Gravity Wave Influences On Mesoscale Divergence: An Observational Case Study

Stephan, Claudia Christine; Lane, Todd P.; Jakob, Christian

doi:10.1029/2019gl086539

Cited by 8 publications

(11 citation statements)

References 35 publications

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“…Stephan et al . (2020) confirmed such fine‐scale structures in divergence profiles derived from the Tropical Warm Pool‐International Cloud Experiment (TWP‐ICE; May et al ., 2008).…”

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 54%

“…Stephan et al . (2020) found waves with typical vertical wavelengths of about 4 km, horizontal wavelengths of about 600 km and intrinsic periods of about 12 hr. The observed vertical, horizontal and temporal variability of divergence inside the area they considered are related, as one would expect from these GW properties.…”

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

“…In an attempt to explain these features, Stephan et al . (2020) analyzed radiosonde observations from TWP‐ICE for the presence of low‐frequency GWs, for which

\hat{ω} ≪ N

. GWs that may explain the divergence patterns need to have periods consistent with the temporal autocorrelation scales of the divergence profiles, horizontal wavelengths consistent with their spatial autocorrelation scales, and vertical wavelengths consistent with the vertical variability of the divergence profiles.…”

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

“…The studies by Bony and Stevens (2019) and Stephan et al . (2020) sampled constant‐sized areas with diameters of about 200 km, which did not permit studying how divergence characteristics depend on area size. The EUREC

^{4}

A campaign of 2020, which took place over the western tropical Atlantic (Stevens et al ., 2021) included an extensive radiosounding network composed of a station on the island of Barbados and four ships (Stephan et al ., 2021).…”

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

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Waves and coherent flows in the tropical atmosphere: New opportunities, old challenges

Stephan

Žagar

Shepherd

2021

Quart J Royal Meteoro Soc

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Atmospheric science relies on numerical models to simulate the complex multiscale nature of atmospheric variability, but our confidence in weather and climate predictions relies on theory and simplified models that describe scale interactions at a mechanistic level and can provide causal accounts of atmospheric behaviour. Global simulations at kilometre‐scale resolution are now feasible and offer new opportunities to the atmospheric science community for testing and expanding our understanding of climate variability and change. Taking full advantage of this new tool requires smart strategies for evaluating and analysing the output, especially as kilometre‐scale climate modelling will be limited to relatively short simulations with a rather small number of realizations. We here review some of the available tools for diagnosing and studying the dynamics of waves, coherent flows, and the interactions between them in terms of their ability to provide causal accounts of the behaviour seen in observations and in comprehensive simulation models. We describe their successes but also some of their limitations. The limitations are seen to be especially pronounced in the Tropics, where clouds, convection and atmospheric circulation are inextricably linked. The lack of a natural spatial truncation scale in the Tropics has given rise to many theoretical challenges, but it is for precisely this reason that the Tropics are where we might expect the largest gain from global kilometre‐scale models.

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“…Stephan et al . (2020) confirmed such fine‐scale structures in divergence profiles derived from the Tropical Warm Pool‐International Cloud Experiment (TWP‐ICE; May et al ., 2008).…”

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 54%

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

“…In an attempt to explain these features, Stephan et al . (2020) analyzed radiosonde observations from TWP‐ICE for the presence of low‐frequency GWs, for which

\hat{ω} ≪ N

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

^{4}

Section: Interpreting Observed Behaviour Across Scalesmentioning

confidence: 99%

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Waves and coherent flows in the tropical atmosphere: New opportunities, old challenges

Stephan

Žagar

Shepherd

2021

Quart J Royal Meteoro Soc

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“…Data availability. The vertically gridded (Level 2) radiosounding data described by Stephan et al (2021) in NetCDF format are available to the public at https://doi.org/10.25326/62 (Stephan et al, 2020b). GOES-16 Advanced Baseline Imager data are provided by NASA's Worldview application (https://worldview.earthdata.nasa.…”

Section: Discussionmentioning

confidence: 99%

The signature of the tropospheric gravity wave background in observed mesoscale motion

Stephan

Mariaccia

2021

Weather Clim. Dynam.

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Abstract. How convection couples to mesoscale vertical motion and what determines these motions is poorly understood. This study diagnoses profiles of area-averaged mesoscale divergence from measurements of horizontal winds collected by an extensive upper-air sounding network of a recent campaign over the western tropical North Atlantic, the Elucidating the Role of Clouds-Circulation Coupling in Climate (EUREC4A) campaign. Observed area-averaged divergence amplitudes scale approximately inversely with area-equivalent radius. This functional dependence is also confirmed in reanalysis data and a global, freely evolving simulation run at 2.5 km horizontal resolution. Based on the numerical data it is demonstrated that the energy spectra of inertia gravity waves can explain the scaling of divergence amplitudes with area. At individual times, however, few waves can dominate the region. Nearly monochromatic tropospheric waves are diagnosed in the soundings by means of an optimized hodograph analysis. For one day, results suggest that an individual wave directly modulated the satellite-observed cloud pattern. However, because such immediate wave impacts are rare, the systematic modulation of vertical motion due to inertia–gravity waves may be more relevant as a convection-modulating factor. The analytic relationship between energy spectra and divergence amplitudes proposed in this article, if confirmed by future studies, could be used to design better external forcing methods for regional models.

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Modeling Studies of Gravity Wave Dynamics in Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, and Induced Flow Responses

et al. 2022

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A compressible numerical model is applied for three‐dimensional (3‐D) gravity wave (GW) packets undergoing momentum deposition, self‐acceleration (SA), breaking, and secondary GW (SGW) generation in the presence of highly‐structured environments enabling thermal and/or Doppler ducts, such as a mesospheric inversion layer (MIL), tidal wind (TW), or combination of MIL and TW. Simulations reveal that ducts can strongly modulate GW dynamics. Responses modeled here include reflection, trapping, suppressed transmission, strong local instabilities, reduced SGW generations, higher altitude SGW responses, and induced large‐scale flows. Instabilities that arise in ducts experience strong dissipation after they emerge, while trapped smaller‐amplitude and smaller‐scale GWs can survive in ducts to much later times. Additionally, GW breaking and its associated dynamics enhance the local wind along the GW propagation direction in the ducts, and yield layering in the wind field. However, these dynamics do not yield significant heat transport in the ducts. The failure of GW breaking to induce stratified layers in the temperature field suggests that such heat transport might not be as strong as previously assumed or inferred from observations and theoretical assessments. The present numerical simulations confirm previous finding that MIL generation may not be caused by the breaking of a transient high‐frequency GW packet alone.

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Gravity Wave Influences On Mesoscale Divergence: An Observational Case Study

Cited by 8 publications

References 35 publications

Waves and coherent flows in the tropical atmosphere: New opportunities, old challenges

Waves and coherent flows in the tropical atmosphere: New opportunities, old challenges

The signature of the tropospheric gravity wave background in observed mesoscale motion

Modeling Studies of Gravity Wave Dynamics in Highly Structured Environments: Reflection, Trapping, Instability, Momentum Transport, Secondary Gravity Waves, and Induced Flow Responses

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