Tropical Cyclone Structure
Tropical cyclones are observed to have outward propagating signals at cloud-top height that in phase with the diurnal cycle (the daily rising and setting of thesun). There is some evidence that these signals, visible in upper level clouds, reflect a diurnal cycle in tropical cyclone structure throughout the depth of the troposphere. We have investigated wavelike responses of the tropical cyclone to diurnal forcing in cloud-resolving numerical simulations. The structure of the tropical cyclone wind field supports the propagation of internal inertial gravity waves excited by diurnal and semi-diurnal (second harmonic) forcing only in certain areas (generally away from the TC center). The figure at the right (from O'Neill et al. (2017) shows cross sections of eddy temperature fields in three tropical cyclone simulations, which indicate semi-diurnal gravity wave propagation in the two simulations with diurnal forcing (right two). Variability in the structure of the TC wind field significantly affects the ability of diurnal waves to propagate away from the TC center, which is the subject of continued investigation.
We also investigate other aspects of tropical cyclone structure, including precipitation associated with TCs, and the spatial variability of moist static energy in and around TCs. The latter is relevant for TC development and the spatial co-variability of moist static energy with radiative and surface fluxes contribute to feedbacks that contribute to TC development. We investigate these structures in a hierarchy of model simulations, reanalysis datasets, satellite observations, and in situ observations from aircraft reconnaissance.
Papers on this topic
- Diurnal Waves
- O'Neill, M.E., D. Perez-Betancourt, and A.A.Wing (2017), Accessible environments for diurnal-period waves in simulated tropical cyclones, J. Atmos., Sci., 74, 2489-2505, doi:10.1175/JAS-D-16-0294.1.
- TCs in Global Models
- Moon, Y., D. Kim, A.A. Wing, S.J. Camargo, M. Zhao, R. Leung, M.J. Roberts, D.-H. Cha (2021): An evaluation of tropical cyclone rainfall structures in the HighResMIP simulations against satellite observations, J. Climate, in review.
- Jones, E., A.A. Wing and R. Parfitt (2021): A global perspective of tropical cyclone precipitation in reanalyses, J. Climate, 34, 8461–8480, doi:10.1175/JCLI-D-20-0892.1.
- Moon, Y., D. Kim, S. J. Camargo, A. A. Wing, A. H. Sobel, H. Murakami, K. A. Reed, E. Scoccimarro, G. A. Vecchi, M. F. Wehner, C. M. Zarzycki, and M. Zhao (2020), Azimuthally averaged wind and thermodynamic structures of tropical cyclones in global climate models and their sensitivity to horizontal resolution, J. Climate, 33, 1575–1595, doi:10.1175/JCLI-D-19-0172.1.