Spontaneous QBO‐like oscillations in an atmospheric model dynamical core

Yao, Weiye; Jablonowski, Christiane

doi:10.1002/grl.50723

Cited by 8 publications

(13 citation statements)

References 14 publications

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“…Overall, the TEM analysis for EUL shows similar results to the TEM-SLD analysis in Yao and Jablonowski (2013), which is not repeated here. An interesting observation is that the peak values of the monthly-mean zonalmean E-P flux divergence, vertical advection, and the momentum budget residual term are about 50% higher in EUL than in SLD, suggesting stronger wave activities in EUL.…”

Section: A Transformed Eulerian Mean Analysissupporting

confidence: 54%

“…Furthermore, it is well documented that the QBO acts as a filtering mechanism for upward-traveling waves (e.g., see Yang et al 2011Yang et al , 2012Krismer and Giorgetta 2014) and thereby modulates the wave composition in the mesosphere. More recently, Kawatani et al (2010), Orr et al (2010), Xue et al (2012), Yao and Jablonowski (2013), and Richter et al (2014) also reported on successful QBO and QBO-like simulations. Takahashi (1996Takahashi ( , 1999, Scaife et al (2000Scaife et al ( , 2002, Hamilton et al (2001), and Giorgetta et al (2002Giorgetta et al ( , 2006 were among the first that simulated QBOs or QBO-like oscillations with GCMs.…”

Section: Introductionmentioning

confidence: 95%

“…An interesting observation is that the peak values of the monthly-mean zonalmean E-P flux divergence, vertical advection, and the momentum budget residual term are about 50% higher in EUL than in SLD, suggesting stronger wave activities in EUL. 3a in Yao and Jablonowski (2013)], because of the very strong cancellation effect between the TEM components. 4a) is much weaker than the acceleration in SLD [ Fig.…”

Section: A Transformed Eulerian Mean Analysismentioning

confidence: 99%

“…Using the estimate that SLD's implicit numerical diffusion acts like a horizontal fourth-order hyperdiffusion scheme with an assumed coefficient of about K 4 5 5 3 10 15 m 4 s 21 (Yao and Jablonowski 2013), this leads to the e-folding diffusion time scale t n of about 66 days for wavenumber n 5 3608/248 5 15. However, the actual strength of SLD's nonlinear implicit numerical diffusion varies.…”

Section: Diffusion and The Tem Residual Termmentioning

confidence: 99%

“…All of the aforementioned GCM studies except Yao and Jablonowski (2013) used model setups with realistic topography and comprehensive physical parameterization packages that include processes like moist convective parameterizations. In fact, it is widely believed that the primary source of tropical waves is latent heat release by either resolved-scale precipitation or parameterized deep cumulus convection.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Idealized Quasi-Biennial Oscillations in an Ensemble of Dry GCM Dynamical Cores

Yao

Jablonowski

2015

Journal of the Atmospheric Sciences

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The paper demonstrates that quasi-biennial oscillation (QBO)-like oscillations can be simulated in an ensemble of dry GCM dynamical cores that are driven by a simple Held-Suarez temperature relaxation and lowlevel Rayleigh friction. The tropical stratospheric circulations of four dynamical cores, which are options in NCAR's Community Atmosphere Model, version 5 (CAM5), are intercompared. These are the semi-Lagrangian (SLD) and Eulerian (EUL) spectral transform, finite-volume (FV), and spectral element (SE) dynamical cores. The paper investigates how the model design choices impact the wave generation, propagation, and dissipation mechanisms in the equatorial region. SLD, EUL, and SE develop spontaneous QBO-like oscillations in the upper equatorial stratosphere, whereas FV does not sustain the oscillation. Transformed Eulerian-mean (TEM) analyses reveal that resolved waves are the dominant drivers of the QBOs. However, the Eliassen-Palm flux divergence is strongly counteracted by the TEM momentum budget residual, which represents the forcing by diffusion and thermal damping. Interestingly, a reversed Brewer-Dobson circulation accelerates the downward propagation of the SLD's QBO, whereas the EUL's and SE's QBOs are slowed by a mean ascent. Waves are abundant in the SLD's, EUL's, and SE's tropical atmosphere despite the absence of moist convection as a typical wave trigger. Dynamic instabilities are suggested as a wave-triggering mechanism in the troposphere and wave-dissipation process in the stratosphere. In particular, there are indications that the increased occurrences of strongly negative instability indicators in SLD, EUL, and SE are related to more vigorous wave activities and higher magnitudes of the resolved wave forcing in comparison to FV.

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Section: A Transformed Eulerian Mean Analysissupporting

confidence: 54%

Section: Introductionmentioning

confidence: 95%

Section: A Transformed Eulerian Mean Analysismentioning

confidence: 99%

Section: Diffusion and The Tem Residual Termmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Idealized Quasi-Biennial Oscillations in an Ensemble of Dry GCM Dynamical Cores

Yao

Jablonowski

2015

Journal of the Atmospheric Sciences

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The QBO in two GISS global climate models: 1. Generation of the QBO

et al. 2014

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The adjustment of parameterized gravity waves associated with model convection and finer vertical resolution has made possible the generation of the quasi-biennial oscillation (QBO) in two Goddard Institute for Space Studies (GISS) models, GISS Middle Atmosphere Global Climate Model III and a climate/middle atmosphere version of Model E2. Both extend from the surface to 0.002 hPa, with 2°× 2.5°r esolution and 102 layers. Many realistic features of the QBO are simulated, including magnitude and variability of its period and amplitude. The period itself is affected by the magnitude of parameterized convective gravity wave momentum fluxes and interactive ozone (which also affects the QBO amplitude and variability), among other forcings. Although varying sea surface temperatures affect the parameterized momentum fluxes, neither aspect is responsible for the modeled variation in QBO period. Both the parameterized and resolved waves act to produce the respective easterly and westerly wind descent, although their effect is offset in altitude at each level. The modeled and observed QBO influences on tracers in the stratosphere, such as ozone, methane, and water vapor are also discussed. Due to the link between the gravity wave parameterization and the models' convection, and the dependence on the ozone field, the models may also be used to investigate how the QBO may vary with climate change.

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Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

Kim

Chun

2015

JGR Atmospheres

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The contributions of the equatorial waves to the quasi-biennial oscillation (QBO) are investigated using Hadley Centre Global Environment Model version 2 (HadGEM2). A gravity wave parameterization that couples its source spectrum to the convection is used. The equatorial wave modes are identified in the spectral domain, based on their distinct characteristics associated with momentum and heat fluxes. The Kelvin waves and parameterized gravity waves (PGWs) transport westerly momentum into the equatorial stratosphere by ∼0.35 and 0.8 mPa, respectively, while easterly momentum is carried primarily by the PGWs (∼0.75 mPa). The resolved inertio-gravity (IG) waves transport both easterly and westerly momentum by ∼0.2 mPa. In the lowermost stratosphere, gradual dissipation of the Kelvin waves occurs, and the remaining waves induce eastward forcing in the westerly shear layer by 3-5 m s −1 month −1 . The PGWs primarily dissipate within the sheared layer and provide large easterly and westerly forcing in the middle stratosphere (∼17 m s −1 month −1 ), while the forcing in the lower stratosphere is comparable to the Kelvin wave forcing. The IG wave forcing is small because of the small wave dissipation rate. The Rossby and mixed Rossby-gravity (MRG) waves contribute to the westerly-to-easterly QBO transition by ∼2 m s −1 month −1 . The magnitudes of the simulated Kelvin and Rossby wave forcings are comparable with the Modern-Era Retrospective Analysis for Research and Applications, whereas the MRG and IG wave forcings are underestimated in the lower stratosphere. Differences between the simulation and reanalysis and the uncertainties in both are discussed.

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Spontaneous QBO‐like oscillations in an atmospheric model dynamical core

Cited by 8 publications

References 14 publications

Idealized Quasi-Biennial Oscillations in an Ensemble of Dry GCM Dynamical Cores

Idealized Quasi-Biennial Oscillations in an Ensemble of Dry GCM Dynamical Cores

The QBO in two GISS global climate models: 1. Generation of the QBO

Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

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