[A-AS01] Large-scale moisture and organized cloud systems

[AAS01-08] Impacts of cloud microphysics modifications on diurnal convection and the ISO over the Maritime Continent: A case study of YMC-Sumatra 2017

*Tomoe Nasuno¹ (1.Japan Agency for Marine-Earth Science and Technology)

Keywords:Maritime Continent, Intraseasonal Oscillation, cloud microphysics, diurnal convection

Relationship between diurnal convection and the intraseasonal oscillation (ISO) over the western Maritime Continent (MC) was investigated by a case study of an ISO event that occurred during the Years of the Maritime Continent (YMC)-Sumatra 2017 campaign. Sensitivity experiments regarding cloud microphysics settings were performed with a global cloud-permitting model to understand their impacts on the diurnal convection and ISO. Two typical settings; aimed for ISO prediction (CTL) and for climate simulation (MOD) were examined. CTL had biases of weaker diurnal variation and smaller precipitation amounts over land than in observations; these were reduced in MOD by higher probabilities of local intense convection in the middle troposphere and higher precipitation efficiency. Detailed analysis of vertical motion and moisture advection over the land and oceanic areas of the western MC was conducted. The results showed that enhanced convection over land in MOD were accompanied with suppressed convection over the surrounding ocean, especially at the diurnal peak time of land convection, while during the onset period of the ISO convection, upward moisture advection and precipitation increased also over ocean in MOD than in CTL at the diurnal peak time of oceanic convection. The suppression of the ISO convection over ocean by that over land in the MC is consistent with previous knowledges, and this study also suggests that enhanced diurnal convection can favor the ISO convection development during the onset period. A possible role of cloud-radiative interactions in the ISO will be also discussed.