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

• Published in: Geophysical research letters 2021-05, Vol.48 (10), p.n/a
• Main Authors: Chen, Peng‐Jen, Chen, Wei‐Ting, Wu, Chien‐Ming, Yo, Ting‐Shuo
• Format: Article
• Language: English
• Subjects: cloud object; CloudSat; cluster analysis; coastal convection; convective cloud regime
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL092733

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. Plain Language Summary One of the key features of the Asian‐Australian monsoon is the occurrence of intense rainfall and organized convective systems coupled with the change of large‐scale circulation in the summer hemisphere. In this study, the convective systems from the multi‐year satellite observations over the Asian‐Australian monsoon region were classified objectively into five distinct regimes by a data‐driven approach based on systems' physical properties. The most organized Coastal Intense regime, mainly occurring over the coastal area, exhibits the highest probability of extreme rainfall among all regimes, and tightly follows the sharp seasonal switch of the monsoon circulation. The Coastal regime illustrates smaller organized coastal convections with the strongest convective strength. Three of the less organized regimes represent convection at various life stages over the land areas. Key Points Five convective cloud regimes are derived from CloudSat observations based on object‐based cluster analysis of five physical properties Two regimes are highly organized systems over coastal areas and three regimes are the less organized systems mainly over land The coastal‐intense regime exhibits strong cloud radiative effects and extreme rainfall, clearly coupled with the large‐scale circulation