GRIST模式夏季气候回测试验中东亚降水季节内特征的评估

将自主研发的包含对流参数化、宏观云凝结、云微观物理参数化在内的湿物理过程（简称PhysCN）引入全球-区域一体化预测系统（Global-to-Regional Integrated forecast SysTem，GRIST）。通过大气模式比较计划（AMIP）10 a连续积分考察了PhysCN较原有方案（简称PhysC）对模拟的全球气候基本态的影响。结果显示，PhysCN更真实地重现了热带降水的气候分布特征和季节变化。相比PhysC，PhysCN减少了赤道辐合带（ITCZ）、热带太平洋和印度洋上空的虚假降水，改善了双ITCZ偏差。PhysCN在热带对流层顶附近和中、高纬度地区形成了比PhysC更多的冰云，增强了长波云辐射效应。但另一方面，由于单冰云微物理方案中采用一个变量类别考虑所有冰相粒子，导致中、高纬度低层云冰比湿比PhysC中更大。宏观云凝结中采用基于冰面相对湿度的方法诊断冰云量，使低云更密实，减弱了短波云辐射效应，也使全球净辐射收支偏差大于PhysC模拟结果。研究证明了PhysCN湿物理方案在GRIST模式中的稳定性与合理性，但也展示出冰云诊断和云微物理参数化的协调性有待进一步改进。

Assessment of intraseasonal characteristics of precipitation over East Asia in GRIST model summer climate backtest

A self-developed moist physics parameterization package (PhysCN) is implemented in the Global-to-Regional Integrated forecast SysTem (GRIST) model. PhysCN consists of convective parameterization, macrophysics condensation and microphysical processes. Impact of the moist physical processes on climate modeling are evaluated by comparing with the default schemes (PhysC) based on the 10-year Atmospheric Model Intercomparison Project (AMIP) type simulation. Results show that PhysCN can reproduce mean tropical precipitation and its seasonal variation more realistically. Compared with PhysC, PhysCN reduces artificial precipitation over the intertropical convergence zone (ITCZ) regime, the tropical Pacific and the Indian Ocean. It also decreases the double ITCZ bias. There exist more ice clouds near the top of the tropical troposphere and the mid- and high latitudes in the PhysCN simulation than in the PhysC simulation, which enhances longwave cloud radiative forcing. However, shortwave cloud radiative forcing is weakened in the PhysCN simulation, which increases the bias of global net radiation budget. This is because the single ice microphysics approach uses a single prognostic category to represent cloud ice and snow mixing ratio, while the cloud macrophysics scheme diagnoses ice cloud fraction based on total relative humidity over ice particles. Low clouds increase and become denser, especially in the mid- and high latitudes. This study exhibits the stability and reasonableness of this moist physics package in GRIST, and shows that interaction between the microphysics and diagnosed cloud needs to be improved.