Effective Factors in the Development of Deep Convective Clouds over the Wet Region of Eastern China during the Summer Monsoon Season.

Abstract

A two-dimensional cloud-resolving model, including a supply of sensible and latent heat fluxes from the surface, is used to study the development of deep convective clouds over a southern region far from the Meiyu front (wet region) of eastern China. Some deep convective clouds were observed during the latter half of the GAME/HUBEX IOP (GEWEX Asian Monsoon Experiment/Huaihe River Basin Experiment Intensive Observation Periods, GEWEX: Global Energy and Water Cycle Experiment) 1998, although there is less large-scale convergence over this region. Numerical simulations reproduce the development of deep convective clouds, and their generating/decaying time. The development process of a convective mixing layer and generation of shallow convective clouds around the top of this layer are also simulated.The results of sensitivity tests on the surface land-use (i.e., the supply of the sensible and latent heat fluxes) and the relative humidity in the middle troposphere, indicate that there are two effective factors in the development of deep convective clouds over this region. One is the large amount of latent heat flux from the surface, and the other is the moist environment in the middle troposphere. The latent heat flux from the surface supplies water vapor to generate convective clouds. Paddy fields can supply a large amount of latent heat flux into the lower atmosphere and are widely distributed over this region. On the other hand, the moist environment in the middle troposphere can cause shallow convective clouds to become deep because the positive buoyancy in the shallow convective clouds is not lost by the evaporation cooling of the entrained air mass. Additionally, this moist environment in the middle troposphere is formed by the development of shallow convective clouds, which transport water vapor from the convective mixing layer.

Resolution Dependency of the Diurnal Cycle of Convective Clouds over the Tibetan Plateau in a Mesoscale Model

“…It is very clear that a finer resolution run leads to early maximum of convection while a coarser resolution run leads to the late maximum with strong intensity. In the past study effective upward moisture transport was suggested to be important for initiation of the deep convection (Petch et al 2002;Shinoda and Uyeda 2002). In the current study, efficiency of the vertical moisture transport by the grid-scale and subgrid-scale vertical motion is one of the important processes which may cause the phase difference.…”

Diurnal variation in summer monsoon precipitation during active and break periods over central India and southern Himalayan foothills

“…There are many previous studies showing that these kinds of thunderstorms usually develop in the summertime over landmasses [e.g., Kingsmill and Wakimoto, 1991;Shinoda and Uyeda, 2002;Shusse and Tsuboki, 2006;Case et al, 2008]. It is also plausible that soil moisture over the heated surface may significantly influence the evolution of air mass thunderstorms and the depth of the mixed boundary layer can influence the structure of the thunderstorms [McCaul and Cohen, 2002].…”

Three-Dimensional Structure of a Mesoscale Convective System in a Baiu-Frontal Depression Generated in the Downstream Region of the Yangtze River

“…In addition, the meteorological operational network of the China Meteorological Administration (CMA), whose observational frequency was improved more than usual, was also operated. The important point of this experiment is to have placed the Doppler-radar network near the coastline, rather than inland (Huaihe River Basin) where the first Doppler radar observation was carried out during the Baiu seasons of 1998 and 1999, under the GAME/HUBEX 1 project (e.g., Maesaka and Uyeda 1999;Shinoda and Uyeda 2002). A Baiu-frontal depression accompanied by a MaCS was generated in the downstream region of the Yangtze River on the night of 18 June 2001.…”