Tropical cyclone sensitivities to CO2 doubling: roles of atmospheric resolution, synoptic variability and background climate changes

Gabriel A. Vecchi, Thomas L. Delworth, Hiroyuki Murakami, Seth D. Underwood, Andrew T. Wittenberg, Fanrong Zeng, Wei Zhang, Jane W. Baldwin, Kieran T. Bhatia, William Cooke, Jie He, Sarah B. Kapnick, Thomas R. Knutson, Gabriele Villarini, Karin van der Wiel, Whit Anderson, V. Balaji, Jan–Huey –H Chen, Keith W. Dixon, Rich GudgelLucas M. Harris, Liwei Jia, Nathaniel C. Johnson, Shian Jiann Lin, Maofeng Liu, Ching Ho Justin Ng, Anthony Rosati, James A. Smith, Xiaosong Yang

Research output: Contribution to journalArticle

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Abstract

Responses of tropical cyclones (TCs) to CO2 doubling are explored using coupled global climate models (GCMs) with increasingly refined atmospheric/land horizontal grids (~ 200 km, ~ 50 km and ~ 25 km). The three models exhibit similar changes in background climate fields thought to regulate TC activity, such as relative sea surface temperature (SST), potential intensity, and wind shear. However, global TC frequency decreases substantially in the 50 km model, while the 25 km model shows no significant change. The ~ 25 km model also has a substantial and spatially-ubiquitous increase of Category 3–4–5 hurricanes. Idealized perturbation experiments are performed to understand the TC response. Each model’s transient fully-coupled 2 × CO2 TC activity response is largely recovered by “time-slice” experiments using time-invariant SST perturbations added to each model’s own SST climatology. The TC response to SST forcing depends on each model’s background climatological SST biases: removing these biases leads to a global TC intensity increase in the ~ 50 km model, and a global TC frequency increase in the ~ 25 km model, in response to CO2-induced warming patterns and CO2 doubling. Isolated CO2 doubling leads to a significant TC frequency decrease, while isolated uniform SST warming leads to a significant global TC frequency increase; the ~ 25 km model has a greater tendency for frequency increase. Global TC frequency responds to both (1) changes in TC “seeds”, which increase due to warming (more so in the ~ 25 km model) and decrease due to higher CO2 concentrations, and (2) less efficient development of these“seeds” into TCs, largely due to the nonlinear relation between temperature and saturation specific humidity.

Original languageEnglish (US)
Pages (from-to)5999-6033
Number of pages35
JournalClimate Dynamics
Volume53
Issue number9-10
DOIs
StatePublished - Nov 1 2019

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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    Vecchi, G. A., Delworth, T. L., Murakami, H., Underwood, S. D., Wittenberg, A. T., Zeng, F., Zhang, W., Baldwin, J. W., Bhatia, K. T., Cooke, W., He, J., Kapnick, S. B., Knutson, T. R., Villarini, G., van der Wiel, K., Anderson, W., Balaji, V., Chen, JH. H., Dixon, K. W., ... Yang, X. (2019). Tropical cyclone sensitivities to CO2 doubling: roles of atmospheric resolution, synoptic variability and background climate changes. Climate Dynamics, 53(9-10), 5999-6033. https://doi.org/10.1007/s00382-019-04913-y