Convective Cloud Regimes From a Classification of Object‐Based CloudSat Observations Over Asian‐Australian Monsoon Areas

Abstract

The present study objectively classified the convective cloud objects detected by the space‐borne CloudSat radar over the Asian‐Australian monsoon region using the hierarchical agglomerative clustering algorithm. Based on key properties representing the morphological features and convective intensity of the systems, five distinct convective cloud regimes were derived. The unique Coastal‐Intense (CI) regime exhibits the most expansive horizontal scales (>1,000 km), high convective strength, the strongest cloud radiative effects, the highest probability of extreme rainfall, and a significant coupling with the sharp onset of the Asian summer monsoon circulation. Second, the Coastal regime illustrates smaller but also highly organized coastal convections, with the strongest convective strength. Less than 10% of the systems in the CI and Coastal regimes overlap with the tropical cyclones. The rest three regimes mark the less organized convection at various life cycle stages mainly over the land areas, with small seasonal variation in their occurrence.

The Unexpected Oceanic Peak in Energy Input to the Atmosphere and Its Consequences for Monsoon Rainfall

“…This reduction in energy loss to space coincides with an area covered by high cloud tops (Figure S2 in Supporting Information S1); the frequent occurrence of organized mesoscale convective systems in this region likely contributes to this large high-cloud fraction (P. J. Chen et al, 2021;Hamada et al, 2014;Luo et al, 2017;Yuan & Houze, 2010). The resulting net CRE (Figure 2d) thus makes a large positive contribution to the NEI over the northern Indian Ocean.…”

“…The shortwave and longwave components of the CRE (Figure 2c) confirm this: while the shortwave effect of clouds reflects energy into space and is therefore negative over the region experiencing monsoon rainfall, the longwave effect, which retains energy in the atmospheric column, is largest over the Bay of Bengal NEI maximum. This reduction in energy loss to space coincides with an area covered by high cloud tops (Figure S2 in Supporting Information ); the frequent occurrence of organized mesoscale convective systems in this region likely contributes to this large high‐cloud fraction (P. J. Chen et al., 2021; Hamada et al., 2014; Luo et al., 2017; Yuan & Houze, 2010). The resulting net CRE (Figure 2d) thus makes a large positive contribution to the NEI over the northern Indian Ocean.…”

A Framework to Evaluate Convective Aggregation: Examples With Different Microphysics Schemes

“…From observation, P.-J. Chen et al (2021) showed that the largesize convective systems are highly coupled with the seasonal cycle of the Asian-Australian monsoon system. These systems can effectively modulate the large-scale circulation through diabatic heating (Hamada et al, 2014;Hoskins et al, 2019;Yuan & Houze, 2010).…”

Identifying the Deep‐Inflow Mixing Features in Orographically‐Locked Diurnal Convection

“…Organized diurnal convection is critical to short‐duration rainfall extremes in these regions and, therefore, has been intensively investigated (e.g., P.‐J. Chen et al., 2021; X. Chen et al., 2015; Jian et al., 2021; Krishna et al., 2021; Romatschke & Houze, 2011; Song & Zhang, 2020). Still, substantial biases exist in simulated diurnal convection in the state‐of‐the‐art global weather and climate models (Baranowski et al., 2019; W.‐T.…”