Mesoscale Energy Spectra of the Mei-Yu Front System. Part I: Kinetic Energy Spectra

Peng, Jun; Zhang, Lifeng; Luo, Yu; Zhang, Yun

doi:10.1175/jas-d-13-085.1

Cited by 24 publications

(23 citation statements)

References 41 publications

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“…The integration of the front is performed for z = 0-15 km over the entire horizontal domain. As seen in previous studies of the idealized mei-yu front [33], no convection occurs during the initial adjustment of the front. During the intensification phase (t = 15-25 h), the moist convection bursts at 15 h and reaches its peak at 16 h, with a maximum vertical kinetic energy of 0.044 m 2 s -2 .…”

Section: Overview Of the Simulationssupporting

confidence: 69%

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On the Spectra of Gravity Waves Generated by Two Typical Convective Systems

et al. 2019

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Spectral characteristics of lower-stratospheric gravity waves generated in idealized mei-yu front and tropical cyclone (TC) are compared by performing high-resolution simulations. The results suggest that the systems which organize convection in different forms can generate waves with distinctly different presentation. The mei-yu front appears as a linear zonal wave source and gravity waves are dominated by cross-frontal (meridional) propagating components. The northward (southward) components have dominant meridional wavelengths of 125-333 km (>250 km), periods of 100-200 min (83-143 min), and phase speeds of 0-15 m s −1 (15-20 m s −1 ). The TC appears as a point wave source and gravity waves propagate equally in various horizontal directions. The waves exhibit greater power and broader spectral distributions compared with those in the mei-yu front, with dominant horizontal wavelengths longer than 62.5 km, periods of 33-600 min, and phase speeds slower than~40 m s −1 .Atmosphere 2019, 10, 405 2 of 11 mei-yu front contains lots of convective cells, which successively form along the front and gradually organize into quasi-two-dimensional (2D) precipitation bandings, and thus tends to cause persistent precipitation [28][29][30]. It differs from the common midlatitude front by a weak temperature gradient but a strong moisture gradient, and the frontal zone is characterized by intense equivalent potential temperature gradient [31,32]. Sun [25] analyzed the mesoscale-β-scale gravity-wave activity during a mei-yu front heavy rain process using surface observation data. She identified the waves with wavelength of 200 km, amplitude of 2 hPa, and periods of 6-8 h. Hu [27] discussed the generation, propagation, and dispersion of gravity waves in the mei-yu front based on a linear model with a simple parameterized cumulus heating expression. Based on an idealized model constructed by Peng et al. [33], Wang et al. [34] recently performed high-resolution simulations to investigate the generation mechanism of gravity waves in the mei-yu front system. A mechanical oscillator mechanism was suggested as playing a dominant role in the generation of lower-stratospheric waves.Due to relatively coarse spatiotemporal resolution, most general circulation models (GCMs) have still been unable to resolve short-scale and high-frequency gravity waves precisely. Consequently, representing the effects of gravity waves in GCMs requires parameterization [35]. However, because of the complexity of convection-induced gravity waves, the relevant parameterization remains under development [36][37][38][39][40]. It has been a consensus that a comprehensive knowledge of convective waves is the premise of making a breakthrough in parameterization. Under this background, understanding convective gravity waves and their convective sources is not only a theoretical interest in wave dynamics but also essential to the improvement of gravity-wave parameterization in GCMs. This is because previous studies showed that the lack of an accurate understanding of ...

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Section: Overview Of the Simulationssupporting

confidence: 69%

“…Environmental moisture and temperature are based on a real sounding during a typical mei-yu period. Further details of the model design can be found in Peng et al [33]. The Morrison scheme is used for microphysics parameterization [43], and no planetary boundary layer scheme is used.…”

Section: Experimental Designmentioning

confidence: 99%

On the Spectra of Gravity Waves Generated by Two Typical Convective Systems

et al. 2019

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“…The spectrum of the kinetic energy is calculated using the 2D discrete cosine transform (DCT) method (Denis et al 2002;Peng et al 2014) at each vertical level. More details on this method can be found in the appendix A.…”

Section: B Kinetic Energy Spectramentioning

confidence: 99%

Contributions of Moist Convection and Internal Gravity Waves to Building the Atmospheric −5/3 Kinetic Energy Spectra

Sun

Rotunno

Zhang

2017

Journal of the Atmospheric Sciences

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With high-resolution mesoscale model simulations, the authors have confirmed a recent study demonstrating that convective systems, triggered in a horizontally homogeneous environment, are able to generate a background mesoscale kinetic energy spectrum with a slope close to −5/3, which is the observed value for the kinetic energy spectrum at mesoscales. This shallow slope can be identified at almost all height levels from the lower troposphere to the lower stratosphere in the simulations, implying a strong connection between different vertical levels. The present study also computes the spectral kinetic energy budget for these simulations to further analyze the processes associated with the creation of the spectrum. The buoyancy production generated by moist convection, while mainly injecting energy in the upper troposphere at small scales, could also contribute at larger scales, possibly as a result of the organization of convective cells into mesoscale convective systems. This latter injected energy is then transported by energy fluxes (due to gravity waves and/or convection) both upward and downward. Nonlinear interactions, associated with the velocity advection term, finally help build the approximate −5/3 slope through upscale and/or downscale propagation at all levels.

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“…This novel instantaneous variance scaling methodology may enable detailed examination of the variance scaling of the time evolution of storm systems, such as extratropical cyclones at different stages in their life cycle as previously demonstrated with numerical simulations by Waite and Snyder (2013), or with deep convection along the Mei-Yu front by Peng et al (2014). The changes in the kinetic energy spectra in Waite and Snyder (2013) and Peng et al (2014) occur on time scales of hours to several days. We postulate that scaling exponents derived from instantaneous snapshots obtained from satellite swath data will be useful observational constraints for time-dependent spectra generated from numerical modeling experiments.…”

Section: Discussionmentioning

confidence: 82%

Instantaneous variance scaling of AIRS thermodynamic profiles using a circular area Monte Carlo approach

et al. 2018

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Abstract. Satellite observations are used to obtain vertical profiles of variance scaling of temperature (T) and specific humidity (q) in the atmosphere. A higher spatial resolution nadir retrieval at 13.5 km complements previous Atmospheric Infrared Sounder (AIRS) investigations with 45 km resolution retrievals and enables the derivation of power law scaling exponents to length scales as small as 55 km. We introduce a variable-sized circular-area Monte Carlo methodology to compute exponents instantaneously within the swath of AIRS that yields additional insight into scaling behavior. While this method is approximate and some biases are likely to exist within non-Gaussian portions of the satellite observational swaths of T and q, this method enables the estimation of scale-dependent behavior within instantaneous swaths for individual tropical and extratropical systems of interest. Scaling exponents are shown to fluctuate between β=-1 and −3 at scales ≥500 km, while at scales ≤500 km they are typically near β≈-2, with q slightly lower than T at the smallest scales observed. In the extratropics, the large-scale β is near −3. Within the tropics, however, the large-scale β for T is closer to −1 as small-scale moist convective processes dominate. In the tropics, q exhibits large-scale β between −2 and −3. The values of β are generally consistent with previous works of either time-averaged spatial variance estimates, or aircraft observations that require averaging over numerous flight observational segments. The instantaneous variance scaling methodology is relevant for cloud parameterization development and the assessment of time variability of scaling exponents.

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Mesoscale Energy Spectra of the Mei-Yu Front System. Part I: Kinetic Energy Spectra

Cited by 24 publications

References 41 publications

On the Spectra of Gravity Waves Generated by Two Typical Convective Systems

On the Spectra of Gravity Waves Generated by Two Typical Convective Systems

Contributions of Moist Convection and Internal Gravity Waves to Building the Atmospheric −5/3 Kinetic Energy Spectra

Instantaneous variance scaling of AIRS thermodynamic profiles using a circular area Monte Carlo approach

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