对流参数化方案是大气模式必不可少的一环，对数值模拟结果有着非常重要的影响。然而，当前的对流参数化方案不能完美的表征模式中的云物理过程，特别是在低分辨率的全球大气环流模式中。在原有对流参数方案基础上，通过耦合随机多云模式（stochastic multicloud model；SMCM），改进模式对云物理过程的模拟，从而改进模式的数值模拟结果。ECHAM6.3是一个先进的全球大气环流模式，其也是南信大地球系统模式的大气分量。我院教师马利斌博士、王斌教授、朱志伟教授、李娟教授和曹剑教授等将SMCM耦合到ECHAM6.3中，详细地分析了SMCM对MJO和东亚夏季风模拟的影响。

（1）采用“以动力过程为导向”（dynamics-oriented）的评估方法，分析了模式对改进MJO向东传播的成因。相比原有的EHCAM6.3模式结果，耦合SMCM的ECHAM6.3通过改进对边界层水汽辐合向东传播特征、等价位温和非绝热加热的垂直分布结构、及与MJO相关的高低对流层环流结构和高对流层非绝热加热的水平结构，从而改进模式对MJO向东传播的模拟。该研究成果已发表在《Journal of the Meteorological Society of Japan》。

（2）从气候态角度，通过对比分析，耦合SMCM的EHCAM6.3改进了模式对东亚夏季风区域的降水、西北太平洋副高、季风爆发、季节变化、大尺度环流和水汽输送等的模拟。同时，分析结果表明，通过改善对东亚夏季风区域云物理过程的模拟，进而改进对海陆热力差异和经向温度梯度的模拟，是改进的EHCAM6.3（耦合SMCM）提高对东亚夏季风模拟能力的主要原因。该研究成果已在《Climate Dynamics》上发表。

相关论文：

Ma L B, Peters K, Wang B, and Li J. 2019: Revisiting the impact of Stochastic Multicloud Model on the MJO using low-resolution ECHAM6.3 atmosphere model. J. Meteoro. Soc. Japan, 97, 5, doi:10.2151/jmsj.2019-053.

Ma L B, Zhu Z W, Li J, and Cao J, 2019: Improving the simultion of the climatology of the East Asian summer monsoon by coupling the Stochastic Multicloud Model to the ECHAM6.3 atmosphere model. Clim. Dyn., 53(4), 2061-2081. doi: 10.1007/s00382-019-04787-0.

图1 Eastward propagation of MJO precipitation as indicated by the lead-lag correlation of 20-70 day filtered precipitation averaged over 10°S-10°N with reference to the precipitation at the equatorial eastern Indian Ocean (10°S-10°N, 80°E-100°E) during boreal winter (NDJFMA): (a) observation, (b) ECHAM_CTRL, and (c) ECHAM_SMCM. The red contour in (a) represents correlation coefficient (CC) of ±0.2.

图2 Latitude and seasonal migration of the East Asian monsoon rainfall (mm/day) averaged over 110°-120°E in (a) observation, (b) ECHAM_CTRL, and (c) ECHAM_SMCM. The purple box in (a) represents the domain used to calculate the PCC and RMSE. The black, blue, and red lines in (a), respectively, denote the seasonal evolution of western Northern Pacific subtropical high, represented by the ridgeline averaged between 125°E and 145°E, of observation, ECHAM_CTRL, and ECHAM_SMCM. The white lines in (a)-(c) denote the isolines of rainfall rate with 5 mm/day.