reanalysis data. Latent heating is the focus because it is the most likely source of Rossby wave activity over the Arctic Ocean. Given that the Rossby wave time scale is on the order of several days, the analysis is carried out using a daily latent heating index that resembles the interdecadal latent heating trend during the winter season. The results from regression calculations find a trans-Arctic Rossby wave train that propagates from the subtropics, through the midlatitudes, into the Arctic, and then back into midlatitudes over a period of about 10 days. Upon entering the GBKS, this wave train transports moisture into the region, resulting in anomalous latent heat release. At high latitudes, the overlapping of a negative latent heating anomaly with an anomalous high is consistent with anomalous latent heat release fueling the Rossby wave train before it propagates back into the midlatitudes. This implies that the Rossby wave propagation from the Arctic into the midlatitudes arises from trans-Arctic wave propagation rather than from in situ generation. The method used indicates the variance of the trans-Arctic wave train, but not in situ generation, and implies that the variance of the former is greater than that of latter. Furthermore, GBKS sea ice concentration regression against the latent heating index shows the largest negative value six days afterward, indicating that sea ice loss contributes little to the latent heating.

scholarly journals Rossby Wave Ray Tracing in a Barotropic Divergent Atmosphere

2008 ◽  
Vol 65 (5) ◽  
pp. 1679-1691 ◽  
Author(s):  
Chungu Lu ◽  
John P. Boyd
Keyword(s):  
Wave Propagation ◽  
Ray Tracing ◽  
Rossby Wave ◽  
Level Structure ◽  
Low Frequency ◽  
Present Theory ◽  
Wave Ray ◽  
Divergent Wind ◽  
Rossby Wave Propagation ◽  
Upper Level

Abstract The effects of divergence on low-frequency Rossby wave propagation are examined by using the two-dimensional Wentzel–Kramers–Brillouin (WKB) method and ray tracing in the framework of a linear barotropic dynamic system. The WKB analysis shows that the divergent wind decreases Rossby wave frequency (for wave propagation northward in the Northern Hemisphere). Ray tracing shows that the divergent wind increases the zonal group velocity and thus accelerates the zonal propagation of Rossby waves. It also appears that divergence tends to feed energy into relatively high wavenumber waves, so that these waves can propagate farther downstream. The present theory also provides an estimate of a phase angle between the vorticity and divergence centers. In a fully developed Rossby wave, vorticity and divergence display a π/2 phase difference, which is consistent with the observed upper-level structure of a mature extratropical cyclone. It is shown that these theoretical results compare well with observations.

scholarly journals Intraseasonal and Interannual Variability in North American Storm Tracks and Its Relationship to Equatorial Pacific Variability

2013 ◽  
Vol 141 (10) ◽  
pp. 3610-3625 ◽  
Author(s):  
Kevin M. Grise ◽  
Seok-Woo Son ◽  
John R. Gyakum
Keyword(s):  
North America ◽  
Interannual Variability ◽  
North American ◽  
Southern Oscillation ◽  
Extratropical Cyclones ◽  
The North ◽  
The Pacific ◽  
Cyclone Tracks ◽  
Lagrangian Tracking ◽  
The North Atlantic Oscillation

Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of cyclones track 1) from the lee of the Rocky Mountains eastward across the Great Lakes and 2) over the Gulf Stream along the eastern coastline of North America. However, the cyclone tracks are highly variable within individual winters and between winter seasons. In this study, the authors apply a Lagrangian tracking algorithm to examine variability in extratropical cyclone tracks over North America during winter. A series of methodological criteria is used to isolate cyclone development and decay regions and to account for the elevated topography over western North America. The results confirm the signatures of four climate phenomena in the intraseasonal and interannual variability in North American cyclone tracks: the North Atlantic Oscillation (NAO), the El Niño–Southern Oscillation (ENSO), the Pacific–North American pattern (PNA), and the Madden–Julian oscillation (MJO). Similar signatures are found using Eulerian bandpass-filtered eddy variances. Variability in the number of extratropical cyclones at most locations in North America is linked to fluctuations in Rossby wave trains extending from the central tropical Pacific Ocean. Only over the far northeastern United States and northeastern Canada is cyclone variability strongly linked to the NAO. The results suggest that Pacific sector variability (ENSO, PNA, and MJO) is a key contributor to intraseasonal and interannual variability in the frequency of extratropical cyclones at most locations across North America.

scholarly journals Rossby Wave Propagation in Idealized and Realistic Zonally Varying Flows

1997 ◽  
Vol 75 (3) ◽  
pp. 687-700 ◽  
Author(s):  
Hiroaki Naoe ◽  
Yoshihisa Matsuda ◽  
Hisashi Nakamura
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Rossby Wave Propagation

Teleconnections from Tropics to Northern Extratropics through a Southerly Conveyor

2005 ◽  
Vol 62 (11) ◽  
pp. 4057-4070 ◽  
Author(s):  
Zhuo Wang ◽  
C-P. Chang ◽  
Bin Wang ◽  
Fei-Fei Jin
Keyword(s):  
Wave Propagation ◽  
Rossby Wave ◽  
Rossby Waves ◽  
Propagation Theory ◽  
Wave Source ◽  
Tropical Forcing ◽  
Rossby Wave Source ◽  
Rossby Wave Response ◽  
Rossby Wave Propagation ◽  
The Tropics

Abstract Rossby wave propagation theory predicts that Rossby waves in a tropical easterly flow cannot escape from the Tropics to the extratropics. Here the authors show that a southerly flow component in the basic state (a southerly conveyor) may transfer a Rossby wave source northward; thus, a forcing embedded in the deep tropical easterlies may excite a Rossby wave response in the extratropical westerlies. It is shown that the southerly conveyor determines the location of the effective Rossby wave source and that the extratropical response is relatively insensitive to the location of the tropical forcing, provided that the tropical response can reach the southerly conveyor. A stronger southerly flow favors a stronger extratropical response, and the spatial structure of the extratropical response is determined by the extratropical westerly basic flows.

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