EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The moisture budget of tropical cyclones: large scale environmental constraints and sensitivity to model horizontal resolution

Benoit Vanniere1, Malcolm Roberts2, Pier Luigi Vidale1, Kevin Hodges1, and Marie-Estelle Demory3
Benoit Vanniere et al.
  • 1University of Reading, NCAS, Department of Meteorology University of Reading Whiteknights campus Earley Gate, Reading, United Kingdom of Great Britain and Northern Ireland (
  • 2Met Office Hadley Center, Exeter, UK
  • 3ETH, Zurich, Switzerland

Previous studies have shown that, the number, intensity and structure of simulated tropical cyclones (TC) in climate models get closer to the observations as the horizontal resolution is increased. However, the sensitivity of tropical cyclone precipitation and moisture budget to changes in resolution has received less attention. In this study, we use the five-model ensemble from project PRIMAVERA/HighResMIP to investigate the systematic changes associated with the water budget of tropical cyclones in a range of horizontal resolutions from 1º to 0.25º. Our results show that despite a large change in the distribution of TC intensity with resolution, the distribution of precipitation per TC does not change significantly. This result is explained by the large scale balance which characterises the moisture budget of TCs, i.e. radii of ~15º a scale that low and high resolution models represent equally well. The wind profile is found to converge between low and high resolutions for radii > 5º, resulting in a moisture flux convergence into the TC with similar magnitude at low and high resolutions. In contrast to precipitation per TC, the larger TC intensity at higher resolution is explained by the larger surface latent heat flux near the center of the storm, which leads to an increase in equivalent potential temperature and warmer core anomalies, despite representing a negligible contribution to the moisture budget. We discuss the complication arising from the choice of the tracking algorithm when assessing the impact of model resolution and the implications of such a constraint on the TC moisture budget in the context of climate change.

How to cite: Vanniere, B., Roberts, M., Vidale, P. L., Hodges, K., and Demory, M.-E.: The moisture budget of tropical cyclones: large scale environmental constraints and sensitivity to model horizontal resolution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19270,, 2020


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