Acceleration of tropical cyclogenesis by self-aggregation feedbacks

Journal Article · 05 March 2018 · Proceedings of the National Academy of Sciences of the United States of America

DOI: https://doi.org/10.1073/pnas.1719967115 · OSTI ID:1479393

Muller, Caroline J.  ^[1]; Romps, David M. ^[2]

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1. Sorbonne Université, École Polytechnique, CNRS, Paris (France). Laboratoire de Météorologie Dynamique (LMD)/Institut Pierre Simon Laplace (IPSL), École Normale Supérieure, Paris Sciences & Lettres (PSL) Research University
2. Univ. of California, Berkeley, CA (United States). Department of Earth and Planetary Science; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division

Idealized simulations of tropical moist convection have revealed that clouds can spontaneously clump together in a process called self-aggregation. This results in a state where a moist cloudy region with intense deep convection is surrounded by extremely dry subsiding air devoid of deep convection. Because of the idealized settings of the simulations where it was discovered, the relevance of self-aggregation to the real world is still debated. Here in this study, we show that self-aggregation feedbacks play a leadingorder role in the spontaneous genesis of tropical cyclones in cloudresolving simulations. Those feedbacks accelerate the cyclogenesis process by a factor of 2, and the feedbacks contributing to the cyclone formation show qualitative and quantitative agreement with the self-aggregation process. Once the cyclone is formed, wind-induced surface heat exchange (WISHE) effects dominate, although we find that self-aggregation feedbacks have a small but nonnegligible contribution to the maintenance of the mature cyclone. In conclusion, our results suggest that self-aggregation, and the framework developed for its study, can help shed more light into the physical processes leading to cyclogenesis and cyclone intensification. In particular, our results point out the importance of the longwave radiative cooling outside the cyclone.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1479393
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, Issue 12; ISSN 0027-8424
• Publisher: National Academy of Sciences, Washington, DC (United States)Copyright Statement
• Country of Publication: United States
• Language: English