Variability patterns of Rossby wave source

Shimizu, M. H.; Cavalcanti, Iracema Fonseca de Albuquerque

doi:10.1007/s00382-010-0841-z

Cited by 74 publications

(55 citation statements)

References 25 publications

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“…c The difference between b and a. contour interval is 0.1; differences >0.1 or <−0.1 are shaded To better understand the underlying dynamics of the relatively weak (strong) PSA pattern during the warm (cold) PDO phase, we calculated the NDJFM-averaged Rossby wave source (RWS) at 200 hPa during warm and cold PDO phases, respectively. The RWS (denoted as S) is defined as where v χ is the divergent component of velocity, ζ is the vertical component of the absolute vorticity, and D is the divergence (Sardeshmukh and Hoskins 1988;Shimizu and Cavalcanti 2011). According to Ding et al (2012), the PSA pattern, as a tropically forced Rossby wave train, is related to an active RWS region along the subtropical jet with a maximum to the east of Australia.…”

Section: Changes In the Psa-related Atmospheric And Oceanic Anomaliesmentioning

confidence: 99%

Interdecadal change in the lagged relationship between the Pacific–South American pattern and ENSO

Ding

Tseng

et al. 2016

Clim Dyn

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Section: Changes In the Psa-related Atmospheric And Oceanic Anomaliesmentioning

confidence: 99%

Interdecadal change in the lagged relationship between the Pacific–South American pattern and ENSO

Ding

Tseng

et al. 2016

Clim Dyn

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“…Cunningham and Cavalcanti [], while studying intraseasonal precipitation variability, found that anomalous convection associated with a northward shift in the location of the SACZ produces a wave train that originates in the Amazon and propagates toward the Indian Ocean. Shimizu and Cavalcanti [] found the Amazon basin suitable for initiating tropical‐midlatitude Rossby wave trains that propagate south of Africa and into the SIO. This suitability relies on the region being located near a tropical convection source and a strong gradient of absolute vorticity.…”

Section: Introductionmentioning

confidence: 99%

“…In summary, these studies show that a northward shift of SACZ precipitation during austral summer is associated with a tropical‐midlatitude Rossby wave train [ Cunningham and Cavalcanti , ; Grimm and Reason , , ]. This activity is consistent with theory, which indicates that the SACZ should act as a possible source region for Rossby waves [ Shimizu and Cavalcanti , ]. While Grimm and Reason [] provided some analysis of the downstream impacts, this study was limited to Africa and then only when cooccurring with Benguela Niño events.…”

Section: Introductionmentioning

confidence: 99%

Teleconnection between the South Atlantic convergence zone and the southern Indian Ocean: Implications for tropical cyclone activity

DeBlander

Shaman

2017

JGR Atmospheres

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A link between anomalous austral summer convection over the South Atlantic convergence zone (SACZ) and atmospheric conditions over the South Indian Ocean is investigated. Interannual north‐south shifts in the SACZ produce a dipole of anomalous convection and precipitation over South America. The South Atlantic convergence zone index (SACZI) capturing this variability is presented and associated with a midlatitude Rossby wave train that propagates from South America eastward and south of Africa before curving north into the tropical Indian Ocean. This wave train is reproduced using Rossby wave ray tracing and simulations with a linearized barotropic vorticity equation model forced with divergence and convergence consistent with the observed dipole of anomalous convection. The wave train acts to excite anomalies in wind shear and relative humidity over the tropical south Indian Ocean, which in turn impact tropical cyclone (TC) genesis and distribution over this region. We find that changes in the wind shear and relative humidity associated with the SACZI effect changes in TC genesis, which result in a change in observed TC days over portions of the South Indian Ocean.

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“…This means that momentum is transferred from the zonal mean flow to the waves, being in agreement with the stimulation of Rossby waves and cyclogenesis in this area (cf. Shimizu and de Albuquerque Cavalcanti, ). Further downstream, the EPF vector is divergent, implying that the eddy forcing supports the zonal mean flow against frictional processes, especially over Europe and the Mediterranean basin.…”

Section: Discussionmentioning

confidence: 99%

Changes in mean flow and atmospheric wave activity in the North Atlantic sector

Paeth

Pollinger

2019

Quart J Royal Meteoro Soc

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In recent years, the midlatitudes are characterized by more intense heatwaves in summer and sometimes severe cold spells in winter that might emanate from changes in atmospheric circulation, including synoptic‐scale and planetary wave activity in the midlatitudes. In this study, we investigate the heat and momentum exchange between the mean flow and atmospheric waves in the North Atlantic sector and adjacent continents by means of the physically consistent Eliassen–Palm flux diagnostics applied to reanalysis and forced climate model data. In the long‐term mean, momentum is transferred from the mean flow to atmospheric waves in the northwest Atlantic region, where cyclogenesis prevails. Further downstream over Europe, eddy fluxes return momentum to the mean flow, sustaining the jet stream against friction. A global climate model is able to reproduce this pattern with high accuracy. Atmospheric variability related to atmospheric wave activity is much more expressed at the intraseasonal rather than the interannual time‐scale. Over the last 40 years, reanalyses reveal a northward shift of the jet stream and a weakening of intraseasonal weather variability related to synoptic‐scale and planetary wave activity. This pertains to the winter and summer seasons, especially over central Europe, and correlates with changes in the North Atlantic Oscillation as well as regional temperature and precipitation. A very similar phenomenon is found in a climate model simulation with business‐as‐usual scenario, suggesting an anthropogenic trigger in the weakening of intraseasonal weather variability in the midlatitudes.

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Variability patterns of Rossby wave source

Cited by 74 publications

References 25 publications

Interdecadal change in the lagged relationship between the Pacific–South American pattern and ENSO

Interdecadal change in the lagged relationship between the Pacific–South American pattern and ENSO

Teleconnection between the South Atlantic convergence zone and the southern Indian Ocean: Implications for tropical cyclone activity

Changes in mean flow and atmospheric wave activity in the North Atlantic sector

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