Binary mesovortex structure associated with southwest vortex

Previous work has concluded that the southwest vortex (SWV) is a single mesoscale vortex. Applying the National Centers for Environmental Prediction Final Operational Global Analysis, the Interim European Centre for Medium-Range Weather Forecasts Re-Analysis, and the non-hydrostatic mesoscale Advanced Research Weather Research and Forecasting (WRF) model to a case study, we discovered a new type of SWV associated with another coexisting mesoscale warm and moist vortex. In the case study, meso-β-scale vortex-A was generated at 1800 UTC 17 July, and dissipated around 0500 UTC 18 July 2013, with a lifespan of approximately 11 h. Vortex-B occurred at 0600 UTC 17 July and moved out of the Sichuan Basin at 0800 UTC 18 July 2013, remaining over the basin for approximately 26 h. Stronger atmospheric upward motion and two mesoscale rainbelts associated with each of the vortices further demonstrate the binary mesoscale vortex structure related to the SWV using the WRF model. The quasi-geostrophic balance of the two mesoscale cyclonic circulations is responsible for the generation and maintenance of the two closed mesoscale vortices.