Active Typhoon Control
Active typhoon control has emerged as a new research topic due to the observed increase in frequency of extreme heat waves and heavy precipitation events. Regional climate models with high spatial resolution have been developed to simulate typhoons and tropical cyclones, relating the energy and damage potential of cyclones to sea surface temperatures, which are predicted to increase by an average 2°C by the end of the 21st century. Several techniques have been suggested in recent years to mitigate future catastrophic impacts of typhoons and tropical cyclones on cities and civilians. These different techniques aim at decreasing sea surface temperatures, increasing tropospheric temperatures or disrupting the 3D structure of cyclones by supressing warm rain.
Typhoon dissipation mechanisms
Several mechanisms can inhibit further strengthening of tropical cyclones or cause their dissipation:
- Cool sea surface temperatures
Tropical cyclones are fuelled by warm moist air evaporating from the sea surface, hence lower sea surface temperature values cause cyclone weakening.
- Vertical wind shear
Tropical cyclones are vertically stacked structures that strengthen via their symmetrical three-dimensional circulation. Adding a vertical wind pattern aloft such as wind speeds increasing with height will cause a disruption in the cyclone's symmetry and will impede the release of latent heat in the structure.
As tropical cyclones make landfall they are deprived of their energy source - latent heat from warm ocean waters - and will quickly weaken. To a lesser extent, the surface roughness of the land increases friction, reduces the circulation pattern hence weakens the storm.
- Warm tropospheric temperatures
Tropical cyclones feed on latent heat released during condensation. Moist warm air parcels rising in a cyclone will adiabatically expand and cool, releasing latent heat and allowing that air parcel to stay warmer relative to the environment so that it continues its ascension in the unstable atmosphere. Theoretically, a rising air parcel would tend to be impeded by warm tropospheric temperatures, as it would be colder and denser than its surroundings, preventing further intensification of the storm.