scholarly journals Tropopause level Rossby wave breaking in the Northern Hemisphere: a feature-based validation of the ECHAM5-HAM climate model

2012 ◽  
Vol 33 (14) ◽  
pp. 3073-3082 ◽  
Author(s):  
A. Béguin ◽  
O. Martius ◽  
M. Sprenger ◽  
P. Spichtinger ◽  
D. Folini ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Climate Model ◽  
Rossby Wave Breaking ◽  
Feature Based

Rossby wave breaking through the 21st century in a global climate model

2020 ◽  
Author(s):  
Kevin Bowley ◽  
Melissa Gervais
Keyword(s):  
Rossby Wave ◽  
High Latitude ◽  
Wave Breaking ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Thermodynamic Characteristics ◽  
Historical Period ◽  
Meridional Transport ◽  
Rossby Wave Breaking

<p>Rossby wave breaking on the dynamic tropopause (DT) occurs when synoptic-scale Rossby waves become highly amplified and undergo a breaking process.  This process can result in significant meridional transport of air masses resulting and intrusions of low latitude air poleward, high latitude air equatorward, or a combination of the two.  The ensuing modification of the troposphere and lower stratosphere in response to such events have been areas of considerable research due to their potential impacts on both high- and low-frequency mid- and high-latitude variability.  Furthermore, the processes and feedbacks associated with these events can result in notable changes to the jet structure and are frequently associated with atmospheric river events amongst other phenomena.  As such, the potential impacts of future changes in these events make them of considerable interest for identifying and studying in global climate model (GCM) simulations. </p><p>Here, we apply a Rossby wave breaking identification scheme to three sets of 25-member Community Earth System Model simulations with prescribed sea surface temperature and sea ice conditions over the historical period (2010-2019), mid-Century (2050-2059) and late-Century (2090-2099).  This dataset represents a unique opportunity to study Rossby wave breaking processes in future climate simulations on a dynamically evolving surface rather than the more common pressure levels or isentropic levels as the DT is calculated for each of the CESM members.  Both anticyclonic and cyclonic Rossby wave breaking events are identified and tracked.  Events modeled in the historical period are compared to existing reanalysis data for the same period to explore the ability of the CESM model in this configuration to reproduce these events accurately.  Furthermore, the three periods of interest are examined to determine changes in the locations of Rossby wave breaking as well as the dynamic and thermodynamic characteristics of composited events. </p>

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 Tropospheric Rossby Wave Breaking and the NAO/NAM

2008 ◽  
Vol 65 (9) ◽  
pp. 2861-2876 ◽  
Author(s):  
Courtenay Strong ◽  
Gudrun Magnusdottir
Keyword(s):  
Northern Hemisphere ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Time Lag ◽  
Zonal Flow ◽  
Sea Level Pressure ◽  
Rossby Wave Breaking ◽  
The North ◽  
Nao Index ◽  
The North Atlantic Oscillation

Abstract Objective analysis of several hundred thousand anticyclonic and cyclonic breaking Rossby waves is performed for the Northern Hemisphere (NH) winters of 1958–2006. A winter climatology of both anticyclonic and cyclonic Rossby wave breaking (RWB) frequency and size (zonal extent) is presented for the 350-K isentropic surface over the NH, and the spatial distribution of RWB is shown to agree with theoretical ideas of RWB in shear flow. Composites of the two types of RWB reveal their characteristic sea level pressure anomalies, upper- and lower-tropospheric velocity fields, and forcing of the upper-tropospheric zonal flow. It is shown how these signatures project onto the centers of action and force the velocity patterns associated with the North Atlantic Oscillation (NAO) and Northern Hemisphere annular mode (NAM). Previous studies have presented evidence that anticyclonic (cyclonic) breaking leads to the positive (negative) polarity of the NAO, and this relationship is confirmed for RWB over the midlatitudes centered near 50°N. However, an opposite and statistically significant relationship, in which cyclonic RWB forces the positive NAO and anticyclonic RWB forces the negative NAO, is shown over regions 20° to the north and south, centered at 70° and 30°N, respectively. On a winter mean basis, the frequency of RWB over objectively defined regions covering 12% of the area of the NH accounts for 95% of the NAO index and 92% of the NAM index. A 6-hourly analysis of all the winters indicates that RWB over the objectively defined regions affects the NAO/NAM without a time lag. Details of the objective wave-breaking analysis method are provided in the appendix.

scholarly journals The Morphology of Northern Hemisphere Blocking

2008 ◽  
Vol 65 (5) ◽  
pp. 1653-1665 ◽  
Author(s):  
E. Tyrlis ◽  
B. J. Hoskins
Keyword(s):  
Northern Hemisphere ◽  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Breaking ◽  
Storm Track ◽  
Rossby Wave Breaking ◽  
Planetary Scale ◽  
The Difference

Abstract The morphology of regional blocking in the Northern Hemisphere is discussed using the 40-yr ECMWF Re-Analysis (ERA-40) dataset and a measure of blocking based on the reversal at storm-track latitudes of meridional θ contrasts on a potential vorticity (PV) surface representative of the tropopause. The focus is on cyclonic and anticyclonic Rossby wave breaking that is inherent to the blocking development, and the extent to which this is determined by the climatological jet position and the ambient shears. More generally, the importance of the climatological planetary scale is discussed. The approach is mainly through composite behavior, but informed by consideration of many individual events. A diversity of behavior is found with longitude in both winter and summer, and there is a striking reversal of the sense of the wave breaking between the two seasons that is generally consistent with the difference in the jet locations. Preferred behaviors are found in various regions and seasons, and retrogression of blocking is discussed.

Method for Identifying and Clustering Rossby Wave Breaking Events in the Northern Hemisphere

2021 ◽  
Vol 46 (1) ◽  
pp. 10-18
Author(s):  
A. V. Gochakov ◽  
O. Yu. Antokhina ◽  
V. N. Krupchatnikov ◽  
Yu. V. Martynova
Keyword(s):  
Northern Hemisphere ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Rossby Wave Breaking

A Climatology of Rossby Wave Breaking on the Southern Hemisphere Tropopause

2011 ◽  
Vol 68 (4) ◽  
pp. 798-811 ◽  
Author(s):  
Thando Ndarana ◽  
Darryn W. Waugh
Keyword(s):  
Southern Hemisphere ◽  
Rossby Wave ◽  
Potential Vorticity ◽  
Seasonal Variations ◽  
Wave Breaking ◽  
Polar Front ◽  
Rossby Wave Breaking ◽  
South Pacific Ocean ◽  
Ocean Region ◽  
Summer Minimum

Abstract A 30-yr climatology of Rossby wave breaking (RWB) on the Southern Hemisphere (SH) tropopause is formed using 30 yr of reanalyses. Composite analysis of potential vorticity and meridional fluxes of wave activity show that RWB in the SH can be divided into two broad categories: anticyclonic and cyclonic events. While there is only weak asymmetry in the meridional direction and most events cannot be classified as equatorward or poleward in terms of the potential vorticity structure, the position and structure of the fluxes associated with equatorward breaking differs from those of poleward breaking. Anticyclonic breaking is more common than cyclonic breaking, except on the lower isentrope examined (320 K). There are marked differences in the seasonal variations of RWB on the two surfaces, with a winter minimum for RWB around 350 K but a summer minimum for RWB around 330 K. These seasonal variations are due to changes in the location of the tropospheric jets and dynamical tropopause. During winter the subtropical jet and tropopause at 350 K are collocated in the Australian–South Pacific Ocean region, resulting in a seasonal minimum in the 350-K RWB. During summer the polar front jet and 330-K tropopause are collocated over the Southern Atlantic and Indian Oceans, inhibiting RWB in this region.

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