Interpreting the Diurnal Cycle of Clouds and Precipitation in the ARM GoAmazon Observations: Shallow to Deep Convection Transition

作者：Yang Tian, Yunyan Zhang, Stephen A. Klein, Courtney Schumacher · 发表于：Journal of Geophysical Research Atmospheres · 年份：2021 · DOI：10.1029/2020jd033766 · 被引用次数：62 · 研究领域：Climate variability and models、Meteorological Phenomena and Simulations、Atmospheric aerosols and clouds

Abstract The Green Ocean Amazon (GoAmazon) 2014/5 field campaign data are used to study the diurnal cycle of clouds and precipitation. Through a careful classification of days with shallow cumulus, congestus and deep convection, we investigate the major differences among locally generated convection regimes and the most important environmental factors governing the shallow‐to‐deep convection transition. On shallow cumulus days, a greater sensible heat flux drives deeper boundary layer growth, which entrains drier free‐tropospheric air and lowers the relative humidity, thus leading to a significantly higher cloud base than those on days with deeper convection. Congestus and deep convection regimes exhibit distinct cloud top height distributions with noticeable differences in the vertical wind shear in the mid‐troposphere, suggesting an important role of wind shear in limiting the vertical extent of convection. On deep convection days, with preexisting nocturnal convection or cold‐pools from external disturbances, the timing of peak surface precipitation (12:00–13:00 LST) tends to be in‐phase with the diurnal variation in surface fluxes. However, it takes longer for local deep convection to develop without these disturbances. A plume model with thermodynamic and dynamical constraints is developed to explore the relative importance of various convection‐controlling factors. Initial cloud‐base vertical velocity and buoyancy are important in helping parcels ascend to the level of ...