The study explores the role of ice-phase microphysics and convection for the better simulation of Indian summer monsoon rainfall (ISMR) and monsoon intraseasonal oscillation (MISO). Sensitivity experiments have been performed with coupled climate model- CFSv2 using different microphysics (with and without ice phase processes) and convective [Simple Arakawa Schubert (SAS), new SAS (NSAS)] parameterization schemes. Results reveal that the ice phase microphysics parameterization scheme performs better in the simulation of active and break composites of the ISMR as compared to ice-free runs. The difference between ice (ICE) and ice-free run (NOICE) can be attributed to the availability of copious cloud condensate at the upper level. Better representation of upper-level cloud condensate in ICE run (i.e., with ice phase microphysics) leads to correct representation of specific humidity in active and break spells. Proper depiction of upper-level cloud condensate further leads to realistic modulation of atmospheric circulation and better simulation of convection (as represented by OLR) in active and break spells of ICE run. As a result, better simulation of active and break occurs in the ICE run. In contrast, NOICE run (i.e., with warm phase microphysics) fails to depict upper-level cloud condensate in the active phase. It leads to an improper representation of specific humidity. Circulation features are also unrealistic, and convection is suppressed in the active phase. As a result, the active phase is not adequately simulated in the NOICE run. NOICE run composites during active spells depict the overestimation of the ascending branch of Hadley circulation as compared to MERRA reanalysis, which is relatively better in ICE run. NOICE run composites during active spells depict the overestimation of the ascending branch of Walker circulation as compared to MERRA reanalysis, which is further improved in ICE runs. The north–south space–time spectra of daily rainfall anomaly are also better captured by ICE run as compared to NOICE run. Results indicate that ice-phase processes are more important for capturing the difference between active and break composites, while convection parameterization is relatively more important for the intraseasonal variance analyses. Further improvements in ice microphysics parameterization with better convection schemes in models will be helpful for the betterment of MISO and will lead to the improved simulation of monsoon.

该研究探讨了冰期微物理和对流对更好地模拟印度夏季风季风降水（ISMR）和季风季节内振荡（MISO）的作用。已经使用不同的微物理原理（带有和不带有冰期过程）和对流[简单荒川舒伯特（SAS），新SAS（NSAS）]参数化方案，对耦合气候模型CFSv2进行了敏感性实验。结果表明，与无冰运行相比，冰相微物理参数化方案在ISMR活性和断裂复合材料的模拟中表现更好。冰（ICE）和无冰运行（NOICE）之间的差异可以归因于高层的大量云凝结水的可用性。在ICE运行中更好地表示高层云凝结水（即，使用冰相微物理学）可以在主动法术和断裂法术中正确表示特定的湿度。正确描述高层云凝结水，可以进一步有效地调节大气环流，并在ICE运行的主动和间歇运行中更好地模拟对流（以OLR表示）。结果，在ICE运行中更好地模拟了活动和中断。相比之下，NOICE运行（即采用暖相微物理学）无法描述活跃相中的高层云凝结物。这会导致不正确的比湿度表示。循环特征也不现实，并且在活动阶段抑制对流。结果，在NOICE运行中未充分模拟活动阶段。与MERRA再分析相比，主动式法术期间的NOICE跑步复合材料描述了对Hadley循环上升分支的高估，这在ICE跑步中相对较好。与MERRA再分析相比，主动式法术期间的NOICE跑步复合材料描述了对Walker循环上升分支的过高估计，这在ICE跑步中得到了进一步改善。与NOICE运行相比，ICE运行还可以更好地捕获日降雨异常的南北时空光谱。结果表明，冰期过程对于捕获活性和断裂复合物之间的差异更为重要，而对流参数化对于季节内方差分析则相对更为重要。