Statistical relation between maximum vertical velocity and surface precipitation of tropical convective clouds in a global nonhydrostatic aquaplanet experiment

摘要

This study investigated the properties of heavy precipitation and its associated vertical motion in an aquaplanet ex- periment with a 3.5-km mesh global cloud-system resolving model (GCRM). The statistics of precipitation and vertical velocity were examined in terms of the precipitation top height (PTH) and the maximum in-cloud vertical velocity in each column (w _max) for the grid points with the top 1% and 1-10% of the surface precipitation rate (pr _sfc) in the 10°N-10°S domain. To support the findings, realistic simulation cases were also analyzed. In the columns with the top 1% (1-10%) of pr _sfc, peak frequencies of w max height were found at z = 4-6 (1-4) km with the PTH several kilometers above that. Thermodynamic conditions were more humid and warmer in these columns than in the columns with average precipitation. These results were common to all simulation cases. Composite time evolution of convection with heavy surface precipitation was also examined for the aquaplanet experiment. The results suggest that the vigorous upward motion in the middle (lower) troposphere for columns with the top 1% (1-10%) of pr _sfc enabled efficient moisture transport from the boundary layer to the middle troposphere.