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The Spatial and Temporal Organization of Deep Convective Systems and Its Impacts on the Production of Anvil Clouds
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  • Ruoyu Wang,
  • Yuchen Dou,
  • Jianhao Zhou,
  • Ziqi Ben,
  • Yiming Wang,
  • Weijia Wang,
  • Jian Yuan
Ruoyu Wang
Nanjing University
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Yuchen Dou
Macalester College
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Jianhao Zhou
University of Michigan Ann Arbor
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Ziqi Ben
Beijing Haidian Foreign Language Academy
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Yiming Wang
IC Academy - Kunming No.1 High School Dianchi Resort District Campus
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Weijia Wang
Hamden Hall Country Day School
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Jian Yuan
Nanjing University

Corresponding Author:[email protected]

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Abstract

A multi-threshold technique was used to objectively identify the space-time structure of meso-scale convective systems in the warm pool region using observations of high-resolution Himawari geostationary satellites. Several thresholds of the IR brightness temperature were used to capture the life cycles of cloud clusters with complex behaviors (merging and breaking) and spatial organizations (inclusion, aggregation). According to the inclusions between cloud clusters with different thresholds, cloud clusters were characterized as simple single-core or complex multi-core systems, more likely represented isolated systems or aggregated/merged systems respectively. The mixed depth multi-core clusters existed frequently, even for very cold brightness temperatures (<230K) and more of them were associated with the merging process compared to single core clusters. Thus they were often a mixture of systems at different development levels. A large amount of convective systems experience merging and breaking during their lifetime. Merging and breaking processes were found to result in unrealistic local life stage. These facts questioned the use of any single threshold technique on determining the life cycle of deep convective systems as well as that of their anvil clouds. When the same development height was selected, the multi-core systems systematically produced less warmer clouds around their cold cores than that of single-core systems. Thus per the same cold core area the muti-core systems tended to produce less total cloud coverage and weaker reduction of the TOA OLR. These phenomena were consistent with previous studies suggesting that aggregated convection might resulted in less high cloud coverage and enhanced domain-averaged OLR. The documentation and understanding about the cause of different organizations of cloud clusters and their impacts on clouds and radiation are currently lacking. If these phenomena and effects cannot be effectively documented and stratified in observations, it will be misleading when applying observations as a guide for diagnosing and improving models. This study provided an observational reference to test if current models can realistically reproduce observed organizations of deep convection along with its associated anvil and cirri-form clouds.