Formation of Long-Lived Summertime Mesoscale Vortices over Central East China:Semi-Idealized Simulations Based on a 14-Year Vortex Statistic
- 29 November 2017
- journal article
- Published by American Meteorological Society in Journal of the Atmospheric Sciences
- Vol. 74 (12), 3955-3979
- https://doi.org/10.1175/jas-d-16-0328.1
Abstract
Regions around Dabie Mountain (DBM) in the Yangtze River basin (YRB) are the source of a mesoscale vortex: the Dabie vortex (DBV). Based on a 14-yr statistical study, 11 long-lived heavy-rain-producing DBVs were composited for convection-permitting semi-idealized simulations. A control simulation, initialized 12 h before the composite vortex formation, successfully reproduced a DBV, with all the salient characteristics of the 11 events. Sensitivity experiments were designed to understand the impacts of large-scale environmental conditions, regional topography, and latent heating on DBV formation. The main results were as follows: (i) Supposition of a 500-hPa shortwave trough with an east–west-oriented lower-level transversal trough around the DBM is crucial for the formation of vortices. A nocturnal lower-level jet on the southern side of the transversal trough accelerates DBV formation by enhancing convergence, triggering/sustaining convection, and producing cyclonic vorticity. (ii) During the simulation period, the topography east of the second-step mountain ranges, including the DBM, significantly affects nearby precipitation and convective activity, whereas this is not crucial for DBV formation. (iii) Latent heating is not required for generating DBVs, but it enhances the intensity, longevity, and eastward progression of these vortices along the shear line associated with the transversal trough. (iv) The vorticity budget suggests the convergence-related (horizontal) shrinking and vertical transport dominate the cyclonic-vorticity increase associated with DBVs, whereas tilting and horizontal transport mainly act in the opposite manner.Keywords
Funding Information
- National Natural Science Foundation of China (41775046)
- National Natural Science Foundation of China (91637211)
- National Natural Science Foundation of China (41375053)
- National Natural Science Foundation of China (91437104)
This publication has 25 references indexed in Scilit:
- A Conceptual View on Inertial Oscillations and Nocturnal Low-Level JetsJournal of the Atmospheric Sciences, 2010
- Convection-Allowing and Convection-Parameterizing Ensemble Forecasts of a Mesoscale Convective Vortex and Associated Severe Weather EnvironmentWeather and Forecasting, 2010
- Development and Tropical Transition of an Alpine Lee Cyclone. Part I: Case Analysis and Evaluation of Numerical GuidanceMonthly Weather Review, 2010
- A Climatology of Midlatitude Mesoscale Convective Vortices in the Rapid Update CycleMonthly Weather Review, 2010
- Patterns of Precipitation and Mesolow Evolution in Midlatitude Mesoscale Convective VorticesMonthly Weather Review, 2010
- Climatology of Storm Reports Relative to Upper-Level Jet StreaksWeather and Forecasting, 2009
- Mechanisms for Quasi-Stationary Behavior in Simulated Heavy-Rain-Producing Convective SystemsJournal of the Atmospheric Sciences, 2009
- The Vertical Structure of Mesoscale Convective VorticesJournal of the Atmospheric Sciences, 2009
- Baroclinic Transition of a Long-Lived Mesoscale Convective VortexMonthly Weather Review, 2009
- The Bow Echo and MCV Experiment: Observations and OpportunitiesBulletin of the American Meteorological Society, 2004