On the Arrest of Inverse Energy Cascade and the Rhines Scale

Abstract The notion of the cascade arrest in a β-plane turbulence in the context of continuously forced flows is revised in this paper using both theoretical analysis and numerical simulations. It is demonstrated that the upscale energy propagation cannot be stopped by a β effect and can only be absorbed by friction. A fundamental dimensional parameter in flows with a β effect, the Rhines scale, LR, has traditionally been associated with the cascade arrest or with the scale that separates turbulence and Rossby wave–dominated spectral ranges. It is shown that rather than being a measure of the inverse cascade arrest, LR is a characteristic of different processes in different flow regimes. In unsteady flows, LR can be identified with the moving energy front propagating toward the decreasing wavenumbers. When large-scale energy sink is present, β-plane turbulence may attain several steady-state regimes. Two of these regimes are highlighted: friction-dominated and zonostrophic. In the former, LR does not have any particular significance, while in the latter, the Rhines scale nearly coincides with the characteristic length associated with the large-scale friction. Spectral analysis in the frequency domain demonstrates that Rossby waves coexist with turbulence on scales smaller than LR thus indicating that the Rhines scale cannot be viewed as a crossover between turbulence and Rossby wave ranges.

Download Full-text

Signatures of midlatitude heat waves in Rossby wave variability spectra

10.5194/dach2022-25 ◽

2021 ◽

Author(s):

Iana Strigunova ◽

Richard Blender ◽

Frank Lunkeit ◽

Nedjeljka Žagar

Keyword(s):

Rossby Wave ◽

Large Scale ◽

Rossby Waves ◽

Heat Waves ◽

Probability Distributions ◽

Physical Space ◽

Mean Flow ◽

Single Wave ◽

Fourier Decomposition ◽

Latitude Belt

This work aims at identifying extreme circulation conditions such as heat waves in modal space which is defined by eigensolutions of the linearized primitive equations. Here, the Rossby waves are represented in terms of Hough harmonics that are an orthogonal and complete expansion set allowing Rossby wave diagnostics in terms of their total (kinetic and available potential) energies. We expect that this diagnostic provides a more clear picture of the Rossby wave variability spectra compared to the common Fourier decomposition along a latitude belt.&#160; The probability distributions of Rossby wave energies are analysed separately for the zonal mean flow, for the planetary and synoptic zonal wavenumbers. The robustness is ensured by considering the four reanalyses ERA5, ERA-Interim, JRA-55 and MERRA. A single wave is characterized by Gaussianity in the complex Hough amplitudes and by a chi-square distribution for the energies. We find that the distributions of the energy anomalies in the wavenumber space are non-Gaussian with almost the same positive skewness in the four reanalyses.&#160; The skewness increases during persistent heat waves for all energy anomaly distributions, in agreement with the recent trend of increased subseasonal variance in large-scale Rossby waves and decreased variance at synoptic scales. The new approach offers a selective filtering to physical space. The reconstructed circulation during heat waves is dominated by large-scale anticyclonic systems in northeastern Europe with zonal wavenumbers 2 and 3, in agreement with previous studies, thereby demonstrating physical meaningfulness of the skewness.&#160; &#160;

Download Full-text

The impact of ENSO and the Atlantic Multidecadal Variability (AMV) on the upper tropospheric large scale flow in the PRIMAVERA models.

10.5194/egusphere-egu2020-18113 ◽

2020 ◽

Author(s):

Paolo Ghinassi ◽

Federico Fabiano ◽

Virna L. Meccia ◽

Susanna Corti

Keyword(s):

Rossby Wave ◽

Large Scale ◽

Rossby Waves ◽

Wave Activity ◽

Transient Wave ◽

Weather Regime ◽

Weather Regimes ◽

The Pacific ◽

Large Scale Flow ◽

The Impact

Rossby waves play a fundamental role for both climate and weather. They are in fact associated with heat, momentum and moisture transport across large distances and with different types of weather at the surface. Assessing how they are represented in climate models is thus of primary importance to understand both predictability and the present and future climate. In this study we investigate how ENSO and the AMV affect the large scale flow pattern in the upper troposphere of the Northern Hemisphere, using reanalysis data and data from the PRIMAVERA simulations.The upper tropospheric large scale flow is investigated in terms of the Rossby wave activity associated with persistent and recurrent patterns over the Pacific-North American and Euro-Atlantic regions during winter, the so called weather regimes. In order to quantify the vigour of Rossby wave activity associated with each weather regime we make use of a recently developed diagnostic based on Finite Amplitude Local Wave Activity in isentropic coordinates, partitioning the total wave activity into the stationary and transient components. The former is associated with quasi-stationary, planetary Rossby waves, whereas the latter is associated with synoptic scale Rossby wave packets. This allows one to quantify the contribution from stationary versus transient eddies in the total Rossby wave activity linked to each weather regime.In this study we explore how ENSO and the AMV affect both the weather regimes frequencies and the upper tropospheric waviness in the Pacific and Atlantic storm tracks, respectively. Furthermore we analyse how both the stationary and transient wave activity component modulate the onset and transition between different regimes.

Download Full-text

An Adiabatic Mechanism for the Reduction of Jet Meander Amplitude by Potential Vorticity Filamentation

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-18-0136.1 ◽

2018 ◽

Vol 75 (12) ◽

pp. 4091-4106 ◽

Cited By ~ 3

Author(s):

Ben Harvey ◽

John Methven ◽

Maarten H. P. Ambaum

Keyword(s):

Decay Rate ◽

Rossby Wave ◽

Potential Vorticity ◽

Large Scale ◽

Rossby Waves ◽

Weather Forecasting ◽

Single Layer ◽

Jet Streams ◽

Rapid Reduction ◽

Simple Method

Abstract The amplitude of ridges in large-amplitude Rossby waves has been shown to decrease systematically with lead time during the first 1–5 days of operational global numerical weather forecasts. These models also exhibit a rapid reduction in the isentropic gradient of potential vorticity (PV) at the tropopause during the first 1–2 days of forecasts. This paper identifies a mechanism linking the reduction in large-scale meander amplitude on jet streams to declining PV gradients. The mechanism proposed is that a smoother isentropic transition of PV across the tropopause leads to excessive PV filamentation on the jet flanks and a more lossy waveguide. The approach taken is to analyze Rossby wave dynamics in a single-layer quasigeostrophic model. Numerical simulations show that the amplitude of a Rossby wave propagating along a narrow but smooth PV front does indeed decay transiently with time. This process is explained in terms of the filamentation of PV from the jet core and associated absorption of wave activity by the critical layers on the jet flanks, and a simple method for quantitatively predicting the magnitude of the amplitude reduction without simulation is presented. Explicitly diffusive simulations are then used to show that the combined impact of diffusion and the adiabatic rearrangement of PV can result in a decay rate of Rossby waves that is 2–4 times as fast as could be expected from diffusion acting alone. This predicted decay rate is sufficient to explain the decay observed in operational weather forecasting models.

Download Full-text

Rossby Waves and the Interannual and Interdecadal Variability of Temperature and Salinity off California

Journal of Physical Oceanography ◽

10.1175/2009jpo3898.1 ◽

2009 ◽

Vol 39 (10) ◽

pp. 2543-2561 ◽

Cited By ~ 5

Author(s):

Marcelo Dottori ◽

Allan J. Clarke

Keyword(s):

Sea Level ◽

Rossby Wave ◽

Large Scale ◽

Southern California ◽

Rossby Waves ◽

Salinity Gradient ◽

Time Derivative ◽

Temperature Fluctuations ◽

Dynamic Height ◽

The Mean

Abstract Previous work has shown that large-scale interannual Rossby waves, largely remotely generated by equatorial winds, propagate westward from the coast off southern California. These waves have a large-scale anomalous alongshore velocity field that is proportional to the time derivative of the interannual sea level anomaly. Using these results, a theory is developed for interannual perturbations to a mean density field that varies both vertically and alongshore, like that for the California Current region off southern California. Because both the anomalous vertical and alongshore currents are proportional to the time derivative of the interannual sea level, the theory suggests that the anomalous currents associated with the Rossby waves, acting on the mean temperature field, should induce temperature fluctuations proportional to the anomalous dynamic height. The alongshore and vertical advections contribute to the temperature fluctuations in the same sense, a higher-than-normal sea level, for example, resulting in downward and poleward displacement of warmer water and a local higher-than-normal temperature. Near the surface, alongshore advection dominates vertical advection but both contribute comparably near the thermocline and below. The correlation of observed temperature and dynamic height anomalies from the California Cooperative Oceanic Fisheries Investigation (CalCOFI) data is positive, which is consistent with the theory. The correlation is highest (r ≈ 0.8) near 100-m depth in the thermocline. Although the correlation falls toward the surface, it is still between 0.5 and 0.6, suggesting that the advection mechanism is a major contributor to the temperature anomalies there. The anomalous Rossby wave currents, acting on the mean background salinity gradient, also induce salinity anomalies. At halocline depths of 100–200 m, consistent with the theory, the correlation of observed CalCOFI salinity and dynamic height anomalies is negative and large in magnitude (r ≈ −0.8). However, the surface salinity anomaly is not due to Rossby wave dynamics; instead, much of it is driven by the alongshore wind stress, which it lags by 4 months.

Download Full-text

Weak upstream westerly wind attracts western north pacific typhoon tracks to west

Environmental Research Letters ◽

10.1088/1748-9326/ac3aa4 ◽

2021 ◽

Author(s):

Jun-Hyeok Son ◽

Jae-Il Kwon ◽

Ki-Young Heo

Keyword(s):

Tibetan Plateau ◽

Rossby Wave ◽

Large Scale ◽

Rossby Waves ◽

Circulation Pattern ◽

The Tibetan Plateau ◽

Circulation Anomaly ◽

North East ◽

The North ◽

Typhoon Tracks

Abstract The steering flow of the large-scale circulation patterns over the Western North Pacific and North East Asia, constrains typhoon tracks. Westerly winds impinging on the Tibetan Plateau, and the resulting flow uplift along the slope of the mountain, induce atmospheric vortex flow and generate stationary barotropic Rossby waves downstream. The downstream Rossby wave zonal phase is determined by the upstream zonal wind speed impinging on the Tibetan Plateau. Positive anomaly of westerly wind forcing tends to induce an eastward shift of the large-scale Rossby wave circulation pattern, forming a cyclonic circulation anomaly over North East Asia. In this study, we show that the Tibetan Plateau dynamically impacts the tracks of western Pacific typhoons via modulation of downstream Rossby waves. Using the topographically forced stationary Rossby wave theory, the dynamical mechanisms for the formation of the North East Asian cyclonic anomaly and its impact on the typhoon tracks are analyzed. The eastward shift of typhoon tracks, caused by the southwesterly wind anomaly located to the southeast of the North East Asian cyclonic circulation anomaly, is robust in June and September, but it is not statistically significant in July–August. The physical understanding of the large-scale circulation pattern affecting typhoon trajectories has large implications not only at the seasonal prediction of the high impact weather phenomena, but also at the right understanding of the long-term climate change.

Download Full-text

Rossby Wave Initiation by Recurving Tropical Cyclones in the Western North Pacific

Monthly Weather Review ◽

10.1175/mwr-d-17-0219.1 ◽

2018 ◽

Vol 146 (5) ◽

pp. 1283-1301 ◽

Cited By ~ 7

Author(s):

Jacopo Riboldi ◽

Matthias Röthlisberger ◽

Christian M. Grams

Keyword(s):

Ab Initio ◽

Tropical Cyclones ◽

Rossby Wave ◽

North Pacific ◽

Western North Pacific ◽

Large Scale ◽

Rossby Waves ◽

Boreal Summer ◽

Large Scale Flow ◽

Upper Level Jet

Abstract The interaction of recurving tropical cyclones (TCs) with midlatitude Rossby waves during extratropical transition (ET) can significantly alter the midlatitude flow configuration. This study provides a climatological investigation of Rossby wave initiation (RWI) by transitioning TCs in the specific configuration of an initially zonal midlatitude waveguide and elucidates physical processes governing ab initio flow amplification during ET. Recurving TCs interacting with a zonally oriented waveguide in the western North Pacific (WNP) basin from 1979 to 2013 are categorized into cases initiating Rossby waves (TC-RWI) or not (TC-noRWI). Interactions with a zonally oriented waveguide occurred for 22.7% of the recurving TCs, and one-third of these resulted in TC-RWI. In the presence of a TC, the probability of RWI on a zonally oriented waveguide is 3 times larger than in situations without a TC. The occurrence of TC-RWI exhibits a seasonality and is relatively more common during boreal summer than in autumn. We further reveal that a strong preexisting upper-level jet stream, embedded in a deformative large-scale flow pattern, hinders TC-RWI as air from the diabatic outflow of the TC is rapidly advected downstream and does not lead to strong ridge building. In contrast, an enhanced monsoon trough favors TC-RWI as the poleward moisture transport strengthens diabatic outflow and leads to strong ridge building during ET. Thus, we conclude that TC-related ab initio flow amplification over the WNP is governed by characteristics of the large-scale flow more so than by characteristics of the recurving TC.

Download Full-text

Roles of wave trains and synoptic Rossby waves in creating midlatitude temperature extremes during winter

10.5194/egusphere-egu21-6955 ◽

2021 ◽

Author(s):

Irina Rudeva ◽

Ian Simmonds

Keyword(s):

Wave Propagation ◽

Rossby Wave ◽

Large Scale ◽

Rossby Waves ◽

Temperature Anomaly ◽

Local Temperature ◽

Temperature Extremes ◽

Relative Role ◽

Wide Range ◽

Wave Trains

Rossby waves, found in the westerly flow at the upper troposphere, transfer energy, moisture, and momentum across large distances, being responsible for atmospheric teleconnections. Large-amplitude waves may contribute to rapid changes in wind and temperature, making them import for creating local temperature or precipitation extremes. Wirth et al (2018) separated Rossby waves into a low-frequency type, referred to as Rossby wave trains, and high-frequency, or synoptic, waves. In this work we explore a relative role of these two types in creating seasonal and synoptic temperature extremes in the midlatitudes.We identify wave propagation regions at 300 hPa using ERA-Interim dataset for JFM 1980 &#8211; 2017. Our analysis is based on the daily data. This time scale allows identification of waveguides at a wide range of latitudes, suggesting possibility of Rossby wave propagation between midlatitudes and polar regions, as well as tropics. We show that winter temperature extremes in the midlatitudes are associated with anomalies in both high and low latitudes, while the relative importance of these areas differs across midlatitude regions. Furthermore, we demonstrate, that warm Arctic regions can create cold outbreaks in Siberia and North America.Analysis of the evolution of midlatitude synoptic extremes reveals the importance of a pre-existing local temperature anomaly, that triggers amplification of large-scale Rossby wave trains and creates a local anomaly in the waveguide. The latter modifies propagation of synoptic scale Rossby waves that further amplify the local temperature anomaly.References:Wirth, V., M. Riemer, E. K. M. Chang, and O. Martius, 2018: Rossby Wave Packets on the Midlatitude Waveguide&#8212;A Review. Mon. Wea. Rev., 146, 1965&#8211;2001. https://doi.org/10.1175/MWR-D-16-0483.1.

Download Full-text

Topographic Rossby waves in a rough-bottomed ocean

Journal of Fluid Mechanics ◽

10.1017/s002211207300087x ◽

1973 ◽

Vol 61 (3) ◽

pp. 583-607 ◽

Cited By ~ 52

Author(s):

Peter Rhines ◽

Francis Bretherton

Keyword(s):

Large Scale ◽

Rossby Waves ◽

Bottom Topography ◽

Rapid Change ◽

Computer Experiments ◽

Exceptional Case ◽

Analytical Models ◽

Energy Propagation ◽

Resonant Interactions ◽

Sea Bed

The object is to predict the nature of small-amplitude long-period oscillations of a homogeneous rotating fluid over a ‘sea bed’ that is nowhere level. Analytically, we are limited to special choices of bottom topography, such as sinusoidal corrugations or an undulating continental slope, so long as the topographic restoring effect equals or exceeds that due to planetary curvature (the beta-effect). (Very slight topographic features, on the other hand, provide weak, resonant interactions between Rossby waves.)Integral properties of the equations, and computer experiments reported elsewhere, verify the following results found in the analytical models: typical frequencies of oscillation are [lsim ]fδ, where f is the Coriolis frequency and δ measures the fractional height of the bottom bumps; an initially imposed flow pattern of large scale will rapidly shrink in scale over severe roughness (even the simplest analytical model shows this rapid change in spatial structure with time); and energy propagation can be severely reduced by roughness of the medium, the energy velocity being of order fδa, where a is the horizontal topographic scale (although in an exceptional case, the sinusoidal bottom, the group velocity remains finite for vanishingly small values of a).

Download Full-text