Maintenance Mechanism of Rossby Wave Breaking and Pacific-Japan Pattern in Boreal Summer

2020 ◽  
Vol 98 (6) ◽  
pp. 1183-1206
Author(s):  
Kazuto TAKEMURA ◽  
Hitoshi MUKOUGAWA
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Boreal Summer ◽  
Rossby Wave Breaking ◽  
Maintenance Mechanism

Large-Scale Atmospheric Circulation Related to Frequent Rossby Wave Breaking near Japan in Boreal Summer

2020 ◽  
Vol 33 (15) ◽  
pp. 6731-6744
Author(s):  
Kazuto Takemura ◽  
Hitoshi Mukougawa ◽  
Shuhei Maeda
Keyword(s):  
Atmospheric Circulation ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Boreal Summer ◽  
Rossby Wave Breaking ◽  
The Pacific ◽  
Silk Road Pattern ◽  
Large Scale Atmospheric Circulation ◽  
The Silk Road

AbstractRossby wave propagation along the Asian jet during boreal summer, such as the Silk Road pattern, frequently causes wave breaking near the Asian jet exit region. This study examines the statistical relationship between interannual variability of the Rossby wave breaking frequency near Japan and large-scale atmospheric circulation during the boreal summer. The Rossby wave breaking frequency in the midlatitudes climatologically shows its maximum near Japan, and significantly increases during La Niña years. The upper-tropospheric circulation regressed onto the Rossby wave breaking frequency near Japan in August shows large-scale anomalous convergence from the tropical central to eastern Pacific and divergence around the Indian Ocean. The consequent northward anomalous divergent wind over Eurasia contributes to enhancement and northward shift of the Asian jet. The Asian jet also shows meridional meandering with a phase of anomalous anticyclonic circulation near Japan accompanied by the frequent Rossby wave breaking, which is associated with the Silk Road pattern. The frequent Rossby wave breaking is related to southwestward intrusion of anomalous low potential temperature air mass toward the subtropical western North Pacific associated with an enhanced mid-Pacific trough. West of the southwestward cold-air intrusion, enhanced cumulus convection is seen around the northern Philippines, and the Pacific–Japan pattern is significantly seen in the lower troposphere. This result is consistent with a previous study that revealed a linkage mechanism between the Rossby wave breaking near Japan and the Pacific–Japan pattern through dynamically induced ascent resulting in an intrusion of high potential vorticity associated with the 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.

Rossby wave-breaking analysis of explosive cyclones in the Euro-Atlantic sector

2013 ◽  
Vol 140 (680) ◽  
pp. 738-753 ◽  
Author(s):  
Iñigo Gómara ◽  
Joaquim G. Pinto ◽  
Tim Woollings ◽  
Giacomo Masato ◽  
Pablo Zurita-Gotor ◽  
...  
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Atlantic Sector ◽  
Rossby Wave Breaking ◽  
Explosive Cyclones

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

2021 ◽  
pp. 17-28
Author(s):  
A. V. Gochakov ◽  
◽  
O. Yu. Antokhina ◽  
V. N. Krupchatnikov ◽  
Yu. V. Martynova ◽  
...  
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Breaking ◽  
Large Scale ◽  
Method Development ◽  
Spatial Clustering ◽  
Potential Temperature ◽  
Reanalysis Data ◽  
Rossby Wave Breaking ◽  
Dynamic Phenomena

Many large-scale dynamic phenomena in the Earth’s atmosphere are associated with the processes of propagation and breaking of Rossby waves. A new method for identifying the Rossby wave breaking (RWB) is proposed. It is based on the detection of breakings centers by analyzing the shape of the contours of potential vorticity or temperature on quasimaterial surfaces: isentropic and iserthelic (surfaces of constant Ertel potential vorticity (PV)), with further RWB center clustering to larger regions. The method is applied to the set of constant PV levels (0.3 to 9.8 PVU with a step of 0.5 PVU) at the level of potential temperature of 350 K for 12:00 UTC. The ERA-Interim reanalysis data from 1979 to 2019 are used for the method development. The type of RWB (cyclonic/anticyclonic), its area and center are determined by analyzing the vortex geometry at each PV level for every day. The RWBs obtained at this stage are designated as elementary breakings. Density-Based Spatial Clustering of Applications with Noise algorithm (DBSCAN) was applied to all elementary breakings for each month. As a result, a graphic dataset describing locations and dynamics of RWBs for every month from 1979 to 2019 is formed. The RWB frequency is also evaluated for each longitude, taking into account the duration of each RWB and the number of levels involved, as well as the anomalies of these parameters.

A novel identification and tracking method of weather-relevant 3D Potential vorticity streamers

2021 ◽  
Author(s):  
Christoph Fischer ◽  
Elmar Schömer ◽  
Andreas H. Fink ◽  
Michael Riemer ◽  
Michael Maier-Gerber
Keyword(s):  
Rossby Wave ◽  
Potential Vorticity ◽  
Wave Breaking ◽  
Extreme Weather ◽  
Individual Characteristics ◽  
Distance Functions ◽  
Extreme Weather Events ◽  
Rossby Wave Breaking ◽  
Feature Vectors ◽  
Weather Events

<p>Potential vorticity streamers (PVSs) are elongated quasi-horizontal filaments of stratospheric air in the upper troposphere related to, for example, Rossby wave breaking events. They are known to be related to partly extreme weather events in the midlatitudes and subtropics and can also be involved in (sub-)tropical cyclogenesis. While several algorithms have been developed to identify and track PVSs on planar isentropic surfaces, less is known about the evolution of these streamers in 3D, both climatologically but also for a better understanding of individual weather events. Furthermore, characteristics of their 3D shape have barely been considered as a predictor for high impact weather events like (sub-)tropical cyclones.</p><p>We introduce a novel algorithm for detection and identification of PVSs based on image processing techniques which can be applied to 2D and 3D gridded datasets. The potential vorticity was taken from high resolution isentropic analyses based on the ERA5 dataset. The algorithm uses the 2 PVU (Potential Vorticity Unit) threshold to identify and extract anomalies in the PV field using signed distance functions. This is accomplished by using a stereographic projection to eliminate singularities and keeping track of the reduced distortions by storing precomputed distance maps. This approach is computationally efficient and detects more interesting structures that exhibit the general behavior of PVSs compared to existing 2D techniques.</p><p>For each identified object a feature vector is computed, containing the individual characteristics of the streamers. In the 3D case, the algorithm looks at the structure en bloc instead of operating individually on multiple 2D levels. This also makes the identification stable regarding the seasonal cycle. Feature vectors contain parameters about quality, intensity and shape. In the case of 2D datasets, best-fitting ellipses computed from the statistical moments are regarded as a description of their shape. For 3D datasets, recent visualizations show that the boundary of these structures could be approximated by quadric surfaces . The feature vectors are also amended by tracking information, for example splitting and merging events. This low-dimensional representation serves as base for ERA5 climatologies. The data will be correlated with (sub-)tropical cyclone occurrence to spot useful and novel predictors for cyclone activity and preceding Rossby Wave Breaking events.</p><p>Overall, this new type of PVS identification algorithm, applicable in 2D or 3D, allows to diagnose the role of PVS in extreme weather events, including their predictability in ensemble forecasts.</p>

scholarly journals Stratospheric intrusions induced by a Rossby Wave breaking and its interaction with the subtropical jet during PICO3 campaign

2005 ◽  
Vol 5 (5) ◽  
pp. 10301-10337
Author(s):  
A. Carré ◽  
F. Ravetta ◽  
J.-P. Cammas ◽  
P. Mascart ◽  
J. Duron ◽  
...  
Keyword(s):  
Rossby Wave ◽  
Vortex Core ◽  
Wave Breaking ◽  
Mesoscale Model ◽  
Rossby Wave Breaking ◽  
Airborne Measurements ◽  
Subtropical Jet ◽  
Stratospheric Intrusions

Abstract. This study documents several processes of stratosphere-troposphere transport (STT) in the subtropical region. A case study of the interaction between a Rossby Wave breaking over the Canary Islands and a subtropical vortex core situated further south is analysed with ozone airborne measurements (in-situ and Lidar). The investigation is conducted using a Reverse Domain Filling technique to reconstruct high-resolution potential vorticity fields with a Lagrangian approach and with simulations of a mesoscale model. Results show irreversible STT associated with tropopause folding, Rossby Wave Breaking and the filamentation of the subtropical vortex core.

3-D tomographic observations of Rossby wave breaking over the Northern Atlantic during the WISE aircraft campaign in 2017

2021 ◽  
Author(s):  
Lukas Krasauskas ◽  
Jörn Ungermann ◽  
Peter Preusse ◽  
Felix Friedl-Vallon ◽  
Andreas Zahn ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Water Vapour ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Thin Filament ◽  
Small Scale ◽  
Data Sets ◽  
Mixing Processes ◽  
Air Masses ◽  
Rossby Wave Breaking

<p>We present measurements of ozone, water vapour and nitric acid in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. We show a case study of a Rossby wave (RW) breaking event observed during two subsequent flights two days apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere-troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NO<sub>x</sub> production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again two days later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over two days. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, witch is of great importance to understanding STE and poleward transport in the UTLS.</p>

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