The Role of Tropical Cyclones in the Global Energy Budget Revisited — Australian Meteorological and Oceanographic Society

The Role of Tropical Cyclones in the Global Energy Budget Revisited (#55)

Greg Holland 1 , Andreas Prein 1
  1. C3WE, NCAR, Boulder, Colorado, USA

The total atmospheric radiation budget of the atmosphere leads to a net cooling of tropical regions by 1-2oC per day, cooling that is balanced locally by mass subsidence and compression heating. In phase one of this study we demonstrated that moist vertical motion in tropical cyclones is sufficient to balance around 40% of this cooling. But this leaves a question on how the connection can be made between transient cyclone occurrences and the largely-clear areas where the bulk of the cooling occurs.

Here we utilise a comprehensive trajectory analysis of reanalysis data to demonstrate that this connection occurs via mass transport. Air flowing out of tropical cyclones in the upper levels spreads throughout the tropical clear regions. Because of the long time frames involved in such mass transport, the subsidence and warming to balance the energy budget may occur weeks to months after the cyclone has disappeared.

Thus, upper-level mass transport from tropical cyclones contributes substantially to the net radiation budget over substantial spatial and temporal scales. This finding concurs with those of Jakob et al (2018), who found that general radiative-convective equilibrium is only satisfied over spatial scales greater than several thousand kilometers. The resulting relationship between cyclone and general convective contributions also will be discussed.

 

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