A unified parameterization scheme of moist process in the atmospheric boundary layer

A "cloud resolving model" in which loading of cloud properties is treated explicitly is often used at a low resolution such as a 10 km grid size. In considering the atmospheric boundary layer, such a cloud resolving model at the low resolution, however, causes the following matters. 1) The delay of a development of a convective mixed layer, 2) subgrid-scale cloud water loading, and 3) an expression of a fractional cloud cover.

The first matter takes place due to the insufficient grid resolution to express a convective motion which should originally takes place, resulting in underestimating the evolution of the mixture. The second matter arises due to the insufficient resolution to express individual clouds. For this reason, even if the relative humidity at the grid point is less than 100%, it is necessary to take a subgrid-scale condensation into consideration. For the third matter, the fractional cloud cover is conventionally diagnosed from a relative humidity. In this method, even if the influence of cloud radiation on cloud water loading is taken into consideration, a reverse feedback process is not correctly. Thus, it is necessary to assess the fractional cloud cover from cloud properties such as a cloud water amount. It is desirable to parameterize these three processes in a unified form, since they correlate each other. In this research, in order to improve these matters, we shall focus on the atmospheric boundary layer and develop a unified parameterization scheme of a moist process occurred in it.