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.

Rossby Wave Breaking and Transport between the Tropics and Extratropics above the Subtropical Jet

2013 ◽  
Vol 70 (2) ◽  
pp. 607-626 ◽  
Author(s):  
Cameron R. Homeyer ◽  
Kenneth P. Bowman
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Lower Stratosphere ◽  
Potential Temperature ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Mean Flow ◽  
Rossby Wave Breaking ◽  
Subtropical Jet ◽  
The Tropics

Abstract Rossby wave breaking is an important mechanism for the two-way exchange of air between the tropical upper troposphere and lower stratosphere and the extratropical lower stratosphere. The authors present a 30-yr climatology (1981–2010) of anticyclonically and cyclonically sheared wave-breaking events along the boundary of the tropics in the 350–500-K potential temperature range from ECMWF Interim Re-Analysis (ERA-Interim). Lagrangian transport analyses show net equatorward transport from wave breaking near 380 K and poleward transport at altitudes below and above the 370–390-K layer. The finding of poleward transport at lower levels is in disagreement with previous studies and is shown to largely depend on the choice of tropical boundary. In addition, three distinct modes of transport for anticyclonic wave-breaking events are found near the tropical tropopause (380 K): poleward, equatorward, and symmetric. Transport associated with cyclonic wave-breaking events, however, is predominantly poleward. The three transport modes for anticyclonic wave breaking are associated with specific characteristics of the geometry of the mean flow. In particular, composite averages show that poleward transport is associated with a “split” subtropical jet where the jet on the upstream side of the breaking wave extends eastward and lies poleward and at lower altitudes of the subtropical jet on the downstream side, producing a substantial longitudinal overlap between the two jets. Equatorward transport is not associated with a split subtropical jet and is found immediately downstream of stationary anticyclones in the tropics, often associated with monsoon circulations. It is further shown that, in general, the transport direction of breaking waves is determined primarily by the relative positions of the jets.

A Case Study of Rossby Wave Breaking along the Subtropical Tropopause

2001 ◽  
Vol 129 (10) ◽  
pp. 2555-2569 ◽  
Author(s):  
Gregory A. Postel ◽  
Matthew H. Hitchman
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Rossby Wave Breaking

scholarly journals Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012

2015 ◽  
Vol 15 (16) ◽  
pp. 9143-9158 ◽  
Author(s):  
C. Rolf ◽  
A. Afchine ◽  
H. Bozem ◽  
B. Buchholz ◽  
V. Ebert ◽  
...  
Keyword(s):  
Water Vapor ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Trajectory Analysis ◽  
Exchange Process ◽  
Near Surface ◽  
Air Masses ◽  
Rossby Wave Breaking ◽  
The Antarctic

Abstract. Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is annually observed by satellites and occasionally observed by balloon-borne measurements. However, in situ measurements of dehydrated air masses in the Antarctic vortex are very rare. Here, we present detailed observations with the in situ and GLORIA remote sensing instrument payload aboard the German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S in an altitude between 12 and 13 km in the lowermost stratosphere. The dehydration can be traced back to individual ice formation events above the Antarctic Peninsula and Plateau, where ice crystals sedimented out and water vapor was irreversibly removed. Within these dehydrated stratospheric air masses, filaments of moister air reaching down to the tropopause are detected with the high-resolution limb sounder, GLORIA. Furthermore, dehydrated air masses are observed with GLORIA in the Antarctic lowermost stratosphere down to 7 km. With the help of a backward trajectory analysis, a midlatitude origin of the moist filaments in the vortex can be identified, while the dry air masses down to 7 km have stratospheric origins. Antarctic stratosphere–troposphere exchange (STE) and transport of dehydrated air masses into the troposphere are investigated. Further, it is shown that the exchange process can be attributed to several successive Rossby wave events in combination with an isentropic exchange of air masses across the thermal tropopause. The transport into the troposphere is caused by air masses that are detached from the potential vorticity (PV) structure by Rossby wave breaking events and subsequently transported diabatically across the dynamical tropopause. Once transported to the troposphere, air masses with stratospheric origin can reach near-surface levels within several days.

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>

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