Rapid intensification of tropical cyclones: Vortex waves seeded by aurorally-generated atmospheric gravity waves?
- 1Natural Resources Canada, Ottawa, Canada (lidia.nikitina@canada.ca)
- 2Physics Department, University of New Brunswick, Fredericton, NB, Canada
- 3Haystack Observatory, Massachusetts Institute of Technology, Westford, MA, USA
Convective bursts have been linked to intensification of tropical cyclones [1]. We consider a possibility of convective bursts being triggered by aurorally-generated atmospheric gravity waves (AGWs) that may play a role in the intensification process of tropical cyclones [2]. A two-dimensional barotropic approximation is used to obtain asymptotic solutions representing propagation of vortex waves [3] launched in tropical cyclones by quasi-periodic convective bursts. The absorption of vortex waves by the mean flow and formation of the secondary eyewall lead to a process of an eyewall replacement cycle that is known to cause changes in tropical cyclone intensity [4]. Rapid intensification of hurricanes and typhoons from 1995-2018 is examined in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere (MIA) system. In support of recently published results [2] it is shown that rapid intensification of TCs tend to follow arrival of high-speed solar wind when the MIA coupling is strongest. The coupling generates internal gravity waves in the atmosphere that propagate from the high-latitude lower thermosphere both upward and downward. In the lower atmosphere, they can be ducted [5] and reach tropical troposphere. Despite their significantly reduced amplitude, but subject to amplification upon over-reflection in the upper troposphere, these AGWs can trigger/release moist instabilities leading to convection and latent heat release. A possibility of initiation of convective bursts by aurorally generated AGWs is investigated. Cases of rapid intensification of recent tropical cyclones provide further evidence to support the published results [2].
References
[1] Steranka et al., Mon. Weather Rev., 114, 1539-1546, 1986.
[2] Prikryl et al., J. Atmos. Sol.-Terr. Phys., 2019.
[3] Nikitina L.V., Campbell L.J., Stud. Appl. Math., 135, 377–446, 2015.
[4] Willoughby H.E., et al., J. Atmos. Sci., 39, 395–411, 1982.
[5] Mayr H.G., et al., J. Geophys. Res., 89, 10929–10959, 1984.
How to cite: Nikitina, L., Prikryl, P., and Zhang, S.-R.: Rapid intensification of tropical cyclones: Vortex waves seeded by aurorally-generated atmospheric gravity waves?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3137, https://doi.org/10.5194/egusphere-egu2020-3137, 2020
