scholarly journals Role of Rossby wave breaking in the west Pacific teleconnection

2010 ◽  
Vol 37 (11) ◽  
pp. n/a-n/a ◽  
Author(s):  
G. Rivière
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
The West ◽  
West Pacific ◽  
Rossby Wave Breaking

scholarly journals Rossby Wave Breaking and Transient Eddy Forcing during Euro-Atlantic Circulation Regimes

2017 ◽  
Vol 74 (6) ◽  
pp. 1735-1755 ◽  
Author(s):  
Erik T. Swenson ◽  
David M. Straus
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Ocean Model ◽  
Heat Fluxes ◽  
Boreal Winter ◽  
Transient Eddy ◽  
Flux Divergence ◽  
Western Atlantic ◽  
Rossby Wave Breaking

Abstract The occurrence of boreal winter Rossby wave breaking (RWB) along with the quantitative role of synoptic transient eddy momentum and heat fluxes directly associated with RWB are examined during the development of Euro-Atlantic circulation regimes using ERA-Interim. Results are compared to those from seasonal reforecasts made using the Integrated Forecast System model of ECWMF coupled to the NEMO ocean model. The development of both Scandinavian blocking and the Atlantic ridge is directly coincident with anticyclonic wave breaking (AWB); however, the associated transient eddy fluxes do not contribute to (and, in fact, oppose) ridge growth, as indicated by the local Eliassen–Palm (EP) flux divergence. Evidently, other factors drive development, and it appears that wave breaking assists more with ridge decay. The growth of the North Atlantic Oscillation (NAO) in its positive phase is independent of RWB in the western Atlantic but strongly linked to AWB farther downstream. During AWB, the equatorward flux of cold air at upper levels contributes to a westerly tendency just as much as the poleward flux of momentum. The growth of the negative phase of the NAO is almost entirely related to cyclonic wave breaking (CWB), during which equatorward momentum flux dominates at jet level, yet low-level heat fluxes dominate below. The reforecasts yield realistic frequencies of CWB and AWB during different regimes, as well as realistic estimates of their roles during development. However, a slightly weaker role of RWB is simulated, generally consistent with a weaker anomalous circulation.

scholarly journals Dynamics of Landfalling Atmospheric Rivers over the North Pacific in 30 Years of MERRA Reanalysis

2014 ◽  
Vol 27 (18) ◽  
pp. 7133-7150 ◽  
Author(s):  
Ashley E. Payne ◽  
Gudrun Magnusdottir
Keyword(s):  
Rossby Wave ◽  
West Coast ◽  
Wave Breaking ◽  
Moisture Transport ◽  
Large Scale ◽  
Eastern Pacific ◽  
The West ◽  
Atmospheric Rivers ◽  
Rossby Wave Breaking ◽  
Upper Level

Abstract A large-scale analysis of landfalling atmospheric rivers (ARs) along the west coast of North America and their association with the upper-tropospheric flow is performed for the extended winter (November–March) for the years 1979–2011 using Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis data. The climatology, relationship to the El Niño–Southern Oscillation and the Madden–Julian oscillation, and upper-level characteristics of approximately 750 landfalling ARs are presented based on the 85th percentile of peak daily moisture flux. AR occurrence along the West Coast is dominated by early season events. In composites of upper-level fields during AR occurrences, certain characteristics stand out irrespective of the tropical climate indices. This suggests that extratropical dynamical processes play a key role in AR dynamics. The influence of the large-scale circulation on AR intensity prior to landfall is examined by objectively selecting an extreme subset of 112 landfalling AR dates representing the 95th percentile of strongest cases. Each landfalling AR date that is identified is traced backward in time using a novel semiautomated tracking algorithm based on spatially and temporally connected organized features in integrated moisture transport. Composites of dynamical fields following the eastward progression of ARs show a close relationship of the location of the jet, Rossby wave propagation, and anticyclonic Rossby wave breaking in the upper troposphere of the eastern Pacific and moisture transport in the lower troposphere. Comparison between the strongest and the weakest ARs within the most extreme subset shows differences in both the intensity of moisture transport and the scale and development of anticyclonic Rossby wave breaking in the eastern Pacific.

scholarly journals On the role of Rossby wave breaking in the quasi‐biennial modulation of the stratospheric polar vortex during boreal winter

2020 ◽  
Vol 146 (729) ◽  
pp. 1939-1959
Author(s):  
Hua Lu ◽  
Matthew H. Hitchman ◽  
Lesley J. Gray ◽  
James A. Anstey ◽  
Scott M. Osprey
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Polar Vortex ◽  
Boreal Winter ◽  
Stratospheric Polar Vortex ◽  
Rossby Wave Breaking

scholarly journals The Role of Dynamic Tropopause Rossby Wave Breaking for Synoptic-Scale Buildups in Northern Hemisphere Zonal Available Potential Energy

2019 ◽  
Vol 147 (2) ◽  
pp. 433-455 ◽  
Author(s):  
Kevin A. Bowley ◽  
John R. Gyakum ◽  
Eyad H. Atallah
Keyword(s):  
Potential Energy ◽  
Northern Hemisphere ◽  
Rossby Wave ◽  
North Pacific ◽  
Wave Breaking ◽  
Synoptic Scale ◽  
Rossby Wave Breaking ◽  
The North ◽  
The North Pacific

Abstract Zonal available potential energy AZ measures the magnitude of meridional temperature gradients and static stability of a domain. Here, the role of Northern Hemisphere dynamic tropopause (2.0-PVU surface) Rossby wave breaking (RWB) in supporting an environment facilitating buildups of AZ on synoptic time scales (3–10 days) is examined. RWB occurs when the phase speed of a Rossby wave slows to the advective speed of the atmosphere, resulting in a cyclonic or anticyclonic RWB event (CWB and AWB, respectively). These events have robust dynamic and thermodynamic feedbacks through the depth of the troposphere that can modulate AZ. Significant synoptic-scale buildups in AZ and RWB events are identified from the National Centers for Environmental Prediction Reanalysis-2 dataset from 1979 to 2011 for 20°–85°N. Anomalies in AWB and CWB are assessed seasonally for buildup periods of AZ. Positive anomalies in AWB and negative anomalies in CWB are found for most AZ buildup periods in the North Pacific and North Atlantic basins and attributed to localized poleward shifts in the jet stream. Less frequent west–east dipoles in wave breaking anomalies for each basin are attributed to elongated and contracted regional jet exit regions. Finally, an analysis of long-duration AWB events for winter AZ buildup periods to an anomalously high AZ state is performed using a quasi-Lagrangian grid-shifting technique. North Pacific AWB events are shown to diabatically intensify the North Pacific jet exit region (increasing Northern Hemisphere AZ) through latent heating equatorward of the jet exit and radiative and evaporative cooling poleward of the jet exit.

scholarly journals North Atlantic Extratropical Rossby Wave Breaking during the Warm Season: Wave Life Cycle and Role of Diabatic Heating

2018 ◽  
Vol 146 (3) ◽  
pp. 695-712 ◽  
Author(s):  
Gan Zhang ◽  
Zhuo Wang
Keyword(s):  
Rossby Wave ◽  
North Atlantic ◽  
Wave Breaking ◽  
Trajectory Analysis ◽  
Diabatic Heating ◽  
Warm Season ◽  
Rossby Wave Breaking ◽  
The North ◽  
Budget Analysis

This study investigates the life cycle of anticyclonic Rossby wave breaking during the extended warm season (July–October) over the North Atlantic basin. It was found that upper-tropospheric breaking waves are coupled with lower-level perturbations and can be traced back to a wave train that extends from the North Pacific. The overturning of potential vorticity (PV) contours during wave breaking is associated with the rapid development of an upper-level ridge, which occurs along the east coast of North America and over a warm and moist airstream. The ridge development is investigated using the PV budget analysis and trajectory analysis. The PV budget analysis suggests that the horizontal advection of PV by the perturbed flow dictates the movement and the later decay of the ridge. The ridge amplification, opposed by the horizontal advection of PV, is driven by the vertical advection and the diabatic production of PV, both of which are connected to diabatic heating. The vital role of diabatic heating in the ridge amplification is corroborated by the trajectory analysis. The analysis suggests that diabatic heating reduces the static stability near the tropopause and contributes to the ridge-related negative PV anomalies. The role of diabatic heating in anticyclonic and cyclonic wave breaking in other regions is also discussed. The findings suggest that moist diabatic processes, which were often excluded from the earlier studies of wave breaking, are crucial for Rossby wave breaking during the warm season. The updated understanding of wave breaking may benefit weather forecasting and climate predictions.

Characteristics of long-duration heavy precipitation events along the West Coast of the United States

2021 ◽  
Author(s):  
Benjamin J. Moore ◽  
Allen B. White ◽  
Daniel J. Gottas
Keyword(s):  
Rossby Wave ◽  
West Coast ◽  
Bering Sea ◽  
North Pacific ◽  
Wave Breaking ◽  
Heavy Precipitation ◽  
The West ◽  
Rossby Wave Breaking ◽  
Long Duration ◽  
Precipitation Events

AbstractProlonged periods (e.g., several days or more) of heavy precipitation can result in sustained high-impact flooding. Herein, an investigation of long-duration heavy precipitation events (HPEs), defined as periods comprising ≥ 3 days with precipitation exceeding the climatological 95th percentile, is conducted for 1979–2019 for the U.S. West Coast, specifically Northern California. An objective flow-based categorization method is applied to identify principal large-scale flow patterns for the events. Four categories are identified and examined through composite analyses and case studies. Two of the categories are characterized by a strong zonal jet stream over the eastern North Pacific, while the other two are characterized by atmospheric blocking over the central North Pacific and the Bering Sea–Alaska region, respectively. The composites and case studies demonstrate that the flow patterns for the HPEs tend to remain in place for several days, maintaining strong baroclinicity and promoting occurrences of multiple cyclones in rapid succession near the West Coast. The successive cyclones result in persistent water vapor flux and forcing for ascent over Northern California, sustaining heavy precipitation. For the zonal jet patterns, cyclones affecting the West Coast tend to occur in the poleward jet exit region in association with cyclonic Rossby wave breaking. For the blocking patterns, cyclones tend to occur in association with anticyclonic Rossby wave breaking on the downstream flank of the block. For Bering Sea–Alaska blocking cases, cyclones can move into this region in conjunction with cyclonically breaking waves that extend into the eastern North Pacific from the upstream flank of the block.

scholarly journals The Role of Rossby Wave Breaking in Shaping the Equilibrium Atmospheric Circulation Response to North Atlantic Boundary Forcing

2010 ◽  
Vol 23 (6) ◽  
pp. 1269-1276 ◽  
Author(s):  
Courtenay Strong ◽  
Gudrun Magnusdottir
Keyword(s):  
Sea Ice ◽  
Rossby Wave ◽  
North Atlantic ◽  
Wave Breaking ◽  
General Circulation ◽  
Broad Class ◽  
Circulation Model ◽  
Zonal Flow ◽  
Rossby Wave Breaking

Abstract The role of Rossby wave breaking (RWB) is explored in the transient response of an atmospheric general circulation model to boundary forcing by sea ice anomalies related to the North Atlantic Oscillation (NAO). When the NCAR Community Climate Model, version 3, was forced by an exaggerated sea ice extent anomaly corresponding to one arising from a positive NAO, a localized baroclinic response developed and evolved into a larger-scale equivalent barotropic pattern resembling the negative polarity of the NAO. The initial baroclinic response shifted the phase speeds of the dominant eddies away from a critical value equal to the background zonal flow speed, resulting in significant changes in the spatial distribution of RWB. The forcing of the background zonal flow by the changes in RWB accounts for 88% of the temporal pattern of the response and 80% of the spatial pattern of the zonally averaged response. Although results here focus on one experiment, this “RWB critical line mechanism” appears to be relevant to understanding the equilibrium response in a broad class of boundary forcing experiments given increasingly clear connections among the northern annular mode, jet latitude shifts, and RWB.

Sign in / Sign up

Export Citation Format

Share Document