An improved PDF cloud scheme for climate simulations

作者：Kuwano Yoshida Akira^*; Enomoto Takeshi; Ohfuchi Wataru

来源：Quarterly Journal of the Royal Meteorological Society, 2010, 136(651): 1583-1597.

DOI：10.1002/qj.660

• stratus
• marine boundary layer
• AGCM
• large-scale condensation

An efficient grid-scale cloud scheme for climate simulation is implemented in the atmospheric general circulation model for the Earth Simulator (AFES). The new cloud scheme uses statistical partial condensation using joint-Gaussian probability distribution functions (PDFs) of the liquid water potential temperature and total water content, with standard deviations estimated by the moist Mellor-Yamada level-2 turbulence scheme. It also adopts improved closure parameters based on large-eddy simulations and a revised mixing length that varies with the stability and turbulent kinetic energy. These changes not only enable better representation of low-level boundary layer clouds, but also improve the atmospheric boundary layer structure. Sensitivity experiments for vertical resolution suggest that O(100-200 m) intervals are adequate to represent well-mixed boundary layers with the new scheme. The new scheme performs well at relatively low horizontal resolution (about 150 km), although inversion layers near the coast become more intense at a higher horizontal resolution (about 50 km).

• 出版日期2010-7