A Seasonal Climatology of Rossby Wave Breaking in the 320–2000-K Layer

2007 ◽  
Vol 64 (6) ◽  
pp. 1922-1940 ◽  
Author(s):  
Matthew H. Hitchman ◽  
Amihan S. Huesmann
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Reanalysis Data ◽  
Polar Night ◽  
Rossby Wave Breaking ◽  
Polar Stratosphere ◽  
Differential Advection ◽  
Shed Light ◽  
Pv Gradient ◽  
Westerly Jets

Differential advection in Rossby waves can lead to potential vorticity (PV; P) contours on isentropic surfaces folding over in latitude (Py < 0) in a process called Rossby wave breaking (RWB). Exploring the properties of RWB may shed light on underlying dynamics and enable quantification of irreversible transport. A seasonal climatology of Py and RWB statistics is presented for the 320–850-K layer using NCEP reanalysis data during 1979–2005 and for the 320–2000-K layer using the Met Office (UKMO) data during 1991–2003. A primary goal is to depict the spatial extent and seasonality of RWB maxima. This analysis shows seven distinct RWB regimes: poleward and equatorward of the subtropical westerly jets, poleward and equatorward of the stratospheric polar night jets, flanking the equator in the stratosphere and mesosphere, equatorward of subtropical monsoon anticyclones, and the summertime polar stratosphere. A striking PV gradient maximum exists at the equator throughout the layer 360–2000 K, flanked by subtropical RWB maxima, integral components of the Lagrangian cross-equatorial flow. Strong RWB occurs in the polar night vortex where β is small. Over the summer pole, strong poleward RWB associated with synoptic waves decays into small amplitude motions in the upper stratosphere, where heating gradients cause Py < 0. The seven spatial regimes are linked to three different dynamical causes of reversals: wave breaking associated with westerly jets, a combined barotropic/inertial instability in cross-equatorial flow, and on the periphery of monsoon anticyclones.

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.

Seasonal Influence of the Quasi-Biennial Oscillation on Stratospheric Jets and Rossby Wave Breaking

2009 ◽  
Vol 66 (4) ◽  
pp. 935-946 ◽  
Author(s):  
Matthew H. Hitchman ◽  
Amihan S. Huesmann
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Boreal Winter ◽  
Quasi Biennial Oscillation ◽  
Rossby Wave Breaking ◽  
Eastern Hemisphere ◽  
Biennial Oscillation ◽  
Mode A ◽  
Pv Gradient ◽  
Middle Stratosphere

Abstract The influence of the stratospheric quasi-biennial oscillation (QBO) on the polar night jets (PNJs), subtropical easterly jets (SEJs), and associated Rossby wave breaking (RWB) is investigated using global meteorological analyses spanning 10 recent QBO cycles. The seasonal dependence of the descent of the QBO is shown by using five layered shear indices. It is found that the influence of the QBO is distinctive for each combination of QBO phase, season, and hemisphere (NH or SH). The following QBO westerly (W) minus easterly (E) differences in the PNJs were found to be significant at the 97% level: When a QBO W (E) maximum is in the lower stratosphere (∼500 K or ∼50 hPa), the NH winter PNJ is stronger (weaker), in agreement with previous results (mode A). Mode A does not appear to operate in other seasons in the NH besides DJF or in the SH in any season. When a QBO W (E) maximum is in the middle stratosphere (∼700–800 K or ∼10–20 hPa), the PNJ in the SH spring is stronger (weaker), also in agreement with previous results (mode B). It is found that mode B also operates in the NH spring. A third distinctive mode is found during autumn in both hemispheres: a QBO W (E) maximum in the middle stratosphere coincides with a weaker (stronger) PNJ (mode C). The signs of wind anomalies are the same at low and high latitudes for modes A and B, but are opposite for mode C. This sensitive dependence on QBO phase and season is consistent with the nonlinear nature of the interaction between planetary waves and the shape of the seasonal wind structures. During the solstices the meridional circulation associated with QBO connects primarily with the winter hemisphere, whereas during the equinoxes it is more symmetric about the equator. QBO W enhance the equatorial potential vorticity (PV) gradient maximum, but the time-mean maximum may be related to chronic instabilities in the subtropics. The equatorial PV gradient maximum and flanking RWB tend to be more pronounced in the Eastern Hemisphere in stratospheric analyses. When QBO W are in the middle stratosphere, the flanking PV gradient minima (SEJs) are enhanced and RWB is more frequent and symmetric about the equator. When QBO W are in the upper stratosphere, a strong seasonal asymmetry is seen, with enhanced RWB in the summer SEJ, primarily during boreal winter. This is consistent with an upward increase of summer to winter flow and modulation by a strong “first” and weak “second” semiannual oscillation.

scholarly journals The Influence of the Lower Stratosphere on Ridging Atlantic Ocean Anticyclones over South Africa

2018 ◽  
Vol 31 (15) ◽  
pp. 6175-6187 ◽  
Author(s):  
Thando Ndarana ◽  
Mary-Jane Bopape ◽  
Darryn Waugh ◽  
Liesl Dyson
Keyword(s):  
Atlantic Ocean ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Reanalysis Data ◽  
Positive Anomaly ◽  
Pressure System ◽  
Rossby Wave Breaking ◽  
Vertical Coupling

The link between Rossby wave breaking and ridging Atlantic Ocean anticyclones in the South African domain is examined using NCEP–DOE AMIP-II reanalysis data. A simple composite analysis, which used the duration of ridging events as a basis of averaging, reveals that ridging anticyclones are coupled with Rossby wave breaking at levels higher than the dynamical tropopause. Lower-stratospheric PV anomalies extend to the surface, thus coupling the ridging highs with the lower stratosphere. The anomaly extending from the 70-hPa level to the surface contributes to a southward extension of the surface negative anomaly over the Namibian coast, which induces a cyclonic flow, causing the ridging anticyclone to take a bean-like shape. The surface positive anomaly induces the internal anticyclonic flow within the large-scale pressure system, causing the ridging end to break off and amalgamate with the Indian Ocean high pressure system. Lower-stratospheric Rossby wave breaking lasts for as long as the ridging process, suggesting that the former is critical to the longevity of the latter by maintaining and keeping the vertical coupling intact.

scholarly journals Secondary maxima in ozone profiles

2004 ◽  
Vol 4 (2) ◽  
pp. 1791-1816
Author(s):  
R. Lemoine
Keyword(s):  
Rossby Wave ◽  
Ozone Concentration ◽  
Wave Breaking ◽  
Total Ozone ◽  
Lower Stratosphere ◽  
Rossby Wave Breaking ◽  
Ozone Distribution ◽  
Ozone Trends ◽  
Differential Advection ◽  
Ozone Column

Abstract. Ozone profiles from balloon soundings as well as SAGE II ozone profiles were used to detect anomalous large ozone concentrations of ozone in the lower stratosphere. These secondary ozone maxima are found to be the result of differential advection of ozone-poor and ozone-rich air associated with Rossby wave breaking events. The frequency and intensity of secondary ozone maxima and their geographical distribution is presented. The occurrence and amplitude of ozone secondary maxima is related to ozone trends in the total ozone column and in the lower stratosphere ozone concentration at Uccle and can be used as a measure of the influence of atmospheric circulation on the ozone distribution at mid-latitudes.

scholarly journals Isentropic Transport within the Antarctic Polar-Night Vortex: Rossby Wave Breaking Evidence and Lagrangian Structures

2013 ◽  
Vol 70 (9) ◽  
pp. 2982-3001 ◽  
Author(s):  
Alvaro de la Cámara ◽  
Carlos R. Mechoso ◽  
Ana M. Mancho ◽  
Encarna Serrano ◽  
Kayo Ide
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Invariant Manifolds ◽  
Chaotic Behavior ◽  
Polar Vortex ◽  
Arc Length ◽  
Polar Night ◽  
Stratospheric Polar Vortex ◽  
Rossby Wave Breaking ◽  
The Antarctic

Abstract The trajectories in the lower stratosphere of isopycnic balloons released from Antarctica by Vorcore and Concordiasi field campaigns during the southern springs of 2005 and 2010 showed events of latitudinal transport inside the stratospheric polar vortex, both away from and toward the poleward flank of the polar-night jet. The present paper applies trajectory-based diagnostic techniques to examine mechanisms at work during such events. Reverse domain-filling calculations of potential vorticity (PV) fields from the ECMWF Interim Re-Analysis (ERA-Interim) dataset during the events show irreversible filamentation of the PV fields in the inner side of the polar-night jet, which is a signature of planetary (Rossby) wave breaking. Balloon motions during the events are fairly consistent with the PV filaments. Events of both large (~15° of arc length) and small (~5° of arc length) balloon displacements from the vortex edge are associated, respectively, with deep and shallow penetration into the core of the elongated PV contours. Additionally, the Lagrangian descriptor M is applied to study the configuration of Lagrangian structures during the events. Breaking Rossby waves inside the vortex lead to the presence of hyperbolic points. The geometric configuration of the invariant manifolds associated with the hyperbolic trajectories helps to understand the apparent chaotic behavior of balloons' motions and to identify and analyze balloon transport events not captured by reverse domain-filling calculations. The Antarctic polar vortex edge is an effective barrier to air parcel crossings. Rossby wave breaking inside the vortex, however, can contribute to tracer mixing inside the vortex and to occasional air crossings of the edge.

North Atlantic Summertime Anticyclonic Rossby Wave Breaking: Climatology, Impacts, and Connections to the Pacific Decadal Oscillation

2018 ◽  
Vol 32 (2) ◽  
pp. 485-500 ◽  
Author(s):  
Breanna L. Zavadoff ◽  
Ben P. Kirtman
Keyword(s):  
Rossby Wave ◽  
North Atlantic ◽  
Pacific Decadal Oscillation ◽  
Wave Breaking ◽  
Reanalysis Data ◽  
Tropical Cyclogenesis ◽  
Rossby Wave Breaking ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

Abstract Anticyclonic Rossby wave breaking (RWB) is characterized by the rapid and irreversible deformation of potential vorticity (PV) contours on isentropic surfaces manifesting as a pair of meridionally elongated high- and low-PV tongues that transport extratropical stratospheric air equatorward and tropical tropospheric air poleward, respectively. Previous studies have noted connections between different types of RWB and the modulation of localized atmospheric phenomena such as the North Atlantic Oscillation (NAO) and tropical cyclogenesis. Despite being the season in which anticyclonic RWB events are most prevalent, no work has focused solely on the frequency, genesis, or variability of the synoptic environment surrounding the equatorward branch of anticyclonic RWB events during the North Atlantic summertime, providing motivation for this study. Using 58 years (1960–2017) of NCEP–NCAR reanalysis data, a comprehensive spatiotemporal climatology of North Atlantic equatorward anticyclonic RWB identified on the 350-K isentropic surface is developed and the synoptic environment surrounding these events from time- and high-PV-tongue centroid-relative perspectives is investigated. Consistent with previous studies, composites suggest that high-PV tongues associated with equatorward anticyclonic RWB introduce anomalously dry, stable extratropical air into the tropical environment, subsequently inhibiting convection there. Additionally, a connection between atmospheric responses to Pacific decadal oscillation (PDO) sea surface temperature (SST) anomalies and the intrabasin frequency of anticyclonic RWB events is uncovered and explored. Results from this study may aid short- to medium-range forecasts of North Atlantic tropical convection, with applications extending into the field of tropical cyclogenesis forecasting.

scholarly journals The dynamical impact of Rossby wave breaking upon UK PM<sub>10</sub> concentration

2017 ◽  
Vol 17 (2) ◽  
pp. 867-881 ◽  
Author(s):  
Christopher P. Webber ◽  
Helen F. Dacre ◽  
William J. Collins ◽  
Giacomo Masato
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Ground Level ◽  
Reanalysis Data ◽  
Synoptic Scale ◽  
Urban Background ◽  
Air Masses ◽  
Rossby Wave Breaking ◽  
Coarse Particulate Matter ◽  
The Uk

Abstract. Coarse particulate matter (PM10) has long been understood to be hazardous to human health, with mortality rates increasing as a result of raised ground level concentrations. We explore the influence of synoptic-scale meteorology on daily mean observed PM10 concentration ([PM10]) using Rossby wave breaking (RWB). Meteorological reanalysis data for the winter months (DJF) between January 1999 and December 2008 and observed PM10 data for three urban background UK (Midland) sites were analysed. Three RWB diagnostics were used to identify RWB that had significant influence on UK Midland PM10. RWB events were classified according to whether the RWB was cyclonic or anticyclonic in its direction of breaking and whether the RWB event was influenced more by poleward or equatorial air masses. We find that there is a strong link between RWB events and UK [PM10]. Significant increases (p  <  0.01) in UK [PM10] were seen 1 day following RWB occurring in spatially constrained northeast Atlantic–European regions. Analysis into episodic PM10 exceedance events shows increased probability of [PM10] exceedance associated with all RWB subsets. The greatest probability of exceeding the UK [PM10] threshold was associated with cyclonic RWB preceded by anticyclonic RWB forming an Ω block synoptic pattern. This mechanism suggests an easterly advection of European PM10 followed by prolonged stagnant conditions within the UK and led to an almost threefold increase in the probability of the UK Midlands exceeding a hazardous [PM10] threshold (0.383), when compared to days where no RWB was detected (0.129).

scholarly journals Secondary maxima in ozone profiles

2004 ◽  
Vol 4 (4) ◽  
pp. 1085-1096 ◽  
Author(s):  
R. Lemoine
Keyword(s):  
Geographical Distribution ◽  
Rossby Wave ◽  
Wave Breaking ◽  
Total Ozone ◽  
Lower Stratosphere ◽  
Stratospheric Ozone ◽  
Rossby Wave Breaking ◽  
Ozone Concentrations ◽  
Differential Advection

Abstract. Ozone profiles from balloon soundings as well as SAGEII ozone profiles were used to detect anomalous large ozone concentrations of ozone in the lower stratosphere. These secondary ozone maxima are found to be the result of differential advection of ozone-poor and ozone-rich air associated with Rossby wave breaking events. The frequency and intensity of secondary ozone maxima and their geographical distribution is presented. The occurrence and amplitude of ozone secondary maxima is connected to ozone variability and trend at Uccle and account for a large part of the total ozone and lower stratospheric ozone variability.

Sign in / Sign up

Export Citation Format

Share Document