1Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou, China
2School of Geographical Sciences, Fujian Normal University, Fuzhou, China
3National Center for Atmospheric Research, Boulder, Colorado
4Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
5Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, and Key Laboratory for Aerosol–Cloud–Precipitation of the China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing, China
6College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
1Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou, China
2School of Geographical Sciences, Fujian Normal University, Fuzhou, China
3National Center for Atmospheric Research, Boulder, Colorado
4Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
5Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, and Key Laboratory for Aerosol–Cloud–Precipitation of the China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing, China
6College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
Received: 07 Jan 2021 – Accepted for review: 31 Jan 2021 – Discussion started: 01 Feb 2021
Abstract. Large-eddy simulations are performed to investigate the process of deep-convection initiation (DCI) over a peninsula. In each simulation, two sea-breeze circulations develop over the two coasts. The two sea-breeze fronts move inland and collide, producing strong instability and strong updrafts near the centerline of the domain, and consequently leading to DCI. In the simulation with a maximum total heat flux over land of 700 or 500 W m−2, DCI is accomplished through the development of three generations of convection. The first generation of convection is randomly produced through the collision of the sea-breeze fronts. The second generation of convection is produced mainly through the collision of the sea-breeze fronts, but only develops in regions where no strong downdrafts are produced by the first generation of convection. The third generation of convection mainly develops from the intersection points of the cold pools produced by the second generation of convection, and is produced through the collision between gust fronts and sea-breeze fronts. As the maximum total heat flux decreases from 700 to 500 W m−2, both the height and strength of the sea breezes are reduced, inhibiting the forcing of the first two generations of convection. These two generations of convection therefore become weaker. The weaker second generation of convection produces shallower cold pools, reducing the forcing of the third generation, and consequently weakening the third generation of convection. As the maximum total heat flux further decreases to 300 W m−2, only one generation of shallow convection is produced.
Deep-convection initiation (DCI) determines when and where deep convection develops, and hence affects both weather and climate. However, our understanding of DCI is still limited. Here we simulate DCI over a peninsula using large-eddy simulation and high output frequency. We find that DCI is accomplished through the development of multiple generations of convection, and the earlier generation affects the later generation by producing downdrafts and cold pools.
Deep-convection initiation (DCI) determines when and where deep convection develops, and hence...
