Banded Convective Activity Associated With Mesoscale Gravity Waves Over Southern China

Yu Du, Fuqing Zhang

Research output: Contribution to journalArticle

Abstract

Banded convective activity that occurred near the south coast of China on 30 January 2018 was investigated through convection-allowing simulations using a nonhydrostatic mesoscale model. The simulations capture reasonably well the observed characteristics of this event. The convective bands are found to be closely related to an episode of mesoscale gravity waves propagating northeastward with a wave speed of around 12 m/s and a primary wavelength of about ~40–50 km. Further analyses and sensitivity experiments reveal that the environment provides a wave duct for these gravity waves, with a thick low-level stable layer below 850 hPa capped by a low-stability reflecting layer with a critical level. The strength and depth of the low-level stable layer determine the intrinsic phase speed and wavelength of the ducted gravity waves. In the sensitivity tests that the stable layer depth is reduced, the wave characteristics change according to what are predicted with the wave duct theory. The convective bands collocate and propagate in phase with the peak updraft regions of the gravity waves, suggesting strong interactions of convection and gravity waves, in which the ducted gravity waves can trigger and modulate convection, while latent heating from convection enhances the waves. In essence, both wave ducting and wave-convection interaction are jointly responsible for the banded convective activity.

Original languageEnglish (US)
Pages (from-to)1912-1930
Number of pages19
JournalJournal of Geophysical Research: Atmospheres
Volume124
Issue number4
DOIs
StatePublished - Feb 27 2019

Fingerprint

Gravity waves
gravity waves
gravity
gravity wave
China
convection
wavelengths
Ducts
ducts
wavelength
Wavelength
vertical air currents
strength (mechanics)
updraft
sensitivity
simulation
Coastal zones
coasts
heat
Convection

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

Cite this

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abstract = "Banded convective activity that occurred near the south coast of China on 30 January 2018 was investigated through convection-allowing simulations using a nonhydrostatic mesoscale model. The simulations capture reasonably well the observed characteristics of this event. The convective bands are found to be closely related to an episode of mesoscale gravity waves propagating northeastward with a wave speed of around 12 m/s and a primary wavelength of about ~40–50 km. Further analyses and sensitivity experiments reveal that the environment provides a wave duct for these gravity waves, with a thick low-level stable layer below 850 hPa capped by a low-stability reflecting layer with a critical level. The strength and depth of the low-level stable layer determine the intrinsic phase speed and wavelength of the ducted gravity waves. In the sensitivity tests that the stable layer depth is reduced, the wave characteristics change according to what are predicted with the wave duct theory. The convective bands collocate and propagate in phase with the peak updraft regions of the gravity waves, suggesting strong interactions of convection and gravity waves, in which the ducted gravity waves can trigger and modulate convection, while latent heating from convection enhances the waves. In essence, both wave ducting and wave-convection interaction are jointly responsible for the banded convective activity.",
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Banded Convective Activity Associated With Mesoscale Gravity Waves Over Southern China. / Du, Yu; Zhang, Fuqing.

In: Journal of Geophysical Research: Atmospheres, Vol. 124, No. 4, 27.02.2019, p. 1912-1930.

Research output: Contribution to journalArticle

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